In a hydrostatic transmission, the pump can be adjusted and the motor is associated with constant displacement. The drive rotation speed is therefore proportional to the flow rate for the pump, i.e. the adjusted displacement volume. This would result - at constant pressure - in a (theoretically) constant torque, with power increasing to the maximum level (Figure P 16). The resulting adjustment range for rotation speed is as follows:
![aecca81b298748f09affc8ede7190c6470976f21 primaerverstellung_01.gif](/fileadmin/smc/files/aecca81b298748f09affc8ede7190c6470976f21.gif)
while the torque ratio would be:
![d94ceceefb12d9ceddd3fce2e79443293cd2fd88 primaerverstellung_02](/fileadmin/smc/files/d94ceceefb12d9ceddd3fce2e79443293cd2fd88.gif)
with the displacement V 2 remaining constant (see also secondary control).
![9536f6853d4d74464d59ea95b9ae85b96c9faa11 0001_primaerverstellung](/fileadmin/smc/files/9536f6853d4d74464d59ea95b9ae85b96c9faa11.gif)
Figure P 16: Options for converting transmission in relation to current-fed systems. a) = pure primary control; b) = pure secondary control; c) = composite control