Hydraulic Fittings

What actually are hydraulics?


Hydraulics is a branch of science devoted to the functional application of fluids and liquids in motion.

Steel Hydraulic Fittings on Transparent background

Hydraulic Systems

Hydraulic systems are those that use pressurised fluid to accomplish a task.  They’re all around us.  We hardly notice them doing their jobs.  They generate movement and repetitive motion.  They’re in automobiles, buildings, construction equipment, and industrial facilities.  Common, everyday examples can be found in the following:

  • Dishwashing Machines. Hydraulics increase water pressure to improve the quality of dish cleaning.
  • Construction Equipment. Cranes, jacks, forklifts, pumps, and safety harnesses use hydraulics to lift and lower items.
  • Amusement Park Rides. Hydraulic machines control and provide motion for certain rides.
  • Hydraulic devices operate control panels.
  • Some systems use hydraulics to power elevators.
  • Hydraulics allow for mass production on conveyor belts.
  • Office Chairs. Hydraulics allow the chairs to go up and down.
  • Hair Stylist Chairs. The Hairstylist steps on the chair list and uses a hydraulic lift to adjust the height.

Hydraulic systems use fluid (water, oil) to accomplish their work.  Prior versions were used centuries ago, but they used gravity to create pressure.

Essentially, a functioning Hydraulic System has four components:

  • Fluid Circuit: the hoses or pipes that move fluid from one component of the system to another.
  • Fluid Reservoir: the tank or another vessel that holds the water to stock the rest of the system.
  • Hydraulic cylinder or motor: the part that triggers something to move, driven by the power of the hydraulic pump.
  • Hydraulic Pump: this gadget thrusts hydraulic fluid through the circuit and delivers the energy to the system to do its job.

Power Source, Control Valves, and Tubing

A Hydraulic System requires power in order to run.  Electric motors, engines, internal combustion engine, water, steam, wind, and water are all power sources.  Then system also needs control valves, pumps, tubing, and pipe.

Hydraulic Fittings


Almost every hydraulic system needs Hydraulic Fittings.  Hydraulic Fittings connect the hoses, pipes, control valves, and tubes to the Hydraulic System.  They form connections that help direct and contain the flow of hydraulic fluid.  They also protect against leaks and preserve pressure.  They are, thus, very important.

Most Hydraulic Fittings are “male and female” and join together to form a union.  Fittings are also based on the size of the conductor (pipe, hose, or tube).

The most widely used Hydraulic Fittings are as follows:

  • All Metal Fittings: these rely on metal threads from the male and female couplings to form a seal. They are prone to leaks, however, during vibration and need frequent inspection.
  • O-ring Type Fittings: O-rings, which are usually made of rubber, go between the wrench flats and fitting threads around the male connection and create a leak-tight seal around the base of the female port on an O-ring. They come in both non-adjustable and adjustable.  Non-adjustable fittings require proper aligning while adjustable fittings are attached in a manner similar to All Metal Fittings.
  • Split-Flange Fittings: these are for high-pressure operations and tubing that is bigger than one inch in width. They come in four parts – an O-Ring set in a constructed grove, two mated locks, and a flanged head.

Fittings come in a range of materials, including brass, plastic, and steel and often match the conductor used in the system.