HET 4 DRIVE AXLE Flashcards
DRIVE AXLE ASSEMBLY FUNDAMENTALS ON-ROAD 190401h (166 cards)
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
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
3
Q
An axle code is D S 40 4 - P, what is the GAWR?
A
40 x 1000lbs = 40 000lbs is GAWR
4
Q
GAWR stands for?
A
Gross axle weight rating per tandem x 1000 lbs
5
Q
Axle code is DP581-P, what does the P stand for?
A
Standard lube pump
6
Q
GVWR stands for?
A
Gross vehicle weight rating
-the total weight of the vehicle and its load
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
8
Q
GCWR stands for?
A
Gross combination weight rating
9
Q
If more traction is needed what kind of axle is added to the vehicle?
A
another DRIVE axle
10
Q
Does adding a second non-driving axle help increase traction?
A
No, helps increase weight that can be carried
11
Q
Describe startability?
A
Percentage of grade at which a drivetrain system can start a loaded vehicle moving at an idle?
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
13
Q
If the startability ratio is too low what is the complaint?
A
poor fuel economy
14
Q
Does straddle mount or overhunt mount drive pinions handle the most torque load?
A
Straddle mount
15
Q
Pinion drives are usually mounted in what drive axle component?
A
Carrier hoursing
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
17
Q
Thrust screw prevents the bevel or the pinion gear from moving away?
A
The bevel from moving away from the pinion
18
Q
Where is the trust screw positioned in relation to the pinon gear?
A
Exact opposite location
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
20
Q
What are the two case halves of a differential that are bolted together?
A
flanged and plain
21
Q
Is the bevel gear bolted to the flanged or plain case half?
A
Flanged
22
Q
True or False
Bevel gear and input pinion are a matched set and must be changed together?
A
True
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.
24
Q
What components are INSIDE the differential assembly?
A
Cross shaft, spider(pinion) and side gears, thrust washers
25
Which side of the differential case does the cross shaft fit into?
Plain case half
26
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)?
The toes are facing in towards the center of the cross shaft
27
True or False
| Both side gears need to move at the same speed?
False
28
Which is the most common differential carrier used today?
Single Speed Single Reduction
29
Why would a high speed clutch plate have a chamfered edge on the splines?
To help the sun engage
30
Where is the first reduction always found in a differential?
Pinion to Ring gear
31
The bevel gear are attached to what in a planetary differential?
Bevel gear is attached to Internal/Ring gears
32
What usually shifts a two speed planetary differential?
Air solenoid or actuator
33
In a two speed planetary, high speed is selected. What is the gear ratio created?
Direct Drive
34
What is the differential assembly in a two speed planetary differential?
Differential assembly - Carrier
35
When cornering, what wheel will have to go faster to cover the same distance as the other wheel?
Outside wheel
36
If wheels that are cornering cannot achieve a speed difference what is the result?
Tire scuffing, steering difficulties
37
Two speed means what in relation to path of power?
Two paths of power available
38
What component supports drive gears in a two speed differential?
Cross shaft
39
If speed is lost at one wheel, what happens to the other wheel on that axle?
Gets the lost speed
40
What is the bevel gear RPM?
Sum of both wheel assembly speeds
41
If you are given an input speed, what else do you need to figure out what speed is getting to the wheel hubs?
Gear ratio
42
Why is the first drive axle oil change usually done after a short period?
To remove break in debris
43
What type of oil should be used in a drive axle?
Manufacture spec
44
At what angle should a standpipe be added to a drive axle to correct the oil level?
12° or more
45
When does a standpipe most likely need to be added to a drive axle to correct oil level?
if the drive axle is 12° or more
OR
if the vehicle is operating on steep grades normally
46
Since oil from the drive axle goes to the wheel ends what should be done during services (fluid changes)?
Tilt the axle to get oil out from wheel ends
47
When is a static seal used?
Non-moving parts
48
Dynamic seals are used with what components?
Over a moving part
| ei. drive axles
49
After a service and drive axle oil has been changed, what should be done before final level check?
Drive the vehicles for a few minutes and then let settle for 5 minutes. Recheck level
50
What is the purpose of a breather on a drive axle?
To allow built up pressure to release
51
What causes an o-ring to fail in a inter-axle differential lock cylinder?
high pressure in the housing
52
Why is input shaft and output shaft end play important?
If out of spec can cause vibration and damage
53
What should be done before a road test to find faults?
Visual Inspection
54
Why should a technician be cautious when doing a plug swap on a drive axle?
High temp - Burns
55
What components need to be inspected to find a drive axle fault?
Wheels, Tires, Hubs
Driveline
Suspension
56
On a driver controlled differential lock how is it applied and released?
Air applied and spring released
57
When differential action is eliminated what happens to speed to the wheels?
Speed is evenly distributed to each drive wheel
58
Why would a steer axle be a drive axle?
To give more traction without adding another axle
59
When does a no-spin traction control make a ratcheting noise?
Normal - during cornering
60
True or False
| A non-spin traction control does NOT replace a standard differential?
False - it does replace it
61
Where do the driven clutch & holdout rings spline to in a no-spin traction control?
To the drive axle side gear
62
What force holds the driven clutch & holdout ring to the spider & center cam?
Spring force
63
Where do the stub shafts on the spider in a no-spin traction control fit into?
The diff case
64
When cornering which wheel can overrun and unlock the no-spin traction control on that side?
The wheel that needs to go faster
65
How is a differential usually lubricated?
Splash is common, but pressure with a pump is possible
66
What throws the oil in a differential?
The bevel gear
67
What is most likely to fail first when the oil level is too low?
The bearings and seals
68
Where is an oil pump usually located on a drive axle?
usually on the inter-axle
69
Why is a lube pump needed on a inter-axle?
High location in the front carrier housing - poor lube
70
What is the normal filter system in a drive axle?
Magnetic plugs
71
What drives a lube pump in a drive axle?
Input shaft - always turning
72
Spinning a bearing with compressed air is totally okay?
NO
73
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 and c
74
When should bearings be replaced?
When they show excessive wear
75
Gear nest is?
Pinions, Side gears and cross shafts
76
True or False
| Pinion bearings need to be pre-loaded
TRUE
77
How is pinion bearing pre-load measured?
Rotating Torque
78
What tool is used to find pinion bearing preload?
a) micrometer
b) spring scale
c) torque wrench
d) multimeter
b) spring scale and cord
79
Before removing a full floating axle, what should a technician do?
lock the lock collar
80
How is a full floating axle removed?
Loosen axle flange nuts, strike raised lugs with hammer
81
What are two ways to apply wheel lock assembly before servicing a drive axle?
Special bolt or shop air 80-120PSI to the shift cylinder at all time
82
At what temperature does drive axle oil start to oxidize?
104°C
83
What is the normal operating temperature of a drive axle?
71-104°C (160-220°F)
84
What temperature of drive axle oil is showing signs of a larger problem?
121°C
85
Does low level of oil or high level of oil cause over heating in a drive axle?
Both
86
What are some causing of overheating in a drive axle?
Low oil level
High oil level - foaming
Improper lube type
Failing oil pump
87
What can cause drive axle noise on turns?
```
Worn:
diff side gears/pinions
diff spiders
diff thrust washers
axle shaft splines
```
88
What can cause noise during cost in the drive line?
Usually noise is heard on drive, but quieter on cost
| Pinion and ring gear is too tight - ADJUST to fix
89
Constant noise in a drive axle could be from?
```
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
Why would mismatched tires cause a differential to have premature wear/failure?
The differential action is always working
91
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?
suspension
| pg 9 190401i
92
Bearings in a drive axle should be installed dry and clean?
No, they should be lightly oiled
93
A technician during a driveline service find the pinon teeth are pitted on the drive side, what could be the cause?
Extreme/Severe service
or
Insufficient Lube
94
A customer complains about a constant noise when driving (on accelerator), tech finds a bent axle housing. What could be the cause?
Vehicle has been overloaded
Vehicle was in an accident
or Shock loaded
95
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?
remove 0.007" of shims
96
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?
0.004" in shims will have to be added
97
Where is the pinon position spacer located on an integral drive pinion mounting?
Between the pinion gear and the bearing
98
Where is the pinion position shims located on a removable pinion bearing retainer?
Between the cage and the carrier housing
99
What is the direct indicator of backlash between the pinion and bevel?
Wear pattern
100
What would cause a excessive toe wear pattern?
Ring gear too far in
101
What would cause an excessive face wear pattern?
Pinion out too far
102
What would cause an excessive flank wear pattern?
Pinion to far in
103
What would cause an excessive heel wear pattern?
Ring gear out too far
104
How would you correct a wear pattern that has too much toe?
Move ring gear away from pinion
or
Increase backlash
105
How would a technician correct a wear pattern that is showing too much face?
Move the pinion IN and re-adjust ring gear for backlash
106
What would a technician do to correct a wear pattern that is showing too much flank contact?
Move the pinion out and re-adjust ring gear for backlash
107
If a pinion position is moved, what has to be done after?
Re-adjust ring gear backlash
108
What must a technician do to correct a wear pattern that is showing too much heel wear?
Move ring gear toward pinion
or
Decrease back lash
109
What can be considered the last adjustment?
Thrust Screw Adjustment
110
What is the purpose of the thrust screw behind the bevel gear?
To prevent the bevel gear from deflecting away from the pinion under head shock loads
111
Generally how much should a thrust screw be backed off after it seats on the bevel?
180° turn, 1/2 turn
112
At what speed does a bevel gear turn?
The average speed between the two wheels
113
When an inter axle is locked, what happens to torque and speed?
Unequal torque
| Equal speed
114
What are the drive axles splined too?
Bevel Gears
115
What could be the cause of noise when driving?
Broken Teeth
116
How is nominal dimension figured out?
Crown centreline to pinon back edge
117
What could a spur cut bevel gear be in a differential?
Side gear
118
In a two speed planetary what speed is it in when the sun is held from rotation?
Low speed
119
When is the differential action of the inter-axle differential stopped?
When clutch teeth are engaged -Locked
120
What does the inter-axle differential allow between forward and rearward drive axle input pinions?
A difference in speed
121
When do the differential pinions STOP ROTATING in an inter-axle differential?
When there is NO speed difference between drive and side gear
122
When differential action is allowed to operate in an inter-axle what happens to torque?
Its divided equally between two axles
123
If a rearward axle on an inter-axle truck hits a patch of ice, what will happen to the forward axle?
The truck will be struck - due to the low friction on the rearward axle
124
How much torque is applied to each axle when the lock is applied in the inter-axle?
Half the torque to the front, half the torque to the rear in non slippery condition
125
Where is the internal ring in an outboard planetary held too?
Spindle
126
What is the output member on an outboard planetary?
Carrier
127
Where is the lube pump usually located in a drive axle?
ON the front diff carrier assembly
128
At what speed does a no-spin spider rotate?
Same speed as bevel gear
129
Does the operator have any control of lock or release of no-spin traction control?
No, automatic from springs
130
When is power transmitted through diff pinion gears?
All times
131
Name the 3 versions of a wheel lock?
Shift collar, Spring, Clutch disc
132
What is the last check done on a differential?
Backlash or Thrust bolt clearance
133
Why is root clearance important?
Space for lube
134
Describe backlash?
The clearance between two tooth profiles that are in mesh
135
One piece axle housing is also known as?
Banjo housing
136
How many gears are in a single speed, double reduction carrier?
4 gears
137
What should be checked after pinion bearing preload?
Carrier bearing preload
138
Should oil be added to the inter-axle differential after a overhaul?
YES
139
Does nominal dimensions measure from the front of the pinion gear or the back edge of the pinion gear?
Back edge
140
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?
Housing leak - from fatigue - overloading
141
A plug breather will cause?
Blown seals - leaking
142
When removing a full floating axle, the retaining nuts should be removed before hitting the axle flange?
No, just loosened
143
Before disassembly of a diff what should be measured?
backlash
144
Which is set first preload or end play in assembly?
End play must be removed
145
How is pinion preload created?
Crush Sleeve, Spacer, Shim
146
Describe side gear?
Spur cut bevel gear
147
If a thinner crush sleeve is used does the pinion have more preload or less preload?
More preload
148
Before removal of diff carrier, what should a tech do?
Secure Vehicle
Apply diff lock - air or mechanically
disconnect drive shaft
mark housings
149
What is important when deciding gear oil?
Ambient temp
150
Do housings use gaskets or RTV?
RTV sealant
151
What would be the operator complaint if differential thrust washers were worn?
Noise ONLY when cornering
152
True or False
| A vehicle should be shut down and inspected if the temperature in the diff is less than 104°C?
FALSE
| 121°C or more
153
Shop air is considered what PSI?
80-120PSI
154
When removing a case half, what should a technician be aware of on a no-spin set up?
It is spring loaded, large bolts should be used to release pressure safely
155
A fractured tooth on the crown gear could be caused by?
Shock impact loading
156
True or False
| The pinion gear tries to move away from the crown gear when under load?
False bevel tries to deflect
157
Not all carrier houses are identical, what can be done along with etch marks to find nominal distance of a pinion?
Special pinion depth measuring tools
| Dial indicator, arbor, plunger, gauge plate
158
At what PSI should air be applied to the inter-axle differential shift collar to adjust shift fork and collar travel?
60PSI
159
On an integral drive pinion mounting, the old pinion mark is +2, the new pinion marking it -2, what size spacer/shim is needed?
+0.004
160
When checking pinion bearing preload with a spring scale, what must be done to the bearing cage?
while applying press force
161
What gear oils should not be used at temps below -40?
a) 0-76A
b) 0-76D
c) 0-76E
d) 0-76M
a and b
162
Should petroleum oil or synthetic oil changes be done more often?
Petroleum (conventional) will be done more often
163
What might be needed to remove a yoke?
a specific puller to prevent damaging the yoke
164
When should a inter axle differential be locked out?
slow speed
| poor traction surface
165
On a vehicle with a differential and a outboard planetary final drive, how many reductions are being used?
two reductions
pinion to bevel
sun to carrier
166
The gear shift knob is called what when a transmission has an auxiliary transmission?
Master Air Control Valve
