Conventional drives relyon a wedging action to lock-up, which means races must endure extremely high radial loads, or hoop stress, to transmit even a moderate amount of torque. In fact, less than 10% of the stress created in roll clutch drives actually generates useful torque. As a result, these drives must be made from expensive, high quality steel which has to be exactly heat treated to withstand the forces generated by the wedging action.

Conventional drives also require exact machining for precise alignment and load sharing of the rollers carrying the enormous radial loads. Additionally, the rollers in conventional drives are in constant contact with the raceway even during overrun. Such high rpm contact generates significant heat during even short overruns leading to clutch spring failures.

True to its heritage, FACET innovation once again redefines the best available in starter drive technology.

By redirecting the forces generated during torque transfer, PositStrut™ drives use compressive loads rather than radial hoop stress to transfer torque. This simple fact allowed FACET engineers to use new materials and manufacturing processes, reducing weight and improving dimensional stability. Lighter drives means less mass, and less drive mass means that the solenoid must overcome less inertia during crank and ignition.

PosiStrut™ drives utlize more than 90% of the stress created to generate useful torque. While PosiStrut™ drives are backward compatible to replace any drive design already in the field, its greater stress-to-torque efficiency permit smaller drive designs to be designed-in to future noseless starter motors.

Unlike conventional drives, the torque transfer components in the PosiStrut™ design dynamically disengage during overrun. This means they generate almost no friction and thus little heat, allowing them longer life and long high-rpm overrun events without failure. In fact, PosiStrut™ designs are available to operate in submerged environments which usually destroy roll clutch drives.

The PosiStrut™ design allowed FACET engineers to extend to all drives applications the same positive engagement feature originally conceived in our Positork™ heavy duty drives. Interestingly, PosiStrut™ drives are more easily rebuildable than conventional drives. Among other features, PosiStrut™ drives engage and carry 100% of the rated load 3X faster than conventional roll clutch drives. That means less time to build torsional wind-up of the starting components, which minimizes engagement impact and prolongs the life of the starter. FACET's PosiStrut™ drives are covered by U.S. and International Patents, with additional U.S. and International Patents Pending.