BASIC TERMS OF HYDRAULICS AND HYDRAULIC MACHINES

1.     ACCUMULATOR A chamber in which a fluid/ gas can be stored under pressure, and can be taken on system demand.

2.     ACTUATOR Converts hydraulic energy into mechanical energy. A motor or cylinder.  

3.     BACK PRESSURE Pressure existing on the discharge side of a load. It adds to the pressure required to move the load. 

4.     BLEED­OFF To reduce a portion of pump delivery to the reservoir. 

5.     CAVITATION Where fluid does not completely fill the existing space. Commonly associated with the pump inlet.

6.     CHARGE To fill a hydraulic system above atmospheric pressure. 

7.     DOUBLE­ACTING CYLINDER Hydraulic force can be applied in either direction. (Extend or retract)

8.     HEAD The force exerted by a column of fluid due to its height and weight (density).

9.     HOSE A flexible tube used to transmit fluid / hydraulic energy to a desired location or device in the system. 

10.ORIFICE A small opening found in various devices and components throughout hydraulic systems. Used to control and restrict flow for many applications.

11.PORT The open end of an internal passage. Usually within or at the surface of a components exterior. 

12.PILOT PRESSURE System pressure used to control components. May be at a lower pressure. 

13.POWER PACK A stand alone hydraulic system containing a pump, reservoir, relief valve and drive unit. To produce its own power, often compact.

14.PRESSURE DROP The reduction in pressure between two points in a line or device caused by the increase in resistance. May be induced by fitting an orifice in the system.

15.STRAINER A component that removes solids from fluid commonly by a wire mesh.

16.SURGE A sudden rise in pressure. Can be associated with a sudden shock or blockage to flow. 

17.VENT To allow a non pressurized reservoir to breath to atmosphere. 

18.VISCOSITY The measure of a fluid’s resistance to flow. The greater the resistance to flow, the higher the viscosity number. 

19.VISCOSITY INDEX An arbitrary scale for lubricating oils that indicates the extent of variation in viscosity with variation of temperature. 

20.THROTTLE Allow the passing of a set amount of fluid flow. May control flow or create a pressure drop.