Auxiliary control units
Hydrostatic transmission circuits

The operating forces of closed-circuit pumps are generally high, depending on operating conditions.

To ensure precise, stable, low-effort operation, the pumps are equipped with hydraulic power-assisted controls, the schematic diagram of which corresponds to that shown in figure 19.

The input for this assisted control can be mechanical (lever or cable), pneumatic (cylinder), hydraulic (low-pressure manipulator), electrical (electric cylinder) or electronic (servovalve).

Despite their high cost, servovalve solutions seem to be gaining ground to the detriment of others. They are particularly appreciated when several pumps need to be controlled simultaneously.