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1. The lubricant classification that meets the American Petroleum Institute (API) standard for heavy truck differential
carriers is known as:
a.
GL-4
b.
GL-5
c.
GL-6
d.
GL-7
2. What properties are associated with synthetic gear lubes when compared with mineral based lubricants?
a.
better lubricity
b.
higher boil temperatures
c.
better boundary lubrication
d.
all of the above
3. Technician A says that synthetic lubricants may be used in truck differential carriers but OEMs have yet to authorize
extended oil drain intervals. Technician B says that using synthetic gear lubes is cost effective compared to mineral-base
gear lube because of greatly increased oil drain intervals and reduced labor. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
4. Technician A says that one reason OEMs have eliminated the initial (break-in) lube drain on a new or rebuilt
differential carrier is improved machining precision of current geartrain components. Technician B says that because
synthetic gear lubes have superior ability to suspend abrasive contaminants, OEMs no longer require a break-lube change.
Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
5. Which of the following would indicate that the lube level in a differential carrier housing was acceptable?
a.
oil level is exactly even with the bottom of the filler hole
b.
lube level pours out the filler hole when the plug is removed
c.
lube level is one knuckle joint below the filler hole
d.
lube level is within two knuckle joints below the filler hole
6. When is the BEST time to drain differential carrier oil on a scheduled lube change?
a.
when it has cooled to ambient temperature
b.
at operating temperature
c.
after cooling for one hour
d.
any time on a summer’s day
7. Where would you usually find the AXLE IDENTIFICATION numbers on a rear axle carrier housing?
a.
stamped into the banjo housing
b.
metal tag attached to the banjo housing
c.
both A and B
d.
neither A nor B
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8. Which of the following is required practice when refilling a differential carrier housing with lube after an oil change?
a.
fill with an API GL-5 rated lubricant to the bottom of the filler hole
b.
add an additional 2 pints (1 liter) to the power divider fill hole
c.
jack the axle sequentially at either end to ensure lube reaches the wheel ends
d.
all of the above
d
9. Which of the following types of axle shaft failures would likely produce a relatively smooth, flat fracture pattern?
a.
shock load
b.
fatigue
c.
lubrication failure
d.
constant torque overload
10. Which of the following are indications of fatigue-type failures in gear components?
a.
pitted and spalled tooth surfaces
b.
star-shaped fracture
c.
scalloped fracture pattern
d.
all of the above
d
11. Which of the following could be produced by a spinout failure?
a.
broken gear teeth
b.
broken axle shaft
c.
overheated power divider
d.
all of the above
d
12. Which of the following types of failures can result in some components becoming blackened and discolored?
a.
fatigue
b.
lubrication breakdown
c.
shock-load
d.
all of the above
b
13. Where is a spigot bearing located in a differential carrier assembly?
a.
end of each axle shaft
b.
on each differential spider
c.
hub the crown gear
d.
pinion gear shaft
d
14. A fractured axle shaft with a star-shaped fracture pattern indicates that the cause of the failure is related to:
a.
bending stress
b.
torsional stress
c.
shock load
d.
lubrication failure
b
15. A truck differential carrier is noisy when cornering. Which of the following would be the more likely cause?
a.
pinion bearings worn
b.
low axle lube level
c.
damaged differential pinion gears
d.
worn carrier bearings
16. When replacing a damaged crown and pinion gearset, the damaged pinion cone (PC) variation number was +2, and the
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new PC variation number is specified as -5. If the original shim pack thickness measured 0.030-inch (0.76 mm), what
should the new shim pack thickness be?
a.
.033-inch (0.84 mm)
b.
.037-inch (0.94 mm)
c.
.023-inch (0.58 mm)
d.
.027-inch (0.69 mm)
17. What is the area of a ring gear tooth that is furthest from the center known as?
a.
toe
b.
heel
c.
root
d.
face
b
18. Which of the following best describe an ideal ring gear tooth contact pattern for a new crown and pinion gearset?
a.
centered between the root and top land
b.
covers 1/2 or more of the length of the ring gear teeth
c.
contact pattern closer to the toe than the heel
d.
all of the above
d
19. When correcting a pinion to crown gear tooth contact pattern that is too close to the top land and off-center, how
should you make an adjustment?
a.
move the pinion gear toward the ring gear
b.
move the pinion gear away from the ring gear
c.
move the ring gear to increase backlash
d.
move the ring gear to decrease backlash
20. When correcting a pinion to crown gear tooth contact pattern that is too far from the toe, what adjustment should be
made?
a.
move the pinion gear toward the ring gear
b.
move the ring gear to decrease backlash
c.
move the pinion gear away from the ring gear
d.
move the ring gear to increase backlash
b
21. Technician A says that API GL-6 lubricant supercedes GL-5 and should be used in all current differential carriers.
Technician B says that API GL-5 is extreme pressure (EP) rated for use in hypoid gearsets. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
b
22. Technician A says that the military gear lube classification MIL L 2105D is equivalent to API GL–5. Technician B
says that API GL-3 and API GL-4 are not approved for use in current heavy truck differential carriers. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
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23. Which of the following gear lube viscosity ratings would best suit severe winter conditions?
a.
75W
b.
80W-90
c.
80W-140
d.
85W-140
24. Which of the following gear lube viscosity ratings would indicate an oil that would possess the best flow
characteristics at 10 degrees Fahrenheit?
a.
75W
b.
80W-90
c.
80W-140
d.
90W-140
25. Technician A says that most differential carriers have two oil fill holes at different levels and that the pinion angle off
a horizontal plane determines which fill hole should be used.. Technician B says that the oil fill hole that is highest on an
axle should always be used to check oil level. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
b
26. Technician A says that when a differential carrier pinion angle exceeds 7 degrees, lube level should be checked at the
banjo housing fill hole. Technician B says that when correcting the lube level in differential carrier housings, the best way
is to remove both fill plugs and pump oil into the fill plug at the side of the carrier until it begins to spill from the fill hole
in the banjo housing. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
27. What is used to lubricate the wheel bearings in a heavy truck drive axle assembly?
a.
wheel end grease
b.
axle grease
c.
gear lube in an isolated hub
d.
gear lube in differential carrier housing
d
28. Technician A says that the lube levels in drive axles on most heavy trucks can be checked by viewing through a hub
inspection window. Technician B says that following a differential carrier oil change, each side of the axle should be in
turn, be jacked up and held for one minute to ensure that lube gets to the wheel ends. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
b
29. Technician A says that a spinout condition can result in an immediate failure in either the power divider or the
differential carrier. Technician B says that a spinout condition can cause geartrain damage that does not result in a
breakdown until sometime later. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
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30. What is the most common cause of lubrication-related failures of differential carriers?
a.
contaminated lube
b.
underfilled rear axle housings
c.
lube breakdown
d.
mixing lubricants
31. Technician A says that mixing synthetic oil with mineral base lube can cause premature lubricant breakdown due to
incompatible additives. Technician B says that a good way of avoiding mixing of lubes in differential carriers is to write
the gear lube required into memory in one of the data bus modules. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
32. Technician A says that Roadranger CD-50 meets the API GL-5 standard. Technician B says that an advantage of using
a synthetic gear lube such CD-50 is that it can all but eliminate spinout failures. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
33. Which of the following gear lubes suitable for use in a differential carrier is rated to have the longest service life?
a.
any GL-5
b.
any GL-6
c.
TranSynd
d.
CD-50
34. How should used gear lube be disposed of from a service facility?
a.
toxic waste disposer
b.
recycling refiner
c.
pour down any drain with a separator
d.
use as gravel dust settling agent
b
35. When disassembling a riveted crown gear and flange case half, how should the rivets be removed?
a.
drill out with bit 1/32 inch (0.8 mm) larger than rivet size
b.
chisel and cold punch
c.
drill with bit 1/32 inch (0.8 mm) smaller than rivet size
d.
press with 10 ton (9 metric-ton) press and cold punch
36. When you attach a cord and fish scale to a pinion bearing, what are you about to measure?
a.
pinion to crown gear backlash
b.
pinion bearing preload
c.
pinion bearing endplay
d.
crown bearing turning resistance
b
37. After measuring pinion bearing preload, the preload value measures less than specified. Which of the following steps
is required?
a.
use a thinner spacer
b.
use a thicker spacer
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c.
increase pinion yoke torque
d.
decrease pinion yoke torque
38. Which of the following tools could be used to measure both crown gear runout and pinion to crown gear runout?
a.
thickness gauges
b.
depth micrometer
c.
fish scale
d.
dial indicator
39. Technician A says that a differential carrier thrust screw should be adjusted to the point that it just contacts the thrust
block or crown gear. Technician B says that if a thrust screw was to be backed out all the way, the thrust block would
drop into the carrier housing. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
40. Technician A says that it is common practice today in truck repair facilities to replace a failed differential carrier with
a rebuilt/exchange unit rather than to overhaul the unit in-house. Technician B says that when rebuilding differential
carriers, it is good practice to measure shim pack thickness on disassembly because it usually speed reassembly times.
Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
41. Technician A says that when rebuilding a differential carrier, a crown and pinion gearset can often be reused.
Technician B says that when either a crown or pinion gear have been diagnosed defective, they should both be replaced as
a matched unit. Who is correct?
a.
Technician A only
b.
Technician B only
c.
Both A and B
d.
Neither A nor B
42. The rear wheels on a tandem drive axle will not turn but the drive axle to the rear differential carrier does turn. Which
of the following should you do FIRST?
a.
pull the power divider
b.
pull the forward differential carrier
c.
pull the rear differential carrier
d.
pull both rear axle half-shafts