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Hydraulic starter delivers high torque

Although electrical and air-powered engine-starting systems are standard for many types of equipment, hydraulic starting also has found a solid niche — particularly in remote or potentially hazardous locations. The marine, oil and gas, power generation, and mining industries use hydraulic starting both as primary and/or auxiliary emergency starting systems. Hydraulic starting's major advantage: by cranking engines faster at a higher torque, the engines start more quickly. The instant availability of torque is particularly effective in cold weather. In addition, elimination of electrical connections (coupled with the availability of beryllium copper gears) results in sparkproof starter operation.

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.

The 90%-efficient Kocsis hydraulic starter is a closed-loop system that is virtually maintenance free. It is continually lubricated and usually will outlast the engine it starts. Because it is insensitive to dirt, dust, and moisture, the starter system can stand idle for long periods of time without losing performance or suffering the deterioration associated with electrical systems.

Flexibility is designed into the packaged systems. Kocsis produces Hydrotor systems with a range of 6 to 64 kW of starting capability. Cranking motor displacements range from 8.2 to 57.4 l/rev. Maximum operating pressure is 207 bar. The system's speed range is 0 to 7000 rpm. Locked-rotor torque is an impressive 12 to 163 Nm. Hydrotors can operate using a variety of fluids. The standard cranking motor has a cast-aluminum housing, but ductile iron is optional for extra spark protection. Clockwise or counterclockwise rotation can be specified, as can diesel or gasoline engine starting. Only the pump and cranking motor have to be mounted on the engine; the other components can be located remotely. Cabinetized systems are capable of starting multiple engines.

For more information about Hydrotor systems, call (708) 597-4177 or visit