In 1925, the 1st State Automobile Repair Plant (later renamed Yaroslavl State Automobile Plant No. 3) developed its first truck. It was a three-ton class machine called I-3. After the necessary checks, the truck went into production and went into operation. However, this sample was not without its drawbacks. At the first opportunity, Yaroslavl engineers began to modernize it and increase its characteristics. The result of these works was the appearance of the Ya-4 truck, a landmark for our industry.
Problems and solutions
The Y-3 truck was developed by the designers of the 1st GARZ in 1924-25 on the basis of the White-AMO project, previously proposed by Moscow car builders. The original project was revised in accordance with the limited technological capabilities of the plant, and in this form was launched into series. The Yaroslavl plant could independently assemble the bulk of the machine's units, but needed supplies from outside. So, the AMO plant supplied engines and most of the transmission units.
Truck I-4. Photo Dalniyboi.ru
The I-3 car turned out to be ambiguous. It combined good carrying capacity with low running characteristics associated with the engine used. Gasoline engine AMO-F-15 with a capacity of only 36 hp. was too weak for a car with a gross weight of more than 7.3 tons. The maximum speed of the truck on a good road and with a partial load did not exceed 30 km / h. There were also complaints about the reliability of individual units, the inconvenient driver's cab, etc.
The existing I-3 project had an important feature: it had a good modernization potential. The frame and other units of the truck made it possible to increase the carrying capacity and running characteristics, but this required a power plant of greater power. Unfortunately, the Soviet industry at that time could not offer an engine with the required parameters. However, the leadership of the automotive industry managed to find a way out. They are German-made engines purchased specifically for the promising YAGAZ No. 3 equipment.
In early 1928, the Soviet Union and the Weimar Republic entered into an agreement for the supply of modern automobile engines. The contract was for 137 Mercedes gasoline engines, as well as compatible clutches and gearboxes. Such power units were ordered specifically for the Yaroslavl Automobile Plant. With their help, it was planned to modernize the existing Y-3 truck, which would significantly improve its characteristics. A special commission was responsible for the choice of engines and the signing of contracts, which included V. V. Danilov is the head of the design bureau of the Yaroslavl plant.
Soon after the signing of the agreement on the engines, YAGAZ designers began to revise the existing project. The new power unit of the Mercedes brand was distinguished not only by greater power, but also by increased dimensions, which made demands on the design of the machine. In addition, some changes should have been made to the original design of the Ya-3 truck, the need for which became obvious from the results of testing and operation of the equipment.
Side view. Photo Russianarms.ru
The new project involved not only replacing the engine, but a deep modernization of the existing car. In this regard, the truck with a German engine received its own designation - Ya-4. It is curious that this name reflected not only the city where the car was built, but also its carrying capacity in tons. The new car became the first Soviet four-ton truck.
The power unit from Mercedes was distinguished by its large dimensions, which affected the design of the future truck. It was still based on a riveted frame assembled from rolled channels. The frame included a pair of longitudinal spars and several cross members. Standard rental was used. The spars were made of channels No. 16 160 mm high with 65 mm shelves. Channel # 10, 100 mm high, ran on the crossbeams. The new engine and other devices forced to abandon the curved channel, which served as a bumper. For the first time in domestic practice, a pair of towing hooks appeared under the new bumper.
As in the previous project, it was proposed to build a bonneted car based on a rectangular frame, but the engine compartment was enlarged, and the cab moved back because of this. While maintaining the same side body, this led to an increase in the total length of the car.
Unfortunately, history has not preserved accurate information about the composition of the imported power unit. Different sources - including materials from that era - provide different data. According to some reports, Germany transferred M26 engines to the Soviet Union, according to others - L3. The power of the motors in different sources ranges from 54 to 70 hp. Moreover, even the number of cylinders of these products is unknown - 4 or 6. A similar situation takes place with data on transmission devices of foreign production.
I-4 in the factory floor. Photo Gruzovikpress.ru
One way or another, the engines of the Mercedes brand were more powerful and larger than the domestic AMO-F-15, and were also supplemented with other units and assemblies. For this reason, for the Ya-4 truck, it was necessary to develop a new, large-sized, straightened hood. The front wall of the hood was given under the radiator. Ventilation was also provided by longitudinal hatches in the lid and side shutters. The engine was serviced with the side parts of the hood raised up.
According to some reports, the engine of the new type was equipped with an electric starter, and also mated with a generator. Thus, unlike its predecessor, the new Ya-4 had an on-board electrical system. Among other things, this allowed the use of electric headlights. The latter were installed on U-shaped supports and could swing in a vertical plane.
The power unit includes a dry clutch. Also, according to some sources, a manual transmission with a floor-mounted control lever was used. The box had four gears. Unfortunately, the type and construction of the clutch and gearbox are unknown. An inclined propeller shaft departed from the box, transmitting torque to the main gear of the leading rear axle. This gearbox was borrowed without changes from the existing Ya-3 truck. The main gear with spur and bevel gears and an increased gear ratio was developed to compensate for the lack of engine power from the AMO, but could also be used with the engine from Mercedes.
The truck retained the 4x2 wheel arrangement, but the chassis was modified. On the Ya-4, larger wheels were used - single-sided on the front axle and gable on the rear. The dependent suspension on longitudinal elliptical springs was retained. At the same time, the jet rods were removed from the rear axle, the functions of which were assigned to the propeller shaft. Its front hinge was fixed on a ball joint, which transmitted shocks to the frame cross member.
At the construction sites of the national economy. Photo Gruzovikpress.ru
One of the reasons for criticism in relation to the I-3 was the mechanically actuated brake. In the new project, a pneumatic system was used, supplemented by a German-made Bosch-Devaunder vacuum amplifier. This device tripled pedal effort.
The cab has been redesigned from the existing one. First of all, its width was increased, due to which, together with the drivers, two passengers were now placed in it. The cockpit had a vertical windshield, above which there was a horizontal roof. Behind the driver was covered by a vertical wall with a window. The sides covered the cockpit only partially. At the same time, doors were present on both sides. There was no glazing above the doors, and canvas curtains with transparent inserts were provided on the rear sides. They could be lifted to the roof or rolled out by attaching them to the lower hooks.
The truck did not have power steering, which affected the size of the steering wheel. Under the steering wheel was a dashboard with a set of basic indicators. Also at the disposal of the driver was a standard set of pedals and a transmission control knob. From the point of view of the layout of controls and general ergonomics of the cabin, the Ya-4 became one of the first domestic trucks of a "modern" look.
In the basic configuration, the cargo Ya-4 was equipped with a body with folding sides. This unit was borrowed without changes from the previous Ya-3 and retained the same dimensions. In the future, however, the dismantling of the standard body for the installation of other devices was not ruled out.
Maintenance of the I-4 machine in the workshop. Photo Gruzovikpress.ru
Due to the installation of a new power unit and related design changes, the total length of the Ya-4 truck increased to 6635 mm. The width and height remained at the level of the base machine - 2, 46 and 2, 55 m, respectively. The track and the base of the chassis have not changed either. The curb weight increased to 4, 9 tons. The increase in power made it possible to increase the carrying capacity to 4 tons. At the same time, the running characteristics improved. The maximum speed increased to 45 km / h - in this respect, the Ya-4 was on par with other trucks of its time, and with a lower carrying capacity.
The ordered engines and other German-made products arrived in Yaroslavl in the second half of 1928. By this time, KB V. V. Danilova managed to prepare the necessary documentation, and in the shortest possible time YAGAZ No. 3 manufactured the first cars of a new type. Power units of the Mercedes brand managed to pass tests abroad, and mastered and proven components were widely used in the design of the car. Thanks to this, the tests of the experienced Ya-4 did not take much time. Soon, the leadership of the automotive industry ordered the launch of a full-scale production of such equipment.
Until the end of 1928, the Yaroslavl State Automobile Plant assembled only 28 four-ton trucks of a new type. In the next 1929, 109 more vehicles were manufactured and sent to customers. At this, the serial production of Ya-4 cars was stopped. The reasons for this were simple and understandable. Only 137 kits with engines and transmission elements were bought from Germany. Using these products, YAGAZ could no longer build new trucks of the existing model.
However, the exhaustion of the stock of components did not lead to a halt in production. Yaroslavl car builders prepared in advance for this and took measures. In 1929, shortly before the termination of production of the Ya-4 trucks, a new project Ya-5 was developed. He proposed the construction of a machine as unified as possible with the existing one, but using a different engine and transmission. This time the products of the American industry were used. Thus, immediately after the last I-4, the first I-5 rolled off the assembly line. It should be noted that the use of new engines not only made it possible to continue the production of equipment, but also led to an increase in the main characteristics.
Model of a tanker truck based on Ya-4. Photo Denisovets.ru
In the army and the national economy
One of the first customers of the new four-ton truck was the Workers 'and Peasants' Red Army. At least several dozen Ya-4s went to serve in artillery units. There, the cars were used as tractors for guns, as well as transporters of ammunition and personnel. Without any problems, the truck pulled artillery systems with a caliber of up to 122-152 mm, while the crew and ammunition were placed in the back.
Another interesting customer was the organization "Sovmongtorg", which ensured the trade turnover between the USSR and Mongolia. The trucks of this organization had to carry various goods and goods along the roads of Altai to neighboring Mongolia and back. In the course of such operation, Yaroslavl cars not only ensured the transportation of the necessary goods, but also showed their potential when working in difficult conditions.
The remaining machines served in other organizations of the national economy and took part in a variety of works. Some trucks worked on construction sites, others were employed in agriculture, and still others in the mining industry. In all cases, the four-ton truck perfectly complemented the less powerful equipment and turned out to be the most convenient means of transportation. In some organizations, I-4, by local auto repair shops, were deprived of the standard body and received other equipment: tanks, vans, fire escapes, etc. However, due to the small number of trucks produced, this was not the most common practice.
During operation, the weaknesses of the new truck were identified. First of all, it turned out to be too heavy for some dirt roads, especially during muddy roads. The total weight of 8, 9 tons was distributed on six tires of two axles, which made certain demands on the quality of the road surface. For this reason, Ya-4s performed well in cities and could not work normally off-road.
Yaroslavl trucks as carriers of anti-aircraft guns. Photo Kolesa.ru
There was also a serious problem associated with imported units. For one reason or another, the supply of German-made spare parts was not established. As a result, a serious engine or transmission failure simply took the truck out of service. In some cases, the Ya-4 was returned to work, replacing the broken engine with a workable motor of an available type. Transmission repairs were often carried out in a similar manner. As a result, it was extremely difficult to find a basic truck by the mid-thirties.
According to various data and estimates, not the most numerous Ya-4 trucks remained in operation until the end of the thirties. Perhaps these machines could have worked longer, but the lack of original German spare parts seriously affected their performance. However, the ingenuity of the drivers and mechanics ensured timely repairs and the return of equipment to work. I-4 in all "modifications" continued to contribute to the development of the country and the national economy. Having developed their resource, the cars were sent for disassembly. Unfortunately, not a single I-4 has survived.
Backlog for the future
YAGAZ's first own car, Ya-3, was a modified version of the White-AMO car based on the outdated White TAD design. The new Ya-4 truck was developed on its basis, but at the same time modern components and technologies were used. The result of this approach was a very successful truck for its time with outstanding performance.
In terms of the totality of parameters and capabilities, the Ya-4 surpassed all domestic trucks of its period, and also was not inferior to many foreign models. Already at the end of the twenties, this machine underwent modernization, which led to the appearance of the Ya-5 truck. In the future, on the basis of existing machines and developments for these projects, YAGAZ designers have developed a number of new trucks with high performance. All this allows us to consider the Ya-4 a milestone development, which seriously influenced the development of the entire direction of Soviet heavy trucks.
Unfortunately, the limited supplies of German power units did not allow for the full-scale mass production of Ya-4 trucks. However, a way out of this situation was found, and soon Soviet drivers began to master Ya-5 cars. This car can only be considered an improved version of the previous one, but even in this case it is of great interest and is also worthy of separate consideration.