Some pumps have control options such as pressure or flow compensators.įilters are used to remove contaminants from fluid. Hydraulic pumps are used to pump oil from the power unit to other parts of the hydraulic system. These valves are usually electrically controlled. Directional control valvesĭirectional control valves are used to direct fluid flow into the appropriate lines for the designated operation.
Make sure to discharge all hydraulic energy before working on any components. When placed inline with an actuator (for example, a cylinder), flow fuses limit the maximum speed of that actuator.Īccumulators are used to store hydraulic energy and to absorb shock in a hydraulic system. The valve can be reset by reversing the direction of flow. NOTE: this valve is typically preset and should not be tampered with.įlow fuses are normally open valves which close if the pressure difference between the inlet and outlet valves is too high compared to the design setting.
Pressure relief valves are used to limit the maximum pressure in all or part of the hydraulic system.Ĭounterbalance valves are used to control overrunning loads and to support loads should a function be stopped at any point throughout its travel. Pressure reducing valves are used to reduce the pressure in individual circuits. These switches may or may not be adjustable. Pressure switches are use to detect a pressure rise or fall through a set pressure point. One use of a temperature switch is to detect when the oil in a reservoir reaches the maximum operating temperature. One use of a level switch is to detect when the oil in a reservoir is reduced to a minimum operating level. Air bleed valvesĪir bleed valves are used to automatically eliminate air bubbles from pressurized hydraulic systems. Shut-off valves are used to isolate one part of a fluid system from another.
When the pilot line in a pilot-to-close valve is pressurized, the check valve is closed, blocking flow in both directions. When the pilot line to a pilot-operated check valve is not pressurized, flow is allowed in one direction but blocked in the opposite direction. Pilot operated check valves, pilot-to-close When the pilot line in a pilot-to-open valve is pressurized, the check valve is open, allowing flow in either direction. Pilot operated check valves, pilot to open Some valves can be pressure and/or temperature compensating. "Metered in" control means that the flow controls are controlling the fluid into the actuator, "metered out" is controlling the fluid out of the actuator. Flow control valvesįlow control valves are used to control oil flow in one direction and unrestricted in the opposite direction. Gauges are used to measure the oil pressure at a given point in the system. Some valves can be pressure and/or temperature compensating.Ĭheck valves are one way valves, allowing flow in only one direction. They usually will vary flow with pressure or viscosity change. Needle valves are used to throttle or shut-off flow of fluids. Specific fluids circuit elements Needle valves
#Hydraulic valve symbols autocad series
Later in this article series we will describe some simple hydraulic and pneumatic circuits composed of these circuit elements. Below are some common illustrations of equipment located on fluids circuit diagrams, followed by descriptions of the most common elements.