Chevrolet 10 Series 1970 Service Manual page 227

terns m ove the sliding clutch into engagement with the
input shaft h elical gea r.
warns when d iffe ren tia l is locked out.
REARWARD REAR AXLE
The rearw ard axle assem bly is maintained in the same
manner as outlined fo r the single speed Eaton re a r axle.
FORWARD REAR AXLE
The pow er d iv id e r and in te r-a x le d iffe re n tia l a re part
INTER-AXLE DIFFERENTIAL LOCK SHIFT SYSTEM
V A C U U M OPERATED
O p eratio n
The toggle switch on the cen ter instrum ent panel con­
tro ls the warning light in the instrument clu ster (fig . 89)
and the solenoid operated lock va lve at the fram e side
r a il (fig . 90).
The solenoid, when en ergized , actuates the lock va lve
connected between the locking cylinder, mounted at the
front o f the fo rw ard r e a r axle, and the engine vacuum
supply (fig . 90).
The locking cylin d er (fig .
shift le v e r so the sliding clutch engages the input shaft
h e lic a l and d iffere n tia l side gear to divide pow er equal
to both axles.
Checking For Leakage
P la c e the truck on le v e l ground with the parking brake
rele a s e d and the transm ission in neutral. Start the en­
gine with the control switch at " on" (the pow er d ivid er
d iffe re n tia l locked out). A c c e le ra te the engine fo r a few
seconds, re le a s e the a c c e le ra to r, and turn o ff the ignition
sw itch. Im m ediately m easure the distance between the
face o f the locking cylin d er mounting bracket and the
cen ter o f the push rod yoke to the le v e r pin and make
note of the dim ension. A t the end o f ten minutes, r e ­
m easure the distance. If the distance has not increased,
the system may be considered vacuum tight. H ow ever, if
the distance has increased, a vacuum leak exists in the
system .
F ir s t check a ll connections. A fte r a ll the hoses and
the pipe connections have been checked and tightened, test
the system again.
Solenoid Lock V a lv e
The solenoid va lve is positioned at the fram e left side
r a il by the vacuum pipe clips and may be rem oved by d is ­
connecting the three fittin gs at the v a lve.
Locking C ylinder
When leakage tests indicate the locking cylin der a s ­
sem bly leaks, it must be rem oved and disassem bled, and
the rubber diaphragm in the cylin d er must be replaced.
1. Disconnect the con trol va lv e hose fro m the cylinder.
Rem ove the cotter pin and the c le v is pin which s e ­
A light installed on the dash
MAINTENANCE AND ADJUSTMENTS
SERVICE OPERATIONS
91) operates the lockout
REAR SUSPENSION AND DRIVE LINE 4-51
NOTE: Use lockout
When d iffe re n tia l is to be locked out, veh icle
must be com p letely
n ecessary use of lockout must be avoided.
o f the forw a rd re a r axle d iffe ren tia l c a r r ie r c o v e r a s ­
sem bly and may be rem oved when the c a r r ie r is eith er in
o r out o f the v eh icle. The d ifferen tia l,
pinion are s e rv ic e d in the sam e manner as outlined fo r
the single speed Eaton re a r axle.
cure the bracket le v e r to the push rod. Rem ove the
snap ring which secu res the cylin der in the bracket,
and rem ove the assem bly fro m the bracket. Rem ove
the boot fro m the push rod.
2. Rem ove the c le v is yoke and nut fro m the push rod
(fig . 91). R em ove the screw s, nuts, and lock wash­
e rs which attach the two halves of the cylin d er and
the rubber diaphragm together.
half o f the cylin d er, and separate the rubber dia ­
phragm fro m the inner half o f the cylinder.
3. Install a new diaphragm and push rod assem bly in the
re a r half of the cylin d er.
4. Make certain the mating faces o f the cylin d er halves
are clean. P osition the outer half of the cylin d er on
the rubber diaphragm , and install the screw s, nuts,
and new lock w ash ers.
c le v is yoke on the push rod.
5. Make certain that the snap ring gro o ve on the inner
half of the cylin d er is clean. Position the cylin der in
the bracket on the pow er d ivid er with the slot in the
r e a r half of the cylin d er at the bottom.
6. Install the retaining snap ring and seat it so lid ly in
the gro o ve. Attach the bracket le v e r to the rod c le v is
with a c le v is pin and a new cotter pin. Attach the
vacuum line to the locking cylinder. T es t the system
fo r vacuum leaks.
AIR OPERATED
O peration
A ir operated d iffe re n tia l lock u tilize s a ir p ressu re
fro m the a ir brake system fo r its operation. Units used
in a ir-o p e ra te d pow er shift system a re: Shift Control
V a lve, mounted on engine side of dash; check va lve, in ­
stalled in a ir line at con trol valve a ir in let; d iffe ren tia l
lock shift cylin d er, mounted on forw ard re a r axle torque
d ivid er case c o v e r; and interconnecting a ir lin es and
fittings.
With lock con trol knob on instrument panel (fig . 92) in
" U N L O C K " position, there is no a ir p ressu re in d if­
fere n tia l lock shift cylin d er.
spring holds cylin d er piston and lock linkage in unlocked
position.
When lock con trol knob (fig . 92) is m oved to " L O C K "
position, a ir p ressu re is admitted behind lock shift c y lin ­
d er piston. As a ir pressu re fo rc e s the piston outward,
the d ifferen tia l lock is shifted into locked position.
only in s lip p ery going.
stopped. Continuous un­
rin g g ea r and
Rem ove the outer
Install the boot, nut, and
Shift return com pression
CHEVROLET TRUCK SERVICE MANUAL