Deck 13: Hydraulics

Question 1

Which of the following best describes what is meant by a perfect vacuum?

A) any pressure below atmospheric
B) a volume in which all matter is evacuated
C) suction side of a hydraulic circuit
D) a psia gauge reading of less than 14.7

Answer 1

B

Question 2

If you had a pressure gauge calibrated in psia that was subject only to atmospheric pressure,what would be displayed on its scale at sea level?

A) zero
B) 14.7
C) 29.8
D) 101.3

Answer 2

B

Question 3

Hydraulic pressure is used in ?

A) Brakes systems
B) Steering systems
C) Automatic transmissions
D) All of the above

Answer 3

D

Question 4

Which of the following expresses flow rate in a hydraulic circuit?

A) feet per second (fps)
B) gallons per minute (gpm)
C) feet head
D) all of the above

Question 5

On a hydraulic circuit with a reservoir vented to atmospheric pressure,which of the following best explains what moves the fluid from the reservoir to the pump inlet?

A) static head pressure from the atmosphere
B) suction at the pump inlet
C) inertia of fluid established at pump outlet
D) vortex of fluid flow through pump

Question 6

If you had a pressure gauge calibrated in psi that was subject only to atmospheric pressure,what would be displayed on its scale at sea level?

A) zero
B) 14.7
C) 29.8
D) 101.3

Question 7

Which of the following fit the description of a fluid?

A) gases
B) liquids
C) vapors
D) all of the above

Question 8

In hydraulics,what is the machine that creates the mechanical force required to rotate a pump known as?

A) lever
B) engine
C) bell crank
D) prime mover

Question 9

Which of the following hydraulics principles would describe how torque is transmitted through a torque converter?

A) hydromechanics
B) hydrostatics
C) hydrodynamics
D) hydroplaning

Question 10

If you had a tubular column of one square inch diameter that extended from sea level to 50 miles into the stratosphere,how much would the air in the tube weigh?

A) 101.3 kilograms
B) 14.7 kilograms
C) 101.3 pounds
D) 14.7 pounds

Question 11

Technician A says that an example of force is any kind of pushing effort.Technician B says that an example of force is any kind of pulling effort.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 12

Which of the following would be found in a sealed vessel that was subject to a perfect vacuum?

A) air only
B) oxygen only
C) nitrogen only
D) nothing

Question 13

Who's law states that when pressure is applied to a confined liquid,the force is applied to the area of containment will be uniform throughout?

A) Bernoulli
B) Pascal
C) Charles
D) Boyle

Question 14

Which of the following is the equation used to calculate work in hydraulic circuits?

A) force multiplied by distance
B) force divided by distance
C) area multiplied by pressure
D) area divided by pressure

Question 15

In a confined hydraulic circuit,what must happen when there is flow through the circuit?

A) pressure rise
B) pressure drop
C) fluid leakage
D) fluid pressure spikes

Question 16

How is the formula for force calculated?

A) work multiplied by area
B) power divided by area
C) pressure divided by area
D) pressure multiplied by area

Question 17

Which of the following would represent atmospheric pressure at sea level?

A) 14.7 psi
B) 29.8 inches Hg
C) 101.3 kPa
D) all of the above

Question 18

Technician A says that all gases can be classified as fluids.Technician B says that all liquids can be classified as fluids.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 19

Technician A says that a reading of one psi on a pressure gauge is equal to approximately 2-inches of Hg (mercury)measured on a manometer.Technician B says that one inch of Hg is equivalent to approximately 2-inches of H₂0 on a manometer.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 20

Which of the following hydraulic principles would best apply to the operation of a truck wet line kit?

A) hydromechanics
B) hydrostatics
C) hydroponics
D) hydrodynamics

Question 21

What is used to apply force to an accumulator in a hydraulic circuit?

A) spring force
B) weight force
C) gas pressure
D) all of the above

Question 22

Technician A says that as pump discharge pressure increases,internal leakage decreases.Technician B says that internal leakage is caused by back pressure.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 23

Technician A says that most hydraulic circuits use positive displacement pumps.Technician B says that pressure only results in a hydraulic circuit when some resistance to flow is provided.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 24

Which of the following truck hydraulic systems would use an open circuit principle?

A) garbage packer cylinders
B) tail lift gate
C) dump ram
D) power-assisted steering

Question 25

Where would you most likely find a hydraulic vane pump in a heavy-duty truck?

A) cab lift hydraulics
B) power-assisted steering circuit
C) engine coolant pump
D) fuel transfer pump

Question 26

Which of the following pumps would usually be classified as non-positive displacement?

A) plunger
B) wobble plate
C) gear
D) engine coolant pump

Question 27

Technician A says that changing the swash angle in a swashplate pump varies the displacement of the pump.Technician B says that some swashplate pumps are fixed displacement.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 28

Where might you find a cam-actuated,radial piston pump on a highway truck?

A) fuel transfer pump
B) common-rail,diesel fuel injection system
C) PTO wet line kit
D) cab-lift hydraulics

Question 29

What is an application of a counterbalance valve?

A) maintaining back pressure
B) acts as a relief valve
C) pressure reduction
D) safety pop-off

Question 30

What is the term used to describe the streamlining of flow through a hydraulic circuit?

A) boundary lubrication
B) hydrodynamics
C) laminar flow
D) pressure wave reflection

Question 31

What type of valve is often used to control the speed of an actuator?

A) pilot operated relief
B) flow control
C) pressure control
D) counter balance

Question 32

Which of the following can be used as directional control valves?

A) check
B) pilot
C) spool
D) all of the above

Question 33

Technician A says that a swashplate pump is sometimes described as a wobble plate.Technician B says that pumping action in a swashplate pump is created when the swashplate rotates.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 34

In a typical vane type pump,what does the rotor turn within?

A) barrel
B) swash cylinder
C) cam ring
D) bushing

Question 35

Technician A says that a vane pump is classified as non-positive.Technician B says that a gear pump uses a positive displacement pumping principle.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 36

Technician A says that accumulators are used to store potential energy in a hydraulic circuit.Technician B says that accumulators can be used to dampen shock and buffer sudden pressure rises.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 37

Which of the following will have most influence in determining the volume of oil moved through a pump described as fixed displacement?

A) inlet flow area
B) outlet flow area
C) restriction downstream from outlet
D) rotational speed of pump

Question 38

Technician A says that in an open center circuit the hydraulic pump is rested (unloaded)when flow is not required by the actuator.Technician B says that in a closed-center circuit,the hydraulic pump runs continuously.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 39

What do car carrier trailers usually use to actuate several separate hydraulic circuits?

A) a battery-driven electric motor
B) several battery-driven electric motors
C) engine-driven PTO pump
D) transmission-driven PTO pump

Question 40

Technician A says that in an unbalanced vane pump,there is usually just a single outlet port.Technician B says that a balanced vane pump will usually have a pair of inlet and a pair of outlet ports.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 41

Which of the following will have most influence over the rpm of a hydraulic pump?

A) output flow of oil
B) pressure of oil
C) input flow of oil
D) load applied to pump output

Question 42

Technician A says that spool valves may be controlled hydraulically or electrically.Technician B says that spool valves can be controlled manually or pneumatically.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 43

What is the usual cause of a hydraulic oil that has a milky appearance?

A) aeration
B) contamination with engine oil
C) contamination with water
D) chemical breakdown

Question 44

Technician A says that a single acting cylinder can have a wet side and a dry side.Technician B says that an example of a double-acting cylinder would be the ram used to raise a dump truck box.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 45

What type of valve is used as the primary directional control valve in most hydraulic circuits?

A) ball and poppet
B) gate valve
C) spool valve
D) pressure relief valve

Question 46

What does a hydraulic analyzer test?

A) circuit flow
B) peak pressure
C) circuit leakage
D) all of the above

Question 47

Technician A says that pump flow at maximum pressure should be at least 75% of the flow measured at 0 pressure in simple hydraulic cylinder circuit.Technician B says that one way of checking internal leakage in a simple hydraulic cylinder circuit is to disconnect the return hose when the cylinder is actuated,and watch for leakage.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 48

What is the nominal diameter of hydraulic hose rated at #6 dash?

A) 1/4 inch
B) 3/8 inch
C) 1/2 inch
D) 5/8 inch

Question 49

Technician A says that when coupling hydraulic fittings,pipe seal compound should usually be applied to female ends only.Technician A says that when final torquing hydraulic fittings,two wrenches should always be used.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B

Question 50

Which of the following terms would properly define a hydraulic cylinder?

A) rotary actuator
B) linear actuator
C) linear motor
D) linear pump

Question 51

Which of the following types of hydraulic hose should be used to sustain the highest pressures and surge spikes?

A) fabric braid
B) single wire braid
C) multiple wire braid
D) spiral wire braid

Question 52

Technician A says that ISO 32 is the most commonly used viscosity grade for hydraulic fluids.Technician B says that ISO 32 is equivalent to SAE 20 grade.Who is correct?

A) Technician A only
B) Technician B only
C) Both A and B
D) Neither A nor B