Drive Axle Assembly Fundamentals (On-Road)

Question 1

List the four functions of the drive axle assembly.

Answer 1

1. The drive axle assembly must withstand and support the weight of the vehicle and load that has been passed through the suspension system to the drive axle assembly.
2. The drive axle assembly provides the last gear reduction in the basic vehicle powertrain.
3. The drive axle assembly must change the direction of torque by 90 degrees.
4. The drive axle must transfer torque evenly between the two wheel assemblies as it is driving while allowing for a difference in speed between the two.

Question 2

The gross combination weight rating refers to the:

a. amount of weight each axle can carry.
b. combined gross axle weight ratings for a vehicle.
c. total combined gross axle weight ratings for a vehicle and it’s trailers.
d. amount a vehicle weighs empty.

Answer 2

c. total combined gross axle weight ratings for a vehicle and it’s trailers.

Question 3

The percentage of grade at which a drivetrain system can start a loaded vehicle moving at idle is called:

a. gradeability
b. startability
c. liftability
d. maintainability

Answer 3

b. startability

Question 4

The main function of the carrier housing is to:

a. house the axle shafts.
b. secure the suspension components.
c. withstand the weight of the vehicle.
d. hold the internal gear components.

Answer 4

d. hold the internal gear components.

Question 5

The overhung pinion differs from the straddle mount in that it has a short stub that extends past the end of the pinion gear.

a. true
b. false

Answer 5

b. false

Question 6

What is the main purpose of the thrust screw?

Answer 6

The thrust screw prevents the bevel gear from deflecting away from the input pinon during heavy torque loads.

Question 7

The differential pinions are driven by the:

a. cross shafts.
b. axle side gears.
c. bevel gear.
d. case halves.

Answer 7

a. cross shafts.

Question 8

In the planetary differential carrier assembly, low gear is achieved when:

a. The sun gear is locked to the retainer plate.
b. The sun gear is locked to the carrier.
c. The carrier is locked to the bevel gear.
d. The bevel gear is locked to the internal gear.

Answer 8

a. The sun gear is locked to the retainer plate.

Question 9

Number the following components in the path-of-power through a single speed reduction carrier assembly. Begin with the input shaft yoke and end with the wheel assemblies.
Input yoke\_\_\_\_\_\_
differential cross shaft\_\_\_\_\_
differential case\_\_\_\_\_\_
axle shafts\_\_\_\_
input drive pinion\_\_\_\_
bevel gear\_\_\_\_
axle side gears\_\_\_
differential pinions\_\_\_\_
wheel assemblies\_\_\_\_\_

Answer 9

input yoke-1
differential cross shaft-5
differential case-4
axle shafts-8
input drive pinion-2
bevel gear-3
axle side gears-7
differential pinions-6
wheel assemblies-9

Question 10

When a vehicle is turning a corner, the differential assembly allows the:

a. inner drive wheel to rotate faster than the outer drive wheel.
b. outer drive wheel to rotate faster than the inner drive wheel.
c. bevel gear to rotate at the same speed as the outer drive wheel.
d. bevel gear to rotate at the same speed as the inner drive wheel.

Answer 10

b. Outer drive wheel to rotate faster than the inner drive wheel.

Question 11

The input shaft drives the helical drive gear through a set of splines.

a. True
b. False

Answer 11

b. False

Question 12

The lockout assembly of the inter-axle differential locks what two components?

a. input shaft and cross shaft.
b. input shaft and helical drive gear.
c. helical drive gear and the output shaft.
d. input shaft and the inter-axle differential case.

Answer 12

b. input shaft and helical drive gear.

Question 13

On a drive axle assembly using a planetary final drive system, the input member of the planetary system is the:

a. internal gear.
b. carrier assembly.
c. sun gear.
d. hub assembly.

Answer 13

c. sun gear.

Question 14

Explain the drive axle filtration systems.

Answer 14

Drive axle assemblies use magnetic drain plugs, magnetic screens and spin on filters to filter and clean the oil.

Question 15

When the operator activates the driver controlled differential lock, the operator is mechanically locking:

a. the axle shafts together.
b. the two case halves together.
c. the differential pinions to the axle side gears.
d. one axle shaft to the differential case.

Answer 15

d. one axle shaft to the differential case.

Question 16

The weight rating that refers to how much each axle can carry is called the:

a. gross combination weight rating. (GCWR)
b. gross axle weight rating. (GAWR)
c. gross vehicle weight rating (GVWR)

Answer 16

b. gross axle weight rating. (GAWR)

Question 17

The reason a driving axle would be added to the rear of a truck rather than a non driving (tag or pusher) would be to:

a. increase the GVWR.
b. increase theGCWR.
c. increase the GAWR.
d. increase traction.

Answer 17

d. increase traction.

Question 18

Which components are attached to the drive axle housing?

a. suspension components.
b. wheels tires and hubs.
c. carrier housing.
d. all of the above.

Answer 18

d. all of the above.

Question 19

The pinion bearing cage is always a removable component of the carrier housing.
True
False

Answer 19

False

Question 20

The input drive pinion is in constant mesh with the:

a. differential pinions.
b. axle side gears.
c. bevel gear.
d. differential case.

Answer 20

c. bevel gear.

Question 21

The bevel gear is bolted directly to the:

a. carrier bearing.
b. differential pinions.
c. plain case half.
d. flanged case half.

Answer 21

d. flanged case half.

Question 22

The most common differential carrier assembly used today is the:

a. single speed single reduction.
b. single speed double reduction.
c. two speed double reduction.
d. planetary carrier.

Answer 22

a. single speed single reduction.

Question 23

On a two speed double reduction carrier assembly, component that drives the helical gear is the:

a. cross shaft.
b. bevel gear.
c. helical driven gear.
d. shift collar.

Answer 23

d. shift collar.

Question 24

The torque available to the wheel with good traction in a wheel spin condition is:

a. full torque.
b. half of full torque.
c. twice that of the torque to the spinning wheel.
d. the same as the torque to the spinning wheel.

Answer 24

d. the same as the torque to the spinning wheel.

Question 25

The inter-axle differential is physically located:

a. between the front and rear drive axle assemblies.
b. in the front drive axle assembly.
c. in the rear drive axle assembly.
d. in the driveline before the front drive axle assembly.

Answer 25

b. in the front drive axle assembly.

Question 26

The cross shafts of the inter-axle differential are driven by the:

a. case halves.
b. helical drive gear.
c. differential pinions.
d. input shaft.

Answer 26

d. input shaft.

Question 27

Semi-floating axle shafts can be removed from a vehicle when the weight of the vehicle is on the drive wheels.
True
False.

Answer 27

False

Question 28

Identify the two main drive axle lubrication systems.

Answer 28

Splash lubrication.

Combination splash and pressure lubrication.

Question 29

A differential assembly equipped with a no spin assembly allows for normal differential action when the vehicle turns a corner.
True
False

Answer 29

True