Final Exam Question Bank Flashcards
Lint from cleaning rags can be harmful to hydraulic systems because the lint ___.
…can clog filters and promote component leakage
If a radial piston hydraulic pump fails to deliver rated fluid volume, the cause can be ___.
…obstructed suction passage
When the tilting box of a variable stroke axial-piston pump is perpendicular to the pump shaft, which of the following conditions will exist?
…there is no fluid flow
The hydraulic system of a deck winch has been drained, flushed, and refilled with hydraulic fluid. An erratic knocking noise from the hydraulic motor when the winch is started would indicate ___.
…air trapped in the system
The usual number of single-acting pistons used in a variable stroke axial-piston pump is ___.
…7 to 9
An axial piston pump differs from a radial piston pump as the pistons of an axial piston pump are positioned ___.
…parallel to each other and to the shaft
Which of the following problems may be encountered by using an oil having a viscosity higher than that specified for an operating hydraulic system?
…increased power consumption
A casing drain is provided for axial piston and bent axis variable stroke pumps to ___.
…prevent damage due to agitation and overheating of oil accumulated in the casing as a result of normal internal leakage
What is the prime mover?
…energy source that drives the pump
When installing a hydraulic hose, which of the following precautions should be taken?
…the hose should not be twisted
…the hose should be protected with a sleeve if it is subjected to rubbing
…there should be some slack in the hose
(all of the above)
What is the pressure at the bottom of a 20ft column of oil?
8 psi
0.4 psi per foot
Fatigue wear is defined as ___.
…particles bridging a clearance causing a surface stress riser or micro-crack that expands into a spall due to repeated stressing of the damaged area
After installing a hydraulic hose, which of the following precautions should be taken?
…the filters and strainers should be checked frequently
The speed of a radial piston hydraulic motor is controlled by…
…varying the fluid flow rate discharged to the motor
New piping and tubing to be installed in a hydraulic system can be safely degreased by using ___.
…a special petroleum solvent
The ability of an oil to separate cleanly from an oil and water mixture is referred to as its ___.
…demulsibility
Which of the following statements is/are true regarding hydraulic pumps in general?
…variable volumes can be obtained with gear pumps only by variation of the pump drive speed
Tubing is sized by…
…nominal outside diameter
Which of the listed pressure control valves would be used to establish the maximum operating pressure of a hydraulic system? Pressure-reducing valve Unloading valve Counterbalance valve Pressure-relief valve
Pressure relief valve
The pressure of an operating hydraulic system, as indicated by a pressure gauge is a result of the fluid flow overcoming:
- internal resistance to flow
- resistance of the internal components
- the load applied to the system
all of the above
What pressure is usually available to push liquid into the pump inlet?
atmospheric pressure
Hydraulic pumps most commonly used in steering systems are of the…
…axial piston type
With which component does the design of a hydraulic circuit begin?
…the actuator
When changing to a fire resistant hydraulic fluid in a system, it is important to check the compatibility of the new fluid with the systems:
seals
metals and plating
paint
all of the above
As a rule of thumb, when pressure is applied to hydraulic oil, the oil will…
…reduce in volume by 1/2 of 1% for every 1000 psi increment
Which of the listed components of a hydraulic system would enable the pump to be temporarily shutdown, and yet still provide an instantaneous source of hydraulic force?
Accumulator
Most solenoid valves are actuated by…
an electromagnet
Sluggish response or action of the hydraulic actuators may be a result of…
…excessively high oil viscosity
What does a directional control valve do?
Directs the flow of fluid
A solenoid direct-acting three-position spring-centered directional control valve is used in a hydraulic system to control a linear actuator. When the remote push button is depressed to extend, the actuator fails to move even though the pump is on. What is going on?
Any one of the following:
- a spring at one spool end has broken…
- the ‘extend’ solenoid coil has developed and open circuit
- the pump coupling is damaged and pump is unable to turn at its required speed
Express 30 psia in psig
30 psia = 15.3 psig
Air entrained in the hydraulic fluid, or trapped in an actuator will cause the actuators to move with a jerky motion. This action is a result of…
the trapped air being compressed to operating system pressure, the dropping…
Air trapped in one end of a hydraulic actuator may be indicated by…
erratic or jerky motion of the actuator
Before performing any maintenance on a hydraulic system storing energy in an accumulator, you should…
bleed off all pressure within the system
Pump working pressure is the sum of which individual pressures?
Friction, fluid weight and load
What determines the size of a pump needed in a hydraulic system?
How fast the actuators need to move
How many envelopes are in the symbol for a relief valve?
One
If the pump for a hydraulic anchor windlass is overheating, the cause may be…
excessive pump discharge pressure
If you install a hydraulic hose on a unit and fail to leave sufficient room for expansion, which of the following problems will develop?
the hose may pull loose from its fittings
When the pressure is applied to the Bourdon tube gauge show in illustration GS-0154…
…the gauge pointer will move in a clockwise direction
The use of a needle valve in a piping system is recommended when requiring…
…close regulation of flow
