Due to certain circumstances during the Great Patriotic War, the Red Army did not have serial tank bridgelayers, which could negatively affect the mobility of troops. The few attempts to create such a technique during that period did not lead to the desired results. New projects started after the war and over time provided the most serious rearmament of the engineering troops. However, not all early samples were approved and put into service. Together with other developments, the ILO bridge tank did not leave the testing stage.
The experience of the past war clearly showed that the engineering units of the ground forces should have auxiliary armored vehicles carrying special bridge equipment. With their help, it was possible to significantly accelerate the overcoming of various obstacles and thereby increase the pace of the offensive. In 1945-46, specialists from the Soviet military department were working on this issue, and as a result, they formed the basic requirements for a promising engineering tool.
Experienced ILO on trial, the bridge is difficult. Photo "Domestic armored vehicles. XX century"
In October 1946, the command approved the requirements for a new engineering vehicle. It was supposed to carry a bridge with a length of at least 15 m and ensure the crossing of armored vehicles weighing up to 75 tons. With the help of such a bridge, tanks had to overcome narrow water barriers, various engineering barriers, etc. Also, the technical task provided for the unification of a promising image with serial T-54 tanks, which made it possible to reduce the cost of its production and operation.
The development of new technology was entrusted to the Kharkov plant №75, which was a branch of the plant №183 (now the plant of transport engineering named after VA Malyshev). The design bureau of the plant offered two options for promising technology at once. Thus, the 421 project proposed the construction of a bridgelayer with a drop-off bridge. Subsequently, in the early fifties, this model was adopted under the designation MTU.
The second project, based on other ideas, received the working title of the ILO - "Bridge-supporting tank". This name reflected the main idea of the project. In this project, it was planned to check an interesting proposal, according to which the bridge units were non-removable parts of the machine. The hull of such a tank, in turn, turned out to be one of the elements of the bridge. This design of the engineering facility could have some advantages over the drop bridge.
Plant No. 75 was loaded with orders, which affected the timing of the development of engineering equipment. The preliminary design of the ILO machine was prepared and presented to the customer only in August 1948. In the summer of 1949, the Main Armored Directorate reviewed a new set of technical documentation and a large-scale model of the tank. The project received approval, after which the construction of a prototype began.
Scheme of a bridge-bearing tank. Drawing "Domestic armored vehicles. XX century"
They decided to build a new bridge-bearing tank on the basis of the T-54 serial medium tank. It was planned to borrow from this machine the lower part of the hull, the power plant and the chassis. At the same time, it was required to develop from scratch a new upper deckhouse of the hull and special equipment that would meet the customer's requirements. A number of new systems were to be added to them. As a result of the implementation of all plans, the ILO product lost its external resemblance to the base tank. Moreover, it could work in the same battle formations with him.
The ILO corps had a distinctive shape. It retained the inclined frontal plates of its predecessor, on the sides of which there were vertical sides with mounts for the chassis devices. On the finished chassis, it was proposed to mount a new armored wheelhouse of large dimensions. Its basis was a large rectangular box made of armored steel. The front plate and sides of the superstructure were located strictly vertically, and the stern part was slightly tilted back. The height of the forehead and stern of the superstructure was different, as a result of which the roof was mounted with a noticeable tilt back. On the frontal and stern plates of the machine, in the top center, there were large covers for the axle drives.
The layout of the vehicle was slightly different from the tank one. In the front part of the hull with the wheelhouse, there were crew jobs. In the compartment behind them was placed some of the new equipment designed to ensure the operation of the bridge. The engine compartment with all the units of the power plant was preserved in the stern.
Based on the design of the T-54, the ILO retained the existing power plant. It was based on a V-54 diesel engine with a power of 520 hp. It was connected to a mechanical transmission, which included an input gearbox, a multi-plate dry friction clutch, a five-speed gearbox, two planetary swing mechanisms and a pair of final drives. The delivery of torque was carried out to the rear drive wheels.
The ILO provides escarpment. Photo "Domestic armored vehicles. XX century"
Due to a change in the design of the hull, the ventilation grilles were moved from the roof to the sides of the superstructure. The project provided for the possibility of overcoming water obstacles along the bottom. To do this, on the sides of the hull, it was necessary to mount removable pipes for supplying air and removing exhaust gases. The underwater driving equipment consisted of four tubes of different sizes, three of which had a rectangular cross-section.
The chassis also remained unchanged. On each side there were five double road wheels of large diameter with external shock absorption. The rollers had individual torsion bar suspension and were installed at different intervals. The distance between the first two pairs of rollers has been increased. In the front of the hull there were idler wheels with tensioning mechanisms, in the stern - leading ones.
A crew of three was supposed to drive the ILO bridgework tank. His workplaces were in the front of the hull. It was proposed to observe the road using a pair of large inspection hatches in the frontal sheet of the superstructure. Access to the crew compartment was provided by side hatches. For some reason, the engineering vehicle was not equipped with its own weapons. In the event of a collision with an enemy, she had to rely only on armor.
The ILO had to carry special equipment, representing the sections of the bridge. It was proposed to operate this equipment using a hydraulic system. The pressure in the circuits was created by a separate pump driven by the main engine. With the help of a special panel, the crew could control the operation of the hydraulic cylinders-drives of the bridge sections.
Bridge tank in a trench. Photo "Equipment and weapons"
The development bridge of the plant No. 75 consisted of three main sections and had a track structure. Its central section was formed by the roof of the tank superstructure. A pair of beams with a flooring for the passage of equipment was laid right on it. This part of the bridge had a length of 5.33 m. In front of and behind the deck on the roof, there were hinges for the installation of two movable sections.
The front section of the bridge consisted of two separate gangways. The basis of each such product was a large metal truss with side elements of complex shape. At the top, the ladder was equipped with a flooring for the passage of cars, at the bottom there was a cover. The front of such a device had a slight bend and dropped slightly downward, which was planned to be used to overcome obstacles. On the back of the ladders there were fasteners for installation on the hinge of the body. There was also a connection with a hydraulic drive.
The rear ladders were smaller and of a different shape. Their trusses were triangular in profile and low in height. The front part of the ladder was mounted on a hinge, the rear part was intended for laying on the ground. Like other axle elements, the rear section had a deck with crossbars to improve traction. Curiously, the deck was installed on both sides of the ladder - both above and below.
In the stowed position, all four movable elements of the bridge had to fit on the roof of the hull. At first, it was proposed to fold the rear ladders, after which the front ladders were placed on top of them. It was this method of folding the bridge that required the use of an inclined roof: the rear sections of the triangular profile, lying on the sloping wheelhouse, formed a flat horizontal surface for laying the front ones.
Organization of crossing the reservoir. Photo "Domestic armored vehicles. XX century"
The deployment of the bridge was carried out in the reverse order. Approaching the obstacle, the bridge-supporting tank had to raise and lay the front section on it, after which the rear section was lowered. If necessary, the rear ladders could remain on the roof of the hull. The front section of the bridge had a length of 6 m, the hull floorings were 5.33 m. The lowered rear ladders were the shortest - 4.6 m. The width of the flooring was 1.3 m, the total width of the bridge was 3.6 m. The hinges of the front section were located on height 2, 6 m from the ground, back - 2 m.
The total length of a three-section bridge could reach 15.9 m, which made it possible to cover obstacles up to 15-15.5 m wide. The maximum height of an obstacle on land was determined at 5 m. no more than 3, 8 m. The strength of the bridge corresponded to the customer's requirements. Vehicles weighing up to 75 tons could drive along it.
In terms of its dimensions, the new ILO slightly surpassed the T-54 basic medium tank. The total length, taking into account the folded bridge, reached almost 7 m, the width was still 3.27 m. The height in the stowed position was no more than 3.5-3.6 m. The combat weight was 35 tons. Due to this, the mobility characteristics were at the level of the serial T-54. The bridge support tank could accelerate on the highway to 50 km / h and overcome various obstacles. The power reserve is about 250-300 km.
The ILO project proposed several options for using the bridge. In the simplest case, the tank had to approach the obstacle, lift the front section of the bridge onto it, and lay the rear section on the ground. At the same time, other options for work were worked out, including with the participation of several bridge-bearing tanks. Several engineering vehicles, working together, could provide overcoming more difficult obstacles. So, the second ILO, standing on the roof of the first, allowed equipment to climb a cliff up to 8 m high. Also, with the help of several tanks, it was possible to block a ravine or a river of large width. To do this, they had to line up and lower sections of the bridges on top of each other.
Variants of using bridge tanks to overcome various obstacles. Drawing "Domestic armored vehicles. XX century"
In the fall of 1949, plant # 75 built the first and only prototype of the ILO bridge support tank. Soon the car entered the training ground and demonstrated its capabilities. She managed to prove her ability to solve basic problems, but at the same time, noticeable problems with real operation were identified. The latter had the most serious impact on the fate of the project.
Indeed, the ILO machine could quickly and easily organize a crossing over ditches, escarps, counter-escarps, reservoirs, etc. In terms of strength and overall characteristics, it fully complied with the customer's requirements. The combined use of several such tanks made it possible to ferry armored vehicles through larger obstacles on land or through shallow water bodies.
However, some operational problems and limitations have been identified. So, the existing bridge could be effectively used only at obstacles with steep walls. Working on gentle slopes was associated with certain difficulties. If necessary, the ILO could go down into a wide ditch and establish a crossing, but not in all cases it could go up on its own. To work on water, as it turned out, the machine needs a lengthy procedure for sealing the body and installing additional pipes.
It was also found that a bridge-supporting tank may have insufficient survivability on the battlefield, and these shortcomings cannot fundamentally be eliminated. While the crossing is working, the ILO tank is forced to stay at the obstacle, which makes it an easy target for the enemy. Moreover, due to his tactical role, he risks becoming a priority target and getting hit by the first blow. The defeat of this machine, in turn, incapacitates the entire bridge and slows down the advance of the troops.
Tank bridgelayer MTU. Photo Wikimedia Commons
Tests of the only experienced ILO tank showed that the proposed and implemented concept has certain positive aspects, but it is not of real interest. Technical and operational problems, combined with insufficient survivability, closed the road to the troops for the bridge tank. No later than 1950-51, the project was closed for lack of prospects.
However, the army was not left without engineering means to overcome obstacles. Simultaneously with the ILO machine, plant # 75 was developing a project with the designation "421". It provided for the construction of a full-fledged tank bridgelayer with a drop bridge. Testing of the prototype 421 Objects started in 1952, and they quickly showed their full potential. By the mid-fifties, this machine was adopted and put into production under the designation MTU / MTU-54.
The project "Bridge-supporting tank" of plant # 75 was intended, first of all, to test a new idea. If the desired results were obtained, such a machine could go into production and increase the mobility of the armored units of the Soviet army. However, the only prototype did not perform well, and the ILO was abandoned in favor of a more successful design. As subsequent events showed, the MTU armored vehicle not only entered service, but also predetermined the further development of domestic engineering technology: in the future, it was tank bridgelayers that were developed.
