Particular attention has been paid to power density, function and versatility. Good proportionality and stability characteristics are due to the special geometry along the control flanges of the individual valve pistons, which ensures that high flow rates are kept under control.
A manually operated version is also available in addition to the models with hydraulic and electro-hydraulic controls. Manually operated versions work in a similar manner to hydraulically actuated pressure reducing valves. The advantage of this kind of actuation is that the leverage forces are low and that the leverage lengths involved can be kept short.
Manual operation serves as a direct proportional control of the directional valve – a feature frequently required for winch controls, for example – or as an emergency hand lever. With electrical activation the hand lever remains in its idle position. This provides added security and keeps hysteresis to a minimum.
These valves are used in large-scale caterpillar cranes, ship cranes, wheel-loaders, earth-drilling equipment and rail-mounted cranes for example. Sensitive and precise load control is critical in these types of applications. Various input modules are available for different kinds of pumps, such as variable- or fixed-displacement pumps.
Consumer modules provide even more additional operations – such as ancillary anti-shock or anti-cavitation valves, or a combination of both, which can be adjusted independently of each other in work connections A and B. Upstream two-way pressure compensators offer the advantage of a pressure cut-off (A and B sides separately).
Further options include electrically-proportionally adjustable pressure cut-offs. SAE flange connectors are also available in addition to threaded connectors (conforming to DIN 3852).