Freelander System Description and Operation
AUTOMATIC GEARBOX - JATCO
44-8
DESCRIPTION AND OPERATION
Description
General
The JATCO JF506E automatic gearbox is an electronically controlled, five speed gearbox which incorporates
software to enable the gearbox to operate as a semi-automaticgearbox. The transmission, previously known as
'Steptronic', is designated 'CommandShift' from 2003 model year.
The gearbox can be operated as a conventional automatic gearbox by selecting P, R, N, D, 4, 2 or 1 on the selector
lever. Moving the selector mechanism across the gate to the 'S/M' position, sends a signal to the Electronic Automatic
Transmission (EAT) ECU and puts the gearbox into sport/manual mode.
In sport mode, the gearbox still operates as a conventional automatic transmission, but the unit becomes more
responsive to driver demands. Lower gears will be held longer and the transmission will downshift more readily. This
gives increased acceleration and improves vehicle response.
When in sport mode, if the selector lever is moved to the + or - positions, the system will automatically change to
operate in manual mode. Manual gear changes can be performed sequentially using the selector lever. Movement of
the selector lever in the forward (+) direction changes the gearbox up the ratios and movement in a rearward (-)
direction changes the gearbox down the ratios.
Gearbox operation is controlled by the EAT ECU and the Engine Control Module (ECM) which communicate via a
Controller Area Network (CAN) Bus. The EAT ECU receives information from the ECM and gearbox sensors to
calculate the appropriate gear ratio for the conditions and controls solenoid valves to operate the gearbox as required.
The advantages gained with the electronically controlled gearbox are smoother gear changes, quicker and more
accurate gear change scheduling and reduced fuel consumption through improved engine/gearbox speed matching.
CommandShift JATCO Automatic Gearbox
The JATCO five speed automatic gearbox is similar to conventional electronically controlled transmissions but
provides the driver with an additional manual mode feature. Manual mode allows the driver to electronically select the
five forward gear ratios and operate the gearbox as a semi-automatic manual gearbox.
The individual gear ratios are achieved through three planetary gear sets. The components of the planetary gear sets
are driven or locked by means of four multi-plate clutches, two multi-plate brakes, one brake band and two one-way
clutch assemblies. Torque is transmitted from the gearbox to the final drive through a reduction gear.
Gearbox Casing
Refer to JATCO Automatic Gearbox illustration.
The gearbox casing contains the input shaft transmitting the power into the drive train. The drive train is made up of
the planetary gear sets and clutches.
The clutches and brake bands control which elements of the planetary gear sets are engaged and their direction of
rotation, to produce the P and N selections, five forward ratios and one reverse gear ratio. Power output is from the
drivetrain through a reduction gear into a differential.
Gear Ratios
Gear
Ratio
1st
3.474
2nd
1.948
3rd
1.247
4th
0.854
5th
0.685
Reverse
2.714
Final Drive Ratio
3.66
