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Heavy Equipment Technician Period 4 > HET 4 DRIVE AXLE > Flashcards

HET 4 DRIVE AXLE Flashcards

DRIVE AXLE ASSEMBLY FUNDAMENTALS ON-ROAD 190401h

1
Q

What are the four functions of a drive axle assembly?

A

Support the weight
Last gear reduction
Change path of power 90°
Handle wheel speed differences

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2
Q

Type, size and number of drive axles depend on what?

A

Weight of vehicle and cargo
Amount of traction required
Final drive ratio

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3
Q

An axle code is D S 40 4 - P, what is the GAWR?

A

40 x 1000lbs = 40 000lbs is GAWR

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4
Q

GAWR stands for?

A

Gross axle weight rating per tandem x 1000 lbs

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5
Q

Axle code is DP581-P, what does the P stand for?

A

Standard lube pump

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6
Q

GVWR stands for?

A

Gross vehicle weight rating

-the total weight of the vehicle and its load

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7
Q

Axle codes second digit is a letter, what are the options that can be seen?

A

S - Single Reduction
P - Planetary double reduction
T - Dual Range
C - Single reduction with controlled traction differential
D - single reduction with wheel differential lock
A - single reduction with in axle speed sensing

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8
Q

GCWR stands for?

A

Gross combination weight rating

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9
Q

If more traction is needed what kind of axle is added to the vehicle?

A

another DRIVE axle

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10
Q

Does adding a second non-driving axle help increase traction?

A

No, helps increase weight that can be carried

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11
Q

Describe startability?

A

Percentage of grade at which a drivetrain system can start a loaded vehicle moving at an idle?

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12
Q

If the startability is at too high of the ration what would be the complaint?

A

continually down shifting, not utilizing top gear, sacrificing fuel economy

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13
Q

If the startability ratio is too low what is the complaint?

A

poor fuel economy

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14
Q

Does straddle mount or overhunt mount drive pinions handle the most torque load?

A

Straddle mount

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15
Q

Pinion drives are usually mounted in what drive axle component?

A

Carrier hoursing

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16
Q

Can full floating axle be removed with weight still going to the wheels of the vehicle?

A

Yes the wheels will carry the weight

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17
Q

Thrust screw prevents the bevel or the pinion gear from moving away?

A

The bevel from moving away from the pinion

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18
Q

Where is the trust screw positioned in relation to the pinon gear?

A

Exact opposite location

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19
Q

Where will the maximum thrust load and deflections be found between the bevel and pinion gear?

A

The exact opposite of the pinion gear

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20
Q

What are the two case halves of a differential that are bolted together?

A

flanged and plain

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21
Q

Is the bevel gear bolted to the flanged or plain case half?

A

Flanged

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22
Q

True or False

Bevel gear and input pinion are a matched set and must be changed together?

A

True

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23
Q

If preload has already been set between the pinion drive and bevel gear can backlash still be adjusted without affecting preload?

A

Yes if LH and RH bearing adjustment rings are moved in and out at the same rates.

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24
Q

What components are INSIDE the differential assembly?

A

Cross shaft, spider(pinion) and side gears, thrust washers

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25
Q

Which side of the differential case does the cross shaft fit into?

A

Plain case half

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26
Q

The spider gears on the cross shaft inside the differential assembly face in or out to the center of the cross shaft? (toe in or heel in)?

A

The toes are facing in towards the center of the cross shaft

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27
Q

True or False

Both side gears need to move at the same speed?

A

False

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28
Q

Which is the most common differential carrier used today?

A

Single Speed Single Reduction

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29
Q

Why would a high speed clutch plate have a chamfered edge on the splines?

A

To help the sun engage

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30
Q

Where is the first reduction always found in a differential?

A

Pinion to Ring gear

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31
Q

The bevel gear are attached to what in a planetary differential?

A

Bevel gear is attached to Internal/Ring gears

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32
Q

What usually shifts a two speed planetary differential?

A

Air solenoid or actuator

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33
Q

In a two speed planetary, high speed is selected. What is the gear ratio created?

A

Direct Drive

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34
Q

What is the differential assembly in a two speed planetary differential?

A

Differential assembly - Carrier

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35
Q

When cornering, what wheel will have to go faster to cover the same distance as the other wheel?

A

Outside wheel

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36
Q

If wheels that are cornering cannot achieve a speed difference what is the result?

A

Tire scuffing, steering difficulties

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37
Q

Two speed means what in relation to path of power?

A

Two paths of power available

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38
Q

What component supports drive gears in a two speed differential?

A

Cross shaft

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39
Q

If speed is lost at one wheel, what happens to the other wheel on that axle?

A

Gets the lost speed

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40
Q

What is the bevel gear RPM?

A

Sum of both wheel assembly speeds

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41
Q

If you are given an input speed, what else do you need to figure out what speed is getting to the wheel hubs?

A

Gear ratio

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42
Q

Why is the first drive axle oil change usually done after a short period?

A

To remove break in debris

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43
Q

What type of oil should be used in a drive axle?

A

Manufacture spec

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44
Q

At what angle should a standpipe be added to a drive axle to correct the oil level?

A

12° or more

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45
Q

When does a standpipe most likely need to be added to a drive axle to correct oil level?

A

if the drive axle is 12° or more
OR
if the vehicle is operating on steep grades normally

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46
Q

Since oil from the drive axle goes to the wheel ends what should be done during services (fluid changes)?

A

Tilt the axle to get oil out from wheel ends

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47
Q

When is a static seal used?

A

Non-moving parts

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48
Q

Dynamic seals are used with what components?

A

Over a moving part

ei. drive axles

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49
Q

After a service and drive axle oil has been changed, what should be done before final level check?

A

Drive the vehicles for a few minutes and then let settle for 5 minutes. Recheck level

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50
Q

What is the purpose of a breather on a drive axle?

A

To allow built up pressure to release

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51
Q

What causes an o-ring to fail in a inter-axle differential lock cylinder?

A

high pressure in the housing

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52
Q

Why is input shaft and output shaft end play important?

A

If out of spec can cause vibration and damage

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53
Q

What should be done before a road test to find faults?

A

Visual Inspection

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54
Q

Why should a technician be cautious when doing a plug swap on a drive axle?

A

High temp - Burns

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55
Q

What components need to be inspected to find a drive axle fault?

A

Wheels, Tires, Hubs
Driveline
Suspension

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56
Q

On a driver controlled differential lock how is it applied and released?

A

Air applied and spring released

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57
Q

When differential action is eliminated what happens to speed to the wheels?

A

Speed is evenly distributed to each drive wheel

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58
Q

Why would a steer axle be a drive axle?

A

To give more traction without adding another axle

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59
Q

When does a no-spin traction control make a ratcheting noise?

A

Normal - during cornering

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60
Q

True or False

A non-spin traction control does NOT replace a standard differential?

A

False - it does replace it

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61
Q

Where do the driven clutch & holdout rings spline to in a no-spin traction control?

A

To the drive axle side gear

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62
Q

What force holds the driven clutch & holdout ring to the spider & center cam?

A

Spring force

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63
Q

Where do the stub shafts on the spider in a no-spin traction control fit into?

A

The diff case

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64
Q

When cornering which wheel can overrun and unlock the no-spin traction control on that side?

A

The wheel that needs to go faster

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65
Q

How is a differential usually lubricated?

A

Splash is common, but pressure with a pump is possible

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66
Q

What throws the oil in a differential?

A

The bevel gear

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67
Q

What is most likely to fail first when the oil level is too low?

A

The bearings and seals

68
Q

Where is an oil pump usually located on a drive axle?

A

usually on the inter-axle

69
Q

Why is a lube pump needed on a inter-axle?

A

High location in the front carrier housing - poor lube

70
Q

What is the normal filter system in a drive axle?

A

Magnetic plugs

71
Q

What drives a lube pump in a drive axle?

A

Input shaft - always turning

72
Q

Spinning a bearing with compressed air is totally okay?

A

NO

73
Q

What should be used to clean internal components of a differential carrier and drive axle housing?

a) petroleum-based cleaning solution
b) steam cleaning/soapy water
c) varsol

A

a and c

74
Q

When should bearings be replaced?

A

When they show excessive wear

75
Q

Gear nest is?

A

Pinions, Side gears and cross shafts

76
Q

True or False

Pinion bearings need to be pre-loaded

A

TRUE

77
Q

How is pinion bearing pre-load measured?

A

Rotating Torque

78
Q

What tool is used to find pinion bearing preload?

a) micrometer
b) spring scale
c) torque wrench
d) multimeter

A

b) spring scale and cord

79
Q

Before removing a full floating axle, what should a technician do?

A

lock the lock collar

80
Q

How is a full floating axle removed?

A

Loosen axle flange nuts, strike raised lugs with hammer

81
Q

What are two ways to apply wheel lock assembly before servicing a drive axle?

A

Special bolt or shop air 80-120PSI to the shift cylinder at all time

82
Q

At what temperature does drive axle oil start to oxidize?

A

104°C

83
Q

What is the normal operating temperature of a drive axle?

A

71-104°C (160-220°F)

84
Q

What temperature of drive axle oil is showing signs of a larger problem?

A

121°C

85
Q

Does low level of oil or high level of oil cause over heating in a drive axle?

A

Both

86
Q

What are some causing of overheating in a drive axle?

A

Low oil level
High oil level - foaming
Improper lube type
Failing oil pump

87
Q

What can cause drive axle noise on turns?

A 
Worn: 
diff side gears/pinions
diff spiders
diff thrust washers
axle shaft splines
88
Q

What can cause noise during cost in the drive line?

A

Usually noise is heard on drive, but quieter on cost

Pinion and ring gear is too tight - ADJUST to fix

89
Q

Constant noise in a drive axle could be from?

A 
Flat spot on pinion or ring gear
Flat spot on bearings
worn pinion splines
worn axle shaft dowel holes
worn hub stubs
bent axle shaft
90
Q

Why would mismatched tires cause a differential to have premature wear/failure?

A

The differential action is always working

91
Q

Operator is complaining about a noise in the drive axle but the technician cannot find any faults in the drive axle, what could be causing the noise?

A

suspension

pg 9 190401i

92
Q

Bearings in a drive axle should be installed dry and clean?

A

No, they should be lightly oiled

93
Q

A technician during a driveline service find the pinon teeth are pitted on the drive side, what could be the cause?

A

Extreme/Severe service
or
Insufficient Lube

94
Q

A customer complains about a constant noise when driving (on accelerator), tech finds a bent axle housing. What could be the cause?

A

Vehicle has been overloaded
Vehicle was in an accident
or Shock loaded

95
Q

On an integral pinion: the new pinion etch mark says +4 but the old pinon had a -3 etch mark, how many shims would have to be added or taken away?

A

remove 0.007” of shims

96
Q

On a removable pinion bearing retainer, the etch mark on the pinion says +4, how many shims would have to be added or taken away?

A

0.004” in shims will have to be added

97
Q

Where is the pinon position spacer located on an integral drive pinion mounting?

A

Between the pinion gear and the bearing

98
Q

Where is the pinion position shims located on a removable pinion bearing retainer?

A

Between the cage and the carrier housing

99
Q

What is the direct indicator of backlash between the pinion and bevel?

A

Wear pattern

100
Q

What would cause a excessive toe wear pattern?

A

Ring gear too far in

101
Q

What would cause an excessive face wear pattern?

A

Pinion out too far

102
Q

What would cause an excessive flank wear pattern?

A

Pinion to far in

103
Q

What would cause an excessive heel wear pattern?

A

Ring gear out too far

104
Q

How would you correct a wear pattern that has too much toe?

A

Move ring gear away from pinion
or
Increase backlash

105
Q

How would a technician correct a wear pattern that is showing too much face?

A

Move the pinion IN and re-adjust ring gear for backlash

106
Q

What would a technician do to correct a wear pattern that is showing too much flank contact?

A

Move the pinion out and re-adjust ring gear for backlash

107
Q

If a pinion position is moved, what has to be done after?

A

Re-adjust ring gear backlash

108
Q

What must a technician do to correct a wear pattern that is showing too much heel wear?

A

Move ring gear toward pinion
or
Decrease back lash

109
Q

What can be considered the last adjustment?

A

Thrust Screw Adjustment

110
Q

What is the purpose of the thrust screw behind the bevel gear?

A

To prevent the bevel gear from deflecting away from the pinion under head shock loads

111
Q

Generally how much should a thrust screw be backed off after it seats on the bevel?

A

180° turn, 1/2 turn

112
Q

At what speed does a bevel gear turn?

A

The average speed between the two wheels

113
Q

When an inter axle is locked, what happens to torque and speed?

A

Unequal torque

Equal speed

114
Q

What are the drive axles splined too?

A

Bevel Gears

115
Q

What could be the cause of noise when driving?

A

Broken Teeth

116
Q

How is nominal dimension figured out?

A

Crown centreline to pinon back edge

117
Q

What could a spur cut bevel gear be in a differential?

A

Side gear

118
Q

In a two speed planetary what speed is it in when the sun is held from rotation?

A

Low speed

119
Q

When is the differential action of the inter-axle differential stopped?

A

When clutch teeth are engaged -Locked

120
Q

What does the inter-axle differential allow between forward and rearward drive axle input pinions?

A

A difference in speed

121
Q

When do the differential pinions STOP ROTATING in an inter-axle differential?

A

When there is NO speed difference between drive and side gear

122
Q

When differential action is allowed to operate in an inter-axle what happens to torque?

A

Its divided equally between two axles

123
Q

If a rearward axle on an inter-axle truck hits a patch of ice, what will happen to the forward axle?

A

The truck will be struck - due to the low friction on the rearward axle

124
Q

How much torque is applied to each axle when the lock is applied in the inter-axle?

A

Half the torque to the front, half the torque to the rear in non slippery condition

125
Q

Where is the internal ring in an outboard planetary held too?

A

Spindle

126
Q

What is the output member on an outboard planetary?

A

Carrier

127
Q

Where is the lube pump usually located in a drive axle?

A

ON the front diff carrier assembly

128
Q

At what speed does a no-spin spider rotate?

A

Same speed as bevel gear

129
Q

Does the operator have any control of lock or release of no-spin traction control?

A

No, automatic from springs

130
Q

When is power transmitted through diff pinion gears?

A

All times

131
Q

Name the 3 versions of a wheel lock?

A

Shift collar, Spring, Clutch disc

132
Q

What is the last check done on a differential?

A

Backlash or Thrust bolt clearance

133
Q

Why is root clearance important?

A

Space for lube

134
Q

Describe backlash?

A

The clearance between two tooth profiles that are in mesh

135
Q

One piece axle housing is also known as?

A

Banjo housing

136
Q

How many gears are in a single speed, double reduction carrier?

A

4 gears

137
Q

What should be checked after pinion bearing preload?

A

Carrier bearing preload

138
Q

Should oil be added to the inter-axle differential after a overhaul?

A

YES

139
Q

Does nominal dimensions measure from the front of the pinion gear or the back edge of the pinion gear?

A

Back edge

140
Q

If an oil leak is found on a differential but the seals do not appear to be the cause, where could the oil be from?

A

Housing leak - from fatigue - overloading

141
Q

A plug breather will cause?

A

Blown seals - leaking

142
Q

When removing a full floating axle, the retaining nuts should be removed before hitting the axle flange?

A

No, just loosened

143
Q

Before disassembly of a diff what should be measured?

A

backlash

144
Q

Which is set first preload or end play in assembly?

A

End play must be removed

145
Q

How is pinion preload created?

A

Crush Sleeve, Spacer, Shim

146
Q

Describe side gear?

A

Spur cut bevel gear

147
Q

If a thinner crush sleeve is used does the pinion have more preload or less preload?

A

More preload

148
Q

Before removal of diff carrier, what should a tech do?

A

Secure Vehicle
Apply diff lock - air or mechanically
disconnect drive shaft
mark housings

149
Q

What is important when deciding gear oil?

A

Ambient temp

150
Q

Do housings use gaskets or RTV?

A

RTV sealant

151
Q

What would be the operator complaint if differential thrust washers were worn?

A

Noise ONLY when cornering

152
Q

True or False

A vehicle should be shut down and inspected if the temperature in the diff is less than 104°C?

A

FALSE

121°C or more

153
Q

Shop air is considered what PSI?

A

80-120PSI

154
Q

When removing a case half, what should a technician be aware of on a no-spin set up?

A

It is spring loaded, large bolts should be used to release pressure safely

155
Q

A fractured tooth on the crown gear could be caused by?

A

Shock impact loading

156
Q

True or False

The pinion gear tries to move away from the crown gear when under load?

A

False bevel tries to deflect

157
Q

Not all carrier houses are identical, what can be done along with etch marks to find nominal distance of a pinion?

A

Special pinion depth measuring tools

Dial indicator, arbor, plunger, gauge plate

158
Q

At what PSI should air be applied to the inter-axle differential shift collar to adjust shift fork and collar travel?

A

60PSI

159
Q

On an integral drive pinion mounting, the old pinion mark is +2, the new pinion marking it -2, what size spacer/shim is needed?

A

+0.004

160
Q

When checking pinion bearing preload with a spring scale, what must be done to the bearing cage?

A

while applying press force

161
Q

What gear oils should not be used at temps below -40?

a) 0-76A
b) 0-76D
c) 0-76E
d) 0-76M

A

a and b

162
Q

Should petroleum oil or synthetic oil changes be done more often?

A

Petroleum (conventional) will be done more often

163
Q

What might be needed to remove a yoke?

A

a specific puller to prevent damaging the yoke

164
Q

When should a inter axle differential be locked out?

A

slow speed

poor traction surface

165
Q

On a vehicle with a differential and a outboard planetary final drive, how many reductions are being used?

A

two reductions
pinion to bevel
sun to carrier

166
Q

The gear shift knob is called what when a transmission has an auxiliary transmission?

A

Master Air Control Valve

Heavy Equipment Technician Period 4 (13 decks)

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