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Module 11B > 11.11 Hydraulic Power MCQ's > Flashcards

11.11 Hydraulic Power MCQ's Flashcards

1
Q

In an aircraft hydraulic system, it is permissible to use:
Any hydraulic fluid available
Only the specified fluid
Any fluid of the same specific gravity

A

Only the specified fluid

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2
Q

One of the functions of the hydraulic accumulator is to:
Supply fluid to the pumps
Dampen out pump oscillations
Prevent fluid loss through leakage

A

Dampen out pump oscillations

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3
Q

If the differential pressure indicator has popped on a filter, this is an indication that:
The pressure drop across the filter is too high and it may be blocked/contaminated
The pressure drop across the filter is too low and the filter may be contaminated
The fluid flow rate through the filter is too high and the by-pass valve has opened

A

The pressure drop across the filter is too high and it may be blocked/contaminated

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4
Q

Pressurising of the hydraulic reservoirs provides:
positive supply of fluid to the pump
correct fluid level in the reservoir
system operation should the pump fail

A

positive supply of fluid to the pump

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5
Q

A hydraulic gear type constant displacement pump:
requires a pressure regulating valve
displaces a variable quantity of fluid per revolution
supplies fluid on demand only

A

requires a pressure regulating valve

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6
Q

Hydraulic reservoirs are pressurised to:
ensure pump is lubricated
prevent pump cavitation
prevent fuel leakage

A

prevent pump cavitation

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7
Q

Separate reservoirs are used for each hydraulic system:
So that if a leak occurs only that particular system will be lost
Enable a single point replenishment to be carried out
To allow fluid to all of the hydraulic pumps at the one time

A

So that if a leak occurs only that particular system will be lost

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8
Q

A shuttle valve is used for
dissipating fluid pressure when the main system fails
preventing loss of fluid from a leaking union
change over from main to an auxiliary system in case of failure

A

change over from main to an auxiliary system in case of failure

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9
Q

The essential components of a closed loop hydraulic system of the constant delivery type are the accumulator and:
Automatic Cut-out valve (ACOV)
shuttle valve
relay valve

A

Automatic Cut-out valve (ACOV)

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10
Q

A hydraulic valve that ensures correct order of movement is called a:
shuttle valve
check valve
sequence valve

A

sequence valve

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11
Q

The law which states that fluid held under pressure in a container exerts the pressure equally is:
Bramah’s law
Pascals law
Beurneulis law

A

Pascals law

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12
Q

In general, a force on a small piston will:
create a larger force on a large piston
create a smaller force on a large piston
create a negative force on a large piston

A

create a larger force on a large piston

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13
Q

In general, a force on a small piston will move a large piston:
a greater distance than the small piston moved
will not move a large piston at all
a smaller distance that the small piston moved

A

a smaller distance that the small piston moved

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14
Q

One of the main differences between the Open Circuit hydraulic system and the Closed Circuit system is:
The operating pressure is maintained at a high value at all times in the Open system, with all consumers having the same pressure available at all times.
The operating pressure is maintained at all times in the Closed system, with all consumers having the same pressure available at all times.
The operating system only pressurises when needed in the Open system, and is held at a higher value than required in the closed system.

A

The operating pressure is maintained at all times in the Closed system, with all consumers having the same pressure available at all times.

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15
Q

What controls the flow of hydraulic fluid to the pitch change mechanism of a Ram Air Turbine:
The pressure relief valve
The Tachogenerator
The governor spool valve

A

The governor spool valve

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16
Q

Filter differential pop out indicators are normally coloured:
black
green
Red

A

Red

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17
Q

Hand pumps in hydraulic systems are generally:
double acting
rotary
single acting

A

double acting

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18
Q

Overspeed of the Ram Air Turbine is prevented by:
Centrifugally operated overspeed valves
overspeed solenoids
overspeed pitots

A

Centrifugally operated overspeed valves

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19
Q

One of the functions of the accumulator is to:
Supply fluid to the pumps
Dampen out pump oscillations
Allow extra fluid capacity in the system

A

Dampen out pump oscillations

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20
Q

The purpose of a hydraulic motor is to convert energy stored in the fluid into:
rotary motion
linear motion
slow motion

A

rotary motion

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21
Q

The Aircraft hydraulic Brake control valves:
boosts hydraulic pressure
equalises the pressure to all wheels
controls the pressure according to the position of the pilots brake pedals

A

controls the pressure according to the position of the pilots brake pedals

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22
Q

The purpose of a hydraulic pump is to develop
fluid pressure
potential energy
fluid flow

A

fluid flow

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23
Q

Vegetable based hydraulic fluid is dyed
blue
red
green

A

blue

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24
Q

The main purpose of the reservoir in a hydraulic system is to:
direct fluid to the selector valves
store the fluid not in use
store the fluid under pressure as a back up in the event of pump failure

A

store the fluid not in use

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25
Q

A throttling valve is a:
pressure reducing valve
two way restrictor valve
pressure maintaining valve

A

two way restrictor valve

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26
Q

Pressurising of the hydraulic reservoirs provide:
positive displacement of fluid to pump
correct fluid level in the reservoir
system operation should the pump fail

A

positive displacement of fluid to pump

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27
Q

One reason for fitting an accumulator in a hydraulic system is to:
absorb pressure surges
minimise the possibility of pump cavitation
relieve excess pressure

A

absorb pressure surges

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28
Q

A shuttle valve is used for
maintaining fluid pressure when the main system fails
preventing loss of fluid from a leaking union
change over from main to auxiliary system in case of failure

A

change over from main to auxiliary system in case of failure

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29
Q

With no hydraulic pumps operating the system pressure indicates 60 psi, this is:
normal if there is air pressure in the reservoir
incorrect, there is a fault in the system
there is residual pressure in the accumulator from when the engine was shut down

A

there is residual pressure in the accumulator from when the engine was shut down

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30
Q

How is the engine driven hydraulic pump driven:
by the lubrication system shaft
by the accessory gearbox shaft
by the engine speed indicator output drive

A

by the accessory gearbox shaft

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31
Q

If different types of hydraulic fluid are mixed within a system, what will be the effect:
no effect
swelling of seals
the pumps will run hotter

A

swelling of seals

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32
Q

The power to move the output of an electrical hydraulic selector is obtained from:
a D.C. torquemotor
the hydraulic system
an A.C. torquemotor

A

the hydraulic system

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33
Q

The case drain fluid from the pump is:
pump cooling fluid
pressure fluid
supply fluid

A

pump cooling fluid

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34
Q

In a constant displacement type pump, how is maximum pressure controlled:
by a servo valve
by a camplate
by a pressure relief valve

A

by a pressure relief valve

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35
Q

A purpose of a ‘cut-out’ in a hydraulic system.
Option A. is to prevent creep in jack operated services which have several selected positions.
Option B. is to limit loss of fluid in the event of pipe fracture.
Option C. is to relieve the pump of load when the operation of services is complete and the accumulator charged with fluid.

A

Correct Answer is. is to relieve the pump of load when the operation of services is complete and the accumulator charged with fluid.

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36
Q

Hydraulic pressure can be restored by.
Option A. compressing the air charge in an accumulator.
Option B. the use of a pressure/heat exchanger.
Option C. compressing the fluid in a reservoir.

A

Correct Answer is. compressing the air charge in an accumulator.

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37
Q

What is the colour of the band on a hydraulic seal?.
Option A. Yellow.
Option B. Green.
Option C. White.

A

Correct Answer is. Green.

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38
Q

A maintainer valve in an hydraulic system will.
Option A. allow continued press to essential systems during times of reduced supply.
Option B. dampen pressure inputs.
Option C. maintain a high pressure to all systems.

A

Correct Answer is. allow continued press to essential systems during times of reduced supply.

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39
Q

Where is the temperature overheat switch located in a hydraulic pump?.
Option A. In the pressure line.
Option B. In the suction line.
Option C. In the case drain.

A

Correct Answer is. In the case drain.

40
Q

What happens if a component has an internal hydraulic leak?.
Option A. Fluid loss.
Option B. Increase in fluid pressure.
Option C. Increase in fluid temperature.

A

Correct Answer is. Increase in fluid temperature.
Explanation. Increase in temperature is an indication of internal leaks.

41
Q

What happens to hydraulic fluid when it is overheated?.
Option A. Increase acidity.
Option B. Increase viscosity.
Option C. Increase alkalinity.

A

Correct Answer is. Increase acidity.
Explanation. Hi acidity is a common problem revealed after an oil system analysis.

42
Q

How is the hydraulic pump depressurising solenoid actuated?.
Option A. Energised both open and closed depending on cockpit selection.
Option B. Energised Open.
Option C. Energised Closed for fail-safe.

A

Correct Answer is. Energised Closed for fail-safe.
Explanation. The depressurising valve (sometimes called an ‘offloading valve’) is energised closed, to fail-safe open.

43
Q

How do you prevent hydraulic fluid frothing?.
Option A. By pressurising.
Option B. Vent Reservoir to atmosphere.
Option C. Pass over a tray.

A

Correct Answer is. By pressurising.

44
Q

Accumulators as fitted to aircraft hydraulic systems.
Option A. are only ever used in an emergency.
Option B. store fluid under pressure.
Option C. provide additional fluid if leaks occur.

A

Correct Answer is. store fluid under pressure.

45
Q

A Skydrol hydraulic fluid seal would be made of.
Option A. natural rubber.
Option B. synthetic rubber.
Option C. butyl rubber, ethylene propylene or Teflon.

A

Correct Answer is. butyl rubber, ethylene propylene or Teflon.

46
Q

Synthetic hydraulic fluid subjected to overheating is high in.
Option A. acidity.
Option B. alkalinity.
Option C. viscosity.

A

Correct Answer is. acidity.
Explanation. Overheating causes acidity.

47
Q

A normal hydraulic system will.
Option A. show pressure and source of hydraulics.
Option B. show fluid temperature and quantity.
Option C. illuminate a light in the cockpit when the system is ready.

A

Correct Answer is. show pressure and source of hydraulics.
Explanation. Some systems show temperature, but they are not ‘normal’.

48
Q

A constant volume hydraulic system uses what to relieve pressure in system when no services are being used?.
Option A. Pressure relief valve.
Option B. Return line back to pump.
Option C. ACOV.

A

Correct Answer is. ACOV.

49
Q

The control of hydraulically powered emergency electrical generator frequency is by.
Option A. restriction valve.
Option B. angle of swashplate.
Option C. IDG.

A

Correct Answer is. angle of swashplate.

50
Q

Hydraulic systems normally operate at.
Option A. 1800 PSI.
Option B. 3000 PSI.
Option C. 300 PSI.

A

Correct Answer is. 3000 PSI.

51
Q

When flushing hydraulic systems.
Option A. flush with methylated spirit.
Option B. flush with any hydraulic oil.
Option C. flush with same hydraulic oil.

A

Correct Answer is. flush with same hydraulic oil.

52
Q

When replenishing a hydraulic system.
Option A. use any hydraulic fluid.
Option B. use any hydraulic fluid made by the same manufacturer.
Option C. use the same/correct hydraulic fluid.

A

Correct Answer is. use the same/correct hydraulic fluid.

53
Q

When replacing a flexible pipe.
Option A. do a bonding check.
Option B. tighten only hand tight.
Option C. use two spanners to stop pipe from twisting.

A

Correct Answer is. use two spanners to stop pipe from twisting.

54
Q

How do you remove air from hydraulic fluid?.
Option A. Vent to atmosphere.
Option B. Pass through a restriction.
Option C. Pass over a tray.

A

Correct Answer is. Pass over a tray.

55
Q

A pressure control relay in a hydraulic pump is.
Option A. energised to the run position.
Option B. used to prevent anything happening until there is hydraulic pressure.
Option C. de-energised to start the pump.

A

Correct Answer is. de-energised to start the pump.

56
Q

A constant delivery pump has its output varied with.
Option A. regulators.
Option B. gears.
Option C. servo pressure.

A

Correct Answer is. regulators.
Explanation. Constant delivery is constant flow rate.

57
Q

A variable angled pump starts at.
Option A. half way position.
Option B. minimum stroke.
Option C. maximum stroke.

A

Correct Answer is. maximum stroke.

58
Q

A check flow valve in a hydraulic system prevents.
Option A. pump cavitation.
Option B. reverse flow.
Option C. overpressure.

A

Correct Answer is. reverse flow.

59
Q

A duplex seal consist of.
Option A. a square section rubber ring within a steel washer.
Option B. a hard rubber square section ring with a soft rubber square section inner ring.
Option C. a rubber ‘T’ section ring sandwiched between two Teflon rings.

A

Correct Answer is. a rubber ‘T’ section ring sandwiched between two Teflon rings.

60
Q

When is an hydraulic de-pressurising valve energised?.
Option A. When selected on.
Option B. When there is sufficient hydraulic pressure available.
Option C. When selected off.

A

Correct Answer is. When selected off.

61
Q

A fixed volume axial pump contains the following rotating parts.
Option A. Drive Shaft, Swash Plate & Valve Block.
Option B. Swash Plate & Valve Block.
Option C. Drive Shaft, Swash Plate & Cylinder Block.

A

Correct Answer is. Drive Shaft, Swash Plate & Cylinder Block.

62
Q

An hydraulic closed system is one where.
Option A. pressure is maintained at the selector valves at all times.
Option B. there is no pressure at the selector valves when no functions are required.
Option C. most of the major components of the system are included in a self contained unit.

A

Correct Answer is. pressure is maintained at the selector valves at all times.

63
Q

What constitutes a hydraulic power pack?.
Option A. Variable swashplate pump.
Option B. Reservoir, pump, selector valve, filter.
Option C. Hydraulic oil accumulator.

A

Correct Answer is. Reservoir, pump, selector valve, filter.

64
Q

If an accumulator loses air pressure there will be.
Option A. rapid depressurisation of system.
Option B. pump cavitation.
Option C. rapid fluctuations of instruments.

A

Correct Answer is. rapid fluctuations of instruments.

65
Q

A marker number on a pipe indicates.
Option A. the thickness of the wall on the pipe.
Option B. the specification of the pipe throughout the pipe run.
Option C. the type of fluid used to pressure test the pipe.

A

Correct Answer is. the specification of the pipe throughout the pipe run.

66
Q

One reason for fitting an accumulator in an hydraulic system is
to.”
Option A. minimize the possibility of pump cavitation.
Option B. absorb pressure surges.
Option C. relieve excess pressure.

A

Correct Answer is. absorb pressure surges.

67
Q

A thermal relief valve is fitted to an hydraulic system to.
Option A. prevent a leak back of pressure.
Option B. prevent excess temperature.
Option C. relieve excess pressure.

A

Correct Answer is. relieve excess pressure.
Explanation. Thermal relief valves relieve the pressure build-up due to excessive temperature.

68
Q

A component in a hydraulic system which ensures instantaneous action when a service is selected is.
Option A. accumulator.
Option B. engine driven pump.
Option C. selector.

A

Correct Answer is. accumulator.

69
Q

A shuttle valve is used for.
Option A. preventing fluid loss from a leaking jack.
Option B. maintaining fluid press when the emergency system fails.
Option C. change over from main to auxiliary system in the case of failure.

A

Correct Answer is. change over from main to auxiliary system in the case of failure.

70
Q

Restrictor valves in an hydraulic system are used to.
Option A. restrict the rate of pressure build up.
Option B. control the rate of system operation.
Option C. limit the maximum pressure.

A

Correct Answer is. control the rate of system operation.

71
Q

The purpose of a mechanical sequence valve is to ensure the operation of.
Option A. landing gear and doors.
Option B. safety switches.
Option C. brake anti-skid units.

A

Correct Answer is. landing gear and doors.

72
Q

The purpose of a non-return valve is to.
Option A. direct fluid to the hydraulic actuator.
Option B. restrict the movement of components.
Option C. isolate one component from another.

A

Correct Answer is. direct fluid to the hydraulic actuator.

73
Q

The end fittings on a NRV are normally different to.
Option A. facilitate bleeding of the system.
Option B. allow a full flow from the valve.
Option C. prevent incorrect installation.

A

Correct Answer is. prevent incorrect installation.

74
Q

A hydraulic accumulator is charged with initial air pressure of 1000 PSI. When the hydraulic system pressure of 3000 PSI is reached, the air pressure is.
Option A. 4000 PSI.
Option B. 3000 PSI.
Option C. 1000 PSI.

A

Correct Answer is. 3000 PSI.

75
Q

Automatic cut-out valve hammering is caused by.
Option A. low accumulator pressure.
Option B. moisture in the fluid.
Option C. relief valve set too high.

A

Correct Answer is. low accumulator pressure.

76
Q

Hand pumps are normally single cylinder double acting because of the.
Option A. two NRVS fitted.
Option B. relief valve.
Option C. piston ram displacement.

A

Correct Answer is. two NRVS fitted.

77
Q

During a leak test of an hydraulic system, system pressure.
Option A. is not important.
Option B. must be minimum working.
Option C. must be at maximum.

A

Correct Answer is. must be at maximum.

78
Q

Constant delivery hydraulic pumps.
Option A. require an automatic cut-out valve in the system.
Option B. require an automatic cut-out valve and accumulator in the system.
Option C. are self idling.

A

Correct Answer is. require an automatic cut-out valve and accumulator in the system.

79
Q

Mechanical sequence valves are operated by.
Option A. a striker pin.
Option B. the pilot.
Option C. the operation of a NRV.

A

Correct Answer is. a striker pin.

80
Q

Pressure relay valves are fitted.
Option A. before a pressure gauge.
Option B. before a pressure sequence valve.
Option C. before a pressure relief valve.

A

Correct Answer is. before a pressure gauge.

81
Q

Before checking the initial pressure in the hydraulic accumulator.
Option A. the reservoir must be checked for correct level.
Option B. the fluid pressure must be released.
Option C. all air must be bled from the system.

A

Correct Answer is. the fluid pressure must be released.

82
Q

Hydraulic reservoirs are pressurized to.
Option A. provide a reserve of stored energy.
Option B. maintain a constant fluid level.
Option C. minimize the possibility of pump cavitation.

A

Correct Answer is. minimize the possibility of pump cavitation.

83
Q

In aircraft hydraulic systems, it is permissible to use.
Option A. only the specified fluid.
Option B. any fluid of the same specific gravity.
Option C. any hydraulic fluid available.

A

Correct Answer is. only the specified fluid.

84
Q

The essential components of a hydraulic system of the constant delivery type are an.
Option A. accumulator and automatic cut-out valve.
Option B. accumulator and shuttle valve.
Option C. accumulator and relay valve.

A

Correct Answer is. accumulator and automatic cut-out valve.

85
Q

An automatic cut-out valve will.
Option A. limit pump wear.
Option B. prevent the hydraulic lock forming.
Option C. raise fluid boiling point.

A

Correct Answer is. prevent the hydraulic lock forming.

86
Q

A maintaining valve is fitted to a hydraulic system.
Option A. to maintain a back pressure to the accumulator.
Option B. relieve excessive pressure to return.
Option C. to ensure a supply of fluid to essential services in the event of system failure.

A

Correct Answer is. to ensure a supply of fluid to essential services in the event of system failure.

87
Q

A thermal relief valve.
Option A. senses fluid temperature change.
Option B. senses fluid pressure.
Option C. provides cooling for the fluid.

A

Correct Answer is. senses fluid pressure.

88
Q

Hydraulic systems are normally flushed with.
Option A. methylated spirits.
Option B. the same type of fluid as used in the system.
Option C. any clean hydraulic fluid.

A

Correct Answer is. the same type of fluid as used in the system.

89
Q

Phosphate Ester hydraulic fluid requires which kind of seals?.
Option A. Butyl Rubber.
Option B. Synthetic Rubber.
Option C. Natural Rubber.

A

Correct Answer is. Butyl Rubber.

90
Q

A RAT hydraulic pump is for.
Option A. landing gear and auto-brake systems.
Option B. nose wheel steering.
Option C. flying controls if hydraulic power lost.

A

Correct Answer is. flying controls if hydraulic power lost.

91
Q

Hydraulic hand-pump fluid supply is taken from.
Option A. a tap into a convenient return line.
Option B. a stack pipe higher than the normal level.
Option C. the bottom of the reservoir.

A

Correct Answer is. the bottom of the reservoir.

92
Q

Hand pumps in hydraulic systems are normally.
Option A. single acting.
Option B. low pressure.
Option C. double acting.

A

Correct Answer is. double acting.

93
Q

To enable an hydraulic system to operate two components requiring different pressures.
Option A. a pressure reducing valve is used.
Option B. a pressure regulating valve is used.
Option C. a pressure relief valve is used.

A

Correct Answer is. a pressure reducing valve is used.

94
Q

The force exerted by a hydraulic cylinder is equal to.
Option A. area * volume.
Option B. area * pressure.
Option C. pressure * stroke.

A

Correct Answer is. area * pressure.

95
Q

A tandem PFCU.
Option A. has two control surfaces under its control.
Option B. has the rams parallel.
Option C. has the actuator rams co-axial.

A

Correct Answer is. has the actuator rams co-axial.

96
Q

The reason why slack must be left in a flexible hose during installation, is a flexible hose under pressure.
Option A. expands in length and diameter.
Option B. contracts in length and diameter.
Option C. contracts in length and expands in diameter.

A

Correct Answer is. contracts in length and expands in diameter.

97
Q

An automatic cut-out valve is necessary in a hydraulic system with.
Option A. a fixed volume pump.
Option B. pressures above 3000 PSI.
Option C. a variable volume pump.

A

Correct Answer is. a fixed volume pump.

Module 11B (42 decks)

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