Final 12/19

Question 1

Non-positive displacement pumps are

Answer 1

Centrifugal

Question 2

Positive displacement pumps are all

Answer 2

Fixed displacement
Or
Variable displacement

Question 3

Why does a Variable displacement pressure compensated piston pump have a case drain on it?

Answer 3

To monitor pump life.
Too much flow over the case drain will cause the pump to go out.

Question 4

What is cavitation?
What causes cavitation?

Answer 4

The formation and collapse of air bubbles.
Caused by too much vacuum on the inlet side of the pump. There is not enough vapor pressure to hold the 10% entrained air dissolved in the oil.

Question 5

True pump cavitation stops where?

Answer 5

At the pump

Question 6

What 2 things can cause true pump cavitation?

Answer 6

Restriction on the inlet side of the pump.
Oil temp too cold causing the fluid to be too thick.

Question 7

Psudo-cavitation or false cavitation is caused by?

Answer 7

Extra air being drawn into the inlet side of the pump. This causes aeration of the fluid throughout the entire system.

Question 8

What are two things that can cause pseudo cavitation?

Answer 8

1) A crack on the inlet piping
2) Fluid level being too low allowing air to be drawn into the inlet of the pump.

Question 9

Definition of hydraulic fluid.

Answer 9

A substance used for transmitting energy from pump to actuator in a working hydraulic system.

Question 10

List the 4 uses of hydraulic fluid in a fluid power system.

Answer 10

1) transmits power
2) lubricates parts
3) cools moving parts
4) seals clearances

Question 11

When is hydraulic fluid most flammable?

Answer 11

When it’s atomized (sprayed in the air at high pressure)

Question 12

What are the two types of hydraulic fluid?

Answer 12

Water based and synthetic

Question 13

Water based hydraulic fluid 3 types

Answer 13

1) water-oil emulsion 60% water 40% oil
2) invert emulsion 40% water 60% oil
3) water glycol

Question 14

Synthetic hydraulic fluid is

Answer 14

A) phosphate ester
Its very expensive and highly corrosive

Question 15

Hydraulic fluid additives (4)

Answer 15

1) AW- Anti wear
2) WR- wear resistant
3) EP- extreme pressure
4) R&O rust and oxidation inhibitor

Question 16

AW stands for

Answer 16

Anti wear

Question 17

WR stands for

Answer 17

Wear resistant

Question 18

EP stands for

Answer 18

Extreme pressure

Question 19

R&O stands for

Answer 19

Rust and oxidation inhibitor

Question 20

Hydronic motors do what?

Answer 20

Convert working energy into rotary mechanical energy.

Question 21

3 Hydraulic motors

Answer 21

1) Vane
2) gear
3) piston

Question 22

How many positions can a DCV have?

Answer 22

2 or 3

Question 23

How many ways can a DCV have?

Answer 23

2,3 or 4

Question 24

4 ways DCVs are operated

Answer 24

Manual
Mechanical
Electrical
Pilot pressure

Question 25

3 kinds of or returned or held

Answer 25

Detent held Spring returned on 2 position Spring centered on 3 position

Question 26

Center conditions of DCVs

Answer 26

Float Blocked Open Tandem

Question 27

Valve size by ports (4)

Answer 27

1) D03 smallest 2) D05 3) D08 4) D010 larger

Question 28

Check valves

Answer 28

Allow flow in only one direction

Question 29

What can check valves be used in applications such as..

Answer 29

By pass check Isolation/back flow check

Question 30

What are accumulators charged with?

Answer 30

Nitrogen

Question 31

Types of accumulators (3)

Answer 31

Weight loaded Spring loaded Hydro-pneumatic

Question 32

What 3 things are accumulators used for?

Answer 32

Develop flow Maintain pressure Absorb shock

Question 33

Reservoir types (3)

Answer 33

Conventional Overhead L-Shaped

Question 34

Types of fluid coolers (2)

Answer 34

Air cooled Water cooled

Question 35

Name the 2 types of flow controls

Answer 35

Fixed Adjustable

Question 36

Locations of hydraulic filters (4)

Answer 36

1) sump strainer 2) suction filter 3) pressure filter 4) return filter

Question 37

Hydraulic cylinder types (4)

Answer 37

Single acting Double acting Single rod Double rod

Question 38

Parts of a hydraulic cylinder (6)

Answer 38

Cylinder body Piston with rings Rod Rod gland seals Rod gland bushing Ports

Question 39

What’s the purpose of cushion valves

Answer 39

Slows the rod speed at the very end of the stroke. Helps eliminate hydraulic shock

Question 40

Relief valve What’s it do and how does it work

Answer 40

Limits system pressure Normally non passing Pilot pressure before the valve opens the poppet to allow flow.

Question 41

Valve that allows one operation to happen before another.

Answer 41

Sequence valve

Question 42

4 features of a sequence valve

Answer 42

1) normally non passing 2) pilot pressure before valve opens the poppet to allow flow. 3) external bleed line vents to tank 4) to have reversible motion with using valve as a bypass check valve must be used in parallel.

Question 43

Valve that reduces down stream pressure after the valve.

Answer 43

Pressure reducing valve

Question 44

3 features of a pressure reducing valve

Answer 44

Normally passing valve Reduces pressure by stopping the flow after the valve. So pressure does not build passed setting. Bleed drains excess fluid back to tank if pressure overshoots set point.

Question 45

Valve that counteracts a heavy weight on an actuator.

Answer 45

Counterbalance valve

Question 46

Baffle plate purposes (4)

Answer 46

Creates quiet zone Allows time for fluid to cool Dirt to settle out Entrained air time to escape