ALLISON-OM1334EN
ALLISON AT, MT, HT SERIES ON-HIGHWAY TRANSMISSIONS
OPERATOR'S MANUAL
2000
ALLISON-OM1334EN - Page 9 of 48
4
Because the converter lockup engagement and release are designed to fit the vehicle’s
vocation, there are many variations among transmission assemblies. Lockup speeds
are determined by many factors. Among these are transmission-engine match,
transmission-vehicle match, model year, throttle position, and calibration of the
hydraulic system. Some models have lockup available in all ranges. Others have
lockup available in the upper ranges. Some models have modulated lockup, which
provides better engine braking by delaying lockup disengagement during closed-
throttle operation. For specific information on the lockup characteristics of your
transmission, contact your dealer or distributor.
Lockup engagement, like range shifts, may be felt under some conditions. The driver
who counts shifts should not confuse lockup with a range change. A little driving
experience with the Allison automatic will enable the driver to distinguish between the
two kinds of shifts.
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