One of the most common directional control valve designs is a type called a spool valve. By nature of the design itself, spool valves can leak across their various internal paths, which may create problems with backpressure in your system, heating of the oil in the pump’s reservoir, as well as a clamp’s holding ability. Vektek does not recommend using spool valves in clamping systems and offers manual andelectrical control valves in either a poppet or a shear seal style design.
When the valve is electrically actuated, the flow is directed from the pump to the actuator and the flow path back to tank is blocked. 2 X 3 normally opened solenoid valve allows the fluid to flow from the pump to the actuator, while blocking flow path to the tank in the un-actuated (no electrical signal) position.
The most common valve configurations used in our industry are,
Two position Three Way Three Position Four Way
When the valve is electrically actuated, the flow path is blocked from the pump and the flow path from the actuator is directed back to tank. Three-position four-way valve has three different valve operator positions, left, center, and right position. It is described as a four-way valve because there are four separate fluid flow paths or ports. They are commonly referred to as “P”, “T”, “A”, & “B”. As described in the two-position valve, “P” refers to the pressure port, “T” is the tank, and “A” & “B” are the two working branches of the circuit, which are typically connected to a clamp, or actuator. When the valve operator is in the left or right position, the valve directs the fluid flow through two separate flow paths at the same time. One position sends fluid from the pump (“P”) path to the working (“A”) side of an actuator while the path from the opposite (“B”) side of the actuator is directed back to (“T”) tank. When the valve is shifted to the opposite position, the internal flow paths are reversed, sending fluid from “P” to “B” and “A” to “T”. This valve configuration is most commonly used to control double acting devices. The third or center position of a three-way valve allows for various circuit control operations or functions.
Two-position three-way valve has two different valve operator positions, open or closed. It is described as a three-way valve because there are three separate fluid flow paths, or ports. These paths or ports are commonly referred to as “P”, “T”, and “A”. “P” refers to the pressure port as supplied from the pump unit, “T” is the tank or return line to the pump reservoir, and “A” is the working branch of the circuit which is typically connected to the clamp, or actuator. This type of value directs flow in one direction at a time, from the pump (“P”) to the actuator (“A”) in one position or from the actuator (“A”) to the tank (“T”) in the other position. Vektek recommends this style of valve to control single acting devices. 2 X 3 normally closed solenoid valve blocks the flow path from the pump while allowing fluid to flow from the actuator to tank in the un-actuated (no electrical signal) position.
Hydraulic Clamping Fundamentals Aug 09 Rev - D
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