3. Auxiliary control units

3.1 Power-assisted displacement control

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...