Belarus 1221.2, Operator'S Manual

Page: 96 / 295

BELARUS-1221.2/1221 В .2/1221.3 Description and operation
95
Transmission Gearbox Reduction Gear
Control System
The electro-hydraulic control system
(Fig. E-15.6) involves a control panel (1)
located in the tractor cab to the right of
the driver, a gear-shift and reduction gear
stage switch-over lever (3), GB neutral
pickup (5), sensors (7 and 8) mounted on
the reduction gear switch-over hydraulic
cylinder (11) (Fig. E-15.5), electro-
hydraulic distributor (6) located atop of
the transmission gearbox cover, and con-
necting cables (4) with terminal blocks
(9). The system is supplied with power
from the on-board power system through
a fuse block (2). Voltage is applied follow-
ing the engine start-up.
The handle of the lever (3) contains the
pushbuttons (10 and 11) and indicators
(LEDs) (13, 12) to signal the high or low
reduction gear stage ON-state, respec-
tively.
The panel (1) contains also the indicators
(15 and 14) to signal the ON-state of the
high or low reduction gear stage and re-
duction gear control relay.
The system allows the reduction gear
stages to be switched over when the
lever (3) is in its neural position only (con-
tacts of the transmission gearbox neutral
position pickup (5) are closed).
Signals are applied to sensors (13, 12)
and (15, 14) from respective pressure-
sensitive pickups (8, 7).
Following the engine start-up, the default
setting is the reduction gear low stage
ON. In this case, the LED indicators (13,
15) should be on.
Switch over to the reduction gear high
stage is to be effected by depressing the
pushbutton (11). Now, the LED indicators
(13, 15) should go off, while LEDs (12,
14) turn on.
Switching over from high to low stage is
achieved be depressing the pushbutton
(10).
The control system circuit diagram for the
GB reduction gear, DL and FDA control is
given at the end of the “Manual”.
ATTENTION! The reduc-
tion gear stages shall be
only changed-over from the
lower stage to the higher
one and vice versa when
the tractor is fully stopped.
Fig. E-15.6
1 – control panel; 2 – fuse box; 3 – gear-shift and reduction gear stage switch-over lever; 4 – connecting ca-
bles; 5 – transmission gearbox neutral position pickup; 6 – reduction-gear electrical distributor; 7 – higher
stage pressure pickup; 8 – lower stage pressure pickup; 9 – terminal blocks; 10 – lower stage switch-on
pushbutton; 11 – higher stage switch-on pushbutton; 12 – higher stage LED indicator; 13 – lower stage LED
indicator; 14, 15 – pilot lamps.