TM-9-2520-254-34
TRANSMISSION, AUTOMATIC, ALLISON, MODEL TX100-1
TECHNICAL MAUAL; DIRECT AND GENERAL SUPPORT MAINTENANCE MANUAL
OCTOBER 1971
TM-9-2520-254-34 - Page 32 of 126
(1) Figure 2-9 illustrates the hydraulic system
in high-range operation even though the manual
selector has been moved to a position which does
not indicate high-range operation. This condition
results when vehicle (transmission output) speed is
too great for safe operation in intermediate-range at
the time a manual downshift is made.
(2) When the manual downshift is made, rear
governor (G2) pressure is sufficient to continue
holding the intermediate-high shift plug, shift
valve, and blocker plug upward against spring force
and
inhibitor pressure.
This extends high-range
operation of the transmission during the period the
vehicle is moving at excessive speed.
(3) When vehicle speed decreases, G2 pressure
also decreases. When G2 pressure falls to a value
which will no longer hold the intermediate-high
shift plug and valve upward against spring force
and inhibitor pressure,
the downshift to in-
termediate range will occur. This is an automatic
shift, which lags behind the manual shift.
b.
Other Functions Same as
1-2-3
Operation
(fig.
2-9).
In high-range operation (selector at 1-2
position), the circuits not involved in action of the
high-intermediate inhibitor operate as described in
paragraph 2-17 for high-range (1-2-3) operation.
2-21. Hydraulic System—Intermediate-Range
Operation (Manual Selector at 1—Inter-
mediate-Low Inhibitor Acting)
NOTE
Inhibitors are safety devices which provide
some measure of protection against engine
overspeed if the operator inadvertently
downshifts above prescribed speed.
2-23
Back to Top
