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W, X, Y, Z
Ullage - The volume of fluid
which a vessel lacks from being full.
Ultrasonic - A vibration with a frequency higher than that normally
audible to the human ear.
Unloading Valve - A Valve which by-passes flow to the reservoir when
a set pressure is maintained on its pilot port.
Unload - To release flow to the reservoir.
Vacuum Press - A hydraulic press
with vacuum enclosed platen working areas to remove air, gas vapors, and
fumes during the forming process. A vacuum style hydraulic press ensures
consistent material flows, as well as precise control over temperature and
Vacuum Pressure - A deficiency of fluid or flow resulting from too
low temperature, incorrect fluid viscosity or too high suction velocity.
Leads to suction difficulties and pump damage.
Valve, Proportioning - This valve is a fixed differential pressure
reducing valve and has a fixed spring and a fixed differential area. It is
used in brake systems to limit the magnitude of the pressure to the rear
Vena Contracta - The region of smallest cross section in a fluid
stream. As fluid emerges from an orifice, it tends to contract in cross
section reaching a minimum and then expanding back to fill the conduit.
Viscosity Index - A measure of the viscosity-temperature
characteristics of a fluid compared to two arbitrary reference fluids.
Window Frame Hydraulic Press - A
hydraulic press with a large open feed area, or window, designed especially
for larger dies, or where access to work area is important. A window style
hydraulic press offers minimal deflection and optimal cross head
Work Height - The distance from the floor to the top of the
Water Hammer - The vibration of a conduit in a fluid system due to
rapid changes in liquid velocity due to valve closure.
Wear Ring - An element used to prevent cylinder seals from being
crushed and metal-to-metal contact from occurring by maintaining seal
concentricity when side loads exist.
Wobble Plate - A rotating canted plate in an axial type piston pump
which pushes the pistons into their bores as it "wobbles."
X, Port - This refers to a pilot
X-ray Emission, Proton Induced PIXE - An X-ray emission spectrometer
based on physics and not on chemistry. It separates the electrons from the
hydrogen atom, then an accelerator drives the protons at a high speed to
collide with the target or specimen. This spectrometer is capable of
evaluating 72 elements simultaneously in one sample.
Y, Port - Refers to a pilot
Yield Strength - The stress at which a material exhibits a specified
deviation from proportionality of stress and strain.
Youngs Modulus - The ratio of a simple tension stress applied
to a material to the resulting strain parallel to the tension.
Z Factor - This factor is defined
by the relation Z = PV/NRT and is based on the assumption that at the same
reduced pressure and temperature all gases have the same compressibility
Zero-lapped - A critical-center condition where the spool land width
is identical to the port width.
ZETA Rating - A contaminant abrasivity rating system that allows the
Omega Life of a component to be transformed to a Zeta Life to reflect the
abrasivity severity of the environmental contaminant.
Z-Transform - Converts the difference equations into algebra form
and normally used to handle discrete or digital samples.