Chapter 4 Flashcards
three types of pumps
gear, vane, and piston pumps
gear pumps
- external and internal (gerotor = inner drive gear and outer driven gear) pumps
- less expensive, only available in fixed displacement
pump
converts mechanical power to fluid power
three general classifications of pumps
- 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)
constant flow circuit (has a fixed displacement pump)
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.
slippage
actual flowrate will be lower than theoretical flowrate (fluid leaking back from outlet to inlet)
gear, vane, and piston pump
- gear: lowest volumetric efficiency, very dirt tolerant
- piston: highest volumetric efficiency
two types of piston pumps
- axial (number of pistons in a circular array within a cylinder block)
- radial (cylinders positioned radially around the axis of rotation)
tandem pumps
two pumps in the same housing
pump mount
gearbox that is designed to power hydraulic pumps
flow dividers
valves that divide flow from a single pump to supply two circuits that operate at different pressures