Chevrolet 10 Series 1970, Руководство по обслуживанию

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REAR SUSPENSION AND DRIVE LINE 4-35
F ig . 6 2 — E le c tric S h ift C o n tro l S w itc h
When the nut has tra v e le d fa r enough to wind the
sprin g, a contact bumper on the nut breaks an e le c tr ic a l
connection on the autom atic switch which d e -e n e rg iz e s
the m otor and stops arm ature rotation. The nut is held
at the end o f its tra v e l on the screw by a detent spring on
the shifting housing front c o ver.
A s the nut m oves downward, the spring winding le v e r ,
which pivots on a pin in the nut, winds the torsion spring.
Thus the tension o f the spring is in creased, and in this
position, the axle is ready to shift into the high speed
ra tio as soon as the load on the axle g e a rs is re lie v e d .
The torsion spring is assem bled in the unit so that it is
under 65 pounds p ressu re. When the spring is wound by
the winding le v e r , this tension is in creased to 115 pounds.
T h is additional p ressu re is used to shift the axle. When
F ig . 6 3 — E le c tric S h ift U n it M o u n te d
F ig . 6 4 —S h ift U n it in H ig h Range P osition
the shift is com pleted, the ends o f the spring com e to ­
geth er, leaving the o rig in a l tension in the spring. This
p relo a d tension holds the axle in eith er range.
Low Speed Range
When the control switch operating arm is m oved to the
down (LO ) position, cu rren t is supplied to the other fie ld
o f the m otor and to the speedom eter adapter. The cu r­
rent now causes the arm ature and screw to turn counter­
clock w ise, and the nut tra v e ls toward the top o f the screw
(fig . 65). T h is winds the torsion spring fo r a shift to low
range which is accom plished in the sam e manner as the
shift to high range.
G eneral M ain ten an ce
The only gen era l maintenance n ecessary on the shift
control system is to make sure that a ll w irin g is in good
F ig . 6 5 —S h ift U n it in Low Range P osition
CHEVROLET TRUCK SERVICE MANUAL