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 34 of 126
a. Inhibitor Prevents 2-1 Downshift at Excessive
Speed
(fig. 2-10).
(1) Figure 2-10 illustrates the hydraulic
System
in
intermediate-range
operation
even
though the manual selector has been moved to a
position which does not indicate intermediate-range
operation. This condition results when vehicle
(transmission output) speed is too great for safe
operation in low 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 low-intermediate shift plug, shift valve,
and blocker plug upward against spring force and
inhibitor pressure. This extends intermediate-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 low-intermediate shift
plug, valve, and blocker plug upward against
spring force and inhibitor pressure, the downshift
to low range will occur. This is an automatic shift,
which lags behind the manual shift.
b.
Other Functions Same as Low-Range
operation
(fig. 2-10). In intermediate-range
operation (selector at 1-position), the circuits not
involved in action of the intermediate-low inhibitor
operate as described in paragraph 2-15 for low-
range operation.
2-25
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