- Park position enables the engine to be started
while preventing the vehicle from moving. For safety
reasons, the vehicle's parking brake should always be
used in addition to the "Park" position. Park position
should not be selected until the vehicle has come to a
- Reverse enables the vehicle to be operated in a
- Neutral position enables the engine to start and
operate without driving the vehicle. If necessary, this
position should be selected to restart the engine while
the vehicle is moving.
- Drive range should be used for all normal driving
conditions for maximum efficiency and fuel
economy. Drive range allows the transmission to
operate in each of the six forward gear ratios.
Downshifts to a lower gear are available for safe
passing, by depressing the accelerator, or by manually
selecting a lower gear with the shift lever.
- When manual mode is selected, the current gear
range will be the highest attainable range with all of
the lower gears available. Plus/Minus buttons may be
used to select the desired range of gears for the current
GENERAL DESCRIPTION SHIFT QUADRANTS
The new Hydra-matic 6L80 (6 Speed) is a fully
automatic, six speed, rear wheel drive, electronic
controlled transmission that features clutch to clutch
shifting. It consists primarily of a four element torque
converter, two planetary gear sets, five clutch packs,
one sprag and a hydraulic pressurization and control
The four element torque converter contains a pump,
a turbine, a pressure plate splined to the turbine, and a
stator assembly. The torque converter acts as a fluid
coupling to smoothly transmit power from the engine
to the transmission. It also hydraulically provides
additional torque multiplication when required. The
pressure plate, when applied, provides a mechanical
"direct drive" coupling of the engine to the turbine
shaft of the transmission.
The two planetary gear sets provide the six forward
gear ratios and reverse. Changing gear ratios is fully
automatic and is accomplished through the use of a
Transmission Control Module (TCM) located within
the transmission. The TCM receives and monitors
various electronic sensor inputs, and uses this
information to shift the transmission at the optimum
The TCM commands shift solenoids and variable
bleed Clutch Pressure Control (CPC) solenoids
within the transmission to control shift timing. The
TCM controls shift feel through the CPC solenoids.
The TCM also controls the apply and release of the
torque converter clutch which allows the engine to
deliver the maximum fuel efficiency without
sacrificing vehicle performance.
The hydraulic system primarily consists of a vane
type pump, two control valve bodies, converter
housing and case. The pump maintains the working
pressures needed to apply the clutch pistons that apply
or release the friction components. These friction
components, when applied or released, support the
shifting qualities of the transmission.
The friction components used in this transmission
consist of five multiple disc clutches. The multiple
disc clutches combine with one mechanical sprag
clutch, to deliver seven different gear ratios through
the gearsets that then transfer torque through the
output shaft. Refer to Figure 4 for the component
application chart for this transmission.
The transmission shift quadrants vary by model.
There may be four to seven different positions shown
on the shift quadrants, as shown in Figure 2 and in
Standard Shift Quadrant
Manual Shift Ranges
Some vehicles are equipped with a shift quadrant
that allow manual range selection. For example, "M"
manual range and/or manual range "2" or "1", as
shown in Figure 2. These ranges can be used for
conditions where it may be desirable to control the
selection of gear ratios. These conditions include
trailer towing, driving on hilly terrain, and are also
helpful for engine braking when descending slight
Continued on next Page
AUTOMATIC TRANSMISSION SERVICE GROUP
Technical Service Information
Copyright © 2007 ATSG