By the mid-thirties, the Yaroslavl Automobile Plant mastered the truly mass production of five-ton trucks. For several years, he was able to produce more than 8 thousand cars of the YAG-3 and YAG-4 types. In parallel with the production of existing machines, the development of new ones was carried out. As it turned out later, the project of deep modernization of the existing model had the greatest prospects. The new version of the car went into production under the name YAG-6.
The appearance of the YAG-6 project was preceded by interesting events. In the mid-thirties, YaAZ and the Scientific Research Automobile and Tractor Institute (NATI) jointly carried out major research work to study their own and foreign experience in the field of the truck industry, and then developed a whole line of vehicles for various purposes. In addition, a project was proposed to modernize production at YaAZ. However, due to objective difficulties, the plant was not updated, and therefore could not build new trucks developed by NATI. For this reason, KB YaAZ was forced to use the old approach, providing for the next modernization of the existing project.
Deep modernization
It should be recalled that the development of Yaroslavl trucks at that time was carried out through the gradual refinement of existing structures. Each new car was a modified version of the previous one, and the main innovations concerned the power plant and transmission. In the next project, the design bureau YaAZ decided to use this approach again. However, this time it was necessary to apply a large amount of new solutions.
Truck YAG-6. Photo "M-Hobby"
A deeply modernized version of the YAG-3 / YAG-4 was designated as YAG-6. The presence of the new name indicated the most serious differences between the trucks. About 270 significant changes were made to the original project. The frame, power unit, chassis, etc. have undergone revision. At the same time, the hood, cab and cargo platform remained the same. Thus, outwardly, the YAG-6 was minimally different from its predecessors. In fact, it could only be distinguished by the shape of the front fenders and a new plate with the manufacturer's emblem.
There are curious reasons for the preservation of the old cab and body, which were not distinguished by high design perfection and did not provide special comfort for the driver and passengers. The fact is that from a certain time the platforms and cabins were assembled by a related enterprise - the Parizhskaya Kommuna timber mill (Yaroslavl). Despite all the complaints, subcontractors were in no hurry to improve the quality of production or master the release of new products. It was not necessary to count on getting a new cabin, and therefore the YAG-6 had to be made to match the old one.
270 changes
The YAG-6 project provided for the use of a proven vehicle architecture. At the same time, its individual features and various machine units were changed using available products and technologies. The truck was still based on a riveted metal frame in the form of a pair of spars and several cross members. A power unit, a cabin and a cargo platform were installed on top of it, and chassis elements were suspended from below.
Under the hood of the truck, they left a power unit of the ZIS-5 type, borrowed from the Moscow-developed machine of the same name. The inline six-cylinder ZIS-5 engine developed 73 hp. The motor was equipped with a MAAZ-5 type carburetor and was connected to a liquid cooling system based on a honeycomb radiator. Through the clutch, the ZIS-5 gearbox with four forward and one reverse speeds was mated to the engine.
Machine diagram. Figure Russianarms.ru
The propeller shaft of the drive of the driving rear axle departed from the gearbox. It was installed with a slope inside a tapered part that transferred loads from the bridge to the frame. The final drive of the car has retained the same design, but has been improved from a technological point of view. The gear ratio remained the same - 10, 9, which was enough to obtain the desired characteristics. For the first time in the practice of YaAZ, a central disc-type handbrake appeared in the transmission. It provided braking by blocking the shafts.
The most significant changes have been made to the chassis design. The main element of the wheel was now a convex stamped disc. The use of such parts has led to the need to increase the length of the axles. In addition, due to the convex discs, it was possible to increase the distance between the tires of the rear dual-pitch wheels and sharply reduce their wear from friction of the side surfaces. The new discs and accompanying changes have led to an increase in the track of both axles. The front track has increased by 30 mm, the rear track by 72 mm.
An updated and improved foot brake was developed especially for the YAG-6. First of all, the brake drum was changed by increasing its thickness. Copper wire was added to the friction linings of the brake pads to improve thermal conductivity. A special worm gear was now used to adjust the brake.
The hood for the new truck was borrowed almost unchanged from the base YAG-3 / YAG-4. The functions of its front wall were performed by a large radiator, and the top and side of the power unit was covered with metal shields. The bonnet had a pair of longitudinal hatches. Blinds were cut into the lifting sides. On the sides of the hood, new fenders of a modified shape were fixed. They were now integrated with the cab steps.
View from above. Figure Russianarms.ru
The design of the cockpit remained the same and included metal and wooden parts. The windshield with the lifting mechanism was retained. The sides had doors with their own windows. All the necessary controls and control devices were located at the driver's workplace. Together with the driver, two passengers could be in the cockpit. A fuel tank with a capacity of 177 liters was placed under the common seat.
The cargo platform for the YAG-6 was similar to the existing ones, but slightly different from them. Changing the rear wheel track made it possible to increase the body width by 130 mm. Its design remained the same: hinged sides were hinged to a wooden horizontal platform.
On the basis of the YAG-6 flatbed truck, a new version of the dump truck was immediately developed. This machine was named YAS-3. From the point of view of architecture, this dump truck was as similar as possible to the existing serial YAS-1. In addition, the similarity of the base cars and the unification of special equipment led to the absence of serious external differences. As in the case of the YaG-6, the YaS-3 could only be identified by individual elements.
The dump truck of the new model was equipped with a hydraulic pump, which ensures the operation of a pair of cylinders. The rear of the frame has been reinforced and fitted with a swing body hinge. The latter was a cargo platform of the old type with fixed sides (except for the movable rear one), upholstered on the inside with metal. The main characteristics of the dump truck remained the same. The new equipment increased the mass of the YAS-3 machine by 900 kg in comparison with the base YAG-6, which led to a reduction in the carrying capacity to 4 tons. The time for raising and lowering the body was 25 seconds each.
Dump trucks YAS-3. Photo Autowp.ru
The redesign of the basic YAG-3 led to a slight change in the dimensions of the machine. The length remained the same, 6.5 m, while the width increased to 2.5 m, and the height remained at the level of 2.55 m. With the old wheelbase (4.2 m), the front axle track was 1.78 m, the rear - 1, 86 m. The curb weight of the truck was 4750 kg, the carrying capacity was 5 tons. The 73-horsepower ZIS-5 engine in a known way limited the characteristics of the equipment, and the maximum speed on the highway did not exceed 40-42 km / h. Fuel consumption is about 43 liters per 100 km.
YAG-6 in series
In 1936, the Yaroslavl Automobile Plant stopped producing cars of the previous family. The YAG-3 and YAG-4 trucks, as well as the YAS-1 dump truck, were removed from the assembly line. Instead, the enterprise was now supposed to produce new samples - YaG-6 and YaS-3. The country still needed five-ton trucks, and the Yaroslavl automakers did their best. Until the end of the first year of production, it was possible to build several hundred vehicles of two types, which soon went to their operators.
As before, high performance trucks were distributed among different organizations from different industries. First of all, five-ton vehicles were supplied to the Red Army. Also, this technique was of interest to construction and mining organizations. Until a certain time, they received only flatbed trucks and dump trucks, but later the production of specialized modifications was mastered by various enterprises.
By removing the standard body and installing new equipment, the YAG-6 turned into a fire tanker, a concrete mixer truck, a fuel truck, a watering machine, and even a self-propelled ice picker on highways. There were also less serious, but interesting improvements. So, two chassis axles could be supplemented with a rolling axle, which improved the characteristics of the car on difficult routes.
It should be noted that the new versions of the YAG-6 were created not only by third-party workshops, but also by the Yaroslavl Automobile Plant. As the serial production continued, the enterprise developed new modifications of equipment of one kind or another.
Tank truck based on YAG-6 in the national economy. Photo "Military Technical Museum" / gvtm.ru
For example, in 1938, the YAG-6M truck was created. The main difference of this technique was an improved cab with improved conditions. In addition, cars with the letter "M" had a new power unit. Some of them were equipped with American Hercules-YXC-B engines, others - with domestic ZIS-16. According to some sources, the YAG-6M were intended for delivery to one of the foreign countries. No more than fifty of these machines were built.
In 1940, a long-wheelbase version of the truck chassis appeared under the name YAG-6A. It was distinguished by an elongated frame, due to which the base was increased to 5 m. Such chassis could be used as a basis for special vehicles, buses, etc. However, the project encountered technical and organizational difficulties. The beginning of the Great Patriotic War put an end to its history. Before the German attack, only 34 YAG-6A vehicles were built in Yaroslavl.
Engine problem
Full-scale production of five-ton YAG-6 trucks continued until 1942. In the next 1943, the Yaroslavl Automobile Plant managed to assemble only three dozen of these cars, after which their production stopped. The reason for this was the lack of the necessary engines. Moscow Plant im. Stalin was loaded with army orders, and he had no "surplus" left to be sent to Yaroslavl. In the first months of 1943, YaAZ used up the available supply of power units, and the production of five-ton cars stopped.
During the entire production period, 8075 trucks of the basic modification were produced. The total production of other machines did not exceed hundreds of copies, and a significant number of them were exported. The production of YAS-3 dump trucks reached 4,765 units.
Realizing that the production of YAG-6 is under threat, and the country still needs equipment with a high carrying capacity, the YaAZ design bureau has developed a new project. The truck under the designation YAG-9 was a revised version of the YAG-6, which had a number of characteristic differences. First of all, it was planned to abandon the domestic engine in favor of the imported one. It was proposed to use a power unit with a 110 hp GMC-4-71 engine, a Long 32 clutch and a Spicer 5553 gearbox. The rear axle should be made by casting, and the standard brake system was replaced with a pneumatic one borrowed from the YABT-4A bus.
Truck YAG-6 with a rolling axle installed by operators. Photo "M-Hobby"
A machine with such a composition of units was supposed to surpass the existing YAG-6 in a number of indicators and could be of greater interest to the army and the national economy. However, it was not possible to start production. YaAZ applied to the State Defense Committee with a proposal to purchase a batch of engines for a new truck. For a number of objective reasons, the proposal was not approved. The plant managed to build only one experienced YAG-9 with a GMC engine, and after that the project was closed for lack of real prospects.
Around the same time, Yaroslavl engineers decided to give a second life to an old project, which was closed several years ago. In the mid-thirties, a pair of Ya-5 trucks with a promising domestic-developed Koju diesel engine passed full-scale tests. The YaAZ design bureau considered the possibility of installing such an engine on the YaG-6 and came to optimistic conclusions. However, work on the Koju family of diesel engines had actually stopped by that time, and their continuation did not make sense. The engines needed further refinement and serial production. In the conditions of war, all this was considered impossible.
Thus, the production of five-ton YAG-6 trucks was left without engines, and therefore it had to be stopped. Moreover, the entire production of automotive equipment in Yaroslavl and the plant's prospects were in question. Fortunately, we quickly found a way out of this situation. YaAZ reoriented to the production of tracked artillery tractors. In 1943, the plant received documentation from NATI for a new machine of this kind, and soon built prototypes. The production of tractors lasted from 1943 to 1946. During this time, several thousand machines of the Ya-11, Ya-12 and Ya-13 types were manufactured.
Contribution to victory
A significant part of the YAG-6 serial trucks were immediately sent to service in the Red Army. After the outbreak of the Great Patriotic War, hundreds of machines of enterprises of the national economy were mobilized and also went to the front. Most often, five-ton tanks were used as artillery tractors capable of towing guns with a caliber of up to 122 mm, as well as transporting ammunition and crew. However, in this capacity, they showed themselves not in the best way - the insufficient engine power affected.
Tank truck YAG-6 in the exposition of the Military Technical Museum, c. Ivanovskoe. Photo "Military Technical Museum" / gvtm.ru
Also, the five-ton truck was a convenient vehicle that perfectly complemented the one-and-a-half and three-ton models of existing models. In addition, during the war, other modifications of the YAG-6 were also used. Four-ton dump trucks took part in the construction of the fortifications, and fuel trucks provided fuel supply to the units. Watering machines based on YAG-6 are especially worth noting. It was these cars that symbolically washed the streets of Moscow after the march of German prisoners of war in July 1944.
However, Yaroslavl heavy-duty trucks could not compete with other equipment in terms of their numbers. Since the beginning of the thirties, the Yaroslavl Automobile Plant has built a total of about 20-22 thousand five-ton cars of various models and modifications. Other domestic trucks were built in much larger quantities. As a result, off-road vehicles, which were of particular importance for the army and the economy, had limited potential.
Trucks of the YAG-6 line were produced only until the beginning of 1943, after which their production was stopped, and the Yaroslavl Automobile Plant was transferred to the construction of tracked tractors. The company returned to the theme of the truck industry again only after the end of the war. In 1947, the first truck of the fundamentally new series YaAZ-200 rolled off the assembly line. A new chapter has begun in the history of Soviet trucks.
