Book 2 Unit 6

Question 1

Boundary lubrication refers to lubrication:
A) Where the bearing clearance space is flooded with oil
B) Where the surfaces are separate by only a microscopic film of the lubricant
C) There is no metal contact between the surfaces
D) When the lubricating film between surfaces is thick enough to completely separate the surfaces
E) When the supply of lubricant is steady and unrestricted

Answer 1

B) Where the surfaces are separate by only a microscopic film of the lubricant

Question 2

If the parallel roller are quite long, the common term for these is _______ bearings.
A) Sleeve
B) Pin
C) Journal
D) Shell
E) Needle

Answer 2

E) Needle

Question 3

Usually the cause of bearing trouble is one of the following:
A) Proper viscosity of oil
B) Proper bearing design
C) Excessive oil supply
D) Misalignment of shaft and bearing
E) Temperature of oil too low

Answer 3

D) Misalignment of shaft and bearing

Question 4

The sliding vane compressor may have a discharge pressure as high as:
A) 1000 kPa (145 psi)
B) 2000 kPa (290 psi)
C) 5000 kPa (725 psi)
D) 4000 kPa (580 psi)
E) 3000 kPa (435 psi)

Answer 4

A) 1000 kPa (145 psi)

Question 5

Theoretically, the maximum lift of a pump at sea level is:
A) 10.34 metre (33.9 ft)
B) 20.5 metre (67.2 ft)
C) 15.8 metre (51.8 ft)
D) 5.4 metre (17.7 ft)
E) 9.1 metre (29.8 ft)

Answer 5

A) 10.34 metre (33.9 ft)

Question 6

An air receiver is a pressure vessel their specifications must conform to the:
A) ASME Code, Section VIII
B) ASME Code, Section III
C) ASME Code, Section VI
D) ASME Code, Section I
E) ASME Code, Section IV

Answer 6

A) ASME Code, Section VIII

Question 7

The rotary screw compressor is suitable for speed up to:
A) 3000 r/min
B) 12 000 r/min
C) 10 000 r/min
D) 8000 r/min
E) 5000 r/min

Answer 7

B) 12 000 r/min

Question 8

One of the most common designs of a rotary compressor is the _________ type.
A) Turbine
B) Centrifugal
C) Axial flow
D) Rotary lobe
E) Positive displacement

Answer 8

D) Rotary lobe

Question 9

One of the most common design of a rotary compressor is the _______ type.
A) Positive displacement
B) Rotary screw
C) Axial flow
D) Turbine
E) Centrifugal

Answer 9

B) Rotary screw

Question 10

Improper fitting can cause premature bearing failure due to:
A) High operating temperatures
B) Cracking of the rollers
C) The force applied indenting or nicking the balls or rollers
D) Uneven loading of the bearing
E) Hard pieces of lubricant being pressed into the bearing surfaces producing flaking and pitting

Answer 10

C) The force applied indenting or nicking the balls or rollers

Question 11

Where the materials of moving surfaces are in contact with each other, they tend to cling or weld together resulting in extra force called the ________ force being required to move the surfaces.
A) Reaction
B) Gravitational
C) Centrifugal
D) Normal
E) Friction

Answer 11

E) Friction

Question 12

As well as separating the bearing surfaces, the lubricant forms a film on the surfaces, thus protecting them from:
A) Pressure
B) Moisture
C) Temperature
D) Corrosion
E) Air

Answer 12

D) Corrosion

Question 13

Generally, dynamic compressors favour:
A) Temperaure
B) Speed
C) Volume
D) Time
E) Pressure

Answer 13

C) Volume

Question 14

The rotary screw compressor features two intermeshing rotors contained within a close-fitting casing the:
A) Male rotor is usually the driven one
B) Male rotor has four concave lobes
C) Rotors do not come in contact with each other so internal lubrication is not required.
D) Female rotor is driven by means of timing gears
E) Female rotor has six concave flutes

Answer 14

B) Male rotor has four concave lobes

Question 15

The temperature of under normal conditions will be about ________ near the end of the compression stroke.
A) 90ºC (194ºF)
B) 150ºC (302ºF)
C) 225ºC (437ºF)
D) 75ºC (167ºF)
E) 175ºC (347ºF)

Answer 15

A) 90ºC (194ºF)

Question 16

Frequently, it is possible to improve the desirable characteristics of lubricating oil by the use of all of the following additives except:
A) Viscosity index (VI) improvers
B) Anti-oxidants
C) Detergent-dispersants
D) Antifoam additives
E) Emulsion breakers

Answer 16

E) Emulsion breakers

Question 17

False brinelling can cause premature bearing failure due to:
A) Uneven loading of the bearing
B) Hard pieces of lubricant being pressed into the bearing surfaces producing flaking and pitting
C) Indentations in the surfaces in contact with the balls or rollers
D) Cracking or splitting of the bearing race
E) Excessive vibrations

Answer 17

E) Excessive vibrations

Question 18

Pressures produced by the rotary lobe compressor are quite low, approximately _________ for single-stage compressor.
A) 125 kPa (18.1 psi)
B) 150 kPa (21.75 psi)
C) 75 kPa (10.9 psi)
D) 50 kPa (7.25 psi)
E) 100 kPa (14.5 psi)

Answer 18

E) 100 kPa (14.5 psi)

Question 19

Misalignment can cause premature bearing failure due to:
A) Crackling or splitting of the bearing race
B) High operating temperatures
C) Indentations in the surfaces in contact with the balls or rollers
D) Uneven loading of the bearing
E) Hard pieces of lubricant being pressed into the bearing surfaces producing flaking and pitting

Answer 19

D) Uneven loading of the bearing

Question 20

Generally, positive displacement compressors favour:
A) Temperature
B) Speed
C) Time
D) Volume
E) Pressure

Answer 20

E) Pressure