Hydraulics 1

The difference between an unbalanced vane pump and a balanced vane pump is the

direction of rotation.

type of oil used.

inlet and outlet vanes.

number of inlet and outlet ports.

Correct! Wrong!

Cavitation could occur when

engine speed is too low.

system pressure is adjusted too high.

return line filters are plugged.

oil viscosity is too high.

Correct! Wrong!

A pneumatic accumulator is pre-charged with

argon

air

nitrogen

oxygen

Correct! Wrong!

An open center system can best be described as one in which

pump oil flow is not circulated until a demand is imposed with operator controls.

pump oil flow recirculates freely to the pump inlet with controls in the neutral position.

pump oil flow is not unloaded to the reservoir in the neutral position.

the hydraulic storage tank does not have filters inside the tank.

Correct! Wrong!

A four connection (four way) spool valve is used in conjunction with a

double acting cylinder.

single acting cylinder.

telescoping ram.

ram type cylinder.

Correct! Wrong!

Viscosity can best be describe by

a small fluctuation of fluid pressures.

a small amount of fluid flow.

the velocity of fluid flow.

the resistance to fluid flow.

Correct! Wrong!

The inlet hole size of a hydraulic pump should

match the driven end of the pump.

be larger than the outlet.

be smaller than the outlet.

have different style threads or fittings than the outlet.

Correct! Wrong!

The force developed by a cylinder is calculated by

pressure times the piston area.

pressure times the cylinder length.

Correct! Wrong!

The most likely cause of a decreased hydraulic actuator speed would be

low oil level.

lack of pump pressure.

decreased oil flow.

excessive pump pressure.

Correct! Wrong!

Hose #SAE100R2AT-8. The dash number used for sizing hydraulic hose refers to its inner diameter in

8ths of an inch.

16ths of an inch.

32nds of an inch.

64ths of an inch.

Correct! Wrong!

When making up a hose that requires the end to be skived to install the replaceable fitting, the amount skived is

two times the diameter of the fitting.

1/2 diameter of the hose.

the length up to the notch on the fitting socket.

the full length of the fitting socket.

Correct! Wrong!

When flow and pressure testing a piece of equipment, the flow rate is best defined as

a measure of the volume of fluid that passes a given point in a given time.

a measure of the speed of fluid that passes a given point in a given time.

the average speed of a fluid past a given point.

a rating of the viscosity of hydraulic oil while in motion past a given point.

Correct! Wrong!

A cylinder tends to creep down when stopped in mid-stroke. The control valve checked out as operational and there is no external leakage. The next thing to check for would be

high viscosity oil.

internal leakage.

low viscosity oil.

an accumulator problem.

Correct! Wrong!

Before a hydraulic system is ready to be worked on, the mechanic must

shut down the engine,

lower all implements to the ground.

relieve all possible pressure in the system.

all of the above.

Correct! Wrong!

To detect pin-hole leaks in hydraulic lines, you should

listen for a squealing sound.

place a piece of cardboard or paper over the suspected area.

pressure test the system.

run system at maximum pressure.

Correct! Wrong!

When the fluid in a hydraulic system appears gray and milky, the problem is likely to be

water in the system.

no problem, it is normal.

excessive pressure.

excessive temperature.

Correct! Wrong!

When replacing a hydraulic pump you should

make certain the new pump has the same rotation, flow and pressure ratings.

make sure the reservoir meets all the pump''s pressure demands.

pour oil into the outlet of the pump to pre-charge and ensure initial lubrication.

all the above are correct.

Correct! Wrong!

Hydraulics is defined as the use of

a gas under pressure.

a liquid under pressure.

a gas, air mixture under pressure.

a liquid, air mixture under pressure.

Correct! Wrong!

Tubing is sized or gauged by its

inside diameter.

outside diameter.

ID and wall thickness.

OD and wall thickness.

Correct! Wrong!

Upon inspection of a failed hose, it is found that the inner core is cracked and the hose is hard and stiff. The probable cause of failure would be

fluid incompatibility.

excessive heat.

high frequency pressure impulses.

hose bent too tightly.

Correct! Wrong!

A truck owner complains that his power steering works fine but is overheating. The oil level is correct and the fluid appears clean and clear. What would you do next?

change the pump, and the problem will go away.

check the system pressure in the neutral position.

check to see if the relief valve set pressure is too high.

check all hoses for heat damage.

Correct! Wrong!

One of the basic principles which makes hydraulic action almost instantaneous is that liquid is:

compressible, transmits power by compressing.

non-compressible, applies pressure in all directions.

can be pumped and directed to do work via simple hoses.

not subject to freezing in cold weather and is easily warmed when worked.

Correct! Wrong!

A double acting cylinder is a device that converts fluid power into

linear motion in one direction.

linear motion in two directions.

rotary motion in one direction.

rotary motion in two directions.

Correct! Wrong!

Hydraulic pumps are rated in terms of

pressure, speed and gear size.

volume at a specified RPM and working pressure.

watts of power at a specified RPM.

volume measured in litres per hour.

Correct! Wrong!

The pressure setting of the relief valve is controlled by a

spring.

control lever setting.

a signal pressure from the oil system actuating on a diaphram.

technician that assembled it to the specs at the factory.

Correct! Wrong!

Directional control valves

direct hydraulic fluid to actuator.

direct hydraulic fluid to pump.

control system pressure.

control hydraulic fluid to pump inlet.

Correct! Wrong!

A hydraulic motor is driven

by fluid under pressure.

mechanically to produce fluid flow.

the same as a hydraulic pump.

mechanically and controlled hydraulically.

Correct! Wrong!

The most frequent cause of hydraulic pump failure is the use of dirty or poor quality oil.

True

False

Correct! Wrong!

CAVITATION is the mixing of water and oil.

True

False

Correct! Wrong!

Water in hydraulic oil will give the oil a clear look.

True

False

Correct! Wrong!

A plugged reservoir air vent may cause the hydraulic pump to make a noise.

True

False

Correct! Wrong!

An orifice creates a pressure drop in the hydraulic circuit.

True

False

Correct! Wrong!

If the down stream side of an orifice is blocked, the pressure will equalize on each side of the orifice.

True

False

Correct! Wrong!

Slight leakage at a dynamic seal is permissible for seal lubrication.

True

False

Correct! Wrong!

Air in the system will cause the system to operate slowly.

True

False

Correct! Wrong!

Low oil level could cause foaming of oil in the hydraulic system.

True

False

Correct! Wrong!

Dirt in the relief valves will cause high oil pressure.

True

False

Correct! Wrong!

One disadvantage of an engineered hydraulic system is that it is subject to leaks from high pressure and from shock loading.

True

False

Correct! Wrong!

An accumulator may be used in a system to store energy.

True

False

Correct! Wrong!

A good safety practice to follow when you begin any troubleshooting or service work on a hydraulic system is to have a container to catch hydraulic fluid.

True

False

Correct! Wrong!

If you are working on equipment manufactured by Caterpillar, it is valid to assume that the hydraulic components will be standard Caterpillar components.

True

False

Correct! Wrong!

On a troubleshooting job, why would it be important to take mechanical drawings for a piece of equipment as well as the hydraulic schematic?

to help identify the piece of equipment.

to show others you are well prepared.

to help identify the precise location of components.

to help verify test results and normal operation.

Correct! Wrong!

Cause of a power source problem might well be the fault of

pump, motor, directional control valve.

engine, pump, drive.

pump, motor, actuator.

pump, actuator, directional control valve.

Correct! Wrong!

When using the flow meter to test the pump, connect the outlet port of the tester to the pressure line.

True

False

Correct! Wrong!

Most flow meters test for

fluid flow.

fluid flow and temperature.

fluid flow, temperature and cycle times.

fluid flow, temperature and pressure.

Correct! Wrong!

Flow meters have a load valve on them. Before starting the equipment to run tests, the load valve should be

open

closed

it depends on what you are testing for.

it can be left half open.

Correct! Wrong!

On most pumps, satisfactory pump flow at maximum pressure should be at least as high as

55% of flow at zero pressure.

65% of flow at zero pressure.

75% of flow at zero pressure.

85% of flow at zero pressure.

Correct! Wrong!

If a load drops when the control valve is in neutral position, it might be caused by

control valve not centering properly.

oil leaking past cylinder packings or O-rings.

oil leaking past control valve or relief valve.

all of the above.

Correct! Wrong!

The most reliable source of information regarding the tests and specifications for a given piece of equipment is the

equipment operator.

equipment sales representative.

equipment technical manual.

service manager.

Correct! Wrong!

If a pump is cavitating, it may be an indication of

a clogged inlet filter.

an improperly installed canister filter.

a damaged filter O-ring.

all of the above.

Correct! Wrong!

The difference between an unbalanced vane pump and a balanced vane pump is the

Cavitation could occur when

A pneumatic accumulator is pre-charged with

An open center system can best be described as one in which

A four connection (four way) spool valve is used in conjunction with a

Viscosity can best be describe by

The inlet hole size of a hydraulic pump should

The force developed by a cylinder is calculated by

The most likely cause of a decreased hydraulic actuator speed would be

Hose #SAE100R2AT-8. The dash number used for sizing hydraulic hose refers to its inner diameter in

When making up a hose that requires the end to be skived to install the replaceable fitting, the amount skived is

When flow and pressure testing a piece of equipment, the flow rate is best defined as

A cylinder tends to creep down when stopped in mid-stroke. The control valve checked out as operational and there is no external leakage. The next thing to check for would be

Before a hydraulic system is ready to be worked on, the mechanic must

To detect pin-hole leaks in hydraulic lines, you should

When the fluid in a hydraulic system appears gray and milky, the problem is likely to be

When replacing a hydraulic pump you should

Hydraulics is defined as the use of

Tubing is sized or gauged by its

Upon inspection of a failed hose, it is found that the inner core is cracked and the hose is hard and stiff. The probable cause of failure would be

A truck owner complains that his power steering works fine but is overheating. The oil level is correct and the fluid appears clean and clear. What would you do next?

One of the basic principles which makes hydraulic action almost instantaneous is that liquid is:

A double acting cylinder is a device that converts fluid power into

Hydraulic pumps are rated in terms of

The pressure setting of the relief valve is controlled by a

Directional control valves

A hydraulic motor is driven

The most frequent cause of hydraulic pump failure is the use of dirty or poor quality oil.

CAVITATION is the mixing of water and oil.

Water in hydraulic oil will give the oil a clear look.

A plugged reservoir air vent may cause the hydraulic pump to make a noise.

An orifice creates a pressure drop in the hydraulic circuit.

If the down stream side of an orifice is blocked, the pressure will equalize on each side of the orifice.

Slight leakage at a dynamic seal is permissible for seal lubrication.

Air in the system will cause the system to operate slowly.

Low oil level could cause foaming of oil in the hydraulic system.

Dirt in the relief valves will cause high oil pressure.

One disadvantage of an engineered hydraulic system is that it is subject to leaks from high pressure and from shock loading.

An accumulator may be used in a system to store energy.

A good safety practice to follow when you begin any troubleshooting or service work on a hydraulic system is to have a container to catch hydraulic fluid.

If you are working on equipment manufactured by Caterpillar, it is valid to assume that the hydraulic components will be standard Caterpillar components.

On a troubleshooting job, why would it be important to take mechanical drawings for a piece of equipment as well as the hydraulic schematic?

Cause of a power source problem might well be the fault of

When using the flow meter to test the pump, connect the outlet port of the tester to the pressure line.

Most flow meters test for

Flow meters have a load valve on them. Before starting the equipment to run tests, the load valve should be

On most pumps, satisfactory pump flow at maximum pressure should be at least as high as

If a load drops when the control valve is in neutral position, it might be caused by

The most reliable source of information regarding the tests and specifications for a given piece of equipment is the

If a pump is cavitating, it may be an indication of

Success!

Heavy-Duty Mechanic - Trucks & Equipment