2.2 Tractor Controls and the Starting of the Tractor Engine

In modern farm tractors powered by diesel engines (or simply diesels) that are started by means of an auxiliary starting engine, all controls are arranged in the driver's cab (Fig. 4), thanks to the remote control of the starting system.

To prepare the starting engine for the operation and to control it, use is made of the following controls: gas (petroleum) tank shut-off cock control handle 1, carburetor choke control handle 5, magneto grounding switch 11, starter switch 15, and starting gear clutch and drive pinion control lever 27.

To prepare the main tractor engine (i.e., the diesel engine) for operation, the following controls are used: decompressor (compression release) control lever 8, fuel pump lever 20, battery ground switch (not shown in the figure), fuel cock, and hand priming pump (located outside the cab).

Fig.4. Controls of the ДТ75М Model tractor

1 - gasoline tank shut-off cock control handle; 2 - tachometer/speedometer;

3 - heater blower and ventilator switch; 4 - fuel pressure gauge; 5 - carburettor choke control handle; 6-ammeter; 7 - head light switch; 8 - decompressor control lever; 9 - left-hand steering control lever; 10 - right-hand steering control lever; 11 - magneto grounding switch; 12 - engine coolant temperature gauge, 13 - oil pressure warning lamp; 14 - torque multiplier oil pressure gauge; 15 - starter motor switch; 16 - engine oil pressure gauge; 17 - battery switch indicator lamp;

18 - horn button; 19 - torque multiplier control lever; 20 - fuel pump lever;

21 - master clutch pedal; 22 - driver's seat; 23 - PTO shifter lever; 24 - right-hand brake pedal lock ratchet; 25 - right-hand brake pedal; 26 - left-hand brake pedal; 27 - starting gear clutch and drive pinion control lever; 28 - gear shift lever;

29, 30 and 31 - hydraulic control levers for the right-hand remote control, main, and left-hand remote control hydraulic cylinders of mounted implements

The tractor is controlled by means of the following levers and pedals located in the driver's cab.

Steering control levers 9 and 10 (in crawler tractors). To turn the tractor through a large-radius arc, smoothly pull back on the corresponding lever.

Torque multiplier control lever 19. Pulling back on this lever engages the multiplier. The lever can be locked in the engaged position by means of a dog.

Fuel pump lever 20. Moving the lever downward increases the fuel feed. The fuel feed is shut off when the lever is moved all the way upwards.

Master clutch pedal 21. The clutch is disengaged by depressing the pedal as far as it will go.

Power take-off shifter lever 23. This control lever engages or disengages the power take-off shaft. The shaft is engaged when the lever is moved backwards.

Right- and left-hand brake pedals 25 and 26. These pedals can be used together with the steering control levers for making short turns. To make such a turn, only that brake pedal is depressed whose corresponding steering control lever is pulled back.

Gear shift lever 28 is used to select the desired transmission gear. Gears can only be shifted when the master clutch is disengaged.

Hydraulic control levers 30, 29, and 31 for the main and remote control hydraulic cylinders of mounted implements, which are located at the rear and on the right- and left-hand sides of the tractor, respectively. All three levers are identical and have four positions as follows: the first locked position – neutral (the corresponding implement is locked in position, i.e. cannot lift or lower), the extreme upward position (not locked) – up pressure (the implement is lifted), the second locked position downwards – down pressure (the implement is lowered), and the third locked position downwards – floating (the implement floats up and down, following the contour of the ground).

Instruments, indicators and signaling devices include tachometer/speedometer 2, fuel pressure gauge 4, ammeter 6, temperature gauge 12, oil pressure warning lamp 13, torque multiplier oil pressure gauge 14, engine oil pressure gauge 16, battery switch indicator lamp 17, and horn button 18.

Preparing the engine for starting. Before starting a cold engine, perform all the daily attention and inspection procedures; bleed air from the fuel feed system (if the engine has been out of service for a long time) and fill the system with fuel, using the hand priming pump; place gear shift lever 28 and hydraulic control levers 29, 30 and 31 in neutral and disengage the power take-off shaft, using PTO shifter lever 23; close the radiator shutter and remove the right-hand side panel of the hood.

Starting the engine. To ease the cranking of the diesel engine, engage the decompressor (compression release) by placing lever 8 in the extreme downward position. If the engine has not been started a long time, crank it two or three revolutions with the crank handle.

Open the shut-off cocks of the main fuel tank and the starting engine fuel tank. The latter is opened by turning control handle 1 counterclockwise. Shut off the fuel feed of the diesel (main) engine by placing fuel pump lever 20 in the extreme upward position. Engage the drive pinion with the diesel flywheel ring gear by moving control lever 27 all the way upwards and then place the lever back in the downward position to disengage the starting gear clutch.

Close the carburetor choke of the starting engine by pulling back on control handle 5. Place the battery in circuit by depressing the larger button of the battery ground switch until it locks in the "ON" position.

Then switch on the starter motor by turning starter switch 15 clockwise as far as it will go.

After the starting engine has started, open the carburetor choke by depressing control handle 5 all the way inwards and let the engine run idle for no more than two minutes. A prolonged idling of the starting engine causes its overheating.

When the starting engine is warm enough, smoothly engage the starting gear clutch and crank the diesel, with the decompressor being engaged, during one or two minutes until oil pressure develops in the lubricating system of the engine, and then disengage the decompressor. If at that time the starting engine begins slowing down, engage the decompressor again, crank the diesel a little longer, and disengage the decompressor once more. With the starting engine running smoothly, turn on the fuel feed of the diesel to the full. After the diesel has started operating stably, disengage the starting gear clutch, kill the starting engine by depressing the button of magneto grounding switch 11, and place the fuel pump lever in the middle position. Operating the starting engine for more than 15 min at a time is not allowed.

If the starter motor or the storage battery is faulty, the starting engine can be started by hand. To do this, remove the engine flywheel guard together with the starter motor, place the knot at the end of the starting rope in one of the recesses in the flywheel, coil one and a half or two turns of the rope around the groove in the flywheel in the direction indicated on the latter by an arrow, and start the engine by tugging sharply at the starting rope handle. Hold the rope by the handle only. It is prohibited to coil the rope around the hand, for the engine may kick back during starting and crush the hand between the flywheel and the rope. If the engine fails to start after three or four attempts, check the ignition and fuel feed systems, rectify faults, and repeat the starting procedures. After the diesel engine has started, close the fuel cock of the starting engine, install the hood side panel in place, and stow the tools used.

After starting, warm up the diesel during two or three minutes, gradually increasing its speed from moderate to maximum. At that time, listen closely to the engine and read the instruments to check its operation. The engine must run smoothly, without missing and knocking and its exhaust must be smokeless. It may be loaded only after the coolant temperature has reached 50°C. After the temperature has climbed to 75°C, the radiator shutter must be placed in the fully open position.

In a warm engine, the oil pressure in the lubricating system must be within 0.3 to 0.5 MPa. If the oil pressure gauge reads no pressure, the engine must be immediately stopped and the trouble removed.

During warm weather the diesel engine can be started without engaging the decompressor. In this case, crank the engine with the fuel feed shut off until oil pressure is developed in the lubricating system and then turn on the fuel feed.

To ease the starting of the engine under low-temperature conditions, use the starting preheater (if available) or fill the cooling system with hot water and the engine crankcase with hot oil. In bitter frosts, first open the radiator drain cock and pass hot water at 60 to 70°C through the cooling system and then close the cock and fill the system with hot water at 90 to 95°C. To facilitate the starting of the engine, pour 2 to 3 cm³ of a gasoline-oil mixture into the starting engine cylinder through the cock on the cylinder head and pull back the governor booster control button on the fuel pump. Tо stop the diesel engine, shut off the fuel feed. Prior to stopping, let the engine run idle at a moderate and then slow speed for three to five minutes so as to allow the coolant and oil temperature to drop down uniformly. Do not stop the engine by closing the fuel cock, for this may cause suction of air into the fuel feed system, which will hamper subsequent starting of the engine. After stopping the diesel, disconnect the battery by depressing the smaller, side button of the battery ground switch. This should cause battery switch indicator lamp 17 to go out.