Process to control the rotation speed by adjusting the torque with a reversible hydraulic motor in a system with impressed pressure (constant pressure network (Figure S 43).
The rotation speed of the motor is controlled such that it is reached at the network pressure, regardless of the load pressure. To that end, the displacement of the motor must be changed until a balance is created between the motor torque and the load, and the desired rotation speed is reached at the same time.
Secondary control is therefore a pressure coupling with a flow reaction contrary to the conventional drive system, in which there is a flow coupling with pressure reaction.
Important benefits of secondary control include:
- The motor works at the prescribed pressure and always in the range of the favourable efficiencies;
- the installed power may be small due to the accumulator;
- when reversing the motor, the braking energy may be fed back to the network.
The secondary control should not be confused with the secondary adjustment of a gear, which designates a gear on the constant current network, in which a constant pump works together with a variable motor.
Figure S 43: Hydraulic motor subject to secondary control