Punps 2

Question 1

What is cavitation?

Answer 1

Formation and collapse of air bubbles.

Question 2

Describe cavitation.

Answer 2

When there is not enough vapor pressure to hold air and oil together.

Question 3

What is cavitation caused by?

Answer 3

A great restriction on the inlet side of pump. Real Cavitation stops at the pump.

Question 4

What is sudo-cavitation?

Answer 4

Extra air in oil.

Question 5

What is sudo-cavitation caused by?

Answer 5

When you introduce extra air on inlet side of pump. Ex. Low fluid in tank. Crack on pipe on inlet side of pump.

Question 6

What happens to machines during sudo-cavitation?

Answer 6

Can cause sponginess. Fluid will be milky.

Question 7

Definition of a pump?

Answer 7

Draws fluid into largest volume area and moves to smallest volume area. Must be turned by a prime mover.

Question 8

Two types of pumps?

Answer 8

Fixed displacement - puts out a set volume of fluid.

Variable displacement- does not have a set volume pump can change its volume with the squash plate.

Question 9

What do you have to have with a fixed displacement pump to limit system pressure?

Answer 9

You have to have a relief valve.

Question 10

Will fluid move without a difference of volume?

Answer 10

No.

Question 11

Have to have a bigger supply (inlet) then demand (outlet)

Question 12

Different styles of pumps?

Answer 12

Vane
Gear
Piston

Question 13

Two types of vane pumps?

Answer 13

Balanced and unbalanced

Question 14

Advantage of balanced vane pump?

Answer 14

Last longer
Easy rebuild
Quick change cartridge

Question 15

Disadvantage of unbalanced vane pump?

Answer 15

Puts too much side load on the shaft.

Question 16

What do you have to have on pump case to keep case from cracking or destroying pump?

Answer 16

Case drain.

Question 17

Major difference between pumps and motors?

Answer 17

All motors can be pumps but not all pumps can be motors.

Question 18

What do motors have that allow them to be pumps but pumps don’t have to be motors?

Answer 18

High pressure seal on the shaft.

Question 19

What is a motor.

Answer 19

Pressurized fluids forced into smallest area and expands into largest volume area creating rotary motion.

Question 20

What are advantages of hydraulic motors over Electric motors?

Answer 20

Instant reversing of motor shaft.

Stalling for indefinite periods without damage.

Dynamic breaking easily accomplished throughout operating speeds.

Torque control throughout operating speeds.