Hydraulic and Pneumatic Power Systems Flashcards
What materials form the base of the three types of hydraulic fluids?
Vegetable, Mineral, and phosphate-esters
What colors denote mineral-base and phosphate-ester base hydraulic fluids?
Mineral base fluids are Red, and phosphate ester based fluids are light purple
What are the results of exposing lacquers, oil based paint, plastic resins, 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 pump, engine-driven pump, and 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, or using variable-displacement hydraulic pumps
What feature prevents engine damage if an engine-driven hydraulic pump seizes or is overloaded?
A shear 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 of the system components.
Engine driven pumps deliver the output fluid flow in what two forms?
As a constant volume or a variable volume
Describe the operation of a gear type pump?
Two meshed gears, driven by a power source, rotate in a housing. inlet fluid is carried around the outside of the gears and delivered to the outlet side as the gear rotate
Describe the purpose of a pressure regulator?
Pressure regulator 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, and bladder
What safety precautions must be taken prior to dissembling an accumulator?
Release all of the air or preload
When a hydraulic unit is replaced, what precautions should be taken to avoid contamination in the system?
all lines should be capped or plugged immediately after they are disconnected