About the minimum transmission size

The layout of a simple hydrostatic transmission within a locomotion power train . shown' F' 1 h h IS .. .Ill Ig~re ,w ic gives evidence to the basic components: (i) diesel engine; (Il) varIable dIsplacement pump with built-in boost and auxiliary Circuit; (iii) gearbox between engine and pump; (iv) fixed or Variable displacement motor' (v) final d ' d d'fD . . ' nve an 1 erentIal; (VI) wheels or, more generally, locomotion device. In th,iS context, t~e design of the hydrostatic transmission involves two basic problems. ~e1e~t the sIZe of the main units, and specify the control law of their displaceme. n. t (If dIfferent from a manual input)' The seolution of th fi rs t prob le m I.S more cntical because it affects the hardware cost, and constrains the whole operating envelope. To help in this sense, practical sizing schemes are offered by some fluid power manufacturers. In the present paper the choice within a given series of machines is set aside, and a sizing procedure is outlined which aims to find the smallest pump and motor able to transjer the rated engine power.