DRESSTA TD-25M EXTRA, Service Manual

Page: 296 / 595

SECTION 8
ELECTRICAL
Page 20
TD-25M EXTRA DRESSTA
WIRING DIAGRAM
There are two extra magnetic switches beside the
WO
switch mentioned above in the auto
downshift system.
•
engine RPM (CS);
•
torque converter output RPM (CIW)
Based on the pulse train coming from these sensors the microprocessor controller will compute the
torque converter kinematics ratio. If the controller is fed with a pulse train from the
CS
sensor, the
red diode
L23
is to come on. Similarly, if the pulse train from
CIW
sensor is fed, then
L22
will come
on.
The controller will operate as described below depending on the torque converter kinematics ratio.
•
if the ratio ranges from 0.75 to 1 – a manual gear change is possible with
Up
and
Dn
buttons as described above;
•
if the ratio ranges from 0.40 to 0.75 - a manual downshift is possible with
Dn
button as
described above; however the controller will not allow for up shift with
Up
button;
•
if the ratio is less than 0.40, and the machine rides in say, the third gear, the controller will
automatically downshift and after about 5 seconds will recheck the ratio. If the ratio is still
below 0.40 (the machine is riding in the second gear), another downshift will take place,
diodes will come on as per algorithm described for a manual downshift. Manual up shift will
be deactivated unless the ratio is over 0.75, regardless of the gear engaged (excluding third
gear).
It goes without saying that with the auto downshift mode disabled, the manual up shift is
immediately activated, regardless of the ratio.
c. Presetting mode
Presetting mode is provided with the highest priority in a gear change system. Generally,
presetting allows the machine motion at well predefined gears; gear can be defined regardless the
machine motion forward or reverse. The controller ignores
Up
and
Dn
buttons in this gear change
mode. The auto downshift mode is not operational either, regardless the
WO
switch position.
Machines are provided with two presetting modes which can be chosen with a gear mode change
switch (presetting)
WB
that can be found at the instrument panel.
1/2 Presetting mode
In this mode the
WB
switch is set to
1/2
position which in turn, will cause a yellow diode
L29
to
come on. The machine will move forward in the first gear (green diode
L18
will come on,
L17
and
L16
will come off, while solenoid valves
EZ2
and
EZ3
will get deactivated), and in the second gear
reverse (diode
L17
will come on,
L18
and
L16
will come off,
EZ2
activated,
EZ3
deactivated). The
display will show the active gear, while the motion direction will be signaled with a suitable diode.
There are two pressure switches in the drive control system that will provide information to the
microprocessor controller on the machine motion direction.
WF
– which will shot the controller to
the machine ground in case the machine would move forward; its operation will cause the yellow
diode
L8
to come on, as well as
WR
- which will shot the controller to the machine ground in case
the machine would move reverse; its operation will cause the yellow diode
L9
to come on. When
the machine is stopped both sensors will not provide any signal to the controller and diodes
L8
and
L9
will be off. Fig. 8.1D. provides a control system schematic in this operation mode.