Service Manual

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BDP-10A/16A/21L
Axial Piston: Type of design for hydraulic motors and pumps in which the pistons are arranged
parallel with the spindle (input or output shaft).
Bantam Duty: A descriptive term relating to the product capacity (meaning: light duty).
Bypass Valve: A valve whose primary function is to open a path for the fluid to bypass the motor or
pump. Also referred to occasionally as the freewheel valve or dump valve.
Case Drain Line (Return Line): A line returning fluid from the component housing to the reservoir.
Cavitation: A phenomenon of boiling in a flowing liquid at normal temperatures, as a result of low
pressure condition. The gas liberated from the fluid implodes rapidly and damages pump compo-
nents.
Center Section: A device which acts as the valve body and manifold of the transmission.
Charge Pump: A device which supplies replenishing fluid to the fluid power system (closed loop).
Charge Pressure: The pressure at which replenishing fluid is forced into a fluid power system.
Charge Relief Valve: A pressure control valve whose primary function is to limit pressure in the
charge circuit.
Check Valve: A valve whose primary function is to restrict flow in one direction.
Closed Loop: A sealed and uninterrupted circulating path for fluid flow from the pump to the motor
and back.
Decay Rate: The ratio of pressure decay over time.
End Cap: See “Center Section”
Entrained Air: A mechanically generated mixture of air bubbles having a tendency to separate from
the liquid phase.
Gerotor: A fixed displacement pump frequently used as a charge pump.
Hydraulic Motor: A device which converts hydraulic fluid pressure and flow into mechanical force
and motion.
Hydraulic Pump: A device which converts mechanical force and motion into hydraulic fluid pres-
sure and flow.
Hydrostatic Motor: See “Hydraulic Motor”
Hydrostatic Pump: See “Hydraulic Pump”
GLOSSARY OF TERMS