Chevrolet 10 Series 1970 Service Manual page 208

REAR SUSPENSION AND DRIVE LINE 4-32
O n-the-V ehicle Check
1. R aise re a r o f v e h ic le until both re a r wheels are o ff
the flo o r.
2. Shift tran sm ission into gea r.
3. Rotate both r e a r w heels as fa r forw a rd as possible.
4. W ith assistant holding le ft wheel forw ard , rotate the
right wheel to the re a r , checking fo r fr e e rotation.
REAR AXLE (CHEVROLET) TWO-SPEED
General D e s c rip tio n .............................................................................. ..... 4-32
Maintenance and Adjustm ent ............................................................ ..... 4-32
C om ponent Parts R e p la c e m e n t................................. .. . .................. ..... 4-32
Electric Shift System ....................................................................... ..... 4-32
Vacuum C ylinder Diaphragm Replacem ent ................................. ..... 4-38
Vacuum Cylinder O il Seal R e p la c e m e n t........................................ ..... 4-38
Maintenance and adjustm ents fo r the tw o-speed axle
a re p erfo rm e d the sam e as those outlined fo r the C hev-
S erv ic e operations in this section a re
those operations pertaining to item s p ecu liar to the two-
speed axle only. F o r those operations common to both
the tw o-speed and sin gle-sp eed axles, r e fe r to applicable
p rocedu re as outlined
S in g le-S p ee d ."
ELECTRIC SHIFT SYSTEM
An e le c tr ic shift con trol is used in conjunction with the
C h evro let 2 -speed axles. The inform ation n ecessary to
understand the construction, operation, maintenance, and
r e p a ir o f the e le c tr ic shift m echanism is presented here
under self-exp lan ato ry headings.
Construction
The e le c tric shift con trol system is com posed o f the
manual control switch, speedom eter adapter, axle shift
unit, circ u it b reak er, and connecting w irin g o r " h a r n e s s "
(fig . 61).
M an u al Control Switch
The control switch, fastened to the tran sm ission con­
tr o l le v e r (fig . 62), has two positions, up fo r high axle
range and down fo r low axle range. When the switch op­
eratin g knob is in eith er o f these positions, a w iper
contact on the arm com p letes a circu it between the
battery and the m otor in the axle shift unit (fig. 61).
DRIVE LINE
GENERAL DESCRIPTION
The C h evrolet tw o-speed axle
available in both the 15,000 and 17,000 lb. capacity.
MAINTENANCE AND ADJUSTMENTS
COMPONENT PART REPLACEMENT
r e s tric te d to
in " R e a r A x le (C h evrolet)
5. Rotate both wheels as fa r to the re a r as possible.
6. W hile holding the le ft wheel rea rw a rd ,
right wheel forw ard, again checking fo r fre e rotation.
7. Repeat Steps 3-6, holding the right wheel and rotating
the le ft wheel fo r le ft side forw a rd and rearw a rd
operation check.
8. If w heels cannot be
above, rem ove and inspect the No-Spin.
INDEX
Page
Shifter Spring R e p la ce m e n t................................................................
Vacuum Shift C ontrol Switch Replacem ent ....................................
Speedom eter A dapter C ontrol Switch R e p la c e m e n t......................
Speedom eter A dapter C ontrol Sw itch Housing
or Case Replacem ent .......................................................................
(fig . 60) is optionally
ro le t sin gle-sp eed axles.
le t) S in gle-S p eed ."
Speedometer A d ap ter
The speedom eter adapter, installed behind the speed­
o m eter, p rovid es c o rre c t speedom eter reading with the
axle in eith er high o r low range. By introducing a gear
reduction into the speedom eter d riv e upon shift to axle
low range, the unit com pensates fo r the in creased p ro ­
p e lle r shaft speed re la tiv e to veh icle forw a rd speed en­
countered in axle low range. When the axle is shifted to
high range, the speedom eter d riv e is "s tra ig h t th ru " the
adapter.
The inner mechanism is prelu bricated and sealed by
the m anufacturer. In the event o f fa ilu re, the adapter is
rep laced as a unit.
A x le Shift Unit
The axle shift unit is mounted on the d ifferen tia l c a r ­
r ie r as shown in F igu re 63. This unit contains a r e v e r s ­
ible e le c tric m otor, which when en ergized , shifts the axle
into the desired range through the mechanism contained
in the unit (fig . 61).
W iring System
The pow er lead fo r the shift unit is connected to the
" c o l d " side o f the ignition switch at the a cc e s s o ry te r m i­
nal, th erefo re, the en tire system w ill be " d e a d " until the
ignition switch is turned to the " O N " position.
rotate the
rotated fr e e ly as described
R e fe r to " R e a r A x le (C h evro -
CHEVROLET TRUCK SERVICE MANUAL
Page
4.39
4.39
4.40
4.40