Sprag Clutch Material Wall Thickness Guide

GMN Bearing USA’s ABEC 7 high precision ball bearings are made for high speed and heavy load applications.

GMN angular contact bearings (spindle bearings) are expertly crafted for speed, precision, & accuracy.

GMN radial ball bearings are versatile, great in small spaces & when axial loads move in both directions.

We know that not every application requires super, high-precision bearings. We stock other industrial parts from quality brands.

Our one-way sprag clutches are great for applications with low to high torque capacity.

Includes built-in ball bearing support. Supports HEAVY loads & has a high torque capacity: 53 to 588 Nm. Bore (ID) sizes: 10 to 60 mm (0.393 to 2.362 in)

Includes built-in ball bearing support. Supports MEDIUM loads & low to medium torque capacity: 53 to 267 Nm. Bore (ID) sizes: 17 to 40 mm (0.669 to 1.57 in)

No built-in ball bearing support. Good for large orders & low to high torque needs: 1 to 2673 Nm. Bore (ID) sizes: 2 to 240 mm (0.078 to 9.448 in)

No built-in ball bearing support. Has no RPM limits & Supports high torque needs: 609 to 14,060 Nm. Bore (ID) sizes: 38.09 to 220 mm (1.499 to 8.66 in)

This heavy-duty clutch (aka a hold-back clutch) is good for high torque operations and ensures motion freezes in place. Bore (ID) sizes: 15 to 40 mm. (0.59 to 1.73 in)

Designed for HEAVY-DUTY applications that require tough durability.

Our non-contact labyrinth seals are the first line of protection for bearing systems.

The best protection for your bearing. Easy to install with a simple “drop-in” next to your bearing. No added space needed. CF seals offer 100% sealing efficiency against splashing liquids.

Protection against low contamination & splashing liquids.

Designed with grooves in the outer ring to offer more protection (than our L-type seal) against contamination and direct spray liquids. Liquid gets pushed out through outer grooves when in rotation.

Our GMN Gap Seals are plastic and a great choice for washdown applications, such as food conveyors and food manufacturing facilities

Material Requirements for Sprag Clutch Mating Parts

GMN Recommendation: Only steel should be used as the mating surfaces for the sprags

At the very basic level, the sprags ability to engage and stay connected against the mating surfaces is based on the sliding friction of the surfaces. The angle of engagement between the sprag and the mating surfaces is designed so that the tangent of the maximum engagement force is less than the force to overcome static friction of steel.

That means if steel is used and everything else is within the design requirements, the sprags will not slip. However, if other materials are used, even if they meet all the other requirements, the change in coefficient of static friction could cause the sprags to slip. For this reason, GMN recommends only steel mating surfaces.

To learn more about the importance of steel mating surfaces, contact GMN Bearing USA.

GMN Recommendation: A hardness of HRC 60 to 64 with an effective hardness depth of at least 1.3mm

In addition to the type of material for the mating surfaces, the hardness and hardness depth are also critical in proper engagement of the sprags. As the sprags engage, they elastically deform the mating surfaces until an equilibrium is reached between the surface pressure applied by the torque and the resistance from the mating surfaces.

If the surfaces are soft due to insufficient hardness or hardness depth, there will be less resistance to the sprags which will cause them to engage higher up on the engagement curve. That could result in a substantially decreased overall torque capacity and could cause premature failure.

GMN Recommendation: A surface finish, Rz, of less than 2.5μm

In overrunning operation, the surface finish of the mating components plays a major role in the life of the sprags. If the surface is too rough, the lubrication will not be enough to prevent degradation of the sprags as they slide over the surfaces.

Note: the system is unable to incorporate all the material requirements for the mating surfaces GMN offers sprag clutch products that incorporate hardened steel inner and outer rings.

Contact us

For optimal sprag clutch performance, GMN offers specific recommendations for mating part material as well as wall thickness.

Wall Thickness Requirements

GMN Recommendation: The sprags should engage against a solid shaft and the housing should have a ratio of the housing outer diameter to the housing inner diameter be 1.4 or greater

Similar issues to the insufficient hardness and hardness depth can occur if the wall thickness of the mating surfaces is too thin. As the sprags start to push into the surfaces, if the walls are too thin, they won’t be able to resist the elastic deformation as much, decreasing the torque capacity.

In some applications these recommendations may not possible, and that doesn’t mean that the sprags will fail. However, a decreased torque capacity should be expected depending on how far the actual application conditions deviate from GMN’s recommendations.

For more information on wall thickness and material requirements for sprag clutches, contact our team of engineers at GMN Bearing USA.

Check out our Sprag Clutch Guide resources below for more information.

Sprag Clutch Material Wall Thickness Guide

Material Requirements for Sprag Clutch Mating Parts

Contact us

Wall Thickness Requirements

Interested in GMN Sprag Clutches?