Which type of direction control valve symbol is shown in Figure?

Explanation:

Centrally Closed 4-Way 3-Position Solenoid Operated D. C. Valve

• A centrally closed 4-way 3-position solenoid operated directional control (D. C.) valve is a type of hydraulic or pneumatic valve that controls the direction of fluid flow.
• It features four ports and three positions, with the center position being closed.
• It is operated electrically by a solenoid, which provides the actuation force to shift the valve positions.
• In this type of valve, the solenoid coil is energized to move the spool, which directs the fluid flow to different ports.
• When the solenoid is de-energized, the spool returns to its central position, blocking all ports and stopping the flow of fluid. The three positions typically include:
  • Position 1: Directs fluid from the pump port to an actuator port and returns fluid from the other actuator port to the tank.
  • Position 2: Central position where all ports are closed, stopping the fluid flow.
  • Position 3: Directs fluid in the reverse direction compared to Position 1.

Advantages:

• Precise control of fluid flow direction, enabling accurate operation of hydraulic or pneumatic systems.
• Electrical operation via solenoids allows for easy integration with automated systems and remote control.
• When in the central position, all ports are closed, which can be useful for holding a load or stopping a motion in mid-position.

Disadvantages:

• More complex than simpler valve types, requiring electrical connections and solenoid maintenance.
• Potential for solenoid failure, which could lead to loss of control over the fluid flow.

Applications: Centrally closed 4-way 3-position solenoid operated D. C. valves are commonly used in hydraulic and pneumatic systems for industrial automation, machinery control, and various fluid power applications where precise control of actuator movement is required.