A factor in the popularity of tractors from the Minsk Tractor Plant is the abundance of machine models with designs both for universal use and adapted for special work. A representative of the line of special models is the MTZ 921 tractor. The purpose of creating the tractor is to meet consumer demand for 1.4 traction class machines with reduced dimensions for cultivating vineyards and orchards. This tractor also meets the requirements and conditions for performing work when servicing livestock workshops with narrow passages and low entrance openings. At the same time, the tractor has not lost its versatility and can be used in standard field operations.
Belarus 921 tractor concept
The base model for the production of MTZ 921 was the universal all-wheel drive tractor MTZ 952, where the main components - the engine, transmission, hydraulic attachment and control system are absolutely the same. The differences between the model lie in the dimensional parameters of the chassis and the dimensions of the cabin, which ensure the compactness of the vehicle.
If we talk about the chassis, the tractor has the ability to change the size of the rear and front tracks only by changing the side of the wheel rims to the wheel hubs and changing the position of the wheel rim to the rim, and thanks to the installed tires with a reduced outer diameter, the ground clearance is reduced, affecting overall height of the tractor.
Tractor MTZ 921
Comparative table of dimensions and chassis parameters
| Tractor brand | MTZ 921 | MTZ 82.1 | MTZ 952 |
| Height, mm | 2380 | 2800 | 2850 |
| Width at the ends of the rear axle shafts, mm | 1600 | 1970 | 1970 |
| Axle adjustment limits, mm Front Rear | 1250-1420 1160-1640 | 1430-1990 1500-2100 | 1535-2120 1500-2100 |
| Ground clearance, mm | 250 | 465 | 465 |
| Maximum ford depth, m | 0,6 | 0,85 | 0,85 |
| Front tires Rear tires | 265/70R16 420/70R24 | 11,2-20 15.5R38 | 360/70R20 18.4R34 |
| Tractor base, mm | 2460 | 2450 | 2450 |
The observation cabin has a slightly truncated shape in height, which also increases the ability of the tractor to pass through low entrance openings. As part of the overall compact concept of the machine, the exhaust pipe is located at the bottom, providing additional visibility and a lower overall height of the machine.
Belarus MTZ 921 front view
Visually, the MTZ 921 is significantly different in its reduced dimensions from its standard counterparts in the traction class, which gave tractor drivers a reason to give their nickname to the tractor - “Gnome”.
Price and reviews
The vast majority of buyers note the high reliability and endurance of the tractor. Some drivers decided to note the low and clearly visible cabin as a plus. On the positive side, relatively low fuel consumption and maintainability were also noted. A high degree of unification of parts allows the use of spare parts for tractors of other models.
The price for the MTZ-921 tractor was set at 821 thousand rubles. It is due to the prevalence and demand of the model in various industries. The closest analogues of the machine are representatives from China LUZHONG and 454YTO-X1204. But every day an increasing number of farmers and gardening owners choose equipment from our Slavic brothers.
Modifications
Regarding the modifications of this tractor, the technical segmentation of the model is subject to the general production strategy of the Minsk plant, where the main differences between the modifications are the environmental standard of the machine and the level of automation of the control system.
Controls
Controls
Today the tractor is presented in three modifications: 921.2, 921.3, 921.4
Belarus 921.2
The vehicle has Stage I environmental standard with a D-245.5S engine. Unlike subsequent versions, the tractor does not have pre-cooling of the air forced by the turbine into the engine cylinders (intercooler). The fuel system has a standard design consisting of an in-line four-plunger injection pump.
Model Belarus 921.3
Modification with Stage II environmental standard and D-245.5S2 engine. In addition to the standard power system, the tractor is equipped with pre-cooling of the charge (intercooler), which increases the efficiency of fuel combustion in the cylinders, ensuring increased power, efficiency and environmental friendliness of the diesel engine.
Belarus 921.3 front linkage
Belarus 921.4
Machine with Stage IIIA standard with D-245.5S3A engine. The diesel engine, in combination with an intercooler, is equipped with a Common Rail battery electronic fuel injection system, a catalytic neutralization system and exhaust gas recirculation. This equipment ensures the most rational fuel consumption by increasing the density of the fuel mixture and increasing the injection pressure with electromagnetic control. The operation of all engine systems and its diagnostics are carried out by the installed electronic engine control system (ECM).
Advantages and disadvantages
Minsk tractors have a positive reputation due to their high level of quality and reliability.
Model 921 has the following advantages:
- the ability to perform repairs on your own, including in the field;
- a simple device that does not require the use of complex diagnostic equipment for maintenance and routine inspection;
- ease of control, comfortable conditions for the operator;
- multifunctionality, there is no need to buy special equipment separately;
- a wide range of inexpensive spare parts and consumables;
- long service life even in the harshest conditions;
- affordable price for CIS citizens.
Among the disadvantages, owners of the Belarus 921 include the lack of an on-board computer and an insufficient level of electronic equipment. The issue of exhaust toxicity remains open.
Engine
The base model of the power unit for the Belarus 921 is a four-cylinder turbocharged diesel engine D-245.5 and, as noted above, in accordance with the modification, the diesel models differ in environmental standards due to improvements in the fuel system.
Engine D 245.5
Characteristics of engines installed on the Belarus 921 modification
| Engine make | D-245.5S | D-245.5S2 | D-245.5S3A |
| Tractor modification | 921.2 | 921.3 | 921.4 |
| Working volume, cm³ | 4,75 | ||
| Rated power, kW/hp | 65/88,4 | 66/89,8 | 70/95 |
| Rated rotation speed, rpm | 1800 | ||
| Specific fuel consumption, g/kW per hour | 232+6 | 229+6 | 220+/-11 |
| Rotation speed at maximum torque, rpm | 1200 | 1400 | 1400 |
| Minimum rotation speed, rpm | 800 | ||
| Nominal torque, N m | 404 | 464 | 464 |
| Torque reserve factor, % | 15 | 25 | 25 |
Service and spare parts supply
If you follow the manufacturer's recommendations and requirements for technical fluids and the frequency of their replacement, expensive major repairs of the equipment will not be required throughout its entire service life. In all regions of Russia there are authorized technical service stations, warranty repairs, and uninterrupted supplies of original spare parts. New special equipment is covered by a manufacturer's warranty.
As the official representative of the Minsk Tractor Plant in Russia, we offer the best delivery conditions and favorable financial programs.
Gearbox and clutch
The tractor is equipped with a single-disc dry, friction, permanently closed clutch, standard for MTZ class 1.4 tractors. The comfort of clutch control is ensured by the integrated hydrostatic drive. The gearbox is mechanical with spur gears with 18 forward speeds and 4 reverse speeds (18F+4R). The unit is absolutely identical and is interchangeable with the MTZ 82(80) box.
Shift diagram for manual transmission 18F+4R
Synchronized gearbox control
Control of a synchronized gearbox with reverse gear
Generated movement speeds:
- Forward – from 1.63 to 28.83 km/h
- Backward – from 2.02 to 14.46 km/h
In comparison with other modern tractors of this class, the maximum speeds of the MTZ 921 are deliberately underestimated by the manufacturer. The rationale for such low speed is to protect the tractor from tipping over, taking into account its narrow track. (for example, the maximum speed in front of the MTZ 952 tractor is 39.9 km/h).
Upon request, the transmission can be equipped with a synchronized manual gearbox with 14 forward gears and 4 reverse gears (14F+4R).
Optional equipment
The versatility and multifunctionality of the MTZ-921 tractor is due to its compatibility with a wide range of mounted and trailed additional equipment.
- The agricultural sector uses all kinds of plows and cutters, cultivators, units for sowing, caring for crops and harvesting. These are sprayers, rotary and segment mowers, which are also used in housing and communal services;
- Housing and communal services - rotary brushes for street cleaning, snow dumps, buckets or rotary snow blowers, transport trailers, etc.;
- Construction – hydraulic tools for road work, pumping equipment, buckets for bulk building materials, tanks for water delivery and other types of equipment.
Thus, when buying a machine for agricultural work, you get a universal tractor for solving a wide range of tasks.
Rear axle and brakes
The axle design is the same as the MT3 82(80) rear axle. The main drive of the bridge is made in the form of a pair of bevel gears with helical teeth, the final drives are pairs of cylindrical gears. The wheels are driven by axle shafts interacting through a splined connection with the driven gears of the final drives.
Dry disc brakes are installed on the final drive gears. The service brakes are hydrostatically driven with suspended pedals.
The only difference between the bridge is the mechanical differential lock similar to the MTZ 50(52) tractor, where the locking is carried out only in forced mode by a splined clutch connecting the splined inner ends of the wheel axles. The locking is controlled by a rod brought into the cabin.
Front drive axle
FDA with a bevel pair of main gears, a self-locking limited slip differential and wheel reducers with pairs of bevel gears. The features of the bridge are: truncated size of the axle housings, ensuring the formation of a minimum track; In the design of the modified wheel gearboxes, the shape of the housings has been changed and the vertical shaft of the mechanism has been reduced to form a corresponding small clearance.
Front axle diagram
The FDA drive has a classic design - from the transfer case (with mechanical activation of forced or automatic mode) to the cardan drive through a safety intermediate clutch in a separate housing.
Vom
The power take-off shaft also has an identical design to the MTZ 82. The drive operates in two modes - two-speed independent and synchronous. The modes are controlled by switching the cam clutch, and the PTO drive is engaged by mechanically controlling the band brakes of the planetary gearbox. The maximum power transmitted to the power take-off shaft is 59 kW.
PTO rotation speed
- Independent mode – I speed 540, II -1000 rpm
- Synchronous mode – 3.03 rpm/meter of travel
Hydraulic suspension system
The tractor is equipped with a three-point rear linkage with a hydraulic lift (with two hydraulic cylinders) and autonomous control through a built-in separate distributor. The hitch in combination with a hydraulic lift ensures the use of land cultivating devices in power, positional, height and mixed control modes. The lifting capacity of the attachment on the suspension axis is at least 3600 kg. The time for raising the hitch from the lower to the upper position is no more than 3.5 seconds.
Rear linkage with hydraulic lift
To work with the hydraulic units of the aggregated equipment, the system is equipped with a three-section distributor RP70-921 with a cable-lever control drive. For ease of maintenance, the distributor and hydraulic tank of the system are located outside the rear wall of the cabin.
Tractor rear linkage diagram
Gear pump NSh-32 with a volumetric flow of 53 liters per minute or NSh 40 - 65 liters per minute. The system's safety valve is set to a pressure of 20 mPa.
To connect hydraulic units used with the tractor, the machine is equipped with two pairs of terminals in the rear linkage area, which are duplicated by side terminals of the same name on the left and right sides.
Hydraulic outlets of the MTZ 921 hydraulic system
Additionally, to connect the system with hydraulic motors, upon request, the tractor can be equipped with a free drain with a quick-release coupling. Also, as an optional extra, a front three-point hitch can be installed.
Specifications
When designing the tractor, they tried to create a specimen that, with all the described advantages, would also be easy to use and distinguished by its maintainability. That is why the car has a classic layout with the cabin located behind the power plant.
At the same time, during the design, the tasks of creating a powerful, unpretentious and all-terrain vehicle capable of working on soils with different bearing capacities were solved. As has already become clear, the engineers managed to do their job and give the MTZ-921 technical characteristics that only some Western analogues have.
The single-occupancy, low-profile cab is ROPS rated and will protect the driver in the event of a rollover. All conditions for comfortable work have been created inside it - an air heating and filtration system, a ventilation hatch, windshield washers and a sun visor will not allow the operator to be distracted from work.
Steering
The tractor is equipped with hydraulic volume steering combined with a metering pump. The operation of the hydraulic booster is ensured by the pressure of a separate hydraulic system with a gear pump. The rotation of the steered wheels is ensured by a double-acting hydraulic cylinder.
Dispenser pump:
- Dispenser capacity 160 cm³/rev
- Response pressure of shock valves 20-21 mPa
- Safety valve pressure 14-15 mPa
System pump:
- Left rotation unit NSh 14L
- Capacity 14 cm³/revolution
Wheel steering cylinder:
- Piston diameter 50 mm
- Stroke 250 mm
- Rod diameter 25 mm
Other design features
The tractor is equipped with a standard pneumatic system to ensure the operation of the brake drive of the towed vehicle, consisting of a compressor, pressure regulator, receiver and brake valve.
The machine is equipped with a plastic fuel tank located on the left side of the tractor with a capacity of 95 liters. Practitioners argue that this placement complicates the clutch adjustment process.
The side and rear windows of the mischievous cabin can be opened for ventilation, the plastic roof has a hatch. Thanks to the downward exhaust pipe, the tractor cab is much quieter when the engine is running, compared to tractors with a standard muffler.
Due to the small width of the front axle beam, the wings of the front wheels are attached directly to the vehicle frame and have a static constant position.
Like all modern models of the MTZ class 1.4 tractor, it has front-mounted starting batteries under the hood of the engine compartment.
