Product Guides
Ratchet Spanner Guide: Tooth Count, Flex Head & Reversible
A ratchet spanner is a fixed-size ring spanner with a ratchet mechanism built into the head. It drives a fastener in one direction and free-spins on the return stroke — meaning you never need to lift the tool off the nut between strokes. That sounds like a small improvement. In practice, especially in tight spaces where you can only swing the handle a few degrees at a time, it is a significant one. This guide covers how ratchet spanners work, the main types, what tooth count actually means and why it matters, when to choose flex head over fixed, the one limitation most buyers miss, and how to select the right set for your work. AIMS stocks Maxigear, Stahlwille, Trax, and Lang Tools ratchet spanners — the range and what to use each for is covered at the end. How a Ratchet Spanner Works Inside the ring end of a ratchet spanner is a toothed gear ring and a spring-loaded pawl. When you rotate the handle in the drive direction, the pawl engages the teeth and transmits torque to the fastener. Rotate the handle in the opposite direction and the pawl rides over the teeth — the ring free-spins without turning the fastener. A direction switch on the head (usually a small lever or button) reverses which way is drive and which is free-spin, allowing you to tighten or loosen without changing your grip. The practical result: you can work in a confined space with a short back-and-forth swing, progressively running down a bolt without ever removing the spanner from the fastener head. With a standard ring spanner, you lift, reposition, engage, and repeat. With a ratchet spanner, you just keep moving. The trade-off — and this is important — is that the pawl-and-tooth mechanism is load-limited. The ratchet mechanism has a maximum engagement force below that of a solid ring spanner of the same size. On a seized, corroded, or significantly over-torqued fastener, the ratchet will skip before the fastener breaks free. More on this under break-out limitations. Types of Ratchet Spanner Combination ratchet spanner — fixed head The standard form: a ratcheting ring end on one side and a conventional open end on the other. The ring end drives and ratchets; the open end is a fixed non-ratcheting jaw for flat sides or hex. This is the most widely stocked type and the correct starting point for any general workshop or maintenance kit. The fixed head sits lower profile than a flex head — better in spaces where height above the fastener is restricted. Combination ratchet spanner — flex head The ring end articulates up to 180° on a pivot. You set the angle before applying torque — the head locks in position under load and pivots freely when repositioning. This opens up access to fasteners in recessed locations, around obstructions, or at awkward angles where a straight handle cannot get a full swing. Flex head spanners are standard in automotive and machinery maintenance. Maxigear's flex head range in metric and imperial is what AIMS stocks for this application. Offset ratchet spanner The head is angled relative to the handle (typically around 15°), placing the ring end above or below the handle plane. The offset provides clearance to reach fasteners that are recessed below a surrounding surface — common in engine work, machinery frames, and structural steel where a flush or recessed bolt head cannot be reached with a straight-shanked spanner. Maxigear's offset reversible ratcheting wrench sets (12pc and 16pc) cover this type. Single-ended ratchet spanner A ratcheting ring end only — no open end at the other side. The handle is typically longer and heavier to accommodate more torque. Used for large-size fasteners where the open end would be too wide to be practical, or for specialist industrial work. Lang Tools' individual ratcheting wrenches (up to 36mm) represent this type in the AIMS range — the sizes alone indicate their purpose: heavy industrial and agricultural equipment where large hex fasteners are the norm. Ratcheting open-end spanner A variant where the open end (not the ring) incorporates a ratcheting action via internal gear mechanisms — sometimes labelled "gear spanner" by certain AU retailers. The open-end profile is lower and thinner than a ring end, making it accessible in spaces where a ring end physically cannot fit over a fastener. Less common in general workshop use; more relevant to automotive and plumbing work where open-end access is necessary and repetitive. The ratcheting open-end design is a specific product subtype, not a general trade term. Stubby ratchet spanner A short-body version — reduced handle length and compact head for use in extremely confined spaces where even a standard ratchet spanner cannot swing. The trade-off is reduced leverage. A stubby is a supplementary tool for specific access problems, not a replacement for a standard-length set. Tooth Count: The Most Important Number on the Box Tooth count is the single most important technical specification when selecting a ratchet spanner, and the one most buyers overlook. It determines the minimum arc — the smallest swing of the handle needed to advance the fastener by one tooth. The formula is straightforward: Minimum arc = 360° ÷ tooth count Tooth count Minimum arc per stroke Practical meaning 36T 10° Entry level. Usable in open access. Struggles in tight spaces where you cannot swing 10°. 45T 8° Budget trade. Better than 36T but still limiting in confined work. 72T 5° Industry standard. Gearwrench's benchmark spec — widely used in professional trade sets. Comfortable in most confined spaces. 90T 4° Premium. Used by Stahlwille Fastratch and high-end professional sets. Noticeably better in very restricted access. 120T 3° Fine-tooth. Maximum practical tooth count for standard designs. Useful in the tightest spaces. The practical difference between 36T and 72T is significant and immediately noticeable when working in an engine bay or behind a panel. The difference between 72T and 90T is smaller but still relevant in genuinely confined work. Whirlpool forum users consistently report that cheap entry-level sets with low tooth counts feel near-useless in tight spaces — the tool clicks but the fastener barely moves per stroke. A note on tooth size and strength: more teeth means smaller individual teeth, which theoretically reduces per-tooth strength. In practice, quality heat-treated Cr-V spanners at 72T and above are not meaningfully weakened — the issue is only relevant if you are over-torquing or breaking out seized fasteners, which you should not be doing with a ratchet spanner regardless of tooth count (see below). Fixed Head vs Flex Head: Which to Choose For most trade and maintenance applications, the answer is both — but if you are starting with one set, here is how to decide: Fixed head Flex head Profile above fastener Lower — better when height above the bolt is restricted Slightly higher due to pivot mechanism Angular access Straight handle only Articulates up to 180° — reaches around obstructions Torque transmission More direct — no flex joint in load path Marginally reduced at extreme angles due to pivot geometry Best for Open access, flat surfaces, general workshop Recessed fasteners, automotive, machinery with obstructions Typical price premium — 20–40% over equivalent fixed head set If you are doing automotive work or maintaining machinery with recessed bolt heads, the flex head set will earn its premium quickly. For general trade and maintenance work in open access, fixed head is sufficient and more economical. The Break-Out Limitation: What Most Guides Don't Say A ratchet spanner is not a break-out tool. The pawl-and-tooth mechanism has a maximum engagement force significantly lower than a solid ring spanner of the same size. On a corroded, seized, or significantly overtorqued fastener, applying break-out force through a ratchet spanner will either skip the ratchet mechanism (clicking rapidly without turning the fastener) or — on cheap tools with fragile teeth — break individual pawl teeth. The correct technique when dealing with a tight or seized fastener: Use a solid ring spanner or a breaker bar with a socket to apply the initial break-out force Once the fastener has broken free and begun to turn, switch to the ratchet spanner for run-down This is how the tools are designed to be used together. A ratchet spanner excels at run-down — progressively turning a fastener once it is moving. A solid ring or breaker bar handles break-out. Using a ratchet for break-out is the most common cause of damaged ratchet mechanisms in workshop environments. When dealing with a seized or corroded fastener in the workshop, clamp the workpiece in a bench vice before applying break-out force. Clamping eliminates component rotation, frees both hands for the breaker bar, and lets you put full body weight into the initial break. Once the fastener moves, switch to the ratchet spanner for run-down. The same principle applies to final tightening: a ratchet spanner is not a torque tool. For any fastener with a specified torque — wheel nuts, cylinder head bolts, structural connections — use a torque wrench for final tightening. What Sizes Should a Set Cover? The most useful metric range for general industrial and maintenance work is 8mm to 19mm. This covers M5 through M12 fasteners — the range you encounter in the vast majority of machinery, fabrication, plant maintenance, and structural work. A 12-piece metric set typically covers 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19mm. For automotive work, extend the range upward — 21mm, 22mm, 24mm cover wheel and suspension fasteners on most passenger and light commercial vehicles. The Maxigear individual sizes available from AIMS extend to 24mm in both fixed and flex head configurations. For heavy equipment, agricultural, and large industrial applications, Lang Tools' single-ended ratcheting wrenches in 29mm and 36mm fill sizes that standard sets do not reach. Imperial sets (SAE — inches) are still relevant for older machinery, American-manufactured equipment, and some agricultural and mining plant. AIMS stocks Maxigear imperial reversible and flex head individual wrenches, as well as a 13-piece SAE reversible set. Ratchet Spanner vs Socket Ratchet Handle: When to Use Each The PAA question "Is a ratchet spanner better than a socket wrench?" comes up consistently in search results, and the answer is that they are complementary rather than competitive: Ratchet spanner Socket ratchet handle Fastener engagement Fixed size ring — integral to the tool Interchangeable sockets via square drive Head profile Thin — fits in spaces a socket + handle cannot Larger head — socket + drive height adds up Versatility One size per spanner — need a set One handle covers all socket sizes Speed Fast on known sizes — no socket swap needed Faster for high-volume repetitive work on one size Torque capacity Lower — use for run-down and moderate torque Higher — better for initial tightening on larger fasteners Best used for Confined spaces, mixed sizes, one-handed access Open access, high torque, single-size repetitive work A ratchet spanner reaches fasteners that a socket and ratchet handle physically cannot — the ring end profile is far thinner. A socket ratchet handle is faster and stronger for open-access high-torque work. Most professional mechanics and maintenance engineers carry both. Ratchet Spanners at AIMS Industrial AIMS stocks ratchet spanners from four professional brands across a range of types and sizes: Maxigear — the broadest range. Individual metric and imperial reversible ratcheting wrenches from 7mm through 24mm (metric) and 15/16" through 1" (imperial). Flex head ratcheting wrenches in metric (to 25mm) and imperial. Sets including a 12-piece metric flex head set and 13-piece SAE reversible set. The Maxigear 12-piece and 16-piece offset reversible metric sets are the go-to for machinery and automotive work requiring offset access. Trax — 12-piece metric ratchet spanner set (ARX-0012GM) for trade use. Also stocks the 3/4" drive professional reversible quick-release ratchet handle for heavy-duty socket work. Stahlwille Fastratch — German-manufactured stainless steel ratchet wrenches in individual sizes. Stahlwille is a prestige German hand tool brand used in aerospace and precision engineering. The stainless steel Fastratch is specified where corrosion resistance is required alongside precision ratchet action — food processing, marine, pharmaceutical, and chemical plant environments. Lang Tools — single-ended ratcheting wrenches in large sizes (29mm, 36mm) for heavy industrial, agricultural, and large plant applications. These are specialist tools for fastener sizes that standard sets do not cover. Browse the full ratchet spanner range at AIMS Industrial For broader spanner selection, see the complete Types of Spanners Guide and the Adjustable Spanner Guide. Frequently Asked Questions What is a ratchet spanner? A ratchet spanner is a fixed-size ring spanner with a ratchet mechanism — a toothed gear ring and spring-loaded pawl — built into the head. It drives a fastener in one direction and free-spins on the return stroke, so you never need to lift the tool off the nut between strokes. A direction switch reverses the drive direction for loosening. Ratchet spanners are widely used in automotive, machinery maintenance, and industrial trade work, particularly in confined spaces where lifting and repositioning a standard ring spanner on each stroke is slow or impossible. What do Australians call a ratchet spanner? In Australia the standard term is ratchet spanner — this is the term used in trade settings, forums, and by Australian retailers and suppliers. The US equivalent term is ratcheting wrench or ratcheting combination wrench, and this language appears in imported product documentation. Some Australian retailers also use the label gear spanner for a specific subtype — the ratcheting open-end spanner — but this is a product category name used by particular brands, not a general trade term. In everyday Australian usage, "ratchet spanner" is universal. Is a ratchet spanner better than a socket wrench? They are complementary tools, not substitutes. A ratchet spanner has a thin, fixed-size ring end that fits in spaces a socket and ratchet handle cannot reach — the combined height of a socket plus a ratchet handle is significantly larger than a ring end profile. A socket ratchet handle is more versatile (one handle, all socket sizes), handles higher torque, and is faster for single-size repetitive work in open access. Most trade workshops use both: ratchet spanners for confined access and one-handed work, socket ratchet handles for open-access and high-torque fastening. Who makes the best ratchet spanners in Australia? For professional trade use, Gearwrench (the 72T benchmark), Stahlwille (German precision, used in aerospace), and Bahco (Swedish-designed Cr-V) are consistently rated as premium brands in Australian trade forums and mechanic communities. For industrial supply and specialist sizes, Stahlwille Fastratch and Lang Tools are stocked by AIMS. At the value-professional level, Maxigear offers a comprehensive range of metric and imperial reversible and flex head ratcheting wrenches. Brand quality varies significantly — the key indicator is tooth count and pawl material, not price alone. What does tooth count mean on a ratchet spanner? Tooth count is the number of teeth on the internal gear ring. It determines the minimum arc — the smallest handle swing needed to advance the fastener by one tooth. Calculated as: minimum arc = 360° ÷ tooth count. A 36-tooth spanner needs a 10° swing per stroke; a 72-tooth spanner needs only 5°. In tight spaces where you can only swing the handle a few degrees, the difference is the gap between a tool that works and one that barely makes progress. 72T is the professional standard; 90T and above is premium. Avoid entry-level sets with 36T in any application involving confined access. What is the difference between a fixed head and a flex head ratchet spanner? A fixed head ratchet spanner has a rigid ring end in line with the handle — lower profile above the fastener, more direct torque transmission, better where height above the bolt is restricted. A flex head ratchet spanner has a ring end that articulates up to 180° on a pivot, allowing access to fasteners at angles and around obstructions that a straight handle cannot reach. Flex head spanners are standard for automotive and machinery maintenance with recessed fasteners. Fixed head is sufficient for open-access and general workshop work and is more economical. What is an offset ratchet spanner? An offset ratchet spanner has the head angled relative to the handle — typically around 15° — so the ring end sits above or below the handle plane. This provides clearance to reach fasteners recessed below a surrounding surface, such as a bolt head in a deep recess, beneath a bracket, or in a frame cavity. Offset ratchet spanners are used in automotive, structural, and machinery work where a flush or recessed fastener cannot be reached with a straight-shanked tool. Available as individual offset wrenches and as offset sets from Maxigear. What is a combination ratchet spanner? A combination ratchet spanner has a ratcheting ring end on one side and a conventional open-end jaw on the other. It is the most common type in general workshop and trade use — the ring end handles the majority of run-down and tightening work, while the open end is available for flat-sided or hex fittings where the ring cannot be positioned. Most ratchet spanner sets are combination configuration. The ring size and open-end size are the same nominal size on each spanner in the set. Can you use a ratchet spanner to break out a seized fastener? No — and this is one of the most common causes of ratchet mechanism damage. The pawl-and-tooth mechanism has a maximum engagement force significantly lower than a solid ring spanner. On a corroded, seized, or overtorqued fastener, the ratchet will skip before the fastener breaks free. The correct technique: use a solid ring spanner or a breaker bar with a socket to apply break-out force first, then switch to the ratchet spanner for run-down once the fastener is moving. Using a ratchet spanner for break-out is likely to damage the pawl teeth, particularly on lower-cost tools. Can a ratchet spanner be used for torque-critical work? No. A ratchet spanner is a run-down and moderate-tightening tool — it is not calibrated and cannot be used with a torque wrench. For any fastener with a manufacturer-specified torque (wheel nuts, cylinder head bolts, structural connections, flanged couplings), use a torque wrench for final tightening. The ratchet spanner is appropriate for running a fastener down to nearly-tight; the torque wrench finishes the job to the specified value. What sizes should a ratchet spanner set cover? For general industrial and maintenance work, an 8–19mm metric set covers the majority of M5–M12 fasteners encountered in machinery, plant maintenance, fabrication, and structural work. For automotive work, extend to 21mm and 24mm to cover wheel and suspension fasteners. For heavy equipment and agricultural machinery, individual large-size ratcheting wrenches in 24mm, 29mm, and 36mm cover fasteners that standard sets do not reach. An imperial (SAE) set is valuable alongside a metric set for older or American-made machinery. Combined metric and imperial coverage is the professional standard for any workshop servicing mixed equipment. What is a stubby ratchet spanner? A stubby ratchet spanner is a short-body version — reduced handle length and compact head — for use in extremely confined spaces where a standard ratchet spanner cannot swing. The shorter handle reduces the torque you can apply, so it is a supplementary access tool rather than a replacement for a full-length set. Stubby ratchet spanners are common in automotive work, particularly in engine bays where standard tools cannot fit. They are typically purchased as a supplementary set after a standard-length set is already in the kit. What material should a quality ratchet spanner be made from? Drop-forged chrome-vanadium (Cr-V) steel is the standard for professional-grade ratchet spanners — the same as combination and ring spanners. Cr-V provides the hardness and toughness needed at the pawl teeth and ring gear interface, which are the highest-stress points in the tool. Heat treatment is as important as material — a well-heat-treated Cr-V spanner outlasts a poorly treated one of the same specification. For corrosive environments (food processing, marine, chemical), Stahlwille's stainless steel Fastratch range offers Cr-V-equivalent performance with corrosion resistance. Look for Cr-V markings and a named brand with documented heat treatment standards. Browse the full AIMS Spanners & Wrenches range including ratchet spanners, combination spanners and open-end sizes. Pair this guide with our Spanner Size Chart for matching the spanner across-flats dimension to the bolt head. People Also Ask — Ratchet Spanners Q: What is a ratchet spanner and how does it differ from a standard spanner? A ratchet spanner incorporates a ratchet mechanism in the ring end that allows continuous tightening or loosening without removing the spanner from the fastener between strokes. Unlike a standard ring spanner that must be repositioned after each partial turn, a ratchet spanner speeds up fastening in confined spaces where a full rotation is not possible. Q: What is the swing arc on a ratchet spanner? The swing arc is the minimum angle through which the spanner must be moved for the ratchet to advance one tooth and re-engage. A smaller swing arc, typically 5 to 7 degrees on quality spanners, allows the tool to work in very confined spaces where only a tiny back-and-forth movement is possible. A larger swing arc requires more clearance to operate effectively. Q: Can ratchet spanners be used for final torquing? Standard ratchet spanners should not be used to apply precise final torque. Use a calibrated torque wrench for torque-critical fasteners. Ratchet spanners are designed for rapid run-down and preliminary tightening. Some heavy-duty ratchet spanners specify a maximum torque value and exceeding it can damage the ratchet mechanism. Q: What is a flex-head ratchet spanner used for? A flex-head ratchet spanner has a pivoting ring end that can be angled relative to the handle, typically up to 180 degrees. This allows the spanner to reach fasteners at awkward angles without requiring the handle to be in line with the fastener axis, making it particularly useful in engine bays, behind panels and in other confined industrial spaces.
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Adjustable Spanner Guide: Jaw Sizes, Brands & Quality
The adjustable spanner is one of the most-used tools on any worksite, workshop, or maintenance kit — and one of the most misused. Used correctly, it handles a huge range of fastener sizes with a single tool. Used incorrectly, it rounds corners, damages chrome fittings, and occasionally takes out a set of knuckles. This guide covers what adjustable spanners are, the terminology Australians use for them, how they work, the main types and variants, how to read and choose the right size, the correct technique, what to look for in quality, and when to reach for something else instead. Whether you are equipping a workshop, restocking a service van, or just trying to understand what you are looking at on the shelf, this is the reference. What Australians Call It: The Terminology The same tool goes by several names depending on where you are: Term Where it is used Shifter Dominant informal term in Australia and New Zealand — used on virtually every job site Shifting spanner Formal AU/NZ written variant — appears in specifications and tool catalogues Adjustable spanner Standard AU/UK written term Adjustable wrench US and Canadian term — used in imported product documentation Crescent wrench US generic term derived from the Crescent Tool Company brand — not widely used in Australia Monkey wrench Originally a different tool (F-shaped, jaws perpendicular to handle) — the term is sometimes used loosely but is not the same thing If you are ordering tools for an Australian worksite, "adjustable spanner" or "shifting spanner" are the correct written terms. In conversation, "shifter" is standard. Online search will find the same tools under "adjustable wrench" due to US-dominated product listings. How an Adjustable Spanner Works An adjustable spanner has two jaws: a fixed jaw that is machined as part of the tool head, and a moveable jaw that slides along a rack built into the jaw throat. A knurled worm gear (the thumb wheel on the side or base of the head) meshes with teeth on the moveable jaw. Rotating the worm gear opens or closes the jaw gap. The moveable jaw is held in position by the friction of the worm gear thread — it is not locked. Under load, the jaw can creep if the fit is not snug against the fastener. This is the fundamental difference from a fixed spanner: the fit is adjustable but it is never as positive as a correctly sized ring or open-end spanner. It is also why jaw quality and worm gear quality matter — in cheap tools, the worm wears quickly and the jaw develops slop. The thumb wheel is typically accessible from both sides of the spanner head, allowing adjustment with one hand while the other holds the fastener steady. Types of Adjustable Spanner Standard adjustable spanner The classic form: a relatively thin head with one fixed jaw and one moveable jaw, adjusted by a side-mounted or base-mounted worm wheel. The jaw throat depth is proportional to jaw opening — a 200mm spanner opens to around 25mm, a 300mm to around 34mm. This is the most widely stocked type and covers the majority of industrial, workshop, and maintenance tasks. Wide-jaw adjustable spanner A wider jaw opening relative to tool length — the Irega 92 is an example, designed to open further than a standard spanner of the same nominal length. Useful for plumbing and gas work where large flange nuts, large BSP fittings, or oversize hex forms are common. The wider jaw-to-handle ratio does reduce rigidity slightly compared to a standard-profile head. Reversible jaw adjustable spanner The Bahco RAW (Reversible Adjustable Wrench) pattern — the moveable jaw can be flipped 180° to either side of the handle. Conventional adjustable spanners have the moveable jaw on one side only, which means you are either pulling toward the fixed jaw or pushing toward the moveable jaw depending on your body position. A reversible jaw lets you pull toward the fixed jaw in either direction without repositioning yourself or the tool. Particularly useful in confined spaces where you cannot choose your stance relative to the fastener. Bahco's reversible jaw range is stocked at AIMS. Self-setting spanner (Joker pattern) The Wera 6004 Joker is the most well-known example. A spring-loaded lower jaw automatically seats against the fastener flat when the tool is placed on the nut or bolt head — no thumb wheel adjustment needed. The spanner self-sizes, engages, and can be pulled immediately. Faster for repetitive work. The self-setting mechanism also includes a secondary contact point that helps prevent rounding on worn fasteners. Premium price, but a genuine productivity tool for high-repetition use. Ratcheting adjustable spanner Combines the variable jaw of an adjustable spanner with a ratchet mechanism in the head, allowing continuous rotation in one direction without removing and repositioning the tool on the fastener. Best suited to bolt-down work with moderate torque requirements — not appropriate for very high torque where ratchet pawl engagement may be the limiting factor. Available as dedicated adjustable ratchet spanners (200mm is a common size) and as an attachment feature on some adjustable spanners. Pipe wrench (for comparison) A pipe wrench (Stillson wrench) looks superficially similar to a large adjustable spanner but is a different tool with a different purpose. The key differences: Jaws: A pipe wrench has serrated, toothed jaws designed to bite into round, smooth, or cylindrical surfaces — pipes, conduit, rods. An adjustable spanner has smooth, flat jaws designed for flat-faced fasteners (hex bolts, square nuts). The teeth on a pipe wrench will damage hex fasteners and chrome fittings. Jaw angle: Pipe wrench jaws are angled so the bite tightens as torque is applied in one direction and releases in the other — directional grip only. Adjustable spanner jaws are parallel and grip in both directions. Application: Use a pipe wrench for pipes, conduit, large threaded rods, and round fittings. Use an adjustable spanner for hex, square, or flat-sided fasteners. Do not substitute one for the other. Size Guide: What the Number Actually Means The size number stamped on an adjustable spanner is the overall tool length in millimetres, not the jaw opening capacity. A 200mm adjustable spanner is 200mm long from end to end. The jaw opening it can achieve is a secondary specification that varies between manufacturers — typically expressed as the maximum jaw opening in mm. This is one of the most common points of confusion when buying adjustable spanners. If you need to fit a fastener of a specific size, check the manufacturer's maximum jaw opening specification, not just the tool length. Nominal length Typical max jaw opening Common applications 100mm (4") ~14mm Electronics, instrumentation, small fittings, very confined spaces 150mm (6") ~19mm Light workshop, fasteners to M12, precision equipment 200mm (8") ~25mm General purpose — the most common site and workshop size. Covers the majority of M8–M18 fasteners. 250mm (10") ~30mm Medium-heavy work, plumbing fittings, automotive, M20–M24 fasteners 300mm (12") ~34mm Heavy industrial, large plumbing and gas fittings, large structural fasteners 375mm (15") ~43mm Industrial pipework, scaffold, large flange work 450mm (18") ~52mm Large industrial fittings, heavy gas and water mains work Jaw opening figures are typical. Check the manufacturer's specification for the exact maximum jaw opening on the model you are selecting. For most tradies and maintenance workers, a 200mm is the primary carry size — it handles the widest range of everyday fasteners. A 300mm alongside it covers heavy plumbing, gas, and industrial work. If space or weight is a constraint, a single 250mm covers both roles adequately. How to Use an Adjustable Spanner Correctly More nuts and bolt heads are rounded by incorrectly used adjustable spanners than by any other single cause. The correct technique is straightforward but not intuitive until you know it. 1. Set the jaw snug before applying force Adjust the worm wheel until the jaws grip the flat faces of the nut or bolt head firmly, with zero play or wobble. The jaw should contact the fastener on at least two opposing flat faces. Any slop in the fit means the jaw will rotate slightly under load before the flat contacts, and the corners of the fastener take the impact — that is how corners round off. 2. Orient the fixed jaw in the direction of pull The fixed jaw is integral to the tool head and is structurally stronger than the moveable jaw. Always position the spanner so the fixed jaw is on the side that takes the load — meaning you pull toward the fixed jaw, not toward the moveable jaw. In practice: when tightening (clockwise), the fixed jaw should be on the upper/leading face of the fastener as you pull the handle toward you. When loosening (anticlockwise), flip the spanner 180° so the fixed jaw is again on the side you are pulling toward. This takes one second and significantly reduces the chance of the jaw spreading under load. 3. Pull, don't push Always pull the spanner handle toward you rather than pushing it away. Pulling gives more control over the force applied, and if the spanner slips, your hand moves away from the work rather than into it. Pushing means a slip sends your knuckles directly into the workpiece — the classic "knuckle-buster" injury. If the geometry of the job forces a push, brace your palm against the back of the handle rather than wrapping your fingers around it. 4. No extensions Do not extend the handle with a pipe or bar to get more leverage. An adjustable spanner is not designed for the torque that a cheater bar produces, and the worm gear joint will open under the load, rounding the fastener and potentially causing the tool to fail. If you need more torque, use a ring spanner or a socket and torque wrench. 5. Recheck the jaw fit after each reposition Every time you lift and reposition the spanner, check the jaw is still snug. Worm gears, especially on mid-range tools, can lose their set slightly during a stroke. A quick half-turn check before each pull takes less than two seconds and prevents rounding. When working on a component that tends to rotate or shift under spanner load, clamp it securely in a bench vice before applying the spanner. A vice eliminates workpiece movement, frees both hands, and lets you direct full force to the fastener rather than fighting to hold the work still. Material and Quality: What to Look For Adjustable spanner quality varies enormously. The price gap between a cheap no-name and a professional-grade Bahco or Irega is real and reflects in tool life, jaw accuracy, and worm gear durability. Chrome-vanadium (Cr-V) steel Chrome-vanadium is the industry-standard material for professional-grade adjustable spanners. It is harder, tougher, and more wear-resistant than plain carbon steel, which matters most at the worm gear interface and the jaw faces. All Bahco and Irega tools are Cr-V drop-forged — the drop-forging process produces a denser, stronger grain structure than casting. Chrome finish vs black finish Chrome-plated spanners resist surface corrosion and are easy to clean. Black-finish (phosphated or oxide) spanners have a non-reflective surface, preferred in some professional and automotive contexts. Both finishes are compatible with Cr-V steel and perform equivalently in standard industrial use. Black finish tools are not inherently higher grade — it is a surface treatment, not a material quality indicator. Worm gear quality — the key differentiator The worm gear (the small wheel and the rack it meshes with) is the first component to fail on a cheap adjustable spanner, and the reason cheap spanners develop slop early. On quality tools, the worm is precision-cut, the fit is tight, and there is minimal backlash. You can assess this by opening the jaw to mid-range and checking for play — push and pull the moveable jaw with your thumb. A quality tool should have essentially zero free movement. If there is perceptible play, the worm gear is already worn or poorly manufactured. AS/NZS 1700 compliance AS/NZS 1700 (Hand Tools: Spanners and Wrenches) sets dimensional and material requirements for spanners sold in Australia and New Zealand. Tools compliant with this standard will have size markings, material grade, and jaw dimensional tolerances that meet the specification. Look for the standard reference in product documentation for professional-grade tools. When Not to Use an Adjustable Spanner The adjustable spanner is a versatile tool, but there are situations where it is the wrong choice: Precision torque work — an adjustable spanner cannot be used with a torque wrench. For any fastener with a specified torque, use a socket set. High-torque or high-repetition work — ring spanners and socket sets provide a six-point engagement around the full hex, distributing load more effectively and dramatically reducing rounding risk under high torque. Use them for critical structural or high-load fasteners. Confined spaces where full jaw seating is not possible — if the geometry means only one or two jaw faces can contact the fastener properly, do not use an adjustable spanner. Use the correct fixed-size tool. Soft material fasteners — brass fittings, aluminium fixtures, and plastic fasteners are particularly vulnerable to rounding under even a slightly misadjusted adjustable jaw. A correctly sized fixed spanner is safer. Round, cylindrical or pipe work — use a pipe wrench. An adjustable spanner's smooth jaws cannot grip round objects reliably. The adjustable spanner earns its place in every kit for its flexibility across a range of fastener sizes. Use it for that. For precision, high-torque, or specialty applications, reach for the specific tool. Adjustable Spanners at AIMS Industrial AIMS stocks professional-grade adjustable spanners from Bahco and Irega — two of the most respected hand tool brands for industrial and trade use. Bahco adjustable spanners — including the reversible jaw (RAW) range, chrome and black finish, from compact 100mm to heavy-duty 300mm. Bahco Cr-V tools are Swedish-designed and meet AS/NZS 1700. Irega adjustable spanners — Spanish-manufactured professional tools with standard and wide-jaw profiles in 250mm and 300mm. The Irega 92 wide-jaw is particularly suited to plumbing and gas work with its extended jaw opening. Ratcheting adjustable spanners — available for repetitive fastening work where ratchet action reduces cycle time. Browse the full adjustable spanner range at AIMS Industrial For broader spanner selection, see our complete Types of Spanners Guide. Frequently Asked Questions What do Australians call an adjustable spanner? In Australia and New Zealand, the most common informal term is shifter. The formal written term is shifting spanner or adjustable spanner. In the US and Canada the same tool is called an adjustable wrench or informally a crescent wrench (after the Crescent Tool Company brand). All these terms refer to the same basic tool: a spanner with one fixed jaw and one moveable jaw adjusted by a worm gear. "Monkey wrench" is sometimes used loosely in Australia but technically refers to a different F-shaped wrench where the jaws are perpendicular to the handle. What is an adjustable spanner used for? An adjustable spanner is used to tighten or loosen hex (hexagonal) nuts and bolts, square-head fasteners, and flat-sided fittings across a wide range of sizes — using one tool instead of a full set of fixed spanners. Common applications include plumbing fittings, electrical conduit, machinery maintenance, automotive work, and general construction and site work. It is not suitable for round or cylindrical objects (use a pipe wrench), precision torque applications (use a socket and torque wrench), or high-repetition high-torque work (use ring spanners or sockets). What is a Joker or self-setting spanner? A self-setting spanner (the Wera 6004 Joker is the best-known example) has a spring-loaded lower jaw that automatically seats against the fastener flat when the tool is placed on the nut or bolt head — no thumb wheel adjustment required. The spanner senses the fastener size and grips immediately. A secondary contact point in the jaw profile also helps prevent rounding on worn or damaged fasteners. Self-setting spanners are faster for high-repetition work and eliminate the step of manually adjusting the worm gear. They carry a premium price but are a genuine productivity tool for professional trade use. What is the best brand of adjustable spanner for professional use? Bahco and Irega are consistently rated among the best professional-grade adjustable spanners for industrial and trade use in Australia. Bahco (Swedish-designed, drop-forged Cr-V) is well established across maintenance, mechanical, and construction trades. Irega (Spanish-manufactured, professional grade) has a strong following in plumbing and gas fitting for its wide-jaw models. Both meet or exceed AS/NZS 1700 requirements. For premium self-setting tools, Wera's Joker range is the benchmark. All three are available through professional trade suppliers. What does the size number on an adjustable spanner mean? The size number stamped on an adjustable spanner is the overall tool length in millimetres, not the jaw opening capacity. A 200mm adjustable spanner is 200mm long from end to end. The maximum jaw opening it can achieve is a separate specification — typically around 25mm for a 200mm tool, 34mm for a 300mm tool, but this varies by manufacturer. If you are selecting a spanner to fit a specific fastener size, always check the manufacturer's listed maximum jaw opening, not just the nominal tool length. Which size adjustable spanner should I buy? For general-purpose site and workshop use, a 200mm is the most practical single size — it covers the majority of everyday fasteners from M8 to approximately M18 and is comfortable to carry and use in most working positions. Add a 300mm if you are doing plumbing, gas, or heavy industrial work requiring a larger jaw opening. If you can only carry one and the work spans a wide range of fastener sizes, a 250mm is a reasonable compromise. For tight-space work or electronics, a 150mm or 100mm compact is useful as a secondary tool. How do I use an adjustable spanner correctly without rounding a nut? Four steps: (1) Adjust the worm wheel until the jaws grip the fastener flat faces with zero play or wobble. (2) Position the spanner so the fixed jaw (the jaw that is part of the tool head, not the adjustable jaw) is on the side you will be pulling toward — the fixed jaw is stronger and takes the load. (3) Pull the handle toward you rather than pushing it away — pulling gives more control and reduces injury risk if the spanner slips. (4) Recheck the jaw fit after each reposition. Most rounding happens from a jaw that has developed slop or was not fully set against the fastener before force was applied. Should I push or pull an adjustable spanner? Pull toward yourself whenever possible. Pulling gives more control over the force applied, and if the spanner slips, your hand and knuckles move away from the work rather than into it. Pushing means any slip sends your knuckles directly into the workpiece — the classic "knuckle-buster" injury. If the work geometry forces you to push, brace your palm against the back of the handle rather than wrapping your fingers around it so your knuckles are protected if it slips. What is a reversible jaw on an adjustable spanner? A reversible jaw adjustable spanner (Bahco RAW pattern) allows the moveable jaw to be flipped to either side of the handle. On a conventional adjustable spanner, the moveable jaw is fixed on one side only. This means that depending on your body position relative to the fastener, you may end up pulling toward the moveable jaw — the weaker side. A reversible jaw eliminates this: no matter which way you are positioned, you can orient the tool so the fixed jaw always takes the load. Particularly useful in confined spaces where you cannot choose your stance. It is a genuine functional improvement, not just a feature. What is the difference between an adjustable spanner and a pipe wrench? An adjustable spanner has smooth, flat, parallel jaws designed to grip the flat faces of hex nuts, square bolts, and flat-sided fittings without marking them. A pipe wrench has serrated, toothed jaws that bite into round, cylindrical surfaces — pipes, conduit, and threaded rods — and are designed to grip tighter as torque is applied in one direction. Do not use a pipe wrench on hex fasteners: the teeth will damage the flats and chrome fittings. Do not use an adjustable spanner on round pipe: the smooth jaws cannot grip reliably and the tool will slip under load. What material should a quality adjustable spanner be made from? Drop-forged chrome-vanadium (Cr-V) steel is the industry standard for professional-grade adjustable spanners. Chrome-vanadium is harder and more wear-resistant than plain carbon steel, which matters most at the worm gear teeth and jaw faces — the areas that take the most wear. Drop forging produces a denser grain structure than casting, improving overall strength and impact resistance. Look for "Cr-V" or "chrome vanadium" in the product specification. The chrome plating (or black oxide finish) on the surface is a corrosion treatment and does not indicate the underlying steel grade. When should I use a ring or open-end spanner instead of an adjustable? Use a ring spanner or socket when: (1) you know the exact fastener size — a correctly fitted ring spanner applies force across all six flats and will not round corners; (2) torque is high or critical — ring spanners handle significantly higher torque than adjustable spanners without jaw spread risk; (3) a specified torque is required — adjustable spanners cannot be used with a torque wrench; (4) repetitive use — sockets and ring spanners are faster and more reliable for high-volume fastening. The adjustable spanner is for situations where you need to span multiple sizes with one tool, the fastener size is unknown, or carrying a full fixed-size set is impractical. Browse the full AIMS Spanners & Wrenches range for fixed-jaw combination spanners, ring spanners and specialist sizes. For metric and imperial spanner cross-references (M3-M30, AF sizes), see our Spanner Size Chart. People Also Ask — Adjustable Spanners Q: What is an adjustable spanner and when should it be used? An adjustable spanner has a movable lower jaw that can be adjusted to fit different fastener sizes. It is best used when the correct fixed spanner is unavailable, when working on non-standard fastener sizes, or in occasional-use situations. For repetitive professional work, a correctly-sized open-end or ring spanner is preferable to reduce the risk of rounding fastener heads. Q: Which way should the load be applied to an adjustable spanner? The load should always be applied toward the fixed upper jaw, not the movable jaw. Position the spanner so that pulling the handle places the turning force against the fixed jaw. Applying force toward the movable jaw can cause the jaw to open under load and round off the fastener. Q: How do I choose the right size adjustable spanner? Choose the smallest spanner whose jaw capacity accommodates the fastener size. A larger spanner than necessary is harder to control and more likely to slip. Adjust the jaw so it grips the fastener snugly with zero play before applying torque, and re-check the fit if the jaw loosens during use. Q: What are the common grades and materials for adjustable spanners? Professional-grade adjustable spanners are typically made from drop-forged chrome vanadium steel, which provides high strength and resistance to deformation under load. Chrome moly steel is also used in premium tools. For corrosive environments, stainless steel or non-sparking aluminium-bronze versions are available.
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Types of Spanners Guide: Types, Sizes & Selection
Spanner vs Wrench — What's the Difference? In Australian and UK English, "spanner" is the standard trade term for a fixed-size hand tool used to turn hex nuts and bolts — ring spanners, open-end spanners, combination spanners. "Wrench" is the US term for the same tools. Both words describe the same family of fasteners-turning tools; only the regional usage differs. Are spanners and wrenches interchangeable terms? Mostly yes — but with one consistent exception. Adjustable-jaw tools (Crescent-style adjustables, pipe wrenches, monkey wrenches) are called "wrenches" worldwide, including in Australia. Fixed-size hex-fitting tools are called "spanners" in Australia and the UK, and "wrenches" in the US. So in an Australian workshop you'll hear "pass me the 19 mm spanner" and "pass me the pipe wrench" in the same conversation. Spanners are the backbone of any trade toolkit — and choosing the wrong type is one of the most reliable ways to round a nut, strip a fitting, or find yourself stuck halfway through a job. This guide covers every type of spanner used in Australian trades and workshops: what each one does, when to use it, and where it fails. Whether you are a maintenance fitter, tradie, mechanic, or setting up a home workshop, this is the complete reference. Spanner or Wrench? The Australian Terminology In Australia, the correct trade term is spanner. In the United States, the same tool is called a wrench. Both terms are understood in Australia, but spanner is the standard in trade settings. Some specific tools retain "wrench" in their name regardless — torque wrench, pipe wrench, and impact wrench are all normal Australian terminology. One important AU-specific term: shifter refers specifically to an adjustable spanner, not to all spanners. If someone on site asks for "the shifter," they mean the adjustable. "A spanner" means the correctly-sized fixed spanner for the job. ℹ️ Note: This guide uses Australian convention throughout — spanner for the tool category, with the US term noted where relevant. The term wrench is retained only in specific tool names (torque wrench, pipe wrench, impact wrench) where that is standard Australian trade usage. The Main Types of Spanners Explained There are more than a dozen distinct spanner types, each designed for specific access conditions, fastener types, and torque requirements. Understanding the limitations of each type is as important as knowing its intended use. 1. Open-End Spanner The open-end spanner has two fixed U-shaped jaws at opposite ends, set at 15° to the handle axis. Most are double-ended with two different sizes (e.g. 10/11mm, 12/13mm, 16/17mm). The 15° offset allows the tool to be flipped end-for-end after each partial turn — effectively doubling the usable arc in confined spaces. Best for: Quick access where a ring or socket cannot fit above the fastener; holding a nut while tightening from the opposite side; pipe fittings where a ring cannot thread over the tube end. Limitation: The open jaw contacts only two faces of the fastener. Under high torque, this concentrates stress on two points and causes slipping and rounding. Open-end spanners are run-down and access tools — not break-out tools. ⚠️ Warning: Never use an open-end spanner for heavy break-out torque on corroded or overtightened fasteners. Two-point contact will round the corners before the fastener moves. Use a ring spanner or socket for break-out — switch to open-end only once the fastener is already moving. 2. Ring Spanner (Box End Spanner) A ring spanner has a fully enclosed circular head engaging all six faces of a hex fastener (twelve engagement points in a bi-hexagonal design). This full engagement makes it the strongest fixed spanner type and the correct choice for any high-torque or corroded fastener situation. 6-point vs 12-point (bi-hexagonal): Most Australian ring spanners are bi-hex (12-point). A 12-point ring repositions every 15° of swing; a 6-point requires 30°. In tight spaces with a limited swing arc, 12-point ring spanners complete a full rotation in half the repositioning lifts. Six-point rings distribute force more evenly per flat and are preferred for extreme torque or already-damaged fasteners. Best for: High-torque applications, corroded or seized fasteners, repetitive tightening cycles where fastener rounding must be avoided. 📌 Key Fact: A 12-point bi-hexagonal ring spanner can be repositioned every 15° — half the arc required by a 6-point ring. In a confined space where the handle can only travel 20° before hitting an obstruction, this difference can determine whether the job is achievable at all. 3. Combination Spanner The combination spanner is the most common spanner in Australian trade toolkits. It has an open-end jaw on one end and a ring on the other — both the same size. A 17mm combination spanner gives you a 17mm open end and a 17mm ring on one tool. The open end runs the fastener down quickly; the ring end provides final high-torque drive or initial break-out grip. One tool, two functions, same size. A metric set from 6mm to 24mm covers the majority of fasteners in automotive, construction, and industrial maintenance work. What to look for: Chrome-vanadium steel (Cr-V) construction, clearly stamped sizes, 12-point bi-hex ring profile, chrome-plate finish for corrosion resistance. 4. Adjustable Spanner (Shifter) The shifter has one fixed jaw and one moveable jaw adjusted via a knurled worm gear. Common Australian sizes are 150mm, 200mm, 250mm, and 300mm — these refer to overall tool length, not jaw capacity. Overall Length Max Jaw Opening Common Use Range 150mm (6") ~22mm M6–M12 equivalent 200mm (8") ~28mm M6–M16 equivalent 250mm (10") ~34mm M10–M20 equivalent 300mm (12") ~42mm M16–M27, larger plumbing Critical technique: Always position the shifter so the pulling force acts on the fixed (lower) jaw. When force acts toward the moveable jaw, it spreads under load and slips off the fastener. Close the jaw snugly to zero play before applying torque, and re-snug every few turns during sustained use. ⚠️ Warning: Always pull toward the fixed jaw. Applying torque toward the moveable jaw causes it to spread under load, slip off the fastener, and round the corners — often suddenly and forcefully. Most shifters have a directional arrow stamped on the body. Follow it. Best for: Non-standard fastener sizes, large plumbing fittings, site work where carrying a full fixed spanner set is impractical. Not appropriate for critical or high-torque fasteners. For a complete guide, see our Adjustable Spanner & Shifter Guide — types, sizes, jaw opening table, and correct use technique. 5. Socket Wrench and Ratchet Handle A socket system separates the driving mechanism from the fastener engagement. Sockets clip onto a square-drive ratchet handle via a spring-loaded detent. Drive size determines both torque capacity and ratchet head bulk. Drive Size Fastener Range Approx. Max Torque Primary Application 1/4" (6.35mm) M4–M8 ~30–40 Nm Electronics, interior trim, small precision work 3/8" (9.5mm) M6–M16 ~80–120 Nm General automotive and workshop maintenance — most versatile 1/2" (12.7mm) M10–M24 ~200–600 Nm Wheel nuts, suspension, heavy industrial M12–M24 3/4" (19.05mm) M20–M36 ~800–1,500 Nm Heavy plant, trucks, large flanged pipework 1" (25.4mm) M30+ ~2,000 Nm+ Mining, crane assembly, heavy industrial structures Six-point sockets are preferred for high-torque and damaged fasteners — better load distribution per flat. Twelve-point allows more entry angles and suits tight spaces at the expense of some contact area per flat. Use deep sockets for nuts on long studs or bolts in recessed holes. A breaker bar — not the torque wrench — is the correct handle for break-out. For a complete size reference, see our Spanner & Socket Size Chart. 6. Ratchet Spanner A ratchet spanner looks like a standard combination spanner but incorporates a ratchet mechanism in the ring end. The ring drives in one direction and free-spins on the return stroke — the tool never needs to be lifted and repositioned. Most have a reversing switch for direction change. Best for: Confined spaces where a socket ratchet handle is too bulky but repeated short-stroke tightening is needed — engine bays, control panels, panel-mount assemblies. Fine-tooth ratchets (72-tooth and above) are preferred for very tight spaces where only a few degrees of swing are available. Limitation: The ratchet mechanism reduces peak break-out torque compared to a solid ring. Use a conventional ring for break-out on seized fasteners, then switch to the ratchet spanner for run-down and tightening. For a complete guide, see our Ratchet Spanner Guide — types, tooth count, flex head vs fixed head, and break-out tips. 7. Torque Wrench A torque wrench is a precision measuring instrument that applies a specified, quantified torque to a fastener. It is not a general-purpose tool — it exists to ensure critical fasteners are tightened to the manufacturer's specification, preventing both loosening and overtightening damage. Types in common Australian use: Click-type (micrometer): Set the desired torque; the wrench clicks and releases when reached. Most common in trade. Available in 1/4", 3/8", and 1/2" drive. Typical accuracy ±4% in the upper 80% of range. Beam-type: A needle deflects against a scale as torque is applied. Simple, accurate, durable — no calibration loss. Requires visual confirmation during use. Digital/electronic: Strain gauge with digital readout and programmable alerts. High accuracy (±1–2%). Used in production and calibration-critical environments. Torque-angle: Applies initial torque then rotates a specified additional angle. Required for torque-to-yield (TTY) stretch bolts — modern cylinder head and con-rod bolts. ⚠️ Warning: Never use a click-type torque wrench as a breaker bar. Applying break-out force damages the internal spring mechanism and invalidates calibration. Keep a dedicated breaker bar for break-out. Also return the torque setting to minimum after use to prevent spring fatigue. For full torque wrench type comparison, drive selection, and calibration intervals, see our guides: Torque Wrench Selection Guide and Torque Wrench Calibration Guide. 8. Flare Nut Spanner (Line Spanner) A flare nut spanner is a ring spanner with a slot cut in one side. The slot allows the tool to slide sideways over a pipe and seat around the fitting nut — providing near-full ring engagement on the nut without needing to thread the tool over the end of the tube. Why it exists: Brake, fuel, hydraulic, and air conditioning lines have fitting nuts at the end of a rigid tube. A full ring cannot thread over the tube. An open-end spanner fits but provides only two-point contact — enough to round the soft fitting nuts these lines use. The flare nut spanner provides ring-level grip with open-end access. Common AU applications: Brake line unions (M10×1.0, M12×1.0 in metric AU vehicles), fuel line fittings, A/C refrigerant line connections, hydraulic instrumentation tubing. A socket-drive crow foot version allows torque wrench use on these fittings. 💡 Pro Tip: Never use an open-end spanner on brake or fuel line fittings if a flare nut spanner is available. The fitting nuts are made from soft steel or copper-nickel alloy and round extremely easily. A rounded brake line fitting requires cutting the line and fitting a new end — not a repair that belongs on the side of a road. 9. Pipe Wrench (Stillson) A pipe wrench — called a Stillson in Australia — has a spring-loaded jaw with serrated hardened teeth designed to grip round pipe. The jaw tightens its bite as torque is applied in the working direction. Pipe wrenches grip by biting into and slightly deforming the workpiece surface — they will mark any surface they contact. Suitable materials only: Black steel pipe, galvanised steel pipe. Not suitable for chrome or decorative fittings, copper, aluminium, brass fixtures, or precision-machined surfaces. The teeth will scar these surfaces permanently. Wrench Length Pipe Capacity (OD) Common Application 200mm (8") Up to ~20mm OD Small bore plumbing, hydraulic steel tube 300mm (12") Up to ~40mm OD DN25–DN32 steel pipe — compressed air and commercial plumbing 450mm (18") Up to ~65mm OD DN50 and larger industrial pipework 600mm (24") Up to ~90mm OD Large bore steel mains 10. Allen Key (Hex Key) An Allen key — also called a hex key or hex wrench — is an L-shaped or T-shaped tool with a hexagonal cross-section, used to drive socket-head cap screws (SHCS), button heads, and grub screws. Common forms: L-shape: Short arm for torque, long arm for reach. Most common form for trade use. T-handle: Fast for run-down. Not appropriate for final torque — overtightening strips the internal hex recess. Ball-end: Allows engagement up to ~25° off-axis. Use for run-down only — full flat-face engagement required for final torque. Hex bit sockets: Hex key inserts for standard drive ratchets or impact tools. Most efficient for production and maintenance work. Metric vs imperial in Australia: Metric hex keys (1.5–12mm) are the primary standard. The 4mm, 5mm, and 6mm sizes are most commonly encountered. Imperial hex keys (3/32"–3/8") are needed for American-specification equipment and some imported power tools. 11. Impact Wrench (Rattle Gun) In Australian trade vernacular, an impact wrench is universally called a rattle gun. It delivers high torque through rapid rotary hammer impacts (typically 1,000–3,200 impacts per minute) rather than continuous rotation. Each impact delivers a high-energy rotational jolt — the accumulative effect produces torques far beyond continuous motor output, with minimal reaction force felt by the operator. Pneumatic vs battery-powered: Pneumatic tools are lighter for a given torque output and lower cost, but require a compressor and fixed air supply — best for workshops. Modern 18V/20V brushless battery tools match quality pneumatic output and go anywhere — best for site and field work. Best for: Wheel nuts, structural bolting (M16+), high-volume fastener removal, and breaking seized fasteners where a breaker bar creates excessive reaction force. ⚠️ Warning: Chrome sockets must never be used with impact tools. Standard chrome-finish sockets are not rated for the sudden high-energy hammer loads of an impact wrench. Chrome sockets can shatter at impact loads, sending fragments at high velocity. Always use impact-rated (black phosphate finish) sockets with rattle guns. This is a safety requirement, not a preference. 12. Scaffold Spanner (Podger) A scaffold spanner — called a podger or podger wrench — combines a fixed spanner head (typically 21mm for AU Kwikstage and Ringlock coupler nuts) with a tapered alignment spike (podger) on the opposite end. The spike aligns bolt holes in scaffolding components before the bolt is inserted; the spanner end tightens the coupler nut. One tool handles both alignment and fastening — critical when working at height where additional tools are dropped-object hazards. 13. Strap Wrench A strap wrench uses a flexible loop of rubber, nylon webbing, or chain attached to a rigid handle. The loop grips through friction across the surface of the workpiece — no jaw contact, no edge loading. Best for: Oil filter removal and installation (no canister piercing); chrome-plated plumbing fittings that must not be scratched; round pipe nipples and smooth cylindrical surfaces with no machined flats; PVC or thin-wall plastic components where jaw pressure would crack the material. Limitation: Friction grip fails on wet or oily surfaces. Rubber or chain-type strap wrenches give better grip on oily filters than nylon webbing. Spanner Types Comparison Table Type Contact Points Torque Capacity Best Application Key Limitation Open-end 2 flats Light–medium Quick access, pipe fittings, confined spaces Rounds fasteners under high torque Ring (box end) 6 or 12 points High High torque, corroded fasteners Cannot pass over pipe; needs overhead clearance Combination Both Medium–high General trade and maintenance Compromises of each end type apply Adjustable (shifter) 2–4 flats Medium Non-standard sizes, plumbing, site work Jaw flex; slips if direction is reversed Socket + ratchet 6 or 12 points Very high Production work, recessed fasteners, studs Requires overhead clearance for socket depth Ratchet spanner 12 points Medium Confined repetitive fastening Reduced break-out torque vs solid ring Torque wrench Square drive Precision measurement Critical fasteners to specification Calibration instrument — not a general tool Flare nut (line) 4–5 points Medium–high Brake, fuel, hydraulic line fittings Slotted ring is weaker than solid ring Pipe wrench (Stillson) Serrated bite Very high Steel pipe and round stock Marks all surfaces; chrome and soft metals unsuitable Allen key (hex key) Full hex face Low–medium Socket head cap screws, grub screws Strips internal hex socket on overtightening Impact wrench (rattle gun) Square drive + impact Extreme (powered) High-volume and high-torque fastening Requires impact sockets; no precise torque control Scaffold/podger 6 points + alignment spike Medium–high Scaffolding and structural steel erection Specialised — not a general workshop tool Strap wrench Friction (surface) Low–medium Round surfaces, chrome fittings, oil filters Slips on wet or oily surfaces Metric Spanner Sizes: What Fits What In Australia, the overwhelming majority of fasteners are metric. The correct spanner for any hex fastener is determined by its AF (Across Flats) measurement — the distance between two parallel opposite faces of the hex head. This is the number stamped on every spanner. The approximate rule for standard metric hex fasteners is AF ≈ bolt diameter × 1.7. Bolt Size Standard AF Spanner Required Common Application M4 7mm 7mm Electronics, instrument mounting M5 8mm 8mm Light assemblies M6 10mm 10mm Most common general fastener — guards, automotive trim, brackets M8 13mm 13mm Engine covers, motor mounting, medium structural M10 17mm 17mm Heavy equipment bolting, automotive chassis, machinery frames M12 19mm 19mm Structural steelwork, flanged pipe connections M14 22mm 22mm Heavy plant, agricultural equipment, trailer hitches M16 24mm 24mm Structural bolting Grade 8.8, crane components M20 30mm 30mm Heavy structural bolting, large machinery mounting M24 36mm 36mm Very heavy structural and industrial applications M30 46mm 46mm Mining equipment, bridge and heavy civil structures 📌 Key Fact: The AF dimensions for metric hex fasteners are fixed by ISO 4014 (bolts) and ISO 4032 (nuts). For Grade 8.8 structural fasteners per AS/NZS 1110, the AF dimensions match the ISO standard — M10 = 17mm, M12 = 19mm, M16 = 24mm, M20 = 30mm. These are consistent across all compliant manufacturers. For a printable metric, imperial, and BSP spanner reference, see our Spanner Size Chart — Metric, Imperial & BSP. Metric vs Imperial Spanners in Australia Australia completed its metric conversion progressively through the 1970s and 1980s. Metric is now the dominant standard across automotive, construction, manufacturing, and engineering. Imperial fasteners have not disappeared entirely — they appear in specific sectors and equipment types. Where metric is the exclusive standard: All Japanese, Korean, European, and post-1980 Australian vehicles; all modern industrial machinery to ISO/DIN/AS standards; all Australian construction hardware (AS 1110, AS 1112). Where imperial is still encountered: American agricultural equipment: Many US tractor and implement brands — John Deere, Case IH, Agco — maintain SAE imperial fasteners on chassis and drivetrain components through to recent models. Any AU farm workshop servicing US-brand machinery needs a complete imperial set. Pre-metric vehicles: Classic and vintage Australian vehicles built before the mid-1970s (pre-metric Holden, Ford, Chrysler AU) use imperial AF sizes throughout. Imported American industrial machinery: Compressors, pumps, conveyors from US manufacturers commonly use SAE fasteners throughout regardless of import date. ℹ️ Note: Metric and imperial spanners are not interchangeable. Common near-mismatches include 19mm vs 3/4" (19.05mm) and 22mm vs 7/8" (22.23mm). On a clean fastener the difference may feel minor — on a corroded fastener under torque, even 0.2mm of slop will begin rounding the corners. When in doubt, measure the AF with a calliper before selecting the tool. How to Read a Spanner Size Every spanner is marked with its size. Understanding what the number means depends on the tool type: Open-end, ring, combination spanners: The stamped number (e.g. 17) is the AF in millimetres — the jaw width matching the across-flats measurement of the hex fastener head. Adjustable spanner (shifter): The number is the overall tool length in millimetres (150, 200, 250, 300), not the jaw opening capacity. Sockets: The socket size is the AF of the fastener it fits. The drive size (stamped on the square drive hole) indicates which ratchet it attaches to. Allen keys (hex keys): The number is the across-flats width of the hexagonal key shank — must match the fastener recess exactly. Pipe wrenches: The size refers to maximum recommended pipe diameter capacity, not the tool length. 📌 Key Fact: AF stands for Across Flats — the perpendicular distance between two opposite parallel faces of a hex head fastener. It is the universal standard for specifying spanner, socket, and hex key sizes. For standard ISO metric hex bolts: M6 = 10mm AF, M8 = 13mm, M10 = 17mm, M12 = 19mm, M16 = 24mm, M20 = 30mm. These are fixed by international standard regardless of manufacturer or country of origin. How to Choose the Right Spanner The right spanner depends on more than whether it fits the fastener head. Work through these five checks before picking up any tool: 1. Confirm metric or imperial. Measure the AF with a calliper if uncertain. A 19mm spanner on a 3/4" bolt (19.05mm AF) appears to seat — under break-out torque it will round the corners. 2. Assess the torque required. Run-down and light snug: open-end, Allen key, ratchet spanner. Standard assembly: combination ring end or socket ratchet. High torque — structural or mechanical joints: ring spanner or 1/2" drive socket with breaker bar. Manufacturer-specified torque: torque wrench — look up the spec, set the wrench, do not guess. Extreme torque or seized fastener: impact wrench with impact sockets. 3. Assess access constraints. Open access: choose by torque requirement. Restricted swing arc: ratchet spanner or flex-head socket ratchet. Limited overhead clearance: low-profile socket or offset ring spanner. Fastener on a pipe end: flare nut spanner or open-end. Round surface with no flats: pipe wrench (steel) or strap wrench (soft/polished). 4. Assess fastener condition. New, clean: any correctly-sized tool at the right torque level. Corroded or overtightened: ring spanner or socket only — maximum contact area. Partially rounded: use a socket or ring first; if still slipping, a damaged-bolt extractor socket. Completely rounded: nut splitter, vice-grips, or controlled cutting as a last resort. 5. Confirm precision requirements. Standard assembly: firm hand-tight-plus using ring end or socket. Manufacturer torque specification: torque wrench — non-negotiable for critical joints. Common Spanner Mistakes to Avoid Rounding fasteners with an open-end under high torque. Two-point contact concentrates force and rounds corners. Use a ring or socket for break-out and final torque. Switch to open-end only for run-down once the fastener is moving freely. Using a shifter in the wrong direction. Force toward the moveable jaw causes it to spread and slip. Check the direction arrow before applying force. Using a close-but-wrong size. 14mm open-end on a 9/16" bolt (14.3mm AF) appears to seat. Under torque, the 0.3mm difference rounds the corners. Measure with a calliper when uncertain. Pushing instead of pulling. Where possible, pull a spanner toward the body. If the tool slips while pushing, knuckles impact the nearest sharp metal surface. Pulling provides more control and reduces injury risk. Cheater bars on standard spanners. Extending a spanner handle with a pipe to gain more leverage is dangerous — the tool is not rated for the torque achievable. If more torque is needed, use a tool rated for the load: longer handle, breaker bar, or impact wrench. Using a torque wrench as a breaker bar. Break-out force damages the internal spring mechanism and invalidates calibration permanently. Keep a dedicated breaker bar for break-out. The torque wrench enters the sequence only after the fastener is already moving. Chrome sockets on impact tools. This is a safety requirement, not a preference. Chrome sockets can shatter under impact loads. Use black impact sockets with rattle guns exclusively. Spanner Safety — Australian Standards In Australian workplaces, hand tool use falls under general duty obligations in the Work Health and Safety Act 2011 and corresponding state legislation. The relevant manufacturing and quality standard for manually-operated spanners is AS/NZS 1700 — Hand Tools: Spanners and Wrenches, which covers dimensional, material, and marking requirements for tools sold in Australia and New Zealand. Pre-use inspection: Check open-end jaw faces for rounding or spreading. Inspect ring internal profiles for wear (oval profile loses engagement). Look for cracks at the jaw root and ring-to-handle junction. Check adjustable spanner worm gear for grit or corrosion. Remove any damaged tool from service immediately. Storage and maintenance: Chrome-vanadium spanners resist corrosion well but benefit from a light oil wipe after wet or marine environment use. Store in roll pouches, shadow boards, or foam-lined drawers — loose storage causes nicks and burrs on jaw faces. In scaffolding and elevated work, tool tethering is required under WHS regulations. 💡 Pro Tip: In any workshop with high fastener volumes, a shadow board with a painted outline for each spanner size delivers faster tool selection, instant visibility of missing tools, and a controlled tool management system for workplace audits. The setup cost is low; the compound benefit over years of use is significant. The right spanner for every job. Shop combination, ring, open-end & torque spanners from Stahlwille & more AIMS Industrial stocks a comprehensive range of spanners, wrenches, and socket sets for trade, workshop, and industrial use — combination spanner sets, adjustable shifters, scaffold podgers, torque wrenches, flare nut sets, and impact socket sets. Browse spanners & wrenches Talk to a specialist Frequently Asked Questions What is the difference between a spanner and a wrench? In Australian and British usage, the tool is called a spanner. In American usage, the same tool is called a wrench. They refer to the same thing — the names differ by region. In Australia, spanner is the correct trade term. Some specific tools retain "wrench" in their name — torque wrench, pipe wrench, and impact wrench are all standard Australian terminology. In casual conversation "wrench" is understood, but in trade settings "spanner" is correct. What is the most versatile spanner for general trade work in Australia? The combination spanner is the standard workhorse for Australian trade work. It combines an open-end jaw for fast run-down with a ring end for high-torque tightening on the same tool at the same size. A quality metric combination spanner set from 6mm to 24mm covers the majority of fasteners encountered in automotive, construction, and industrial maintenance. This is the correct starting point for any trade toolkit. What does shifter mean in Australian trade terminology? Shifter is the Australian colloquial term for an adjustable spanner — one with a fixed jaw and a moveable jaw adjusted via a worm gear to fit different fastener sizes. It is not a generic term for all spanners. Common sizes are 150mm, 200mm, 250mm, and 300mm, where the number is the overall tool length, not the jaw opening capacity. How do I read the size marked on a spanner? For open-end, ring, and combination spanners, the stamped number such as 17 is the AF (Across Flats) measurement in millimetres — the jaw width corresponding to the flat-to-flat dimension of the hex fastener head. A 17mm spanner fits a 17mm AF fastener, which is a standard M10 bolt. For adjustable spanners the number is the overall tool length. For Allen keys the number is the across-flats width of the hex key shank itself. What is the difference between an open-end and a ring spanner? An open-end spanner grips two opposite flats of a hex fastener using a U-shaped jaw. It is fast to position but contacts only two faces, making it prone to slipping and rounding the fastener under high torque. A ring spanner has a fully enclosed circular head engaging all six faces simultaneously, providing maximum grip and torque capacity. The ring is the correct choice for high torque or corroded fasteners. The open-end is correct for run-down speed and access in spaces where a ring cannot fit. Combination spanners carry both. Can I use an adjustable spanner instead of a fixed spanner? Yes, but it should not be the preferred choice. A shifter is most useful when the correct fixed spanner is unavailable, for non-standard fastener sizes, or for large plumbing fittings. The moveable jaw introduces flex that increases the risk of slipping and rounding the fastener, particularly under high torque. Load must always be applied toward the fixed jaw — not the moveable jaw. Whenever the correct fixed spanner is available, use it. What spanner fits an M10 bolt? An M10 bolt has a standard AF of 17mm under ISO 4014. A 17mm spanner or socket is the correct tool. The approximate rule for standard metric fasteners is AF equals bolt diameter multiplied by 1.7, giving 17mm for M10. When uncertain, measure the AF directly with a vernier calliper — some fastener types and grades use non-standard AF dimensions. Why do most ring spanners have 12 points rather than 6? A 12-point (bi-hexagonal) ring can be repositioned every 15 degrees of swing, compared to 30 degrees for a 6-point ring. In confined spaces with a limited swing arc, this halves the repositioning lifts needed per full fastener rotation. Six-point rings distribute force over more of each fastener face and are preferred for very high torque or damaged fasteners. In practice, 12-point is the standard for general use and 6-point is specified for maximum-torque situations. What is a ratchet spanner and when is it the right tool? A ratchet spanner has a ratchet mechanism in the ring end that drives the fastener in one direction and free-spins on the return stroke, eliminating the need to reposition the tool between strokes. It is correct in confined spaces where a socket ratchet handle is too bulky but repeated short-stroke tightening is needed. It is not the right tool for initial break-out on a seized fastener — the mechanism reduces peak torque. Use a conventional ring for break-out, then switch to the ratchet spanner for run-down. How do I choose between 1/4 inch, 3/8 inch, and 1/2 inch drive socket sets? Drive size determines torque capacity and ratchet head size. A 1/4 inch drive suits M4 to M8 fasteners and light precision work. A 3/8 inch drive is the most versatile and the recommended starting point, covering M6 to M16 and handling 80 to 120 Nm comfortably. A 1/2 inch drive is needed for M12 to M24 fasteners, wheel nuts, and heavy industrial work, handling 200 to 600 Nm manually. Most workshops carry all three, with the 3/8 inch set doing the majority of everyday work. What is a flare nut spanner and when must I use one? A flare nut spanner is a ring spanner with a slot cut in one side, allowing it to slide sideways over a pipe and engage the fitting nut at the tube end. It provides near-full ring engagement on the nut — far superior to an open-end spanner. It must be used on brake, fuel, hydraulic, and air conditioning line fittings where a full ring cannot thread over the tube. These fitting nuts are made from soft materials and round extremely easily with an open-end spanner. A rounded brake line fitting requires cutting the line and fitting a new end. What type of spanner is correct for scaffolding work in Australia? A scaffold spanner, also called a podger spanner, is the correct tool. It combines a fixed spanner head — typically 21mm for the Kwikstage and Ringlock coupler nuts used in the dominant Australian scaffolding systems — with a tapered alignment spike (podger) on the opposite end. The podger aligns bolt holes before the bolt is inserted; the spanner end tightens the coupler nut. A standard 21mm combination spanner does not include the alignment spike and is not a substitute. For metric to imperial socket cross-references and 1/4", 3/8" and 1/2" drive sizes, see our Socket Size Chart. Cross-reference our Metric Bolt Size Guide when working with metric M-series fasteners. What spanner size do I need for a wheel nut? Most Australian passenger cars use 19mm or 21mm wheel nuts, while light commercial vehicles and 4WDs often use 22mm or 24mm. Check the wheel nut directly with the spanner before buying a set. A 1/2 inch drive socket and breaker bar is the correct tool for wheel nut work — a torque wrench is then used to finalise the nut to manufacturer specification. What's the difference between a socket and a spanner? A socket is a separate hex-shaped cup that drives onto a ratchet handle via a square-drive connection. A spanner is a one-piece tool with the hex grip and handle integrated. Sockets allow one handle to swap between dozens of fastener sizes and are faster for repetitive work, while spanners are faster to grab for a single fastener and work in tight spaces where a ratchet head won't fit. Are wrench and spanner sizes the same? Sizes themselves use the same Across Flats measurement, but the labelling differs. Australian and UK spanners are marked in millimetres for metric fasteners. American wrenches are typically marked in fractional inches for imperial fasteners. A 19mm metric spanner is close to but not the same as a 3/4 inch wrench — 19.05mm — and using one in place of the other will round a fastener under load. Need adjustable hand reamers? Browse the AIMS range at adjustable hand reamers. AIMS Industrial stocks open end wrenches — see the full range for trade and industrial use.
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