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Ll RANGE - MANUAL FIRST GEAR
Intermediate Clutch - OFF
Direct Clutch - OFF
Forward Clutch - ON
Low and Reverse Clutch - ON
Intermediate Overrun Roller Clutch - INEFFECTIVE
Low and Reverse Roller Clutch - LOCKED
Intermediate Overrun Band - OFF
Maximum downhill braking can be attained at speeds below approximately
50 MPH with the selector lever in Li range position. Low range oil from the
manual valve is then directed to the manual low control valve which in turn
directs it through the 1-2 shift valve train to the low and reverse clutch piston
this clutch. Once the manual low control valve is in the downshifted position, its
spring plus low apply oil acting on it will keep it in this position; therefore, with
the transmission in manual low (Li range), the transmission cannot upshift to
intermediate (second gear) regardless of vehicle or engine speed once low gear
has been engaged.
Basic
Summary
The manual low control valve is positioned to exhaust the manual low apply
line when the manual valve is placed in the manual (Lr) position above approxi
mately 50 MPH. At speeds below 50 MPH low oil is fed into the manual low
apply line which moves the 1-2 shift valve to the downshifted position (ex
hausting the 1-2 clutch) and moves the 1-2 shift control valve to the upshifted
position which sends low apply oil to the low and reverse clutch which engages
The forward clutch and the low and reverse clutch are applied. The trans
mission is in low (first gear) Lr range.
The manual low control valve is used also to protect the engine by pre
venting low range engagement (indicated by high car speed which is sensed by
high governor pressure) at car speeds over 50 MPH, or approximately 3600
engine rpm.
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