Pumps/Hydraulic Motors/Cavitation Flashcards
Formation and collapse of air bubbles
Cavitation
2 ways to know if a pump is cavitating:
1) Very noisy (sounds like rocks in the system)
2) Increased fluid temperature
2 common reasons for cavitation:
1) Partial obstruction at inlet
2) Increased Viscosity
Aerated oil throughout the entire system
Pseudocavitation
2 ways to tell if pseudocavitation is taking place in a system:
1) Foam in the tank
2) Spongy hydraulics
2 common causes of pseudocavitation:
1) Crack in the pump
2) Fluid level too low
If a pump puts out a set volume and it never changes it’s called?
Fixed displacement
What must a fixed displacement pump have to limit system pressure?
Relief valve
If a pump can change volumes to meet system needs it’s called?
Variable displacement pump
2 ways to control pressure in fluid power:
1) Send fluid back to tank
2) Control flow from pump
As volume _____, pressure _____.
Decreases
Increases
Pumps draw fluid into the _____ volume and moves it to the _____ volume area.
Largest
Smallest
Must be turned by prime mover.(motor, generator, turbine, etc)
Pump
A Motor draws pressurized fluid from the _____ volume area and expands into the _____ volume area, creating rotary motion.
Smallest
Largest
3 advantages that hydraulic motors have over electric motors:
1) instant reversing of motor shaft
2) Stalling without damage
3) Better torque control
Converts the working energy of a hydraulic system into rotary mechanical energy.
Hydraulic motor
The external drain of a pump housing is commonly referred to as?
Case drain
What 2 things are a result of the case drain not operating correctly:
1) Loss of flow
2) Pressure will build
What 2 things can happen if case drain fails and pressure builds too high:
1) Pump stops
2) Case breaks
Loss of flow =
Loss of speed
What is an advantage to cartridge pumps
Easy to replace
What happens when an unbalanced vane pump encounters high system pressure?
Side loading
How is side loading eliminated?
Balanced vane pump
2 common vane constructions:
1) Intra-vane
2) Pin-vane
Pump that generates a pumping action by causing vanes to track along a ring?
Vane pump
Pressurized fluid forced into the smallest volume area and expand into largest volume area creating rotary motion.
Hydraulic motor
Draws fluid into the largest volume area and moves it to the smallest volume area.
Hydraulic pump
