Tank bridge TM-34
It should be recalled that the work on the creation of bridge laying on tank chassis began in the mid-thirties. Several projects of similar technology were created on the basis of the T-26, BT and T-28 tanks, but they did not produce the desired results. Most of the new technology did not cope with the tests and therefore did not go into the series. Some collected prototypes were tested in the Soviet-Finnish war. The IT machine 28 was approved by the military, but appeared too late. Due to the German attack, its mass production never began.

Tank bridge TM-34 in the stowed position. The bridge is laid on the roof of the hull. Photo Russianarms.ru
Nevertheless, the troops required various means of overcoming obstacles, and engineers continued to work. The original proposal in the field of tank bridges appeared in late autumn 1942, in the besieged Leningrad. Its author was Colonel G.A. Fedorov, who at that time served at the 27 Repair Plant of the Leningrad Front. The company was engaged in the maintenance and restoration of army armored vehicles, and some of the repaired vehicles could be used in a new role.
According to G.A. Fedorov, some of the medium T-34-76 tanks, primarily unsuitable for service in the original quality, should be equipped with special equipment of relatively simple design. On the case of the car there should be a swinging track-bridge, with the help of which it could provide the overcoming of obstacles by other equipment. The initiative project was simple and did not impose any special requirements. The release of engineering machines of a new type could be mastered even under blockade conditions.
According to known data, the project G.A. Fedorov received approval and was accepted for implementation. By the end of 1942, Plant No. 27 assembled the first new type of machines. This technique was designated as “tank bridge TM-34”. Other names, designations or nicknames are unknown.
In accordance with the proposal of the colonel, a serial tank undergoing repairs, had to lose the regular tower and the main units of the combat compartment. Also on the chassis should install a set of different units, including a large track bridge. This architecture of the tank bridge made it possible to get by with minimal modifications to the existing chassis, which was crucial in the blockade conditions. In this case, the resulting engineering machine could solve all the tasks.

Another TM-34, with noticeable external differences. Photo Wwii.space
As a basis for the TM-34, it was proposed to use serial medium tanks that were available from the 27 repair plant. Despite the installation of new units, the design of the base chassis has not changed. The tank retained the armor hull of sheets of thickness up to 45 mm, located with rational tilt angles. The layout also did not change, although the central compartment, previously a fighting compartment, could now be used to install engineering equipment. Without taking into account the new external units, the body retained its original appearance.
In the stern of the tank bridge, there should have been a B-2-34 diesel engine with a capacity of 500 hp, standard for the T-34 family of tanks. Through the main friction clutch of dry friction, the torque entered the four-speed gearbox, and through it went to the turning mechanism. Also, the tank had a single-stage side gear. As the serial production of the transmission of the T-34 machines was being finalized, it is impossible to establish the exact composition of the equipment of the tank bridges.
The existing undercarriage with Christie suspension on vertical springs was maintained. On each side there were five large support rollers, a front guide wheel and a rear leader. As the preserved photographs show, the TM-34 tank bridge could be equipped with rollers of different designs, which was due to the peculiarities of the repairs and the limitations.
The tunable tank was deprived of a regular turret with a 76-mm cannon and machine gun. In some sources it is mentioned that some of the TM-34 machines retained the towers, but the installation of a new special equipment sharply reduced the angles of horizontal laying. A careful study of the design of the original bridge suggests that such data do not correspond to reality. The dimensions of the towers, even the compact early ones, did not comply with the restrictions imposed by the design of the newly developed bridge.
It was proposed to mount metal supports assembled from several parts of different shapes on the sides of the frontal part of the hull of the tunable tank. The latter were raised to a considerable height above the hull; in the stowed position on them was to lie the front of the bridge. Some tank bridges did not have such equipment. At the rear of the hull, at the level of the engine compartment, a hinge appeared for mounting the movable bridge. Inclined feed sheet became the basis for a pair of additional ladders. They were fixed on the body hard and dropped to the level of the bottom.
Actually, the bridge for the new engineering machine was quite simple. It was based on two longitudinal side beams of complex shape, assembled from sheet metal and profiles. Their front part differed in smaller height, and behind it there was a reinforced aggregate of increased dimensions. Side beams were connected by several transverse bridges into a single rectangular structure. On top of them mounted flooring type rut.
With the help of a simple hinge, it was proposed to install the finished bridge on the base chassis housing. In the stowed position, the bridge lay on the roof and front pillars (if any). The design of the new units made it possible to change the position of the bridge, raising it above the hull or lowering it onto the supports. How the management of the bridge was organized is unknown. Probably, the chassis received a new hydraulic units, installed on the site of the crew compartment or above the engine compartment.
Installation of the bridge required to remove from the base tank turret with cannon and machine gun weapons. In this case, such an alteration did not affect the machine gun installation frontal sheet. This suggests that tanks-bridges of the Leningrad assembly retained one of the DT machine guns that could be used for self-defense. Also, the crew could have a private shooting weapon and a few grenades.
The crew of the TM-34 is not exactly known. Probably, two or three tankers were supposed to drive the car. In front of the hull, the driver’s workplace was preserved, equipped with a characteristic front sheet hatch. A commander-gunner could be located next to him, including one with bridge controls.
The tank chassis, despite the removal of old units and the installation of new ones, retained the same dimensions. Its length did not exceed 6 m with a width of 3 m and a height less than 2 m. It is not known how the mass of the car changed in comparison with the base tank.
Dimensions of the bridge in terms of almost coincided with the size of the tank. Its length, without taking into account the feeding ramps, reached 6-6,5 m with a width of about 3 m. Thus, the TM-34 tank bridge could help various domestic armored vehicles, primarily T-34 medium tanks.
According to the idea of Colonel Fedorov, the new tank bridge was supposed to provide for overcoming a number of obstacles encountered in the way of armored vehicles. First of all, it was about anti-tank ditches and escarpes. Accompanying armored combat vehicles, TM-34 had to approach an obstacle and enter it, coming close to the opposite slope. After that, it was necessary to raise the bridge to the required angle - so that its front end was on the same level as the upper platform. In this position, the bridge was fixed, allowing the passage of a technique.

Tank bridge drove into the moat and is ready to ensure the passage of other equipment. Photo "Technique - youth"
A tank or any other vehicle had to approach the TM-34 from behind and drive into its stern inclined ladders. Through them it was possible to get on the main deck of the bridge and pass through it to the upper platform, overcoming an obstacle. According to known data, the design of the tank bridge allowed overcoming obstacles up to 12 m in depth from 2,2 to 4,5 m. In the case of the widest obstacles between the bridge and the platform, there could be a significant gap, and therefore the armored vehicles would have to use their “skills” overcoming trenches.
The design of the tank bridge was proposed in the autumn of 1942, and soon repair plant No. XXUMX mastered the assembly of such equipment. With the available medium tanks removed extra units, and then completed them with means of mounting the bridge and the bridge itself. Surviving materials suggest that the design of finished products depended not only on the project, but also on the capabilities of the manufacturer. As a result, different bridges of the same series could have noticeable differences of one kind or another. In particular, it is known about the existence of TM-27 without front supports for the transport of the bridge. In addition, similar supports on different tanks could have a different design.
In December, the 1942 of the year and the first few months of the next 1943, the Leningrad Repair Plant No. XXUMX, re-equipped a number of the existing T-27 tanks with a new design. Their exact number is unknown, but, apparently, collected only a few cars. The army needed such equipment, but it did not need dozens and hundreds of tank bridges.
Probably, TM-34 was not officially adopted. Such equipment was produced in small series in the interests of one of the fronts, but the launch of full-scale production at other enterprises was not planned.
According to the fragmentary surviving data, TM-34 tank bridges were used to a limited extent on the Leningrad front and helped other equipment to move across rough terrain. However, the situation on this front did not contribute to the frequent and massive use of engineering technology. In addition, having a specific look and a special design, the TM-34 machines could face certain problems during operation and work on the battlefield.
Detailed information on the operation and combat work of the tank bridges of the 27 plant has not been preserved. Probably, they could find application and help the offensive of their troops, as well as contribute to lifting the blockade. Nevertheless, it cannot be excluded that a few engineering machines were lost in time in various battles.
Recent reports of tank bridge engineering refer to the first months of 1943. After this, new data on such a technique did not appear. Why - it remains only to guess. However, the approximate fate of all collected TM-34 is known. None of these machines did not live to date. Apparently, they either died in battle, or were dismantled as useless. They could be disposed of both during the Great Patriotic War and after.
By the beginning of the war, there were no serial and mass tank bridge-laying machines in the park of the Red Army equipment capable of ensuring the movement of troops over rough terrain and helping them overcome various obstacles. The lack of engineering means led to the development of initiative, one of which was the TM-34 tank bridge. It is known that during the war years, Soviet engineers and military men proactively proposed and implemented several similar projects, but TM-34 turned out to be the only engineering vehicle with a non-drop bridge. Later similar ideas were implemented at a new technological level.
Based on:
http://russianarms.ru/
http://wwii.space/
Tank Bridge // Technique - Youth, 1943. No.2-3.
Solyankin A. G., Pavlov M. V., Pavlov I. V., Zheltov I. G. Domestic armored vehicles. XX century. - M .: Exprint, 2005. - T. 2. 1941 – 1945.
Baryatinsky M.B. T-34. The best tank of World War II. - M .: Yauza, Eksmo, 2006.
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