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Blog - Spool Valve Diagram

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Hydraulic Spool Valve Diagram

Hydraulic directional valve also called hydraulic spool valve, is the most popular valve in all sorts of hydraulic systems in industrial machine, the key part of spool plays main role while the valve in operation. Guess what, if you select an improper spool valve in your machine, it is sure that the machine either works like a naughty boy or refuse to work. Most of our customers are choosing the correct spool type as they expected, but for few clients, it is better to know more than about hydraulic spool valve diagram before purchasing hydraulic directional valves. –finotek.com

Hydraulic directional spool valve is a relative motion between the valve spool and valve housing, used for controlling fluid-flow direction of actuator motion(movement), select alternative hydraulic oil control circuits, achieve logic control function. The hydraulic spool valves target is to reach different mechanical movement of actuator, like to release pressure, stop or redirect the pressure or flow in hydraulic systems.

The key part of hydraulic spool valve is spool, a spool valve function depends on the spool type, using different spool type in the middle of valve housing position will achieve different purpose in hydraulic system, therefore, appropriate function spool in middle position must be selected as per its feature during the design of hydraulic systems. There are various type of spool, like “E”, “J”, “H” etc., here we introduce regularly spool type purchased by our clients. Thanks Mr. Harvey and Mr. Elliot for information about popular hydraulic spool valves in their market.

Hydraulic Spool Valve Diagram Introduction:

E -Type
Features: In the neutral position , all oil ports closed, not flow .
Functional characteristics:
1. The inlet and outlet ports of device are closed, hydraulic actuator can be fixed in any its’ working mechanism position, and no movement or rotary further even if there is external force on it, therefore, the E spool type can not be used with the hand mechanism actuators.
2. It is stable operation from start to stop, because of full oil in return channel, which may have a dampening effect. When the pressure starts pushing actuator to move, the speed is not too fast due to the influence of oil resistance, it is a big hydraulic shock caused by braking movement inertia.
3. The pressure can not be unloaded in pump chamber.
4. High precision of spool switching position.

H –Type
Features: In the neutral position, all oil ports are open, no pressure.
Functional characteristics:
1. The inlet port P, return port T and work oil port ports A, B all connected, the hydraulic actuator is in a floating state, movement or rotary can be made if there an external force on it, therefore, the H spool type can be used in hand mechanism actuators.
2. The hydraulic pump can load the pressure.
3. There is an impact from stop to start. The return oil flows to oil tank when the actuator stops working, there is no dampening effect of H spool type, the spool is more stable than E type when spool switching.
4. For single-pole double-acting cylinder, due to effective area on both sides of the piston is not equal, so the H type valve can not hold the cylinder piston in the stopped state.

J –Type
Features: In the neutral position, the inlet P port is closed, oil ports of A, B and T are connected.
Functional characteristics:
1. Because oil ports of A, B and T are connected, operation actuator is in the floating state, movement or rotary can be made if there is an external force on it, therefore, the J spool type can be used in hand mechanism actuator.
2. There are some hydraulic impact from stop working to start, switching performance is between E spool type and H spool type.
3. Pump is unable to unload pressure.

G -Type
Features: In the neutral position, A, B oil ports are closed, P and T oil ports are connected.
Functional characteristics:
1. The working actuator allows to stop stably, due to A and B ports closed.
2. Hydraulic pump can unload pressure.
3. Not available for hand operation actuator.
4. Smooth start and stop working process.
5. Large hydraulic impact because of inertia when switching.
6. The G spool type is used for pump unloading and cylinder locked in hydraulic oil circuit.

M -Type
Features: In the neutral position, T port is closed, and P, A, B oil ports are connected.
Functional characteristics:
1. Double pole & double-acting cylinder with equal diameter, both sides of cylinder piston keeps balance in hydraulic pressure, operation actuator stops stably. The M type can be used in manual operation actuator, not available for single pole or diameter not equal to double pole and double-acting cylinder, where operation actuators will not be at static condition to compose differential hydraulic oil circuit.
2. Relatively stable stop and start operation, smooth switching for hydraulic pressure in two chambers of cylinder.
3. Hydraulic pump is unable to unload pressure.
4. Little switching space position than H spool type, widely applications.

Hydraulic-Spool-Valve-Diagram-

F -Type
Features: In the neutral position, P port connects to A and oil return port, the B oil port is closed.
Functional characteristics:
1. Pump is able to unload pressure.
2. Different working characteristics while switching two directions.

U -Type
Features: In the neutral position, P and A oil ports are closed, the B oil port connects to T oil return port.
Functional characteristics:
1. Pump is unable to unload pressure.
2. Different working characteristics while switching two directions.

Finotek Modular Valve Series, Rexroth Type Valve Spool:
Finotek-Valve-Series-Rexroth-Type-Valve-Spool
Finotek Valve Series,  Northman Type Valve Spool:
Finotek-Valve-Series-Northman-Type-Valve-Spool

Finotek Valve Series, Yuken Type Valve Spool:
Finotek-Valve-Series-Yuken-Type-Valve-Spool

Before selecting hydraulic directional spool valves, it must be sure to choose appropriate spool valve in neutral position as per requirements of hydraulic system.
For example:
1. Design pressure unloading circuit by spool function in neutral position to achieve energy savings. When H, F and G spool type in neutral position of 4way, 3postion directional spool valve, the oil fluid from pump returns to oil reservoir directly to complete unloading hydraulic oil circuit, which allows pump to work under no load or a very small output power to achieve energy saving.

2. Take advantage of spool function in neutral position to design brake or lock hydraulic oil circuit, to lead running operation actuators stops in any desired position, the braking hydraulic circuit to prevent actuators movement due to outside influence. Choosing G or E spool type of hydraulic spool valve to cut inlet fluid flow and quick stops actuators’ movement when the spool in central position.

3. Achieving floating status of actuator by H or J spool type. Such as slewing mechanism in hydraulic crane is running under heavy load, the inertia force will general a huge hydraulic shock if switching the hydraulic power too fast, therefore, the problem is able to be solved by choosing H or J spool type of hydraulic spool valve.

2017-03-05T01:41:48+00:00