Chapter 7 Differentials and Drive Axles
Answers to Review Questions
•Classroom Manual, Pages 172–174
Short Answer Essays
1.
Final drive is the final gear set of reduction gears in the power train
on its way to the drive wheels.
2.
A differential is needed between any two drive wheels because the
two drive wheels must be at different speeds when the vehicle is turning. If the
tires cannot rotate at different speeds, one will scrub on the road. This scrubbing
causes abnormal tire wear.
3.
Hypoid gears allow the drive shaft to be positioned low in the
vehicle because the final drive pinion gear center line is below the ring gear
center line. This allows the vehicle, as a whole, to be lower.
4.
Three major functions of a differential are: to allow for different
speeds between the two drive wheels; to multiply torque, and to change the
direction of power flow.
5.
The drive shaft drives the pinion gear, which is in mesh with the
ring gear. The ring gear is bolted to the differential case. The power flowing from
the drive pinion and ring gear causes it to rotate. The differential case normally
houses the pinion gears and axle side gears, which are mounted over splines at
the end of the axle shafts.
6.
The difference between an integral carrier housing and a
removable carrier housing is in the integral type housing: the differential carrier
housing and the axle housing are the same casting, whereas in the removable
type, the carrier housing can be removed from the axle housing.
7.
The differences between hunting, non-hunting, and partial
nonhunting gears are based on the number of teeth on the ring and pinion gears.
A nonhunting gearset is one in which any one pinion gear tooth comes in contact
with the same teeth on the ring gear during each revolution of the ring gear. A
partial nonhunting gearset is one in which one pinion tooth comes in contact with
the same teeth on the ring gear, but more than one revolution is required. The
hunting gearset has all pinion gear teeth coming in contact with all of the teeth on
the ring gear.
8.
The straddle-mounted pinion has two opposing tapered-roller
bearings positioned close together and ahead of the pinion gear, using a third
bearing behind the pinion to support the rear of the pinion gear. The overhung
mounted pinion uses two opposing tapered-roller bearings but does not use a
third bearing. The two roller bearings are placed further apart to support the
shaft.
9.
A limited-slip differential provides more driving force to the wheel
with traction when one wheel begins to slip. Limited-slip differentials are similar
to conventional units except for a large internal recess around each axle side
gear. This recess accepts a clutch assembly. The clutch plates are splined to
each axle gear’s hub and the ears of the clutch plates are fitted into the
differential case to provide resistance to the movement of the axle side gears in
relation to the differential case.
10.
There are basically three designs by which axles are supported in a
live axle: full-floating, three-quarter floating, and semi-floating. These refer to
where the axle bearing is placed in relation to the axle and the housing. The
bearing of a full-floating axle is located on the outside of the housing, which
places all of the vehicle’s weight on the axle housing with no weight on the axle.
Three-quarter and semi-floating axles are supported by bearings located in the
housing and therefore carry some of the vehicle’s weight on the axles.
Fill-in-the-Blanks
1.
Pinion, ring, pinion, side
2.
Integral, removable
3.
Spiral, bevel gears, hypoid gears
4.
Convex, concave, toe, heel
5.
Pinion, ring
6.
Hunting, non-hunting, partial non-hunting
7.
Three, two
8.
Helical, planetary, hypoid
9.
Clutch pack, cone clutch, and viscous clutch
10.
Ball-type, straight roller, tapered-roller
Multiple Choice
1.
C
2.
B
3.
C
4.
B
5.
B
6.
D
7.
C
8.
C
9.
D
10.
C
•Shop Manual, Pages 310–312
ASE-Style Review Questions
1.
B
2.
C
3.
C
4.
A
5.
B
6.
C
7.
B
8.
C
9.
D
10.
C
ASE Challenge
1.
D
2.
A
3.
D
4.
B
5.
D