Hydraulic System Components: Reservoir, Filters, Hoses and Coolers 190103h

Question 1

1. List four (4) functions of hydraulic oil:
a)
b)
c)
d)

Answer 1

a) transmit power
b) lubricate moving parts
c) seal close fitting parts
d) cool the system

Question 2

2. The term viscosity refers to an oil’s:
   a) ability to prevent rust.
   b) ability to prevent oxidation.
   c) internal resistance to flow.
   d) change in thickness with temperature.

Answer 2

c) internal resistance to flow.

Question 3

3. List three (3) results of using a hydraulic oil with a viscosity that is too high:
   a)
   b)
   c)

Answer 3

Any three (3) of the following are correct.

a) increased power required to drive the system
b) increased temperature due to higher friction
c) greater pressure drops throughout the system
d) possible sluggish operation
e) de-aeration will be more difficult

Question 4

4. The two (2) most common oil viscosity grading systems are:
   a)
   b)

Answer 4

a) Society of Automotive Engineers (SAE)

b) International Standards Organization (ISO)

Question 5

5. Viscosity index (VI) refers to:
   a) the amount that the oil’s viscosity changes with temperature.
   b) the amount that the oil’s viscosity changes with pressure.
   c) a method of grading oils by their viscosity.
   d) the lowest temperature at which the oil will flow.

Answer 5

a) the amount that the oil’s viscosity changes with temperature.

Question 6

6. Boundary lubrication refers to a condition where:
   a) moving parts are completely separated by a film of oil.
   b) minute imperfections on the surfaces of moving parts are in contact.
   c) anti-wear additives are not required.
   d) oxidation of the oil will occur.

Answer 6

b) minute imperfections on the surfaces of moving parts are in contact.

Question 7

7. Define the term oxidation as it relates to hydraulic oil.

Answer 7

Oxidation refers to the reaction of the hydraulic oil with oxygen in the air.

Question 8

8. Three (3) factors that will determine how quickly a hydraulic oil will oxidize are:
   a)
   b)
   c)

Answer 8

a) the amount of air that the oil is exposed to
b) the oil temperature
c) the chemical makeup of the oil

Question 9

9. The most important consideration when selecting a hydraulic oil is:
   a) viscosity.
   b) viscosity index.
   c) pour point.
   d) manufacturer’s specifications.

Answer 9

d) manufacturer’s specifications.

Question 10

10. State three (3) functions of the hydraulic reservoir.
    a)
    b)
    c)

Answer 10

a) hold the system oil supply
b) cool the oil
c) allow air and contamination to settle out of the oil

Question 11

11. The ideal capacity for a hydraulic tank is ______________ __
    Most mobile heavy equipment hydraulic reservoirs are much smaller than that
    because of:

Answer 11

between 2 to 3 times the pump flow rate.
Most mobile heavy equipment hydraulic reservoirs are much smaller than that
because of space limitations.

Question 12

12. Pressurized reservoirs are used in applications where:
    a) air must be prevented from entering the oil.
    b) the pump inlet line may not otherwise be filled with oil.
    c) additional oil cooling is required.
    d) very high pressures are encountered.

Answer 12

b) the pump inlet line may not otherwise be filled with oil.

Question 13

13. What procedure must be done before you service a hydraulic system equipped with a
    pressurized reservoir?

Answer 13

. depressurize the reservoir

Question 14

14. List three (3) functions of the baffle plate in a hydraulic reservoir.
    a)
    b)
    c)

Answer 14

. a) prevent return oil from flowing directly into the pump inlet line

b) provide time for air and contamination to settle out of the oil
c) prevent slosh

Question 15

15. Contamination in a hydraulic system comes from the following three (3) sources:
    a)
    b)
    c)

Answer 15

a) built-in contamination
b) ingressed contamination
c) internally generated contamination

Question 16

16. The greatest amount of component wear is caused by contamination that is:
    a) the same size or smaller than component internal clearances.
    b) larger than component internal clearances.
    c) 20 µm or larger.
    d) ingressed.

Answer 16

a) the same size or smaller than component internal clearances.

Question 17

17. Contamination that restricts the flow of lubricating oil to components is:
    a) the same size or smaller than component internal clearances.
    b) larger than component internal clearances.
    c) 20 µm or larger.
    d) ingressed.

Answer 17

b) larger than component internal clearances.

Question 18

18. Coarse filters are called

Answer 18

Coarse filters are called strainers.

Question 19

19. Mesh or sieve number refers to

Answer 19

Mesh or sieve number refers to the number of openings per linear inch.

Question 20

20. A filter having a Beta Rating of P10 = 1 indicates that the filter removes:
    a) all contamination that is 10 µm and larger.
    b) all contamination that is 10 µm and smaller.
    c) 10% of all 1 µm contamination.
    d) none of the 10 µm contamination.

Answer 20

d) none of the 10 µm contamination.

Question 21

21. The filtering device most commonly used in the pump inlet line is a:
    a) l0 µm filter.
    b) 20 µm filter.
    c) 100 mesh strainer.
    d) 200 mesh strainer.

Answer 21

c) 100 mesh strainer

Question 22

22. The most common filter location on mobile heavy equipment hydraulic systems is

Answer 22

The most common filter location on mobile heavy equipment hydraulic systems is in
series in the return line.

Question 23

23. The pressure drop created by filter media is a result of:
    a)
    b)

Answer 23

a) oil viscosity

b) filter media permeability

Question 24

24. The function of the filter bypass valve is to:

Answer 24

24. The function of the filter bypass valve is to prevent damage to the filter caused by
    excess pressure.

Question 25

25. Steel pipe is sized by

Answer 25

nominal inside diameter and wall thickness.

Question 26

26. The term that refers to the wall thickness of steel pipe is:
    a) schedule number.
    b) dash number.
    c) nominal ID.
    d) nominal OD.

Answer 26

a) schedule number.

Question 27

27. One disadvantage of using steel pipe as a hydraulic conductor is that it:
    a) does not dissipate heat well.
    b) is not compatible with all hydraulic oils.
    c) can only be used where vibration or movement is present.
    d) cannot be bent.

Answer 27

d) cannot be bent.

Question 28

28. Steel tubing is sized by

Answer 28

Steel tubing is sized by outside diameter and wall thickness.

Question 29

29. The main advantage that tubing connectors offer over pipe connectors is that:

Answer 29

they do not use connector threads to seal the connection.

Question 30

30. State the flare angle of the following connectors:
    a) Joint Industrial Council (JIC)
    b) Society of Automotive Engineers (SAE)

Answer 30

. a) JIC 37°
.
b) SAE 45°
.

Question 31

31. Split-flange connectors seal the connection by using:
    a) tapered threads.
    b) a 37° flare.
    c) a 45° flare.
    d) an O-ring.

Answer 31

D) Oring

Question 32

32. Hydraulic hose is used in areas where _________________

is encountered.

Answer 32

vibration or movement is encountered.

Question 33

33. A hydraulic hose that is designated by a “-12”(dash 12) has an:
    a) outside diameter of¾ in.
    b) inside diameter of¾ in.
    c) outside diameter of 1.2 cm.
    d) inside diameter of 12 cm.

Answer 33

b) inside diameter of¾ in.

Question 34

34. Two (2) common types of reusable hose connectors are:
    a)
    b)

Answer 34

a) screw-on socket type

b) press-on sleeve type

Question 35

35. Hydraulic oil coolers are usually connected in __________ in the
    system ____ _______ line.

Answer 35

Hydraulic oil coolers are usually connected in series in the system return line.