Electrical Part Of Gearbox Control - Belarus 3522.5 Operator's Manual

3.5 Electrical part of gearbox control

Speed shifting is controlled by means electronic-hydraulic control system.
The electrical part of speed shifting system consists of CECS electric unit 1 (figure
3.5.1), a gear shifting joystick 3, which are located in the cab to the right of the operator; of
a button 14 to set up gearbox braking mode, located on the handle of the range shifting
lever; of electrohydraulic distributors 15, 17, 19, 21, 23, 25 with electric magnets and of
pressure sensors 16, 18, 20, 22, 24, 26, mounted on a plate 12 of transmission hydraulic
system distributors, located above on the clutch body; of a sensor 11 of clutch disengaged
condition on forward motion, mounted in the cab above the clutch pedal; of a sensor 2
(figure 3.5.1) of clutch disengaged condition on reverse; of a sensor 8 (figure 3.5.1) of a
neutral condition of the range reduction unit, mounted on the right side on the reduction
unit body and also used by the system of electrical equipment as a switch of engine start-
up lock with the gearbox range engaged; of a sensor 13 of a travel range (IV), mounted in
the cab near the range shifting lever; of connecting harnesses 9 with a socket connector
10, positioned under the cab, and with junction blocks.
Annunciators 36, 37, 27, 28, 29 of the gear engaged – 0, 1, 2, 3, 4, 5, 6, respec-
tively; an annunciator 32 of emergency state of gear engagement hydraulic distributors; an
indicator 33 of operation mode (light, medium, heavy); an indicator 35 of number of gear
engaged and of gearbox braking mode are located on the front board of CECS unit 1.
The system is powered from on-board electrical line through the protection and
switching unit 2 according the attached electrical circuit diagram of the complex system of
DL, FDA, PTO and gear shifting control (Annex C). The power supply voltage is delivered
to the system after the starter and instrument switch has been turned into position "Instru-
ments on".
In the initial condition all gears are disengaged. The annunciator 36 (speed "0")
lights up on the front board of CECS panel and "0" digit lights up on the digital indicator 35.
This testifies that the voltage is supplied to the gear shifting system, and the system does
not generate a signal to any of electromagnets of gear shifting hydraulic distributors. After
the engine is started, a pump of gear shifting hydraulic system is actuated. "0" speed indi-
cation remains.
To start movement first it is required to set a selected mode with the range shifting
lever, having preliminary engaged the "braking" mode of the gearbox. The "braking" mode
is actuated under the following conditions: the button 14 on the range shifting lever is
pushed and held depressed, the range shifting lever is in neutral position (the sensor 8 of
neutral position of the range reduction unit and the sensor 13 of the travel range (IV) go
off), the clutch is disengaged (the sensor 11 goes off as the clutch is disengaged on for-
ward motion or the sensor 2 (figure 3.5.3) goes off as the clutch pedal is depressed on re-
verse). With actuation of the "braking" mode a symbol "P" is displayed on the indicator 35
(figure 3.5.1) meaning the gearbox "braking" is on.
When setting a gear with the joystick 3, a sequential automatic gear shifting to
reach the selected one ("drive" mode) is as follows: the digital indicator 35 displays a num-
ber of the gear selected, and the annunciators of the gears engaged turn on in accordance
with actuation of the corresponding pressure sensors.
Under normal operation mode the indicator 35 displays a number of the gear se-
lected and the corresponding annunciator 37, 27, 28, 29, 30, 31 is permanently on (ap-
proval of actuation under the required pressure).
As marker lights turn on, the indication illumination will decrease.
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