Question 1

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

Accepted Answer

All of the above methods (spring force, weight force, and gas pressure) can be used to apply force to an accumulator in a hydraulic circuit, depending on the specific design and requirements of the system.

Question 2

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?

Accepted Answer

Technician B is correct because internal leakage in a pump system is indeed caused by back pressure, which is the resistance to flow within the system. Technician A is incorrect because as pump discharge pressure increases, internal leakage typically increases due to the higher pressure differential across the pump components, leading to more leakage paths.

Question 3

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?

Accepted Answer

Both statements are correct. Most hydraulic circuits indeed use positive displacement pumps because they can efficiently maintain the flow necessary for the system's operation. Technician B is also correct in stating that pressure in a hydraulic circuit only results when there is some form of resistance to flow, which is fundamental to how hydraulic systems operate.

Question 4

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

Accepted Answer

Power-assisted steering systems typically use an open circuit hydraulic system, where the fluid is continuously circulated and pressure is only applied when steering assistance is needed.

Question 5

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

Accepted Answer

Hydraulic vane pumps are commonly used in power-assisted steering circuits of heavy-duty trucks to provide the necessary hydraulic pressure for steering assistance, enhancing the driver's ability to steer the vehicle.

Question 6

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

Accepted Answer

Non-positive displacement pumps, such as engine coolant pumps, operate by imparting velocity to the fluid; they do not trap a fixed volume of fluid before forcing it out, unlike positive displacement pumps (e.g., plunger, wobble plate, and gear pumps).

Question 7

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?

Accepted Answer

Changing the swash angle in a swashplate pump indeed varies the displacement of the pump, which is what Technician A states. Some swashplate pumps have a fixed displacement, meaning their swash angle and, consequently, their displacement cannot be adjusted, which is what Technician B states. Therefore, both technicians are correct.

Question 8

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

Accepted Answer

Cam-actuated, radial piston pumps are commonly used in high-pressure applications such as common-rail, diesel fuel injection systems to deliver fuel at high pressures required for modern diesel engines.

Question 9

What is an application of a counterbalance valve?

Accepted Answer

Counterbalance valves are used to maintain back pressure in hydraulic systems to prevent the load from free falling. They help in controlling the motion of a load when directional control valves are opened.

Question 10

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

Accepted Answer

Laminar flow describes the smooth, orderly movement of fluid, which is essential for streamlining flow through a hydraulic circuit, minimizing turbulence and resistance.

Question 11

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

Accepted Answer

Flow control valves are specifically designed to regulate the flow rate of a fluid, which directly affects the speed of an actuator in hydraulic and pneumatic systems.

Question 12

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

Accepted Answer

Directional control valves can include check valves, pilot-operated valves, and spool valves, as they all can control the direction of fluid flow in a hydraulic system.

Question 13

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?

Accepted Answer

The answer of Technician A says that a swashplate pump...

Question 14

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

Accepted Answer

In a typical vane type pump, the rotor turns within a cam ring. The cam ring's eccentric shape causes the vanes to extend and retract as the rotor turns, facilitating the pumping action.

Question 15

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?

Accepted Answer

Technician B is correct because gear pumps use a positive displacement pumping principle, moving a specific amount of fluid through mechanical action. Technician A is incorrect because vane pumps are also considered positive displacement pumps, as they move a specific volume of fluid with each rotation.

Question 16

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?

Accepted Answer

Accumulators in hydraulic systems are indeed used for storing potential energy, which can be released when needed, and they also serve to dampen shock and buffer against sudden pressure spikes, making both Technician A and Technician B correct.

Question 17

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

Accepted Answer

The volume of oil moved through a fixed displacement pump is primarily determined by the rotational speed of the pump. Fixed displacement pumps move a specific volume of fluid with each rotation, so the faster the pump rotates, the more volume is moved per unit of time.

Question 18

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?

Accepted Answer

The answer of Technician A says that in an open...

Question 19

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

Accepted Answer

The answer of What do car carrier trailers usually use...

Question 20

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?

Accepted Answer

Both Technician A and Technician B are correct. Unbalanced vane pumps typically have a single outlet port due to their design, which does not equally distribute forces across the pump. Balanced vane pumps, on the other hand, are designed to distribute forces more evenly, often featuring a pair of inlet and outlet ports to manage this balance.

Quiz 13: Hydraulics