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Question 1

A reversible pump means it is able to do what exactly?

Answer 1

Reverse the direction of oil flow through the pump

Question 2

As pump outlet pressure increases the pumps internal leakage___________

Answer 2

Increases.

Question 3

Oil that gathers in the case of an axial piston pump comes from ______________

Answer 3

Internal leakage.

Question 4

What are three general guidelines that should be followed when taking a pump apart?

Answer 4

1. Mark pump housings.
2. Determine the correct direction of driveshaft rotation.
3. Be sure to keep mated components together.

Question 5

Most common cause of pitted erosion on internal surfaces is __________________

Answer 5

Cavitation.

Question 6

What are thee ways a pump can lack in lubrication?

Answer 6

1. Improper oil used.
2. Low reservoir oil level
3. Sever aeration (possibly over speeding)

Question 7

Four tasks that should be done when a pump is installed to ensure the system is clean enough?

Answer 7

1. Oil may need to be changed or filtered.
2. Change the filters.
3. Reservoir cleaned thoroughly.
4. Complete system flush.

Question 8

What are several things to consider when analyzing hydraulic motor failure?

Answer 8

1. The condition of each motor part.
2. Type and condition of oil and filters.
3. Operating conditions and symptoms before failure.
4. Conditions of other hydraulic system components.
5. Severity of job application.
6. How long the motor has been in service before the failure.
7. Previous failures and repairs to the system.

Question 9

What are 4 start up procedures that should be done after a new motor is installed?

Answer 9

1. Back off system pressure controls.
2. Operate motor at no load and check for leaks or unusual noises.
3. Apply load to the motor and warm up the oil, adjust system pressure controls.
4. Perform operational tests to confirm machine is working correctly.

Question 10

What is the purpose of the trap in a gear pump pressure plate?

Answer 10

Provides an escape path for oil that is trapped between the teeth

Question 11

Why is oil pressure from the pumping chambers of an axial piston pump connected to the piston shoes?

Answer 11

1. To lubricate the ball and socket
2. To balance the piston

Question 12

Hydraulic pumps that are able to change the capacity of their pumping chambers are called

Answer 12

variable displacement pumps

Question 13

Why do manufactured of gear pumps with aluminum housings allow the gears to cut a gear path into the pump housing during break-in?

Answer 13

To provide low gear tip clearance and high volumetric efficiency

Question 14

Why is some internal leakage necessary within all hydraulic pumps?

Answer 14

Because it lubricates moving pump parts

Question 15

Why should the adjustment of system pressure controls be backed off prior to starting a machine in which the hydraulic pump has been replaced?

Answer 15

To prevent overloading the pump in the event the relief valve has been misadjusted