The charge pump on a closed-circuit, hydrostatic transmission has a number of important functions. These include:

1. Replenish fluid lost from the transmission circuit due to volumetric inefficiency of the pump and motor.
2. Replace fluid purged from the circuit via the hot-oil flushing valve (where fitted).
3. Supply make-up fluid to compensate for load-induced oil compression and conductor (pipe/hose) … Read more