Circlip Pliers Guide: Internal vs External, Types & Correct Use

What Are Circlip Pliers?

Circlip pliers are a specialised hand tool designed for one purpose: installing and removing circlips without damaging them. A circlip — also known as a retaining ring, snap ring, or C-clip — is a small spring-steel ring that sits in a machined groove on a shaft or inside a bore. When seated correctly in its groove, it creates a removable shoulder that prevents axial movement of the component it retains. The circlip plier works by gripping the ring through two small holes at its ends and applying a controlled expand or compress force — just enough to clear the groove lip — so the ring can be positioned or removed without distortion.

Circlips appear throughout engineering and industrial applications: automotive gearboxes, CV joints, wheel bearings, hydraulic cylinders, electric motors, pumps, compressors, agricultural machinery, and general fabrication all use them. They are fast to install, require no threading, and create a reliable retention point that is also fully removable. The challenge is that using the wrong plier — wrong type, wrong size, or poor quality — turns a straightforward operation into a safety hazard. A circlip under spring tension that slips the plier tips becomes a fast-moving projectile in a fraction of a second.

In Australia, the correct term is circlip pliers. In North America the same tool is sold as snap ring pliers or retaining ring pliers. These names are interchangeable — the tools are identical. The only distinctions that matter are internal versus external, straight versus bent, and the correct size range for the application.

Circlip Types: What the Pliers Work With

Before selecting pliers, it helps to understand the range of circlip types they may be used with. Not all circlips are the same, and some require different plier configurations.

C-Clips (Standard Circlips)

The most common type. A C-shaped spring-steel ring with a hole at each end for plier engagement. Available as internal (fits inside a bore) or external (fits on a shaft). Standardised under DIN 471 (external shafts) and DIN 472 (internal bores) in metric sizes, and equivalent AS/NZS standards in Australia. This is what most workshops encounter in everyday automotive and engineering work.

E-Clips

An E-shaped ring that clips into a circumferential groove without requiring holes for plier engagement. E-clips are pushed on from the side rather than expanded or compressed axially. Most E-clip installation uses a flat-blade screwdriver or dedicated E-clip tool rather than conventional circlip pliers. If you are working with E-clips frequently, a purpose-built E-clip applicator is a better choice than adapting a standard circlip plier.

Bow-Type / Bowed Circlips

A standard C-clip that has been manufactured with a deliberate axial bow (curve out of plane). This bow acts as a spring, preloading the retained component against the groove face to eliminate end-float. Bowed circlips are common in bearing applications where axial play must be controlled. They are installed with standard circlip pliers — internal or external as appropriate — but require care not to flatten the bow during installation.

Spiral Retaining Rings

A multi-turn spiral ring that provides uniform radial load distribution. Common in high-load applications where a standard single-turn circlip would be overstressed. Spiral rings are typically installed with push or wind-on tools rather than conventional circlip pliers. They are less common in general workshop work but appear in heavy engineering and some gearbox applications.

Interlocking Rings

Two-piece rings designed to be installed and removed without spreading or compressing. Found in applications where the bore or shaft groove cannot accommodate the expansion of a standard ring during fitting. Relatively uncommon in general workshop applications.

The Four Types of Circlip Pliers — In Detail

All circlip pliers share the same basic mechanism: two handles with a pivot, a spring to hold the tips open or closed at rest, and two hardened tips that engage the holes in the circlip. The four configurations are defined by two independent variables: internal versus external action, and straight versus bent tip geometry.

1. Internal Straight-Tip Circlip Pliers

The tips point straight forward, parallel to the handle axis. When the handles are squeezed, the tips move apart (expand outward). Used for internal circlips that sit inside a bore or housing, where the ring must be compressed to be removed (squeezing the plier expands the tips, which expands the ring, allowing it to clear the bore wall and slide out of the groove).

When to use: Any internal circlip with clear, direct axial access — engine cylinder bores, motor housings, straight-access hydraulic cylinders, general bearing housings. This is the most commonly used configuration in general engineering work.

Typical size markings: 12–25mm (fine/small), 19–60mm (standard), 40–100mm (large bore). Always confirm the plier's stated range covers your application before use.

2. Internal Bent-Tip Circlip Pliers

The tips are angled — typically 45° or 90° — relative to the handle axis. This allows the plier to reach internal circlips that are recessed inside a deep bore, behind a flange or casting wall, or obstructed by surrounding components where a straight approach cannot engage both circlip holes simultaneously.

When to use: Automotive gearboxes and transfer cases where the circlip is deep inside the casing; differential work; deep cylinder bores with limited clearance above the circlip; any application where the housing geometry prevents a straight-entry plier from engaging the ring cleanly. In automotive workshop environments, bent-tip internal pliers are used as frequently as the straight version.

Common angles: 45° and 90° are standard; some manufacturers offer a range of angles on convertible pliers. If you frequently encounter a specific application, matching the tip angle to the geometry reduces tool slippage significantly.

3. External Straight-Tip Circlip Pliers

The tips point straight forward. When the handles are squeezed, the tips move together (compress inward). Used for external circlips on shafts and pins, where squeezing the ring allows it to clear the outer diameter of the shaft and be seated into or removed from the groove.

When to use: Shaft-mounted circlips with clear access — driveshaft ends, axle shafts, hydraulic cylinder rods, pin retention on excavator buckets and agricultural linkages, electric motor shafts. This is the standard tool for the majority of external circlip work.

Size ranges: External pliers are sized to the shaft (outer) diameter — a plier marked '8–32mm shaft' handles external circlips on shafts 8–32mm in diameter. Do not confuse shaft diameter ratings with bore diameter ratings.

4. External Bent-Tip Circlip Pliers

Angled tips (45° or 90°) for external circlips in confined or obstructed positions. Less frequently needed than internal bent-tip, but essential when the circlip is on a shaft adjacent to a housing wall, behind a flange, or in a position where a straight approach cannot simultaneously engage both holes.

When to use: Stub axle applications where the circlip sits close to a hub face; pivot pins on agricultural or construction equipment where the pin is partially obstructed; any external circlip location that cannot be accessed cleanly with a straight plier.

Internal vs External — Identifying Which You Need

The distinction is straightforward once you know where to look. The question is always: where does the circlip groove sit relative to the component?

Internal Circlip — Groove Inside a Bore

If the groove is machined into the inner wall of a bore or housing — so the circlip sits inside the cylinder and faces inward — you need internal circlip pliers. The ring is expanded to clear the bore diameter, slid to the groove position, then released to compress into the groove. To remove it, the ring is expanded again to clear the groove walls and withdrawn from the bore.

Common examples: bearing housings, gearbox bores, hydraulic cylinder barrels, motor end-bells, differential casings.

External Circlip — Groove Outside a Shaft

If the groove is machined into the outer surface of a shaft, pin, or rod — so the circlip wraps around the outside of the shaft — you need external circlip pliers. The ring is compressed to reduce its diameter below the groove's outer edge, positioned over the groove, then released to expand into the groove. To remove it, the ring is compressed again and slid off the shaft end.

Common examples: driveshaft ends, axle shafts, hydraulic cylinder rods, pivot pins, motor shafts, wheel stud retention.

Quick Test

• Circlip visible inside a hole or cylinder → internal → pliers that expand when squeezed
• Circlip wrapped around the outside of a shaft or rod → external → pliers that compress when squeezed

If you are unsure, look at the ring's orientation: an internal ring curves inward toward the centre of the bore; an external ring curves outward around the shaft. The holes for the plier tips are always at the open ends of the C.

Reading the Size Markings

Circlip pliers are stamped or labelled with a size range indicating the bore or shaft diameters they are designed to handle, expressed in millimetres. Understanding these markings prevents the most common sizing error: using a plier that is marginally too large or too small for the ring, which causes tip engagement problems and increases ejection risk.

What the Numbers Mean

• Internal pliers: The numbers refer to bore diameter — the internal diameter of the housing the circlip sits in. A plier marked 19–60mm handles internal circlips in bores from 19mm to 60mm diameter.
• External pliers: The numbers refer to shaft diameter — the outer diameter of the shaft the circlip sits on. A plier marked 8–32mm shaft handles external circlips on shafts 8–32mm in diameter.

Why Size Range Matters

The size range determines how far the plier tips are spaced at rest and how far they can travel. If your circlip is at the outer edge of the plier's range — say a 58mm bore circlip on a plier rated 19–60mm — the tips will be near their maximum extension. This reduces the mechanical advantage available and means any tip misalignment is amplified. For critical applications at the edge of a plier's rated range, consider moving up to the next size plier.

If your circlip is well within the rated range — say a 35mm bore on the same 19–60mm plier — engagement will be solid and controlled.

How to Measure When Uncertain

Use a vernier calliper to measure:

• For internal rings: measure the bore inner diameter
• For external rings: measure the shaft outer diameter

The circlip itself will be slightly smaller (internal) or slightly larger (external) than the bore or shaft to provide the correct installed tension — but the bore or shaft dimension is what determines the plier size selection.

Circlip Size Ranges: What Each Class Covers

Circlip pliers are broadly grouped into size classes. Most 4-piece sets fall into the standard range; industrial and mining applications frequently require large or heavy-duty configurations as well.

For a general-purpose automotive or engineering workshop, a quality 4-piece set rated across 12–100mm covers almost everything. Workshops specialising in precision equipment (small motors, instrumentation) will additionally want a mini set. Industrial and plant maintenance operations dealing with large machinery need to stock heavy-duty extended pliers in the 85mm+ class as well.

DIN Standards and Australian Equivalents

Circlips used in engineering applications are standardised dimensionally. Understanding the relevant standards helps when ordering replacement rings and selecting the correct plier range for precision applications.

In Australian industrial practice, DIN 471 and DIN 472 metric circlips are the standard. When replacing a ring, identify the shaft or bore diameter and the applicable DIN standard from the machine's service documentation. Circlip pliers sized to the DIN specification will engage the standardised hole positions correctly.

Correct Technique: How to Use Circlip Pliers

Circlip installation and removal is straightforward in principle. Consistent, controlled execution is what separates a clean result from a flying ring and a scored groove. The technique covers preparation, engagement, operation, and verification.

Step 1 — Preparation

• Identify the circlip type: internal or external.
• Identify the tip configuration needed: straight or bent, based on access.
• Confirm the plier's size range covers the bore or shaft diameter.
• Inspect the plier tips: they should be clean, straight, and free of burrs or rounding. Worn tips are a leading cause of ring ejection.
• Inspect the circlip: check for cracks, distortion, or damage to the retaining holes. A damaged ring should be replaced, not reused.
• Put on safety glasses.

Step 2 — Engaging the Plier Tips

This is the most critical step. Insert the plier tips fully into both holes in the circlip ends. The tips should sit squarely in the holes with no rocking or tilting. Partial tip engagement is the primary cause of circlip ejection — when only the tip of the tip is in the hole, a small amount of force at the wrong angle is enough to displace it.

If the tips will not fully engage the holes, recheck the plier size range. If the plier is the correct size and the tips still won't seat, the circlip holes may be damaged or the ring may be the wrong standard for the application.

Step 3 — Expanding or Compressing the Ring

• Apply pressure to the handles smoothly and evenly — not with a sudden jerk.
• Expand or compress only as far as needed to clear the groove. Over-travel fatigues the ring and can permanently deform it, reducing its retaining force in service. As a working rule: if the ring is fully clear of the groove, you have gone far enough.
• If the ring is stiff (common in large or older rings), apply gradual pressure and pause. Do not force it.
• Maintain firm, consistent grip. If your grip is tiring, stop, release, re-engage, and continue.

Step 4: Installation

1. With the ring expanded (internal) or compressed (external), position it over the groove.
2. Align the ring so it sits squarely — not at an angle — relative to the groove.
3. Slowly and evenly release handle pressure. The ring will spring back toward its natural diameter and seat into the groove.
4. Do not release suddenly — controlled release prevents the ring from bouncing out of the groove on seating.

Step 4: Removal

1. With tips fully engaged, expand (internal) or compress (external) just enough to lift the ring clear of the groove walls.
2. Slide the ring axially out of the groove position while maintaining the expanded/compressed state.
3. Move the ring to a safe location away from the bore or shaft, then slowly release handle pressure.

Step 5 — Verification

• After installation: visually and physically confirm the circlip is fully seated in the groove all the way around its circumference. A partially seated ring — even sitting proud in one location — is a failure waiting to happen under load.
• Run a finger around the ring perimeter to feel for any section that is not flush with the groove face.
• After removal: inspect the ring for distortion, cracking, or damage to the retaining holes before deciding whether to reuse it.

Containing the Ring During Work

When working in an open area or workshop with a concrete floor, take one of these precautions:

• Work over a rubber-lined tray to catch the ring if it ejects
• Wrap a clean rag loosely around the work area — it won't stop a determined circlip but significantly reduces travel distance
• Position the bore or shaft so that if the ring does eject, it travels into a wall or soft surface rather than across the workshop floor

Maintaining Your Circlip Pliers

Circlip pliers are a precision hand tool. The tips are the critical wear point — when they degrade, performance and safety both suffer. A few straightforward maintenance habits extend plier life significantly.

Tip Inspection

Before each use, inspect the tips under good light:

• Rounding: Tips should be cleanly tapered to a consistent diameter. Rounding at the very end reduces engagement depth in the circlip holes.
• Splaying: Tips should be parallel or converging correctly at rest. If they splay outward, the plier body or pivot is worn or damaged.
• Burrs: Any raised metal on the tip surface will score the circlip holes and reduce engagement. Stone or file burrs off carefully.
• Corrosion: Surface rust on tips increases friction during engagement. Light corrosion can be removed with a fine file and light oil; heavy corrosion means replacement.

Pivot and Spring

Check the pivot pin periodically for wear — a loose pivot allows the tips to shift under load. The return spring should hold the handles at the correct resting position; a weak or broken spring makes tip engagement harder to control. Both are replaceable on quality pliers; on budget tools, replace the plier if the spring or pivot fails.

Cleaning and Storage

After use, wipe the pliers down to remove metal filings, grease, and grit. A light coat of oil on the pivot and tips prevents corrosion. Store in a dedicated slot in a tool roll or drawer rather than loose in a general drawer — tips in contact with other tools will develop burrs over time.

When to Replace

Replace circlip pliers when tips are visibly rounded, splayed, or worn to the point where full engagement in standard circlip holes is unreliable. Running worn tips increases ejection risk significantly — the cost of a replacement set is trivial compared to the cost of an injury or a launched circlip damaging a precision bore.

Buying Guide: Selecting the Right Set for Your Workshop

The market covers everything from single-dollar budget pliers to professional-grade Knipex sets. The right choice depends on use frequency, application criticality, and the range of work your workshop handles.

Brand Guide for Australian Workshops

5 Common Mistakes with Circlip Pliers

1. Using Internal Pliers for an External Circlip (or Vice Versa)

The most common mistake — and the most likely to cause a ring to eject. Because internal and external pliers work in opposite directions, grabbing the wrong tool means you are applying force against the ring's intended movement. The ring will either refuse to move until the tips slip, or it will suddenly release with significant energy. Check the ring type every time, not just the first time you encounter an application.

2. Worn or Splayed Tips

Tips that have rounded, splayed, or chipped do not seat properly in circlip holes. Under load, they migrate out of the holes — sometimes slowly and controllably, sometimes suddenly. Inspect tips before use. If there is visible rounding, splaying, or if the tips no longer align cleanly when the plier is held up to a light, replace or sharpen the tool before continuing. This is particularly important with cheaper pliers that use softer tip steel.

3. Over-Expanding or Over-Compressing the Ring

Circlips are designed to be deformed within a specific elastic range. Opening an internal ring further than necessary to clear the groove, or compressing an external ring more than required, permanently fatigues the spring steel. A fatigued ring will not return to its designed diameter and will not exert the correct retention force in the groove. The rule is simple: expand or compress only until the ring clears the groove — no further.

4. Skipping Eye Protection

A circlip under spring tension that slips the plier tips travels fast and unpredictably. The most common ejection direction is straight toward the operator. Safety glasses take five seconds to put on and prevent a potentially serious eye injury. There is no legitimate reason to skip them for a "quick" job.

5. Partial Tip Engagement

Engaging only the very end of the tip — rather than seating it fully into the circlip hole — is a consistent cause of ring ejection during operation. The partial engagement means the tip is bearing against a small contact area under high unit load. Any slight vibration, angle change, or additional force will displace the tip. Always take the time to seat the tips fully before applying pressure to the handles.

Frequently Asked Questions

What are the two types of circlip pliers?

The two fundamental types are internal circlip pliers, which expand outward when squeezed to fit inside a bore and compress an internal ring, and external circlip pliers, which compress inward when squeezed to fit over a shaft and expand an external ring. Each type comes in straight-tip and bent-tip (angled) variants, giving four configurations in total. A complete 4-piece circlip plier set includes all four.

What is the difference between internal and external circlip pliers?

Internal circlip pliers have tips that open (expand) when you squeeze the handles — they are used for circlips that sit inside a bore or housing, where squeezing the ring allows it to be removed from or seated into an internal groove. External circlip pliers have tips that close (compress) when you squeeze — they are used for circlips on the outside of a shaft or pin, where compressing the ring allows it to clear the external groove. Using the wrong type applies force in the wrong direction and risks over-stressing or ejecting the ring.

When do I need bent-tip versus straight-tip circlip pliers?

Use straight-tip pliers when you have clear, direct access to the circlip. Use bent-tip (angled) pliers when the circlip is recessed deep in a housing, behind a flange, or in a confined space where a straight approach cannot reach both circlip holes cleanly. Bent tips are commonly needed in automotive applications such as gearboxes, transfer cases, and CV joints, and in hydraulic cylinder work where the circlip sits deep inside the barrel.

What do the numbers on circlip pliers mean?

The numbers stamped on circlip pliers indicate the size range they are designed to handle — expressed as a bore or shaft diameter in millimetres. A plier marked '19–60mm' is suited to circlips in bores from 19mm to 60mm diameter. Always match the plier range to your circlip; using an undersized plier that is forced to over-extend risks tip damage, tip breakage, and ring ejection. When the diameter is unknown, measure with a calliper before selecting.

Can I use circlip pliers for snap rings?

Yes — circlip pliers, snap ring pliers, and retaining ring pliers are different names for the same tool. 'Snap ring pliers' is the common North American term; 'circlip pliers' is standard in Australia and the UK. The tools are interchangeable across all these names. The only distinction that matters is internal versus external, and the correct size range for your application.

What is the use of circlip pliers?

Circlip pliers are used to install and remove circlips — the small spring-steel retaining rings that lock components onto shafts or inside bores. Applications include automotive gearboxes, suspension components, wheel bearings, hydraulic cylinders, electric motors, pumps, compressors, and general engineering assemblies wherever a component needs to be axially retained without threading. The plier allows the ring to be expanded or compressed just enough to clear its groove, then released to snap into place.

What can I use if I don't have circlip pliers?

In a genuine emergency, two small flat-blade screwdrivers or picks inserted into the circlip holes can be used to expand or compress the ring. However, this approach gives almost no control over ring travel, greatly increases the risk of the circlip ejecting at speed, and can distort the ring so it no longer seats correctly or provides the designed retaining force. For anything beyond a one-off emergency on a non-critical application, proper circlip pliers are essential.

How do you get a circlip off without circlip pliers?

Insert two picks or thin flat-blade screwdrivers into the circlip holes and lever carefully and evenly. Work in a controlled direction, keep your face clear, and wear eye protection — a circlip under tension can eject suddenly and travel several metres. If the ring is inaccessible, under significant load, or in a safety-critical application, do not attempt removal without proper tooling. A launched circlip in an engine bay or gearbox can cause serious injury.

How do I stop the circlip from flying off during installation or removal?

Several techniques help: ensure the plier tips are fully seated in both circlip holes before applying any pressure; expand or compress only as far as needed to clear the groove — no further; use pliers with retaining pins or clip guards if available; wrap a rag loosely around the work area; and work over a tray when possible to catch the ring if it does eject. Never over-travel the ring beyond what is required to clear the groove lip.

What size circlip pliers do I need?

Match the plier size range to your circlip diameter. For small internal circlips under 20mm bore, use a fine-tip or mini plier set. For standard automotive and engineering work, a 4-piece set covering roughly 12–100mm handles the large majority of applications. For large industrial circlips above 100mm on heavy plant or hydraulic cylinders, heavy-duty extended pliers are required. Measure the bore or shaft diameter with a calliper when the size is uncertain.

Are Knipex circlip pliers worth the price premium?

For professional and trade use, yes. Knipex circlip pliers are manufactured to tight dimensional tolerances with hardened, precision-ground tips that maintain alignment and resist wear under repeated daily use. Cheaper pliers often have tips that splay, soften, or lose alignment quickly, leading to circlip damage and increased ejection risk. For occasional use, a mid-range set from Kincrome, Toledo, or SP Tools provides adequate performance. For a workshop that uses circlip pliers daily, the Knipex investment pays back in tip longevity and control.

Can I use the same pliers for both internal and external circlips?

No. Internal and external circlip pliers operate in opposite directions — internal pliers expand when squeezed; external pliers compress. You cannot substitute one for the other. A complete 4-piece set (internal straight, internal bent, external straight, external bent) is the correct starting point for a workshop that deals with the full range of assembly work. Some manufacturers offer convertible pliers with reversible mechanisms, but dedicated tools in each configuration are more reliable in practice.

Shop Circlip Pliers at AIMS Industrial

AIMS Industrial stocks a comprehensive range of circlip pliers — internal and external, straight and bent-tip, individual and sets — from leading brands including Knipex, Kincrome, Toledo, and SP Tools. Browse the circlip pliers range for current stock and pricing. For related hand tool selection guidance, see our articles on types of spanners and allen key sizes and types.