Hydrostatic Transmissions Controls - Is There Space for Optimization?

Efficiency characteristics are considered of simple control types (constant pressure and constant power) applied to a variable displacement pump as single unit or in connexion with a fixed displacement motor or a dummy actuator (having efficiency features of a transmission line). The most efficient way to implement a specific control is identified in terms of speed and displacement, while basic control parameters result from the optimization of maximum or mean efficiency. Some effects of controls on driving engine fuel consumption and sizing are also discussed. Computations are based on efficiency models devised by authors as approximation of a number (sometime large) of reference data, and carried out with an original Non-Linear Programming code (FALL77).