Design and operation of the planetary mechanism (PMP) DT-75M

Gearbox DT 75: characteristics and general information

All modifications of DT 75 tractors, including the latest version DT-75M, are equipped with the same type of seven-speed manual transmissions. A special feature of the transmission is the presence of an additional shaft and movable gears. With such a relatively simple DT 75 gear scheme, it is possible to achieve many different configurations - and choose the optimal operating mode in each specific case.

The basic design of the DT 75 box provides eight speed modes: seven for forward movement and one for reverse movement. The number of gears can be increased by installing additional equipment:

• reverse gearbox,
• creeper.

The schematic diagram of the DT 75 gearbox is as follows:

• The transmission mechanism is housed inside a die-cast metal housing.
• In the first compartment of the box, four shafts are installed - primary, secondary, additional and for reverse.
• The shafts are equipped with movable gears of different diameters and different numbers of teeth.

To start moving at the desired speed, the gears are engaged. To obtain neutral mode, one of the gears is disengaged.

DT 75 gearbox diagram with description

The diagram of the DT 75 gearbox shows a kinematic projection (*), a diagram of the relative arrangement of the shafts (**) and a drawing of the location of the lever when changing speeds (***).

The primary and secondary shafts in the DT 75 gearbox shift diagram are marked with Roman numerals I and II. The reverse shaft is marked III, and the additional shaft is marked IV. Arabic numbers on the diagram of the DT 75 box indicate the corresponding gears.

The torque from the power plant is transmitted to the input shaft through the clutch. Its drive gear (1) is constantly engaged with the gear (4) of the reverse shaft, which in turn is engaged with the gear (5) located on the additional shaft. There are loosely fixed gears on the input shaft - on the DT 75 gear shift diagram they are marked 2-3 and 10-11.

The drive gear (14), as well as splined gears 12-13, a block of twin gears 15-16 and 17 are statically fixed on the secondary shaft. When selecting gears from first to fourth, the gears of the primary and secondary shafts mesh in the following configuration:

1. The first speed is 10-15.
2. The second speed is 11-13.
3. Third speed - 2-17.
4. The fourth speed is 3-16.

Gears from fifth to seventh are engaged using an additional shaft. The DT 75 gear shift in the diagram looks like this:

1. Fifth speed - 1-4-5-6-17 (gear (6) of the additional shaft is connected).
2. Sixth speed - 1-4-5-7-17 (gear (7) of the additional shaft is connected).
3. The seventh speed is 1-4-5-8-12 (the gear (8) of the additional shaft is connected).

To engage the reverse speed, a large gear from the block 15-16 of the secondary shaft is engaged with the movable gear (9) of the reverse shaft.

A visual diagram of DT 75 speeds is shown in the figure.

The lever positions corresponding to each mode are indicated on the speed shift diagram of the DT 75 gearbox (***).

Detailed diagram of the DT 75 gearbox: photo with enlargement

We present the most detailed diagram of the DT 75 gearbox with a description. The photo is clickable and can be enlarged.

The decoding of the DT 75 switching circuit is collected in a table. Go to the bottom of the table.

Where to buy high-quality and reliable spare parts for the DT-75, read here.

Diagram of the DT 75 gearbox with reverse

The photo shows a DT 75 gearbox with a reversible gearbox installed. This is a special reversing mechanism that makes additional gears available on the DT 75 tractor of any modification. This makes special equipment more versatile and suitable for use in more difficult conditions.

In the assembly diagram, the reverse of the DT 75 is installed in front of the transmission box on the front wall of the housing. It adds three speeds to the tractor:

• straight line with gear ratio 1.67;
• rear with gear ratio 1.35;
• straight line with gear ratio 1.

Thus, a reverse gearbox installed according to the correct scheme on the DT 75 gearbox allows you to obtain an additional reduced speed when moving forward and an increased speed when driving backward.

You will find a detailed diagram of the DT 75 gear shift with gearbox here.

Mechanism as part of the transmission

The final left transmission of the DT-75 is symmetrical to the right, and together they perform several important tasks, without which the movement of the tractor would be impossible. First of all, they transmit rotation from the shafts located in the rear axle housing to the sprockets that drive the tracks. Secondly, as they pass, the torque increases due to a decrease in angular velocity.

View the entire price list

By its type, it is a gearbox consisting of cylindrical gears (drive and driven). Being in constant engagement, they set the movement of the machine. The remaining parts are designed to ensure rotation (shafts, bearings, etc.) or tightness (gaskets, seals, etc.). The internal space is filled with oil, which reduces friction and protects the surface of the gears.

You might be interested in:

JCB sets speed record for tractors

DIY pickup truck from Tesla 3

Corn crusher: quickly separates the grain from the cob

Crawler bulldozer: how to choose reliable equipment

What types of tractors are there: photos, classification and types

Specifications

Over the more than fifty-year history of the tractor, the machine has undergone major modernization.

Interesting: in 2009, a modernized DT-75M tractor came out of the workshops of the Volgograd plant, equipped with an updated cabin, an improved hood and a Finnish engine that complied with modern environmental standards. Subsequently, the motor unit began to be produced directly in Volgograd.

The basis of the tractor is a welded frame. It is made of two rectangular welded spars, which are connected to each other by transverse links.

Tractor engine

The 90-horsepower A-41I diesel engine was used for the first time as a power device in the tractor. Subsequently, agricultural machines also began to be equipped with D-245.552 units, which are equipped with various modifications of trucks and special equipment. There are differences between these units:

• A-41I produces 94 l/s at 69 kW;
• D-245 - 95.2 l/s at 70 kW.

The engines are in-line, the tractor crankshaft rotates at 1750 rpm for the A-41I, at 1800 rpm for the D-245.

Fuel consumption:

• a tractor with A-41I consumes 166.6 g/l.s*h. DT;
• consumption of tractor D-245 – up to 161.7 g/hp*h diesel fuel.

Tractor motors have a torque reserve of 15 and 25 percent, respectively.

The tractor power units are cooled by a liquid system.

Interesting: the most modern tractor models, to ensure operation at low temperatures, are equipped with a pre-heating system that starts the engine at low (from -5) temperatures.

Main parameters of the tractor:

• tractor length: 4.24 m;
• in transport position (with rear linkage: 4.53 m;
• width: 1.85 m;
• height (when measured along the roof of the tractor cabin, plus or minus 30 millimeters): 2.705 mm;
• length of the longitudinal base of the tractor: 1.612 m;
• track track: 1.33 m;
• tractor clearance: 37 cm;
• width of tractor tracks: 39 cm;
• weight with A-41I engine: 6530 kg;
• with the specified engine and additional attachment: 6590 kg;
• with the D-245 power unit: exactly 6 tons;
• with this engine and attachments - 6420 kg.