Hummer H1 Service Manual page 201

5-2 Transmission/Transfer Case
FOURTH
CLUTCH
OVERRUN
CLUTCH
TRANSMISSION GEAR RANGES
The 4L80-E gear ranges consist of: Park, Reverse, Neutral,
Overdrive D range, manual D range, manual 2 range and Man-
ual 1 range.
In Park (P) range, none of the clutches and bands are applied.
In addition, the transmission output shaft is locked by a pawl
that engages gear teeth on the output carrier. The pawl is actu-
ated by a rod and detent operated by the manual lever. Park
range (along with Neutral), is used for engine starting.
In Reverse (R) range, the direct clutch and rear band are ap-
plied and the overdrive roller clutch is holding. The vehicle
will backup (move rearward) only in this range.
In Neutral (N) range, none of the clutches or bands are applied.
Vehicle movement is not provided for. Neutral is used prima-
rily for engine starting, or when the vehicle must be moved
while the engine is not running.
In Overdrive D range, the transmission will shift from first
through fourth gear. This range is used for all normal driving
conditions and also provides maximum fuel economy. Over-
drive range is not, however, recommended for use on ex-
tremely steep terrain, or when pulling heavy loads. Manual D
range should be used under these conditions.
In manual D range, the transmission will shift from first to
third gear only. This range is recommended for high load, steep
______________________________________________
TORQUE
CONVERTER
OIL PUMP
OVERDRIVE
ROLLER
CLUTCH
Figure 5-1: Transmission Drive and Apply Elements
OVERDRIVE
PLANETARY
FRONT
BAND
DIRECT
FORWARD CLUTCH
INTERMEDIATE
CLUTCH
SPRAG CLUTCH
terrain driving. Manual D range also provides some engine
braking when descending slight grades.
In manual second (2) range, the transmission will only shift
from first to second. This range is useful on steep terrain or
when pulling loads up an incline. Manual 2 range also provides
overrun braking which is helpful on mild grades.
In manual low (1) range, the transmission remains in first gear.
Upshifts will not occur. This range is useful for pulling heavy
loads at low speed, or when ascending steep inclines. Overrun
braking is also provided which is helpful when descending
steep terrain.
TRANSMISSION GEAR RATIOS
Transmission gear ratios are:
First gear
Second gear
Third gear
Overdrive Fourth
Reverse
REACTION
PLANETARY
OUTPUT
PLANETARY
LO
ROLLER
REAR
CLUTCH
BAND
INTERMEDIATE
CLUTCH
2.48:1
1.48:1
1.00:1
.75:1
2.08:1
®
PARK
PAWL