Electronic System For Rear-Axle Differential Lock Control, Front Driving Axle Drive Control, Front And Rear Power Take Off Shafts Control; Rear-Axle Differential Lock Control - Belarus 3522.5 Operator's Manual

3.13 Electronic system for rear-axle differential lock control, front driving axle
drive control, front and rear power take off shafts control

3.13.1 Rear-axle Differential Lock Control

The rear-axle DL is controlled by electrohydraulic system. The electronic part of DL
is a part of complex control system and consists of electronic unit CECS 1 (figure 3.13.1),
located in cabin on the panel to the right of the driver; of wheel turning angle sensor 11
mounted on the left side on FDA; of two sensors 15 and 16 of working brakes engaged
condition, mounted in cabin over brakes pedals; of distributor 20 with electromagnet and
pressure sensor 19 of DL engaged condition, mounted on plate 8 of transmission hydraulic
system distributors, connecting harnesses 14 with plug-and-jack connection 7.
The system is powered from onboard power system through security and switching unit
2, according wiring scheme of complex control system for DL, FDA and PTO and gear chang-
ing (Appendix B). System supply voltage is delivered after turn of starter and instruments switch
in position «Instruments ON».
On face plate of CECS are buttons 30 and 31 of on/off switching of automatic and positive
operation mode, annunciators 22 of set operation mode and annunciator 23 of engaged condition
of rear-axle differential lock.
Rear-axle differential lock is off in starting position. The pressure is not supplied to elec-
tromagnet of distributor 20, DL clutch is connected with drain, differential is unlocked. When
during operation rear wheels will slip, it is necessary to switch on differential automatic locking.
It is necessary to press button 31 «AUTO» to switch on automatic operating mode
for differential lock. At steering wheel position, corresponding to linear movement, distribu-
tor 20 is activated and it send oil flow in DL clutch and locks differential.
Differential unlocking occurs automatically at turn of steering wheels by angle from
above 13º (sensor11 activation), or pressing both, or any of brakes pedals (brakes sensors
15, 16 activation, respectivily), or at driving speed over 16 km/h. When driving speed is
under 13 km/h blocking should again switch on automatically.
Automatic mode of rear wheels differential locking is switched off at second press-
ing of button 31 «AUTO» or at pressing and release of positive blocking button 30.
If it is necessary to lock positive rear wheels for short time, independent of any condi-
tions, press and keep button 30. Blocking remains for the period of button 30 keeping in pressed
position. When buttons 30 is up rear axle differential locking returns to the starting (disengaged)
condition.
It is enough to press and keep button 30 for change of DL engagement automatic
mode for positive mode.
As indicator for switching on of system operation mode serve annunciators 22 situ-
ated close to corresponding on/off mode switching buttons 30 and 31. Engaged condition
of rear axle DL (pumping of oil under pressure into DL clutch) is indicated by annunciator
23, situated between buttons 31 and 30 of automatic and positive operation modes. An-
nunciator 23 is switched on according to signal from pressure sensor 19, that is actuated
(contact closure) at pressure above 0,6 ... 0,8 MPa.
When it is necessary to install wheel turning angle sensor 11(after dismantle or at
replacement) keep an eye on installation truth:
- ensure backlash of 3±0,2 mm between end face of wheel turning angle sensor 11
and support, mounted on left FDA reduction unit;
- At steering wheels position, corresponding to linear movement, the axle of wheel
turning angle sensor 11 should match with centre (axle) of support on FDA reduction unit
(It should be provided symmetry of sensor activation at steering wheel turning in both di-
rections by angle ±13º).
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