Volume of hydraulic fluid

The pump consists of dual reciprocating pistons which are hydraulically controlled. Oil is distributed by the system to the two pistons which are 180° out of phase (as with the Altex and Waters systems). A fixed volume of hydraulic fluid is delivered to the control system for every revolution of a special gear pump. The latter is controlled by a motor having a constant speed and a tachometer feedback circuit. Other compensating circuits... 

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