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Trailer MMZ-81021: characteristics and operation manual

Trailer MMZ-81021: characteristics and operation manual
Trailer MMZ-81021: characteristics and operation manual
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With the commissioning of the VAZ plant, intensive saturation of the private car park in the USSR began. Many car owners sought to make road trips over long distances. It was for them that special trailers were developed and put into production. One of them will be discussed below.

General data

One of the first serial products designed specifically for the products of the VAZ plant was the MMZ-81021 trailer. The release started in 1972 and was carried out at the production facilities of the machine-building plant in Mytishchi. The main feature of the trailer was the wide unification of parts with Zhiguli cars, from which disks, tires, wheel bearings, and suspension elements were borrowed. Thanks to this, car and trailer repairs on the road could be carried out using the same tool. At the same time, there was no question with the search and selection of spare parts and assemblies.

MMZ-81021

An important characteristic of the MMZ-81021 was a unified towing device, which allowed the trailer to be operated with any car. A big plus was the significant dimensions of the cargo platform, which was almost 1.85 meters in length.and 1.6 meters wide. Due to the sides with a height of 45 cm, it was possible to place a significant amount of cargo, the weight of which should not exceed 135 … 285 kg (depending on the brand of car). The tarpaulin awning on the MMZ-81021 was installed on special arcs, which were included in the standard package of the trailer. Due to the tarpaulin, the useful internal volume of the trailer was 1200 liters, which was a very good indicator.

Differences between models

The trailer could be used by cars of small (VAZ, IZH and AZLK) and medium ("Volga") classes. According to the MMZ-81021 operating manual, the maximum load for machines of the first category should not exceed 135 kg, and for the second - 285 kg.

Trailer MMZ-81021

At the same time, the trailer itself was identical and had a construction weight of 165 kg. Due to competent weight distribution, the maximum load on the coupling device did not exceed 50 kg. The use of a trailer imposed restrictions on the maximum speed of the road train, which should not exceed 80 km / h.

Tow hitch

VAZ and AZLK cars that came off the assembly line never had a standard towing device (tow hitch). This node was installed by the owners themselves, purchasing the product separately. For towing the MMZ-81021 trailer, the Mytishchi plant produced two types of devices that differed in the way they were attached to the load-bearing elements of the bodies.

Characteristics of MMZ-81021

One device had catalog number 11.2707003 and was intended exclusively for the production of the plant in Tolyatti. Second, undernumber 12.2707003, went for "Moskvich". The ball parts and sockets of the devices were the same. The differences were in the wiring harness from the outlet, with the help of which it was integrated into the on-board network of cars.

Chassis

To install the wheels on the trailer, there was an all-metal axle, on which there were mounting earrings for suspension elements and a place for installing hub bearings. The design of the hub used tapered roller bearings from the Togliatti "penny". The gap in the assembly was regulated by a nut, which was fixed from spontaneous unscrewing by jamming part of the girdle into the groove on the shaft.

To ensure the technical characteristics of the MMZ-81021, tube-type tires were used, completely identical to the VAZ-2101. When operating the trailer, it was necessary to maintain pressure within 1.7 atmospheres, which guaranteed the long life of the rubber and the ease of rolling the trailer.

Pendant

Suspension elements are installed between the axle and the frame, which reduce vibrations that occur when the trailer moves over uneven road surfaces. The suspension consists of a spring and a shock absorber mounted on each side of the axle. To attach the shock absorber body, there are two reinforcing elements installed between the upper attachment point of the body and the trailer frame. The damper is installed inside the spring.

MMZ-81021 specifications

To protect against sharp shocks during suspension breakdown (full stroke of the elements), there are conical rubber buffers mounted on the frame. They hit the backon the axis and due to the deformation of the rubber dampen the impact energy. To connect the axle to the frame, there are two longitudinal bars. There is another cross bar that serves as a stability stabilizer. All elements are assembled on threaded connections, many of which have safety cotter pins. Over time, these connections rust, and it is very problematic to disassemble these nodes.

Rama

The structure is based on a welded frame weighing 27 kg. This element is the most important part of the MMZ-81021 trailer and is used to install the suspension and loading platform. There is a reciprocal towing device on the frame, which is put on the towbar ball. All electrical wiring is routed along the frame members.

Operation manual MMZ-81021

Structurally, the part is non-separable and in case of deformation and damage it must be replaced. It is unacceptable to operate a trailer with a frame that has cracks or tears. On the front of the frame and the rear cross member there are three pedestal stops used when storing the trailer in the uncoupled state. Additional fixation is carried out by wheel chocks included in the trailer package.

The hitch is mounted on the front of the frame, equipped with a safety chain design and a spring-loaded cracker.

Electrical

The circuit includes a socket and wires from it, leading to the position lights, brake lights and direction indicators. The rear lights are borrowed from the ZAZ-966 and installed on the back of the platform. Ibida platform for attaching the registration plate of the trailer was installed. For its illumination at night there is a separate lamp of illumination. Two reflective elements are screwed on the front board, which improve the visibility of the obstacle when the road train is moving at night. Just above one of the reflectors, a marking plate is riveted indicating the year of manufacture, model and serial number of the MMZ-81021 trailer.

Due to the parallel connection of the trailer's electrical system to the car's on-board network, synchronous operation of all lighting devices is ensured. During operation, the condition of the wiring should be checked by cleaning oxidized or rusty elements.

Loading platform

At the base of the platform are four beams of non-interchangeable design. The platform itself has an all-metal scheme and is attached through the bars to the frame. Fasteners are bolts and washers. These attachment points often become hotbeds of corrosion. The tailgate of production products until 1986 had a deaf design. Later, a small folding section appeared in it.

To install the awning, four regular arcs and one linen 9-strand rope with a diameter of 5 mm are used. With the help of this rope, the awning is tightened and fixed along the sides of the trailer. There are three removable rubber mats on the floor of the platform. When using a trailer, they should be removed to dry the floor of the platform.

Awning MMZ-81021

A big disadvantage of the MMZ-81021 trailer platform is wheel arches, which narrow the useful width of the trailer in the central part. Another disadvantageis a solid tailgate, which imposes a limit on the maximum length of the load. Although at present this problem is not relevant, since it is easy to find and rent a truck with any platform length. When the metal of the floor of the platform is destroyed, it gradually separates from the frame, which can cause the trailer to tip over. During operation, it is necessary to monitor the condition of the fasteners and periodically tighten the connections.

Conclusion

Trailers were produced until the early 90s and are now quite often used by gardeners and small repair teams to deliver tools and building materials. Subject to the rules of operation and proper care, the MMZ-81021 trailer is a reliable design that can last for many more years.

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