1、 Hydrostatic drive for crawlers: Some design advantages Hydrostatic operation of vehicles such as dozers and loaders implies use of in engine to operate a hydraulic pump or pumps. High pressure hoses are used to transmit the fluid pressure and flow to separate drive motors which can be located some
2、distance from engine and pump. The engine can be run at its most efficient conditions with a reversible, variable swash plate pump. The hydraulic motors can also make use of variable swash plates, simplifying both hydraulic designs. Only the design advantages of such a system are covered here, thoug
3、h service procedures, life expectancy, and operators all can benefit from other aspects of such drives. A major design objective in the construction equipment manufacturing business since the 1960s has been more efficient use of installed horsepower. Low efficiency means energy wasted as heat which,
4、 in its turn, usually requires extra power to drive fans and maintain temperature. The more inefficient the machine, the hotter it gets, so heat serves as a measuring scale for overall efficiency. Within a machine, engine horsepower is transformed into force (psi) and speed (gal/mm). For purposes of
5、 comparing different systems one can use the expression: Engine hp Force x Speed where force means drawbar pull (lbs) and speed means travel speed (mph). Since all machines have internal losses, the ideal force/speed hyperbola cannot be achieved. However, the more efficient, the closer a machine system approaches the ideal curve, and the more work it can produce from a given amount of installed engine horsepower (Fig. 1). To appreciate the efficiency of a hydrostatic drive, it is necessary to look at the power utilization of conventional drives .
