ABSTRACT
Figure 7.1 illustrates the principle of operation of any hydrostatic transmission, also called positivedisplacement hydraulic drive. Here are two pistons 1 and 2 moving in their cylinders 3 and 4 connected by duct 5 and lled with uid. When driving piston 1 moves downwards with speed V1, it forces a certain volume of uid out of cylinder 3 during each unit of time. To free the place for this displaced volume, piston 2 has to move upwards with speed V2 that enables emptying the even volume in cylinder 4 in the same unit of time:
V
d V
d V V
d d
4 4 pi pi
= =
; .
