Chevrolet 70 1969 Series, Руководство по ремонту

Страница: 595 / 913

TANDEM REAR AXLE
REAR AXLE 4-40
(ROCKW ELL— M O D ELS SLHD A N D SQHD)
This section includes description and overhaul inform a­
tion on Rockwell tandem M odels S L H D and S Q H D hy-
poid rear axles with inter-axle differential.
Refer to “ Specifications” at end of this section for new
limits, fits, tolerances, torque readings, available shim
thicknesses and other im portant inspection and reassem ­
bly inform ation.
GEN ERAL DESCRIPTIO N
R ear axle unit consists of two hypoid drive type axle
assemblies. Forw ard unit (fig. 1 and 1A) in addition to a
conventional differential, incorporates an inter-axle differ­
ential, thru-shaft, and idler gear. Inter-axle differential al­
lows the two axles to operate independently or to be
locked together as a single unit. The thru-shaft permits
power to be transm itted from input shaft through inter­
axle differential to inter-axle propeller shaft.
PINION AND SHAFT
The hypoid drive pinion
011
front and rear axle units is
straddle m ounted with two tapered roller bearings at front
and one straight roller bearing at rear. Pinion on front
unit is driven by a helical gear from an idler gear. Rear
unit pinion is driven by an iriter-axle propeller shaft con­
necting front axle thru-shaft to rear axle pinion.
INTER-AXLE DIFFERENTIAL (FORWARD AXLE)
The function of the inter-axle differential is to divide
the torque between the two axles in the sam e m anner as
the differential in a single axle divides the torque between
two wheels.
Action of the inter-axle is controlled by the driver
through an air shift cham ber attached to side of inter-axle
differential cover (fig. 2).
W hen inter-axle differential is locked by sliding clutch
gear, the front and rear axles operate as one unit. This is
desirable in event one of the axles encounters loss of trac­
tion.
W hen inter-axle differential is in unlocked position,
front side gear drives rearw ard axle, while rear side gear
drives forward axle.
IDLER GEAR AND SHAFT (FORWARD AXLE)
An idler gear, supported by tapered roller bearings, is
m ounted between drive gear m ounted in ad apter case, and
drive gear m ounted on pinion. Entire assem bly is support­
ed in adapter case by a shaft.
AXLE DIFFERENTIAL
Differential in each axle is conventional four pinion
type with helical drive gear riveted to flanged half of dif­
ferential case. The two halves of differential case are m a ­
chined as an assem bly and m ust be replaced as such.
Thrust washers are used between pinions an d case, also
between side gears and case. T hrust washers m ust be re­
placed in sets.
C om plete differential assembly is supported by opposed
tapered roller bearings located in legs of carrier. Bearings
are adjustable to provide proper drive gear location and to
adjust bearing pre-load.
AXLE SHAFTS
Axle shafts are full floating type, splined to differential
side gears at inner end, and attached to hubs by studs and
nuts at flanged end. Stud holes in flange are taper-ream ed
to accom m odate split tapered dowels.
O V ERH A U L
R ear axle assemblies should be completely removed
from vehicle whenever carrier assembly is to be disas­
sembled for overhaul. However, axle shafts can be re­
moved without removing axle assembly.
Except for construction of pinion shafts and the inter­
axle differential on front unit, front and rear differential
units are the same. Following procedures describe front
units and apply to both front and rear units unless other­
wise noted in text.
1. C heck axle housing for lubricant leaks before clean­
ing, then steam clean thoroughly.
2. C heck pinion and bevel gear backlash. Refer to “ Spe­
cifications” at end of this section.
3. Check pinion gear shaft, also bevel gear shaft and dif­
ferential bearing end play. This inform ation should be
recorded for reference at reassembly.
D ISA SSEM BLY SHIFT REMOVAL (FORWARD AXLE)
Before and during axle disassembly check the follow­
ing:
I. A t right side of adapter case, remove shift housing
cap screws and lock washers, then rem ove housing.
CHEVROLET SERIES 70-80 H EAVY DUTY TRUCK S H O P M A N U A L