Finer Power torque Limiter, 4.8 - 21.4

This is a RTL series torque limiters protect a drive from overload. The limiter transmits torque through spring-loaded friction surfaces and slips on its shaft when the preset torque is reached, then carries on driving once the overload or jam is cleared. Unlike a shear pin, it does not have to be reset by hand.

10 models in 5 sizes, RTL50 to RTL178, with slip torque ranges from 0.3 to 111 kgf-m (about 2.9 to 1,089 N-m) and a bore range from 8 to 64mm. The slip torque is set by tightening or loosening the adjusting nut or bolts, and the friction disc, spring and bush are available as spares. The centre member that the limiter slips against, normally a sprocket, is not included.

Where this product is used

• Protecting chain and sprocket drives from shock loads and jams
• Overload protection on conveyors, mixers and feeders
• Protecting gearboxes and motors from overload
• Replacing a shear pin arrangement with a limiter that resets itself

Features

• Spring-loaded friction slip clutch, resets itself after an overload
• Slip torque preset by the adjusting nut or bolts
• 5 sizes, RTL50 to RTL178, two torque ranges per size
• Slip torque 0.3 to 111 kgf-m, bore 8 to 64mm
• Bush, friction disc and spring available as spares
• Centre member (sprocket, pulley or plate) not included

Key specifications

Sizes available

Choosing the right option

Work out the slip torque you need from the loading conditions or the design strength of the machine. Pick a size whose torque range and bore range cover the job.

The limiter slips against a centre member, which is your own sprocket, pulley or plate held between the friction facings. The centre member is not included with the limiter, so you supply it and machine it to suit.

The centre member should be machined flat, parallel and square with the bore on its rubbing surface (surface finish Ra 1.6 is recommended) and kept free of rust, scale and oil. If it is not, the slip torque will be erratic.

Set the torque after the limiter is fitted on the shaft. On RTL50 to RTL89, turn the adjusting nut tight by hand so the disc spring seats on the plate, then tighten it about 60 degrees with a wrench. On RTL127 and RTL178, seat the nut that holds the disc spring, tighten each adjusting bolt about 60 degrees, and if the limiter slips under normal load, tighten the bolts a little at a time and evenly until it stops slipping.