MTW BELARUS 952.5, Руководство оператора

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952.5-0000010 OM
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2.7.2 Functioning algorithm of pilot lamp to indicate operation of heating plugs
As a means of start facilitation heating plugs (HP) are used in tractors “BELARUS –
952.5”, they are mounted in the cylinder head. For individual control of heating plug opera-
tion modes, indication of their operation a heating plug control unit is used.
The heating plugs are activated, if the engine temperature e5°C. Hereby a
heating plug pilot lamp 3 (figure 2.7.1) lights up for 2 sec., or doesn’t light up at all.
If engine temperature is below +5°C, the heating plugs are activated automatically
as the key of starter and instrument switch is turned from position “0” (off) into position “I”
(Instruments on). Hereby the heating plug pilot lamp 3 lights up in the pilot lamp unit of the
dashboard. The heating plug operation time depends on engine temperature as per table
2.2. The engine is to be started as the lamp 3 goes out after the time, specified in table
2.2. After the engine start-up, the heating plugs remain on for some time, then they go out.
The heating plug operation time after the engine start-up depends on the engine tempera-
ture at the moment of the heating plug activation. (see table 2.2).
If during (10±1) sec. after the lamp 3 goes out the engine will not be started, heating plugs
become switched off.
The heating plug operation algorithm has the following emergency modes:
- as the key of starter and instrument switch is turned from position “0” (Off) into
position “I” (Instruments on) the heating plug pilot lamp starts to flash continuously with
2 Hz frequency. This means that there is a failure in the heating plug operation – all heat-
ing plugs are closed-circuit or their connection is disturbed (disconnected from the heating
plug control unit), the heating plug control unit is not powered or the power supply wire is
damaged. Herewith, in case of short circuit the heating plug control unit cuts power supply
(12V) to the heating plugs.
- after the engine start-up the heating plug pilot lamp 3 starts flashing for one minute
with 3 sec. of cycle duration and 0,25 sec. of flash duration. The number of flashes can be
different. The start-up procedure runs in an ordinary way. This means that one or mote
(but not all) heating plugs are faulty. The number of flashes within one cycle equals to the
number of faulty heating plugs;
If the specified trouble is not eliminated, it might be difficult to start the engine at low
temperature.
- during the pre-start heating before engine start-up the pilot lamp 3 flashes with
1 Hz frequency. This points at short-circuit of the heating plug temperature sensor,
or breakage in the heating plug temperature sensor circuit, or sensor failure. Time
of engine pre-start heating as well as plug heating after engine start-up is set forth
in the table 2.2
IT IS FORBIDDEN TO OPERATE THE TRACTOR UNTIL FAILURES OF THE
HEATING PLUG SYSTEM ARE FOUND OUT AND ELIMINATED, AS IT MAY LEAD TO
DISCHARGE OF ACCUMULATOR BATTERIES!
Table 2.2 – Heating plug operation time depending on engine temperature
Engine
temperature, ° С
Time of engine pre-start
heating, sec.
Time of heating after en-
gine start-up, sec.
more than 5 0 0
from plus 5 to 0 15 25
from 0 to minus 10 20 50
from minus 10 to minus 15 25 75
from minus 15 to minus 20 35 100
from minus 20 to minus 25 42 125
more than minus 25 50 150
short circuit or sensor
breakout, sensor failure
50 150