In a hypothetical non-leaking hydrostatic transmission composed of a 100% efficient pump and a 100% efficient motor, both pump and motor are connected by two equal-length hoses.

Posted: January 9th, 2022

In a hypothetical non-leaking hydrostatic transmission composed of a 100% efficient pump and a 100% efficient motor, both pump and motor are connected by two equal-length hoses. The resisting torque at the motor shaft and the motor displacement are 50 N m and 25 cm³/rev, respectively, and the pump supplies a flow of 30 l/min at 140 bar. The transmission uses a 60 cSt hydraulic fluid whose density is 870 kg/m³ and the inner diameter of the hoses is 15 mm. Disregard the power needed to drive the charge pump and obtain an expression for the transmission efficiency as a function of the hose length, L.