TORQUEA force or combination of forces
that produces or tends to produce a twisting or
TUBINGA type of fluid line whose
dimensions are designated by actual measured
outside diameter and by actual measured wall
TURBINEA rotary motor actuated by
the reaction, impulse, or both, of a flow of
VALVEA device that controls fluid flow
direction, pressure, or flow rate.
VALVE, CHECKA directional control
valve that permits flow of fluid in only one
VALVE, COUNTERBALANCEA pressure
control valve that maintains back pressure to
prevent a load from falling.
VALVE, DIRECTIONAL CONTROLA
valve whose primary function is to direct or
prevent flow through selected passages.
VALVE, FLOW CONTROLA valve whose
primary function is to control flow rate.
VALVE, HYDRAULICA valve for con-
VALVE, PILOTA valve used to operate
another valve or control.
VALVE, PNEUMATICA valve for con-
VALVE, PRESSURE REDUCINGA
pressure control valve whose primary function is
to limit outlet pressure.
VALVE, PRIORITYA valve that directs
flow to one operating circuit at a fixed rate and
directs excess flow to another operating circuit.
VALVE, RELIEFA pressure control valve
whose primary function is to limit system
VALVE, SELECTORA directional control
valve whose primary function is to selectively
interconnect two or more ports.
VALVE, SEQUENCEA valve whose
primary function is to direct flow in a pre-
VALVE, SERVOA directional control valve
that modulates flow or pressure as a function of
its input signal.
VALVE, SHUTOFFA valve that operates
fully open or fully closed.
VALVE, UNLOADINGA pressure control
valve whose primary function is to permit a pump
or compressor to operate at minimum load.
VELOCITYThe rate of motion in a
particular direction. The velocity of fluids is
usually expressed in feet per second.
VENTURIA tube having a narrowing
throat or constriction to increase the velocity of
fluid flowing through it. The flow through the
venturi causes a pressure drop in the smallest
section, the amount being a function of the
velocity of flow.
VISCOSITYA measure of the internal
friction or resistance of a fluid to flow.
VISCOSITY INDEXA measure of the
viscosity-temperature characteristics of a fluid as
referred to that of two arbitrary reference fluids.
VISCOSITY, SAYBOLT UNIVERSAL
SECONDS (SUS)The time in seconds for 60
milliliters of oil to flow through a standard orifice
at a given temperature.
VISCOSITY, KINEMATICThe absolute
viscosity divided by the density of the fluid. It is
usually expressed in centistokes.
VOLUME OF FLOWThe quantity of fluid
that passes a certain point in a unit of time. The
volume of flow is usually expressed in gallons per
minute for liquids and cubic feet per minute for
WORKThe transference of energy from one
body or system to another. That which is
accomplished by a force acting through a distance.