Chapter 4

Question 1

three types of pumps

Answer 1

gear, vane, and piston pumps

Question 2

gear pumps

Answer 2

• external and internal (gerotor = inner drive gear and outer driven gear) pumps
• less expensive, only available in fixed displacement

Question 3

pump

Answer 3

converts mechanical power to fluid power

Question 4

three general classifications of pumps

Answer 4

• fixed displacement (delivers a fixed volume of fluid for each revolution)
• variable displacement (output of fluid can be changed as pump operates)
• pressure compensated variable volume pump (stops delivering flow at a set pressure)

Question 5

constant flow circuit (has a fixed displacement pump)

Answer 5

Each revolution of a fixed displacement pump delivers a certain volume of fluid to the circuit. This fluid ultimately returns to the reservoir, either as a return flow, or a leakage flow.

Question 6

slippage

Answer 6

actual flowrate will be lower than theoretical flowrate (fluid leaking back from outlet to inlet)

Question 7

gear, vane, and piston pump

Answer 7

• gear: lowest volumetric efficiency, very dirt tolerant

- piston: highest volumetric efficiency

Question 8

two types of piston pumps

Answer 8

• axial (number of pistons in a circular array within a cylinder block)
• radial (cylinders positioned radially around the axis of rotation)

Question 9

tandem pumps

Answer 9

two pumps in the same housing

Question 10

pump mount

Answer 10

gearbox that is designed to power hydraulic pumps

Question 11

flow dividers

Answer 11

valves that divide flow from a single pump to supply two circuits that operate at different pressures