Quiz on Chapter 8: Air and Hydraulic Pumps

1. A rule of thumb for air compressor output for each input horsepower is:

1. 2 scfm @ 100 PSI
2. 3 scfm @ 100 PSI
3. 4 scfm @ 100 PSI

2. Large air compressors load and unload as pressure drops and builds. Small air compressors:

1. do the same.
2. never build enough pressure.
3. turn on at a minimum pressure and off at a maximum pressure.

3. A hydraulic pump produces:

1. flow in gallons per minute (gpm).
2. pressure in pounds per square inch (psi).
3. both of the above.

4. A positive-displacement pump:

1. cannot turn if the outlet is blocked.
2. can turn with the outlet blocked.
3. can only turn with the outlet blocked.

5. Gear pumps:

1. can be variable volume.
2. cannot be variable volume.
3. can be pressure compensated.

6. Vane pumps:

1. can be variable volume.
2. cannot be variable volume.
3. cannot be pressure compensated.

7. Piston pumps .

1. can be variable volume.
2. cannot be variable volume.
3. cannot be pressure compensated.

8. An open-center circuit:

1. blocks pump flow in the center condition.
2. does not have a center condition.
3. allows pump flow to go to tank in center condition.

9. A closed-center circuit:

1. blocks pump flow in the center condition.
2. does not have a center condition.
3. allows pump to go to tank in center condition.

10. The symbol at right is a: pressure-compensated variable-volume pump. fixed-volume pump. bi-directional pump.

11. While the input shaft of a bi-directional pump is turning in one direction of rotation, it:

1. can move fluid from either port.
2. can only move fluid from one port.
3. must have a suction line hooked to tank.

12. Wobble-plate piston pumps:

1. must rotate in the opposite direction to reverse flow.
2. can reverse flow while turning the same way.
3. cannot reverse flow at anytime.

13. Swash-plate piston pumps:

1. have moveable or fixed-angle swash plates.
2. are always bi-directional.
3. can only move fluid one way.

14. Bent-axis pumps :

1. cannot be fixed volume.
2. operate better at higher vacuum inlet.
3. cannot be bi-directional flow.

15. Load-sensing pumps:

1. operate at load pressure plus load-sense bias spring pressure.
2. operate at compensator pressure at all times.
3. cannot be variable volume.

16. Horsepower- and torque-limiting pumps:

1. use extra horsepower all the time.
2. use minimum horsepower all the time.
3. never use more than a preset horsepower regardless of pressure.

17. Pump shaft alignment is not important at any time.

1. True
2. False

18. Closed-loop circuits:

1. use a makeup pump to keep the loop full.
2. must have extra large flow lines to keep the pump from cavitating.
3. cannot reverse the direction of an actuator.

19. A pump-motor adapter is:

1. a device to keep the pump from cavitating.
2. a unit to match pump horsepower to motor horsepower.
3. a device to directly attach a pump to an electric motor.

20. Cavitation is caused by:

1. too little fluid volume at the pump inlet.
2. too much fluid volume at the pump inlet.
3. too much fluid volume at the pump outlet.