The corresponding equation for the b side of the circuit can be constructed as well. By integrating this pressure change rate, and the pressures in the circulation and thus the effective pressure difference on the engine. This in turn determines the producible by the engine torque. In the Figure the characteristic field is one of the engines used in the studies presented. Here, the characteristic curves for all possible cases is given, not only for the engine operation, but also for the generator, that means Pump operation.