Practice Questions Flashcards by user delete

The displacement of a pump refers to?

The discharge rate per minute
Discharge rate per hour
Discharge rate per revolution
Discharge rate per cycle

Discharge rate per revolution

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A Gear type hydraulic motor

Is not reversible
Has more shaft seal protection due to dual rotation
Is similar to a gear pump but contains three pressure plates
Will damage the shaft seal if reversed

Has more shaft seal protection due to dual rotation

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A piston pump that has the pistons parallel to the drive shaft is called?

Non positive displacement pump
Axial Pump
Radial Pump
Bent Axis Pump

Axial Pump

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Tandem section gear pumps

Always use two sections of equal size
are two pumps mounted together
always contain two inlets and outlets
Use adjustable gear sections to control output

Are two pumps mounted together

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Variable Displacement pumps are

The volume can be altered per cycle
The speed of the pump can be altered
The pressure can be altered
The flow rate is fixed

The volume can be altered per cycle

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Vane pumps may be

Positive displacement
Fixed displacement
Variable Displacement
All of the above

All of the above

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The pressure that will just open a valve is called

Opening pressure
Main pressure
high pressure
cracking pressure

Cracking pressure

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A valve section regenerative position

Allows a fast drop of crawler loader boom
Supplies the oil to rear mounted equipment
Connects the becket cylinder rod ends to the head ends for a fast dump
Returns the bucket cutting edge to a digging position

Connects the bucket cylinder rod ends to the head ends for a fast dump

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A spool valve is used to control

Direction of oil flow
System Pressure
Accumulator pressure
None of the above

Accumulator Pressure

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When installing hydraulic pumps, the inlet lines should be kept?

As long as possible
Have at least one bend to relieve pressure
As short and as straight as possible
In a slight curve to prevent cavitation

As short and as straight as possible

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A Pump of unbalanced design is so named because

Its disproportioned weight will cause it to vibrate
There is a side load on the rotor and drive shaft
The design is not balanced to system needs
None of the above

There is side load on the rotor and driveshaft

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Gear pumps

Use pressurized wear plates
Are variable displacement
Are always non positive displacement
Always use tapered bearings on the shaft

Use pressurized wear plates

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What is the purpose of a cushion in a cylinder?

Provide a reserve of air
Eliminate fluctuation of pressure
Reduce mechanical shock
Prevent back pressure

Reduce mechanical shock

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What is used for overload protection in a hydraulic system

The pump
The directional Control
the pressure control
The actuator

The pressure control

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In any hydraulic circuit if only the actuator area is changed

the speed of operation will be changed
the minimum force exerted will be changed
the maximum pressure obtainable will be changed
the input horsepower will be changed

The speed of operation will be changed

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Leakage from the housing drain port on axial piston pumps may not be caused by

Damaged drive shaft seal
Scored valve plate or cylinder block face
Cylinder Block Lifting
Return oil from a yoke control unit

Damaged drive shaft seal

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In a variable radial piston pump, what controls the stroke of the pistons?

System Pressure
Case Pressure
Spring Pressure
Centrifugal Force

System Pressure

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The maximum safe working pressure of a hydraulic system is reduced by

Installing a smaller pump
Changing relief valve setting
Installing a check valve
Installing a smaller motor

Changing a relief valve setting

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If two directional control valves are connected in series in a hydraulic system

Both valves must be operated simultaneously
only one can be operated at a time
either one or the other or both can be operated
can not be hooked in series

Either one or the other or both can be operated

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A detent mechanism is used to

Alert the operator be feel that they are in a certain position
Hold the spool in certain positions
hold the auxiliary valve in the raise position
none of the above

Hold the spool in certain positions

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Fixed displacement motors have

Variable speed, variable torque
fixed torque fixed speed
fixed torque fixed displacement
fixed torque and speed controlled by system

Fixed torque

Fixed displacement

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A stop tube

Allows fluid to move in one direction only
overrides pressure relief in case of reservoir loss
minimizes actuator side loads
limits swash plate angle in an axial piston pump

Minimizes actuator side loads

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A valve that is used to coordinate the times of actuation is

Pressure Relief
Unloading Valve
Sequence Valve
Pressure Reducing

Sequence Valve

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Hydraulic motors may be of the style

Variable speed
Fixed speed
Reversible speed
All of the above

All of the above

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The purpose of a lift check is To allow a fast drop of a cylinder Prevent cavitation of the pump Trap flow spikes in the valve Stop a function from settling just before it starts to move

Stop a function from settling just before it starts to move

Piston type pumps Have the lowest volumetric efficiency May require supercharging in some applications if variable displacement should not be operated too near the centre position when the inlet is pressurized Are not used in high pressure applications

May require supercharging in some applications

A style of pump that has a device called a crescent is a? Gear Vane Piston Centrifugal

Gear Pump

The type of pump that cannot be made variable is? Gear Vane Piston All of the above

Gear Pump

Bent Axis Pump is a? Gear Vane Piston Centrifugal

Piston Pump

If you work on or replace a directional control valve you must Be careful when tightening he mounting bolts Drain and replace the hydraulic fluid Also replace the pump Use a lower viscosity oil during the break in period

Be careful when tightening the mounting bolts

The difference between the cracking pressure and the full flow is called Pressure reducing Pressure override Pressure Relief none of the above

Pressure override

Pressure compensated axial piston pumps have the following characteristics Their displacement is automatically changed to meet system demands They generate more heat in a system Always require another relief valve Displacement is controlled on both sides of the yoke position

Their displacement is automatically changed to meet system demands

A directional control valve is rated at 3/4", this means that the valve is 3/4" High Mounted with 3/4" Bolts To be piped with a 3/4" Pipe All of the above

To be piped with a 3/4" Pipe

When a restriction is placed on the return line of an advancing Cylinder, the results would be System pressure on piston decreases Tank PRessure increased Force output of cylinder decreases Force output of cylinder increases

Force output of cylinder decreases

The results of closing off the discharge side of a positive displacement pump would be? Pump motor would stall pump casing would split pump discharge line would burst all of the above

All of the above

In a valve section float position The pump is connected to the piston end of a cylinder The pump is connected to the rod end of a cylinder Work ports, pump supply and return are connected so the cylinder may move freely Both ends of the cylinder area are connected together to increase its extension speed

Work ports, pump supply and return are connected so the cylinder may move freely

An anti cavitation check valve Stops a function from settling just before it starts to move Opens to allow oil to fill an actuator when the pump supply is unavailable Limits pressure peaks in the control valve then the circuit relief valve sticks B and C

Opens to allow oil to fill an actuator when the pump supply is unavailable

A Minimum starting speed of 600 RPM is recommended for vane pumps To avoid cavitation to push the vanes into the rotor To start pumping action To prevent aeration

To start pumping action

Vane motors used on most industrial equipment Do not contain spring loaded vanes never use double edged vanes usually use a replaceable cartridge all of the above

Usually use a replaceable cartridge

A double vane cylinder exhausts oil through External Drain lines one way check valves internal passages directional control valves

Internal Passages

When two identical motors are connected in series they will develop Same torque but different speeds Same torque same speed Different torques same speed Different torques different speeds

Different torques | Same Speed

if a system is unable to function with full force the problem could be caused by broken pump drive shaft low pump flow relief valve set too low none of the above

Relief valve set too low

Shock Loads imposed upon motors may be safeguarded by? Deceleration valves Pressure relief valves Accumulators All of the above

All of the above

A valve used to divery oil to alternate end of a cylinder is Pressure reducing valve Check valve Four Way Valve Quick Drop Valve

Quick drop valve

Methods of varying the displacement of variable pumps is? Moving the pressure ring in respect to the rotor Varying the angle of bent axis pumps Varying the stroke of piston pumps All of the above

All of the above

Gear pumps are Fixed displacement Hydraulically unbalanced Positive Displacement All of the above

All of the above

An anti cavitation valve Stops a function from settling just before it starts to move Opens to allow oil to fill a cylinder when the pump supply is unavailable or inadequate Limits pressure peaks in the control valve when the system relief valve sticks B and C

Opens to allow oil to fill a cylinder when the pump supply is unavailable or inadequate

Centrifugal pumps are classed as? Rotary pumps Non positive displacement pumps Axial Flow Pumps Ram Pumps

Non Positive Displacement Pumps

According to your module a simple check valve can be considered a Pressure Relief Valve Directional Control Valve None of the above Both A and B

Directional control valve

Hydraulic pumps are usually rated in terms of their? Mechanical and Hydraulic output Volumetric input and pressure Volumetric output and pressure Mechanical input and pressure

Volumetric output and pressure

A defective shaft seal in an internally drained vane pump will Leak oil when the pump is running Have no effect on pump operation keeps air from entering the system Make the pump noisy

Makes the pump noisy

Directional Control Valves may be operated Manually Mechanically Electrically All of the above

All of the above

The relief valve in a hydraulic system relieves excess pressure by Venting to atmosphere By-passing the fluid to the reservoir By-passing the fluid to the pump discharge Venting to the fluid cooler

Venting to the fluid cooler

When a lower than main pressure is required in a secondary circuit the type of valve that would be used is a Relief valve sequence valve Check valve Pressure reducing valve

Pressure reducing valve

To vent a pressure relief valve means that The valve is uncoupled from the circuit The valves pilot pressure is increased The valves pilot pressure is decreased The valves pilot pressure is returned to tank

The valves pilot pressure is returned to tank.

An unloader valve is always set at least 150 psi above relief is held open by spring pressure is the only valve that can replace a relief valve controls slowing down of the load

Is the only valve that can replace a relief valve

The speed at which a cylinder moves is controlled by? The pump the pressure control the pump or flow control the flow control

The pump or flow control

Reversing drive shaft rotation of axial piston pumps May require a relative change in the valve plate or sub assembly Will change oil flow direction through the pump unless yoke is moved to opposite side of centre Should not be tried ever Can only be done on variable displacement units

May require a relative change in the valve plate or sub assembly

The swash plate pump is a? Gear Vane Piston Centrifugal

Piston Pump

The time taken for a cylinder to make a definite stroke is dependent upon the Pump output and piston area pump pressure output and length of stroke pump volume output stroke length and piston area pump volume output and length of stroke

Pump volume output stroke length and piston area

Flow direction through a variable displacement piston type pump is affected by Direction of drive rotation Angle of degrees of yoke displacement from centre position Yoke position one side to the other of centre Drive shaft speed in RPM

Yoke position one side to the other of centre

Single section gear pumps do not contain a driving gear contain an idler gear contain pressure plate have external drains

Have external drains

Which of the following pumps could not be operated as a variable displacement pump with a fixed speed? Vane Radial Piston Gear Axial Piston

Gear Pump

Circular grooves cut around the valve spool Serve no purpose Allow lubrication and sealing of the spool allow metering of a function Match the edges of the bore lands to decrease pressure peaks

Allow lubrication and sealing of the spool

A Fixed Displacement Motor Provides a variable torque regardless of speed Provides constant torque regardless of pressure May be reversed by reversing oil flow to and from motor Should not be used in a closed loop

May be reversed by reversing oil flow to and from motor

When it is required to allow flow in one direction and prevent flow in the opposite direction we would use a Relief Valve Sequence Valve Check Valve Reducing Valve

Check Valve

The main pressure relief valve in a hydraulic system is located in the main line to the cylinder in the oil return line in the pump suction line between the pump and the control valve

Between the pump and the control valve

Air in a hydraulic pump causes? Smoother operation Cooler operation Better operation Noisy operation

Noisy Operation

What type of valve is used to control a double acting cylinder? Two Way Valve Glove Valve Four Way Valve Three Way Valve

Four way Valve

Oil flow through an open centre control valve when in the neutral position Returns to the reservoir is at a pressure as low as possible is routed through the valve so that all spools can recieve oil All of the above

All of the above

A Meter in valve is classified as Pressure control device Flow control device Both flow and pressure control device None of the above

Flow control device

Hydraulic pumps are devices used to? Convert mechanical energy to electrical Convert Hydraulic energy to electrical Convert Hydraulic energy to mechanical energy Convert mechanical energy into hydraulic energy

Convert mechanical energy into hydraulic energy

Balanced Vane Pumps rated output flow in fallons per minute is determined by Rise in cam ring Width of pumping cartridge Drive shaft rated speed All of the above

All of the above

Where fixed output pumps are used, a method of controlling the speed of actuators is by means of? Meter in valves Meter out valves Bleed off valves All of the above

All of the above

A Non positive displacement pump refers to a type of pump Where the inlet must be higher than the outlet Where the outlet must be lower than the inlet Which will slip the liquid at a certain pressure Which will not slip the liquid at a certain pressure

Which will slip the liquid at a certain pressure

A Pressure relief valve will operate because Pressure are equal over equal areas Pressures are unequal over unequal areas Pressures are unequal over equal areas A spring setting has been reached or overcome

A spring setting has been reached or overcome

A pump that could be used without a pressure relief valve is? vane pump fixed displacement Manually controlled variable displacement vane pump Fixed displacement Gear Pump Pressure Compensated, Variable displacement, Piston Pump

Pressure Compensated, Variable Displacement Piston Pump

A Hydraulic cylinder is known as Torque Converter Rotary Actuator Linear Actuator All the above

Linear Actuator

As the speed at which a pump is driven changes Its displacement changes its pressure changes its swash plate angle changes its volume changes

Its volume changes

A Directional control valve is categorized in two types Low and medium pressure medium and high pressure Spool and Rotary Check and Relief

Spool and rotary

The purpose of the swash plate in an axial piston pump is to adjust pump pressure to open and close the discharge ports Change pump displacement Change pump speed

Change Pump Displacement

Horsepower required at 83% to drive a hydraulic pump is? Gallons Per Min X PSI X 0.000583 Gallons Per Min X PSI X 0.00583 Gallons Per Min X PSI X 0.007 Gallong Per Min X PSI X 0.0007

All of the above

A Power beyond feature Allows a second control valve to receive oil when the system control is in neutral Allows a second control valve to receive oil through the main system control valve at all times Supplies pressure oil to the crawler dozer selected valve None of the above

Allows a second control valve to receive oil when the system control is in neutral

Two gear pumps placed in series will Affect the pressure Affect the flow Not work unless mounted within 2" of tank None of the above

Affects the pressure

A Piston pump that has the pistons arranged at right angles to the drive shaft is called? Non Positive Displacement Pump Axial Pump Radial Pump Bent Axis Pump

Radial Pump

A Positive displacement pump refers to a type of pump where? The liquid is discharged by a flexible delivery hose The inlet of the pump is sealed from pump discharge The inlet of the pump is a flexible hose The inlet is not sealed from the outlet

The inlet of the pump is sealed from pump discharge

Single direction hydraulic motor is usually controlled by Two way two position Two way four position Four way two position Four way four position

Four way | Two Position

When two identical hydraulic motors on the same output shaft are connected in parallel with each other they will develop Twice the speed and twice the torque Half the speed and half the torque Twice speed half torque Half speed Twice torque

Half the speed | Twice the Torque

When a telescoping cylinder actuates it usually has The smallest diameter piston first The largest diameter piston first All the pistons at the same time None of the above

The largest piston first

When it is required to allow a pump to run when the system is not being used, it is useful to fit a ___________ valve in the system Relief Sequence Unloading Reducing

Unloading

Jerky or erratic motion in a hydraulic cylinder is usually due to Presence of water in system Presence of air in system presence of oil in system synthetic fluids are being used

Presence of water in system

An accepted point of control valve leakage is Between the valve spool and its bore relief valve seats anti cavitation check valve seats circuit relief valve o rings

Between the valve spool and its bore

On a axial piston pump, which statement does not apply? Excessive valve plate or cylinder block wear may cause cylinder block lift Replenishing pumps are required on all piston unit circuits The housing drain port should be piped in such a way that the case is always full of oil The housing or case of a piston unit should be filled with oil before it is operated

Replenishing pumps are required on all piston unit circuits

A reversible hydraulic motor that is required to coast or free wheel in the neutral position is usually controlled by Three position, four way open centre valve Four position, four way closed centre valve Four position, three way tandem centre valve Three position, four way tandem centre valve

Three position Four way Open centre valve

The force output of a conventional cylinder is the greatest when The piston is advancing the piston is retracting the cylinder is mounted horizantally the cylinder is mounted vertically

The piston is advancing

The volumetric efficiency of a vane pump Increases with an increase in drive shaft RPM within recommended operation range. remains constant under all operating conditions decreases as oil temperature decreases

Increases with an increase in drive shaft RPM within

Delivery in a Gallons per minute of a variable displacement piston type pump is affected by? Direction of driveshaft rotation Angle of degrees of yoke displacement from centre position on the same side Yoke position, one side or other of centre on same angle The size of the drain line hose

Angle of degrees of yoke displacement from centre position on the same side

A restricted hydraulic pump suction line Cut down pump oil intake without damage Damages the pump Causes excessive oil back pressure Blow out the filter gasket

Damages the pump

Notches or holes in a valve spool land Allow the operator to precisely meter or feather oil to a cylinder Restrict the flow of oil to a circuit relief valve Allows the gradual stoppage of oil through the valve center which limits pressure peaks All of the above

Allow the operator to previsely meter or feather oil to a cylinder

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