Spool valves
regulate the flow of fluid in hydraulic systems
. Spool valves would slide backward and forward so that the fluid flow can be either in one direction or another around a circuit of pipes. Spool valves have two basic components, a cylindrical barrel in which slides a plunger or spool.
What is the purpose of spool valve?
A spool is a cylindrical valve element that opens and closes ports when moved axially within the valve bore. Most spool valves use
elastomers to seal between flow paths
.
What is the spool in the spool valve?
A spool is
a cylindrical valve element that opens and closes ports when moved axially within the valve bore
. Most spool valves use elastomers to seal between flow paths.
How do you adjust a hydraulic spool valve?
To adjust the spool valve,
loosen the valve-locking nut on the side
. Removing the locking nut gives you access to the adjustment screw. Turn the screw clockwise to raise the pressure, and twist it counter-clockwise to lower the pressure.
How do you test a hydraulic spool valve?
To check this,
install a pressure gauge and flow meter in the drain/tank port line
. All hydraulics work on differential pressure. If back pressure is excessive, the actuation pressure must overcome it first before it can move the spool. Most systems require minimum back/drain pressure to function smoothly.
What is the difference between poppet and spool valve?
Unlike spool valves, poppet valves
open an immediate flow path to the outlet
. This results in a fast response time. … The large surface area that is essential for poppets results in a higher flow rate. Poppet valves require small actuation strokes, which allows for shorter switching times.
What is a 2 spool valve?
2 spool hydraulic valve is
a device used to control hydraulic systems
. 2 spool hydraulic valves are very wide used from automotive power-steering systems to constructions machines like cranes, loaders, diggers. 2 spool hydraulic valve can manage the flow of hydraulic fluid from a hydraulic pump to an actuator.
How do I know if my hydraulic valve is bad?
Many of the failures in a hydraulic system show similar symptoms: a
gradual or sudden loss of high pressure
, resulting in loss of power or loss of speed in the cylinders. The cylinder(s) may not move at all, or if they do they may move too slowly or may stall under light loads.
Can you adjust a relief valve?
Adjust the relief valve by
turning the adjuster clockwise until the reading on the gauge builds to the pressure indicated on the machine drawings
. This is what is known as the valve “cracking” pressure, which is the pressure at which the relief valve starts to open.
How do you adjust a main relief valve?
With a slotted screwdriver, turn the screw in the center of the knob clockwise, until flow can be heard escaping from the internal valve. Slowly turn the screw
counterclockwise
until the flow from the relief valve stops. Turn the screw an additional 1/8 to 1/4 turn counter-clockwise. Replace the silver cap in the knob.
What causes a spool valve to fail?
When a valve sticks, the spool cannot change positions when an operator applies normal force. Several factors can cause this sticking action, including
contamination, silting, mechanical failure or operator failure
.
What are the symptoms of a bad VVT solenoid?
- Rough Engine Idle.
- Check Engine Light.
- Misfiring engine under loads.
What will happen if there is air trapped in the hydraulic system?
When air contaminates a hydraulic fluid, usually via the pump’s inlet, aeration,
cavitation, or foaming can occur
. Aeration is bad news, as it degrades the hydraulic fluid causing damage to the components of the system due to loss of lubrication, resulting in overheating and burning of the seals.
How do I identify a spool valve?
These valves are
cylindrical in cross-section
and its lands and grooves are cylindrical too. In this spool valve, the spool is grooved and slides in and out of position within the sleeve, alternately blocking and opening the fluid intake and outtake portals.
What is a 4 way 2 position valve?
A 4-way 2 position valve is known as a
4/2
. These valves are common in double acting cylinder applications where they are always supplying pressure to one side of the cylinder while venting the opposite side to atmosphere.
What is the meaning of poppet valve?
A poppet valve (also called mushroom valve) is
a valve typically used to control the timing and quantity of gas or vapor flow into an engine
. It consists of a hole or open-ended chamber, usually round or oval in cross-section, and a plug, usually a disk shape on the end of a shaft known as a valve stem.
