The modular Hydrotor cranking system — from Kocsis Technologies, Inc., Alsip, Ill. — consists of a piston pump, a back-up hand pump, a directional control valve, a piston-type hydro-pneumatic accumulator, a reservoir with inlet and outlet filters, and a cranking motor. During starting, the control valve (which can be electrically or mechanically shifted) simply releases pressurized fluid from the accumulator to drive the cranking motor. Oil flow is directed against a series of free pistons within the rotor assembly, which is splined to the drive shaft.
The pistons are forced against an inclined thrust bearing, causing the rotor to turn. The drive shaft carries a Bendix drive that engages with the engine's ring gear. Two needle bearings and a central ball bearing support the motor drive shaft, maintaining low-friction operation over a wide ambient temperature range. Even at –40° C, the Kocsis starter provides the same high torque as at moderate temperatures.
Once the engine starts, the Bendix disengages and the pump automatically recharges the accumulator. (The hand pump also can charge the accumulator.) Typically, a fully charged accumulator can power about five starts. A range of accumulator sizes – from 5.7 to 57 l – is offered. If necessary, multiple accumulators can be part of the system.