17- 5
ShiftMaster Operation Characteristics
Central to the system is the ShiftMaster ECU (Electronic
Control Unit)
A
. The unit receives ‘inputs’ from electrical
devices such as the gear select switch
B
. Depending on the
input signals the ECU ‘outputs’ energise electrical devices
such as gearbox solenoid control valves
C
. For a full
description of how the ShiftMaster electrical system works
see
Electrical Connections - Powershift Gearbox - 6
Speed
Start up
When the starter switch is set to the ON position the ECU
performs a series of self checks. If the checks are valid
three
beeps
sound. After the checks the ECU selects neutral even
if forward or reverse is selected on the column lever. To
select forward or reverse the operator must cycle the lever
through neutral.
If the checks fail,
1 or 2 beeps
will sound and the ECU will
enter an appropriate limp mode (see
Limp modes
)..
‘Manual’ gear select
The operator can ‘manually’ select 1st, 2nd and 3rd gears
using the column switch. When down shifting (say from 3rd
to 2nd) the ECU checks to see if the machine road speed is
suitable before down shifting the gearbox. If the road speed
is too high a
repeating double beep
is sounded. When the
road speed reduces to a pre-set value the ECU down shifts
the gearbox and the beeps will stop.
Kick down operation
A floor mounted kickdown switch enables the operator to
down shift to the next lowest gear. The ECU checks to see if
the machine road speed is suitable before down shifting the
gearbox. If the road speed is too high a
single double beep
is sounded.
Pressing the kick down switch a second time causes the
ECU to select the previous gear.
‘Automatic’ gear selection
When A (auto) and F (forward) are selected on the column
switch, the ECU selects 4th, 5th or 6th gears, mainly
according to road speed. The gearbox will automatically up
shift and down shift. 2WD†† will also be selected.
To enable up shifts the accelerator pedal must be pressed,
this prevents up shifting when coasting down hill for
example, thus ensuring maximum machine control.
Note that the ECU does not automatically shift gears in
response to engine load.
When A (auto) and R (reverse) are selected the ECU selects
4th gear and 2WD††. There is no automatic gear shifting in
reverse.
†† On machines with 4WB (4 wheel brake), if the operator
has selected 4WB the ECU will automatically select 4WD (4
wheel drive) when the brake pedal is pressed.
Park brake ON
When the park brake is on, the ECU will hold the gearbox in
neutral even if forward or reverse are selected. A
continuous
tone
is sounded.
Transmission dump
When the operator presses the dump switch the ECU selects
neutral by de-energising one clutch only. This enables
smooth re-engagement of gears when the dump button is
released.
Limp modes
When necessary the ECU will provide alternative gear
selection should faults occur. This enables the machine to be
moved (‘limped’) under its own power. For full details of the
limp modes see
Fault Finding - Powershift Gearbox
.
Section F
9803/3280
Section F
17 - 5
Issue 1
Basic Operation
Powershift Gearbox - 6 Speed
F
N
R
1
2
3
A
A405710
A
B
C
