Components of a Hydraulic System

Hydraulic systems are used in a broad range of markets like aerospace, defense, marine, agricultural, plant, automotive, and more. For example, in aircraft, hydraulic systems are used to operate landing gear, flaps, flight control surfaces, and brakes, just to name a few. They generate power by utilizing pressurized liquid through a group of cylinders, hoses, and valves. The complexity of a hydraulic system ranges from those in small aircraft, which are used for manual operation of brakes, to sizeable transport aircraft with large, sophisticated systems. Although the vast majority of a hydraulic system is composed of cylinders and hydraulic hoses, there are many lesser-known accessories which are just as critical to the proper operation of the system. These accessories are pressure switches, hydraulic seals, pressure filters, flow indicators, and plugs. This blog will explain each one and its greater role in the hydraulic system as a whole.

Pressure switches are adjustable, pressure-actuated electrical switches that are used to make or break an electrical circuit when the system reaches a predetermined pressure. Once this pressure has been reached, additional work can be started or stopped manually by another electrical signal. Hydraulic pressure switches have many uses. For example, in automobiles, hydraulic systems are used to warn if the engine’s oil pressure falls below a safe level, or to control automatic transmission torque converter lock-up.

Hydraulic seals are soft, non-metallic rings that form a seal assembly to block or separate fluid within reciprocating motion applications. Hydraulic seals are essential in high pressure systems, allowing them to function and provide a way for fluid power to be converted to linear motion. O-rings, nitrile rubber seals, and dual material seals are all examples of frequently-used hydraulic seals. Depending on the operating conditions and other limitations, hydraulic seals are made from a variety of materials including polyurethane, rubber, or Polytetrafluoroethylene (PTFE).

Pressure filtration is the process of separating a suspended solid like a precipitate from the liquid in which it is already suspended by using pressure to strain it through a porous medium that can be easily passed through by liquid. In hydraulic systems, a pressure filter is used to remove particle contamination and protect downstream hydraulic systems from becoming dirty. The return line filter stops particles as they enter the reservoir and provides clean fluid to be returned into the system. Though it is less common, hydraulic filters can also be used in the pressure line, after the pump.

Flow indicators or flow meters are used to measure the amount of liquid passing through something. This makes them ideal for monitoring the performance of hydraulic systems during tasks like pump testing. In most applications, flow is measured in liters per minute, U.S. gallons per minute, or U.K. gallons per minute. Lastly, hydraulic plugs provide a temporary or permanent means of covering holes in high pressure hydraulic devices. Plugging holes prevents leaks and promotes efficient operation of the hydraulic system. Because they often must withstand many fluids, most plugs are resistant to oil, corrosion, and harmful chemicals.

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