1. Refer to data sheet 1.11.2140E. The typical 3 way, two position control circuits utilize virtual zero leak Wandfluh solenoid operated poppet valves for load lift, hold, and lower functions, but the user still must provide means to dump or shut-off the fixed displacement pump providing pressure and flow. Else, power will be wanted, heat will be generated, and at least 2 more components, plus fittings and piping must be added to the manifold control station. Wandfluh offers a fourth function as part of the system and housing by also installing another 3 way solenoid valve which (see model A3406 under “Symbols” on page 1)., when signaled can both dump the pump flow to tank and also unload any pressure remaining in the cylinder and piping. At the rest position (all power to solenoids off), all three ports are locked thus also holding a loaded cylinder in a virtual zero drift position, regardless of any undue forces on the cylinder load. A further benefit is that a “float position is created for cylinder and its load (such as needed by small snowplows or road scrapers.). This model is also offered in the NG4 and NG10 valve sizes.
2. Refer to data sheet 1.11-2150E. Here we offer a poppet style 4 way 3 position, double solenoid operated directional control valve that will hold all ports virtual zero leak when in the no power (neutral) situation (each port is blocked virtual zero leak.). This is often a requirement in the test bench and fixture clamp markets, as well as on certain positioning loaders/transporters, and in any designed machine that requires both safety when holding a load and fail-safe shut-off of actuators when signaled.