H - Hydraulic System Components: Reservoir, Filters, Hoses, and Coolers

Question 1

List four functions of hydraulic oil:

Answer 1

Transmit power, lubricate moving parts, seal close fitting parts, and cool the system.

Question 2

The term viscosity refers to an oil’s:

Answer 2

Internal resistance to flow.

Question 3

List the results of using a hydraulic oil with a viscosity that is too high:

Answer 3

Increased power required to drive the system, increased temperature due to higher friction, greater pressure drops throughout the system, possible sluggish operation, and de-aeration will be more difficult.

Question 4

The two most common oil viscosity grading systems are:

Answer 4

Society of Automotive Engineers (SAE) and International Standards Organization (ISO).

Question 5

Viscosity Index (VI) refers to:

Answer 5

The amount that the oil’s viscosity changes with temperature.

Question 6

Boundary Lubrication refers to a condition where:

Answer 6

Minute imperfections on the surface s of moving parts are in contact.

Question 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

Three factors that will determine how quickly a hydraulic oil will oxidize are:

Answer 8

The amount of air that the oil is exposed to, the oil temperature, and the chemical makeup of the oil.

Question 9

The most important consideration when selecting a hydraulic oil is:

Answer 9

Manufacturer’s specifications.

Question 10

State three functions of the hydraulic reservoir:

Answer 10

Hold the system oil supply, cool the oil, allow air and contamination to settle out of the oil.

Question 11

The ideal capacity for a hydraulic tank is (?). Most mobile heavy equipment hydraulic reservoirs are much smaller than that because of:

Answer 11

The ideal capacity for a hydraulic tank is between 2 to 3 times the pump flow rate. Most mobile heavy equipment hydraulic reservoirs are much smaller than that because of limitations.

Question 12

Pressurized reservoirs are used in applications where:

Answer 12

The pump inlet line may not otherwise be filled with oil.

Question 13

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

Answer 13

Depressurize the reservoir.

Question 14

List three functions of the baffle plate in a hydraulic reservoir:

Answer 14

Prevent return oil from flowing directly into the pump inlet line, provide time for air and contamination to settle out of the oil, and prevent slosh.

Question 15

Contamination in a hydraulic system comes from the following three sources:

Answer 15

Built-in contamination, ingressed contamination, and internally generated contamination.

Question 16

The greatest amount of component wear is caused by contamination that is:

Answer 16

A same size or smaller than component internal clearances.

Question 17

Contamination that restricts the flow go lubricating oil to components is:

Answer 17

Larger than component internal clearances.

Question 18

Coarse filters are called:

Answer 18

Strainers.

Question 19

Mesh or sieve number refers to:

Answer 19

The number of openings per linear inch.

Question 20

A filter having a Beta Rating of B10 = 1 indicates that the filter removes:

Answer 20

None of the 10 um contamination.

Question 21

The filtering device most commonly used in the pump inlet line is a:

Answer 21

100 mesh strainer.

Question 22

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

Answer 22

In series in the return line.

Question 23

The pressure drop created by filter media is a result of:

Answer 23

Oil viscosity and filter permeability.

Question 24

The function of the filter bypass valve is to:

Answer 24

Prevent damage to the filter caused by excess pressure.

Question 25

Steel pipe is sized by:

Answer 25

Nominal inside diameter and wall thickness.

Question 26

The term that refers to the wall thickness of steel pipe is:

Answer 26

Schedule number.

Question 27

One disadvantage of using steel pipe as a hydraulic conductor is that it:

Answer 27

Cannot be bent.

Question 28

Steel tubing is sized by:

Answer 28

Outside diameter and wall thickness.

Question 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

State the flare angle of the following connectors - Joint Industrial Council (JIC)
Society of Automotive Engineers (SAE)

Answer 30

JIC 37 degrees

SAE 45 degrees

Question 31

Split-flange connectors seal the connection by using:

Answer 31

An O-ring.

Question 32

Hydraulic hose is used in areas where (?) is encountered.

Answer 32

Vibration or movement is encountered.

Question 33

A hydraulic hose that is designed by a “-12” (dash 12) has an:

Answer 33

Inside diameter of 3/4 in.

Question 34

Two common types of reusable hose connectors are:

Answer 34

Screw-on socket type and press-on sleeve type.

Question 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.