Directional Control Valve
A directional control valve is the element that determines which actuator port the flow from the pump goes to and which port drains to tank. Its most common type on mobile equipment is the four-port, three-position 4/3 valve. A valve controlled by a manual lever is the element that retrofit kits actually drive.
The two numbers in the designation are meaningful: the first is the number of ports (P pressure, T tank, A and B actuator), the second the number of positions. The three positions of a 4/3 valve are typically forward, neutral, and reverse. The internal connection of the neutral position defines the valve's character: in open center, P connects directly to T; in closed center, all ports are blocked.
- Actuation type: manual lever, electric solenoid, pilot pressure, or proportional coil.
- Intermediate positions: with a manual lever, how far the lever is pushed sets the orifice; this makes the lever itself a proportional element.
- Return to neutral: most mobile valves return to neutral on their own via a spring.
HCT400 and HCT402 use exactly these intermediate lever positions. The motor pushes the lever from the outside to create the orifice you want; there is no intervention inside the valve, in the oil, or in the coils. When the kit is removed, the valve returns exactly to the manual operation it had on day one.
Where this term is used: How Are Manual Hydraulic Levers Controlled Remotely? A Comparison of 6 Methods