Pumps/Hydraulic Motors/Cavitation

Question 1

Formation and collapse of air bubbles

Answer 1

Cavitation

Question 2

2 ways to know if a pump is cavitating:

Answer 2

1) Very noisy (sounds like rocks in the system)
2) Increased fluid temperature

Question 3

2 common reasons for cavitation:

Answer 3

1) Partial obstruction at inlet
2) Increased Viscosity

Question 4

Aerated oil throughout the entire system

Answer 4

Pseudocavitation

Question 5

2 ways to tell if pseudocavitation is taking place in a system:

Answer 5

1) Foam in the tank
2) Spongy hydraulics

Question 6

2 common causes of pseudocavitation:

Answer 6

1) Crack in the pump
2) Fluid level too low

Question 7

If a pump puts out a set volume and it never changes it’s called?

Answer 7

Fixed displacement

Question 8

What must a fixed displacement pump have to limit system pressure?

Answer 8

Relief valve

Question 9

If a pump can change volumes to meet system needs it’s called?

Answer 9

Variable displacement pump

Question 10

2 ways to control pressure in fluid power:

Answer 10

1) Send fluid back to tank
2) Control flow from pump

Question 11

As volume _____, pressure _____.

Answer 11

Decreases
Increases

Question 12

Pumps draw fluid into the _____ volume and moves it to the _____ volume area.

Answer 12

Largest
Smallest

Question 13

Must be turned by prime mover.(motor, generator, turbine, etc)

Answer 13

Pump

Question 14

A Motor draws pressurized fluid from the _____ volume area and expands into the _____ volume area, creating rotary motion.

Answer 14

Smallest
Largest

Question 15

3 advantages that hydraulic motors have over electric motors:

Answer 15

1) instant reversing of motor shaft
2) Stalling without damage
3) Better torque control

Question 16

Converts the working energy of a hydraulic system into rotary mechanical energy.

Answer 16

Hydraulic motor

Question 17

The external drain of a pump housing is commonly referred to as?

Answer 17

Case drain

Question 18

What 2 things are a result of the case drain not operating correctly:

Answer 18

1) Loss of flow
2) Pressure will build

Question 19

What 2 things can happen if case drain fails and pressure builds too high:

Answer 19

1) Pump stops
2) Case breaks

Question 20

Loss of flow =

Answer 20

Loss of speed

Question 21

What is an advantage to cartridge pumps

Answer 21

Easy to replace

Question 22

What happens when an unbalanced vane pump encounters high system pressure?

Answer 22

Side loading

Question 23

How is side loading eliminated?

Answer 23

Balanced vane pump

Question 24

2 common vane constructions:

Answer 24

1) Intra-vane
2) Pin-vane

Question 25

Pump that generates a pumping action by causing vanes to track along a ring?

Answer 25

Vane pump

Question 26

Pressurized fluid forced into the smallest volume area and expand into largest volume area creating rotary motion.

Answer 26

Hydraulic motor

Question 27

Draws fluid into the largest volume area and moves it to the smallest volume area.

Answer 27

Hydraulic pump