Ker-Train Research Inc.

  Variator Transmission

  Incrementally Variable Transmission

  Coplanar Gear Loops

  Bidirectional Clutch

  Sales Information



Ker-Train's patented bi-directional overrunning clutches offer significant improvements on the conventional roller ramp and sprag designs currently in use. The bi-directional clutch uses involute spiral inner and outer races that maintain their concentricity as they rotate. As a result of there being many more roller elements in a given circumference, much greater torque load capacity is achieved.


  • A full compliment of needles
  • Can be programmed in four modes: one-way clockwise, one-way counterclockwise, free-wheel both directions, or locked both directions.
  • Indexing rates up to 100 Hz
  • Hertzian stresses in a given application are much lower than with conventional roller-ramp or sprag type clutches
  • Self-centering - no end bearings required
  • Has the characteristics of a journal bearing when free wheeling
  • Small size/high capacity (up to five times that of a sprag type clutch)
  • Inner/outer slipper spiral type clutches can be made to fit between the existing races of sprag units with little if any redesign
  • Transient accelerations do not affect performance

Current Developments:

Torque-on-Demand 4WD Transfer Case
Positive Drive

Locking Differentials
Manual Transmission Synchronizer Replacement