Connected: A condition where pipe connections are on normally
exposed surfaces of hydraulic equipment. (Gasket mounted units are
Pressure: Usually refers to pressure existing on the discharge
side of a load. It adds to the pressure required to move the load.
A device usually a plate, installed in a reservoir to separate
the pump inlet from return lines.
An international standard unit of pressure equal to 100,000 Pascals
approximately 14.5 psi.
EMF: The voltage produced across a winding of a motor due to
the winding turns being cut by a magnetic field while the motor
is operating. This voltage is directly proportional to rotor velocity
and is opposite in polarity to the applied voltage. Sometimes referred
to as counter EMF.
A measure of system response. It is the frequency range that a control
system can flow.
Binary Coded Decimal is an encoding technique used to describe
the numbers 0 through 9 with four digital (on or off) signal lines.
Popular in machine tool equipment, BCD interfaces are now giving
way to interfaces requiring fewer wires, such as RS-232C.
Number System: A number system used in digit equipment that
has a base of 2. The digits 0 and 1 are the only digits used in
forming numbers in this system.
Abbreviation of Binary Digit, the smallest unit of memory equal
to 1 or 0.
To divert a specific controllable portion of pump delivery directly
Diagram: A simplified schematic representing components and
signal flow through a system.
Valve: A valve used in the exhaust line of a hydraulic motor
to (1) prevent overspeeding when an overrunning load is applied
to the motor shaft and (2) prevent excessive pressure buildup when
decelerating or stopping a load.
A device which permits air to move in and out of a container or
components atmospheric pressure.
Plot: A graph of system gain and phase versus input frequency
which graphically illustrates the steady state characteristics of
Frequency: Frequency(ies) at which the gain changes slope on
a Bode plot (break frequencies correspond to the poles and zeroes
of the system).
DC Servo: A general term referring to a motor drive that generates
trapezoidal shaped motor currents in a motor wound as to generate
trapezoidal Back EMF.
A group of 8 bits treated as a whole, with 256 possible combinations
of one and zeroes, each combination representing a unique piece