WORKHORSE CUSTOM CHASSIS
Service Manual
Automatic Transmission – Allison
2007 W Series
© 2006 Workhorse Custom Chassis — All Rights Reserved
SECTION
7.2
PAGE
51
2007 W Series Chassis
WSM082106
pedal travel
Wide-Open Throttle (WOT):
Full travel of the
accelerator pedal, 100% throttle
Closed Throttle:
Foot is off the accelerator pedal or
pedal is not depressed, 0% throttle
Throttle-Related Shift Condition Defi nitions
Closed Throttle Manual Downshift:
A condition where
the engine is used to slow the vehicle by manually
downshifting during a closed throttle coast down
Closed Throttle Coast Down:
A full release of the
accelerator pedal while the transmission remains in
DRIVE range, allowing the transmission to downshift as
vehicle speed reduces
WOT Detent Downshift:
Quick apply of the accelerator
pedal to its full travel, forcing a downshift
WOT Upshifts/Downshifts:
Accelerator pedal is fully
depressed and transmission shifts sequentially through
ranges as dictated by load and grade
Shift Condition Defi nitions
Bump:
A sudden and forceful apply of a clutch
Delayed: A shift was expected but did not occur for
several seconds, as during a manual downshift or
WOT detent downshift - may also be defi ned as Late or
Extended
Double Bump:
Two bumps felt during a clutch apply
Early:
Shift occurs at lower speed than expected, often
accompanied by engine laboring after an upshift
End Bump:
A fi rmer feel at the end of a shift than at the
start of a shift
Firm:
A noticeably quick apply of a clutch at medium or
heavy throttle conditions - DO NOT confuse with Harsh
or Rough
Flare:
A quick increase in engine speed along with a
momentary loss of torque during a shift transition - also
defi ned as Slipping
Harsh – Rough:
More noticeable clutch apply than Firm
- considered unacceptable at any throttle position
Hunting:
A repeating quick series of upshifts and
downshifts that cause a noticeable change in engine
speed, such as 4-3-4, etc. - sometimes defi ned as
Cycling
Initial Feel:
A distinctly fi rmer feel at the start of a shift
than at the fi nish of a shift
Late:
A shift that occurs at a higher speed than normal
for a given throttle position
Shudder:
Multiple, rapid jerks usually associated with
an oncoming clutch
Slipping:
A noticeable increase in engine speed without
an increase in vehicle speed - usually occurring just
after the initial application of a clutch
Soft:
A slow, almost unnoticeable, clutch apply
Surge:
A repeating engine-related condition of
