DET-250

The DET-250 bulldozer is a legendary machine that has been produced at the Chelyabinsk plant since 1961. The abbreviation DET stands for diesel-electric tractor. And the number 250 means it belongs to the traction class of 250 kN. This is a multi-purpose tractor with increased cross-country ability and a number of revolutionary (for its time) design solutions. The decent performance characteristics of the tractor are more than eloquently evidenced by the fact that it is still in production.

Area of ​​demand for tractors

Significant dimensions and caterpillar tracks are not designed for use of the tractor on a city scale. The main scope of application is industries that will require equipment with increased engine power characteristics. The tractor is used in the mining, oil and gas industries. The construction of railways, highways, and hydraulic structures cannot be done without it.

The scope of use of DET 250 depends on the attachment. It is attached to the rear of the unit. The bulldozer is operated with earthmoving, drilling, and trenching equipment. With the help of a loosening installation, at the stage of preparatory work, rocky, rocky and frozen soils are loosened. Thanks to the caterpillar drive, the tractor exerts low pressure on the ground and can be used in hard-to-reach places, even swamps.

History of DET 250

Tractor features

Overall dimensions of the bulldozer DET-250

The uniqueness of the technology is in the electromechanical transmission. This is the first model with such a technological solution. Compared to a hydromechanical transmission, an electric transmission makes it possible to operate in low temperature conditions. Disadvantages include heavy weight, which requires the installation of a powerful engine and a complex cooling system for operation. Therefore, the first tractors were heavy and resembled a powerful tank.

Comparisons with military equipment are not accidental. The DET-250 bulldozer is equipped with a modernized tank diesel engine; the cooling system uses exhaust gas energy.

The DET-250 tractor was replaced in 2002 by the DET-320. It is distinguished by a reinforced chassis, a liquid cooling system and an improved operator cabin.

DET-250

DET-250M2

- a brand of tractor produced by the Chelyabinsk Tractor Plant.
The abbreviation DET-250 means Diesel
-
Electric
Tractor

with traction
class 250
. The first tractor in the USSR with an electric transmission. The first energy-rich industrial tractor in the USSR.

The tractor is designed to operate as a bulldozer and ripper (in a single bulldozer-ripper unit). In addition, the tractor can carry equipment for a pit drill, a drilling and crane machine (for installing reinforced concrete power line supports), and a trench excavator. The electric transmission, consisting of a mixed excitation commutator generator and an independent excitation commutator motor, provides good traction characteristics, high speed at low loads and simplifies the process of controlling the tractor. The diesel engine of the tractor rotating the traction generator is a 12-cylinder V-shaped, model V-31M2 (development of the V-2 tank engine), with a capacity of 323 horsepower.

Features of the tractor include ejection cooling of the engine (the energy of exhaust gases is used). This solution is also borrowed from tanks.

Compared to other Soviet tractors, the DET-250M2 is distinguished by increased comfort of the driver’s workplace.

The tractor is also used on railways to operate recovery trains.

It was first shown to the general public at a workers' demonstration on May 1, 1957, walking through the streets of Chelyabinsk in a column of ChTZ workers.

It is the only tractor in the world (along with DET-320 and DET-400) with an electromechanical transmission. This is explained by the fact that tractor manufacturers in the USA and Japan already in the 1950s gave preference to hydromechanical transmission. At the same time, the use of a mechanical transmission for a 200 hp tractor. and above was considered inappropriate. Therefore, it was necessary to use an electromechanical transmission on the tractor, which led to a number of features of the tractor: too much weight (31 tons versus 42 tons for the T-330 tractor of a similar traction class, but with a hydromechanical transmission), low efficiency, and the need to use a complex cooling system for electric machines. At the same time, when operating a tractor in cold climatic zones of Russia, an electromechanical transmission has advantages over a hydromechanical one.

Before the appearance of the T-330 tractor, the DET-250 tractor was the only heavy industrial tractor in the USSR. Widely used on large Soviet construction sites.

The two main electric machines of the tractor are the power generator and the traction electric motor (TEM), both of which are commutator machines. An exciter is also installed on the generator. The generator is driven by a diesel engine through a single-stage spur gearbox, the engine drives the drive wheels through the main gearbox, planetary turning mechanisms and final drives. The main excitation to the generator is supplied from the battery through a rheostat connected to the gas pedal. The exciter serves to enhance the excitation of the electric motor under heavy loads: part of the current of the traction motor is diverted into the exciter winding, but a part of the battery with a voltage of 6-7 volts is connected opposite it, and a diode is also connected in series to this exciter excitation circuit. If the battery voltage is greater than the voltage created by the traction current, then the resulting voltage is less than zero and the diode is closed, there is no current in the exciter winding. If the traction current is more than 340 A, then the voltage drop it creates is more than 7 V, the diode opens, the exciter excitation current appears and the current generated by the exciter is supplied to a special excitation winding of the TED, the flow of which acts in accordance with the flow of the main winding. The resulting flow F increases and, according to the formula M = SFI, the engine torque increases.

Main characteristics

The main technical characteristics of DET-250 are given in the table.

Characteristics of the bulldozer DET 250

Specifications

As already mentioned, for the 60s the characteristics of the DET-250 tractor were considered very worthy. The bulldozer was equipped with a 12-cylinder engine with a power of 300 horsepower. The 4-stroke unit had a volume of 38.9 liters and an undivided combustion chamber. Such a large engine consumed about 45 liters of fuel per hour of operation at maximum power. The fuel tank capacity was 700 liters. The engine was not equipped with a turbocharger.

The DET-250 bulldozer was the first example of special equipment produced in the USSR, which received an electronic transmission. Thanks to this technological solution, it became possible to easily operate the tractor in cold regions of the state. However, the electronic transmission had a number of disadvantages. Firstly, with it the car has become much heavier than competitors of similar power equipped with a hydromechanical transmission. Secondly, the bulldozer required a more sophisticated cooling system. And thirdly, the heavy weight entailed the need to use a more powerful unit. The result is increased fuel costs and the inability to use the full potential of a powerful engine.

It is interesting to note that the first samples of the DET-250 bulldozer looked more like a tank than an agricultural machine. Of course, this is only an external impression. In fact, the tractor received only a few systems from the tank, in particular, ejection cooling of the engine using exhaust gas energy.

Technical characteristics of DET-250:

1. Dimensions: 6.62/3.18/3.21 m.
2. Track base - 4.44 m.
3. Track width – 2.45 m.
4. Ground clearance – 430 mm.
5. Weight – 32.3 tons.
6. The specific pressure on the soil is 0.56 kg/cm2.
7. Traction force – 25 tons.
8. Maximum speed: 3 km/h forward and 19 km/h reverse.

Cabin design features

The cabin of the DET-250 tractor at the time of the start of production was considered very comfortable. It is optimally insulated, heated, well lit due to high-quality glazing, and protected from noise and dust. Convenience of transport management is ensured by the following technical solutions:

• the driver's seat is on the right;
• The design provides for height adjustment of the seat;
• vibrations are reduced due to the springs, and a smooth ride is ensured with the help of an elastic suspension;
• control sensors are located in different parts of the dashboard, this protects the operator from accidental actions;
• the metal body guarantees driver safety;
• the tractor does not have a steering wheel, control is carried out using levers.

Single-lever control of the DET-250 tractor

But, by the standards of the present time, the cabin of the DET-250 tractor cannot be called comfortable. There is no air conditioning system at all, only a fan is installed, ventilation is provided by a window.

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Cabin

Compared to other Soviet-made tractors, the DET-250 is distinguished by an increased level of cabin comfort. All versions of the vehicle had a two-seater all-metal cabin with an increased level of comfort. The springs on which it was installed neutralized most of the vibrations that occur during operation of the bulldozer. The cabin had an autonomous heater, which warmed up the interior well even at extremely low outside temperatures. And in hot weather, a fan, which was included in the basic equipment of the bulldozer, came to the aid of the operator.

The instrument panel in the cab was located conveniently enough for the operator to easily monitor the most important indicators. And the controls were grouped and separated into sectors so as not to confuse the operator. The cabin was completely insulated from noise and dust, which is very important given the specific use of the bulldozer. If the client desired, the manufacturer could additionally insulate the interior. In general, the tractor could operate in a temperature range from -40 to +40 degrees.