Flow Divider and Flow Divider/Combiner Valves for Closed Loop Hydrostatic Transmissions 901554
Flow divider or divider/combiner valves are applied in closed loop hydrostatic transmission applications with an over centering pump and multiple motors to aid traction recovery in the event one or more motor driven wheels begin to slip. These valves proportionally divide pump flow into two or four streams of fluid flow to serve two, three or four motor circuits. Given each circuit may be at a different load pressure, the divider or divider/combiner valve is applied to divide a single flow stream of fluid into several proportional streams regardless of the individual load pressures. In the reverse direction, the flow divider/combiner valve proportionally sums these fluid streams into a single flow. (further references to the flow divider/combiner valve shall also refer to the flow divider valve except where flow combination is discussed exclusively.)
Flow divider/combiner valves have been avoided by mobile machinery designers because of their propensity for lock up failure when subjected to metering circuit cavitation or to pressure intensification. The solution is to fully protect the metering ports from anti-cavitation and from pressure intensification transients. Fully protected closed loop hydrostatic circuits for both the two and four way flow divider/combiner valves are shown as examples in the following presentation.