Hydraulic And Pneumatic Power Systems Flashcards
What materials formed the base of the three types of hydraulic fluids?
Vegetable.
Mineral.
Phosphate-ester.
What colors denote mineral based and phosphate ester based hydraulic fluids?
Mineral based - red.
Phosphate ester based - light purple.
What are the results of exposing lacquers, oil based paint, plastic resin, and vinyl compounds to phosphate-ester based hydraulic fluid
The materials will be damaged and/or softened.
Or the paint will peel.
Name several sources used to develop hydraulic pressure.
Hand pumps.
Engine driven pumps.
Electrically driven pumps.
What would cause the bypass valve in a hydraulic filter to open and allow unfiltered fluid to circulate in the system?
A clogged filter element.
Describe several methods of pressurizing a hydraulic reservoir:
Engine bleed air.
System pressure acting on a small piston in the reservoir.
Using variable displacement hydraulic pumps.
What feature prevents engine damage if an engine driven hydraulic pump seizes or is overloaded?
A sheer section in the pump driveshaft will break, disconnecting the pump from the engine.
Describe the purpose of a pressure relief valve.
Pressure relief valves limit the maximum pressure produced by the pump, thereby preventing failures from the system components.
Engine driven pumps deliver the output fluid flow in what two forms?
Constant volume.
Or variable volume.
Describe the operation of a gear type pump.
Two meshed gears, driven by a power source, rotating in a housing.
Inlet fluid is carried around the outside of the gears and delivered to the outlet side as the gears rotate.
Describe the purpose of a pressure regulator
Pressure regulators manage the output of the pump to maintain system pressure.
They allow the pump to be unloaded, so it turns without significant resistance.
What is the device that is used in some systems to supplement the pump output during periods of high demand?
An accumulator.
What are the three different types of accumulators?
Piston.
Diaphragm.
Bladder.
What safety precautions must be taken prior to disassembling an accumulator?
Release all of the air or preload.
When a hydraulic unit is replaced, what precautions should be taken to avoid contamination of the system?
All lines should be capped or plugged immediately after they are disconnected.
