Holding .0002″ Over A Half Mile Coil

The performance of your clutch may be riding on the quality of our sprags.

A major supplier of clutch assemblies used by a number of U.S, Japanese and European automakers has been relying on PEP cold drawn “sprag clutches” for nearly four decades. These clutches are known for their high performance and reliability. PEP’s Profile Business Unit supplies the critical sprag coils used in making these clutches. Over all these years defect levels have been near zero.

There are two types of clutches used in automotive applications– roller and sprag. The sprag clutch is generally preferred for high performance (i.e. high torque applications) because of its positive locking characteristics and high reliability. The sprags, about 20 of them in a clutch, provide a bearing surface that allows the drive shaft to spin freely in one direction but lock in the opposite direction with minimal backlash.

The sprag has a very complex shape and ultra-smooth surface, which must be maintained throughout coils which weigh about 400 lbs. and are a half-mile long. Four separate quality checks are performed during the drawing process and the most critical dimensions are held to within .0002″. In addition, every coil is tested for functionality before shipment.

Over the years there have been many times when sprag clutch designs have been replaced or modified. On these occasions PEP works closely with our customer’s engineers to assure that the new sprag concepts can be manufactured cost-effectively without sacrificing any design intent. Once the program is underway, the product is delivered to the customer’s manufacturing locations on a just-in-time basis.

Automotive is not our only sprags application. Sprags are also used in helicopters, roller coasters, heavy-duty conveyors and a wide range of equipment where it is essential to have a reliable locking safety mechanism. Over the past four decades the Profiles Business Unit has been producing about 2100 miles of sprag coils a year. That would be more than enough to wrap around the world four times.