Pressure lass than atmospheric pressure. It is usually expressed
in inches of mercury (in Hg) as reffered to the existing atmospheric
A device which controls fluid flow direction, pressure, or flow
The speed of flow through a hydraulic line. Expressed in feet
per second (fps) or inches per second (cps). The speed of a rotating
component measured in revolution per minute (rpm).
To permit opening of a pressure control valve by opening its
pilot port (vent connection) to atmospheric pressure. An air breathing
device on a fluid reservoir. To remove trapped air flow from a component.
A measure of the internal friction or the resistance of a fluid
Damping: Inherent losses are present in all motors which result
in lower torque delivered at the output shaft than developed at
the rotor. Losses which are proportional to speed(i.e. speed dependent
terms such as windage, friction, eddy current) are related through
the motor's viscous daming constant, measured as the slope of the
The amount of electromotive force (emf) produced by a power
source or available at points in a circuit, expressed in units volts.
Constant: KE = The back EMF generated by a DC motor
at a defined speed. Usually a quoted in volts per 1000rpm.
The size of a space or chamber in cubic units. Loosely applied
to the output of a pump in gallon per minute (gpm).