When buying modular reducing valves or reducing-relieving valves, different options help reduce heat in a circuit while still maintaining good control.

Figures 16-20 and 16-21 show a reducing-relieving valve in the pump port line. The valve has an internal pilot that maintains reduced pressure at the outlet port. This means there is heat-generating flow from the drain line whenever the pump is running.

Figures 16-20












Remotely piloting the reducing-relieving valve from port A, as in Figure 16-22, reduces pressure only on the extension stroke of the cylinder. While the cylinder retracts and holds, as in Figure 16-23, the reducing valve drain is not bypassing oil. (Some manufacturers put the reducing valves directly in the A or B ports and use bypass checks for reverse free flow.)

Figure 16-22












In either case, drain flow only takes place during a small portion of the cycle. This may sound unnecessary, but some circuits have multiple reducing valves. Excess drain flow can cause heating and fluid waste. (Pilot flow cannot be used to operate other actuators.)

Extra time spent on circuit design pays off in energy-efficient systems that perform better in the work place.