Since the end of the sixties, the Special Design Bureau of the Plant im. I. A. Likhachev was actively involved in the topic of auger snow and swamp-going vehicles. The construction and testing of three types of machines made it possible to find out the real capabilities of such technology, as well as to determine the ways of its further development. Taking into account the experience of recent projects, the development of a new all-terrain vehicle ZIL-2906 was started. With the successful completion of the project, such a machine was to become part of a promising search and evacuation complex, which was to search for and take out "to the mainland" cosmonauts and pilots.
In 1972, SKB ZIL began testing a full-size all-terrain vehicle ZIL-4904, equipped with a screw-rotor propeller. The complete determination of all characteristics took several years, but the main features of the proposed sample were established as soon as possible. So, it quickly became clear that the proposed auger is not highly mobile. The car could not independently move on paved roads and needed a tractor with a special trailer, and because of its large dimensions, it did not fit into the cargo compartments of military transport aircraft. Thus, the operation of the ZIL-4904 / PES-3 with obtaining practical results was not possible.
ZIL-2906 at the test site
In the same period, the Special Design Bureau, together with representatives of the space industry, worked out the appearance of the future search and evacuation complex PEC-490, which in the future was to search for and take out the landed cosmonauts. As conceived by the designers, the basis of the new complex was to be a three-axle all-terrain vehicle ZIL-4906 with crane equipment. It was also proposed to supplement it with a passenger car on a unified chassis. To work in especially difficult areas in the complex "490" there had to be an all-terrain vehicle with rotary-screw devices.
The new auger was supposed to be relatively small in size to meet the requirements of military transport aviation. Moreover, it had to fit in the back of a ZIL-4906 "truck". It was assumed that for most of the way, this car will go on another all-terrain vehicle. She had to go down to the ground and start work only in cases when the wheeled vehicles could no longer continue to move. Such a proposal made it possible to realize all the advantages of an unusual chassis, but at the same time not to face its disadvantages.
A new project of a relatively compact all-terrain vehicle for the PEK-490 complex received the factory designation ZIL-2906. In accordance with the recently introduced classification, it showed that the new machine belongs to the class of special equipment and weighs no more than 2 tons.
Machine diagram
In the summer of 1973, the designers of SKB ZIL formed the general appearance of the future all-terrain vehicle. A characteristic feature of the preliminary design was the maximum reduction in the size and weight of the structure. In particular, for this it was proposed to use a pair of relatively low-power air-cooled automobile engines. The transmission should have been built according to the onboard scheme, which also facilitated the design. It was also planned to reduce the weight and dimensions by eliminating the high sides and roof. The crew and the cosmonauts being rescued were to be located in an open cockpit.
Soon, on the basis of the preliminary project, the necessary set of design documentation was developed, which determined the final appearance of the future all-terrain vehicle. At the same time, the main features of the car have not changed. In addition, in its design and appearance, one could see a lot of features of the already tested samples.
Unlike its predecessors, the experienced ZIL-2906 received a supporting body assembled only from metal parts. A characteristic feature of such a case were extremely simple shapes, formed only by straight surfaces. The upper part of the hull, which contained the cockpit and power compartment, received an inclined front sheet with front glazing. Behind it were vertical sides of low height. In the stern, an engine casing was provided, which was distinguished by a slightly increased height. In front of the lower housing unit there was a pair of beveled ski surfaces for entering obstacles, behind which the augers were placed. Between the unusual propellers there was a bottom with a trapezoidal cross-section. Rear auger supports were located under the hull.
Stern view
In the aft engine compartment, side by side, a pair of MeMZ-967A gasoline engines with a capacity of 37 hp were installed. The engine flywheel was at the back and connected to a single-plate clutch. A planetary gear was used as a two-stage gearbox. Also in the transmission, a shaft range gearbox was used, installed at an angle to other units. The all-terrain vehicle received two similar power units. Each of them, through the propeller shaft and final drive, rotated its own auger. By changing the speed and direction of the augers, the driver could control the movement or maneuver.
The project involved the use of two metal screws 2888 mm long. The diameter of each of the rotors along the outer lug line was 860 mm. The lugs were installed with an inclination angle of 39 °. As in previous projects, the augers were made hollow, so that they could keep the car on the water, complementing the buoyancy of the sealed hull.
A cockpit for the crew and passengers was located directly in front of the hull. The ZIL-2906 cockpit housed a pair of crew seats, as well as two recumbent spaces for evacuated cosmonauts. It was proposed to get into the cockpit through the side. For a certain convenience of the crew and passengers, there were folding ladders in front of the sides. According to the project, the cabin was not equipped with high sides and a roof. At the same time, it was covered with a windshield in front. The glass frame was hinged and could fit on the front sheet of the case.
Winter tests on land
The cockpit had a steering wheel, pedals and a set of indicators at the helm station. Turning the steering wheel controlled the revolutions of the two engines, due to which the required rotor was braked. One lever through a synchronized system controlled the gearboxes of both power units. The clutch pedal worked in a similar way. The gas pedal, in turn, simultaneously increased the speed of both engines.
The ZIL-2906 all-terrain vehicle was considered as an addition to other rescue equipment, and therefore received a set of appropriate equipment. The crew had at their disposal a Pelican radio station, an NKPU-1 portable direction finder, a magnetic compass, a stretcher, medical equipment, life jackets, an entrenching tool, a fire extinguisher, etc. The auger crew could find the astronauts, help them and take them to other rescuers.
The new car had special requirements in terms of dimensions and weight. They were successfully completed. The length of the ZIL-2906 was only 3.82 m, the width was 2.3 m, the height along the body was 1.72 m. The ground clearance on a hard surface was 590 mm. The own weight of the all-terrain vehicle did not exceed 1280 kg. Gross weight - 1802 kg, including 420 kg of payload.
The assembly of an experimental vehicle of a new type was completed in the middle of the summer of 1975. On August 21, the first stage of testing began, the site for which was the ponds of the Nara fish factory. Noticeable shortcomings of the power plant were quickly identified. The MeMZ-967A engines used air cooling, which imposed some restrictions. For example, on water, the all-terrain vehicle accelerated only up to 10-12 km / h, and the oncoming air flow could not cool the engines normally. In the fall, tests were continued on drained ponds and on rough terrain. Under such conditions, the undercarriage and power plant faced increased loads. The engines lacked power and broke down several times.
Auger in the swamp
The first conclusions drawn from the test results concerned the power plant. MeMZ-967A products from the Zaporozhets car did not meet the assigned tasks. They had to be replaced with other automobile engines, but this required the most serious processing of the auger, which was proposed to be performed later. In this regard, the experienced ZIL-2906 entered the next tests in the same configuration.
In March of the next 1976, all the machines of the future PEK-490 complex were sent to Rybinsk for joint tests. Moving through the snow, the experienced auger-driven snow and swamp-going vehicle showed very high performance. On a snow cover 700 mm thick, the car accelerated to 15 km / h. The speed in the swamp was about half that. The all-terrain vehicle climbed the slopes with a steepness of 24 ° without any problems.
About a month after that, ZIL-2906 was sent to Star City for a demonstration to representatives of the space industry. Among other things, the car was shown in motion on a frozen lake. During such a trip, the weak ice broke, and the feed of the all-terrain vehicle fell into the water. Nevertheless, he continued to move and began to break the ice in front of him. Having made a long break in the ice, the all-terrain vehicle returned to the shore. The prototype received high marks from specialists.
Lifting the snow and swamp-going vehicle aboard the ZIL-4906
In June-July 1976, the "490" complex was tested in the area of the city of Kagan (Uzbek SSR). The new type auger was tested on sands, on the water of Lake Dingyzkul, as well as on reed beds, areas with a salty crust, etc. At the same time, the air temperature often reached + 50 ° C. The possibility of transporting an all-terrain vehicle on board a ZIL-4906 wheeled vehicle with unloading and loading using standard crane equipment was also tested.
It was found that in the special conditions of Uzbekistan, low-power engines are prone to overheating and certain breakdowns. It also turned out that the all-terrain vehicle needs a closed cockpit. Falling under the all-terrain vehicle, the reed stalks broke and literally wound around the rotors. Some of them, rotating with the augers, strove to hit the cockpit and could injure the crew. Specific conditions and a number of negative factors led to the fact that as a result of these tests, a significant part of the machine parts were covered with rust.
In January 1977, winter tests of the ZIL-2906 began. They were carried out in Vorkuta at air temperatures down to -35 °. It turned out that at least an hour elapses from the moment the heaters are turned on until the engines are fully warmed up. At low temperatures, a new problem appeared in the form of freezing of the bearings on the front bearings of the augers. Because of this, it was only allowed to move in first gear.
Astronauts aboard the ZIL-2906 all-terrain vehicle
After returning from Vorkuta, tests of the experienced auger were suspended. New inspections took place only in the winter of the following 1978. On the snow-covered ponds of the Nara plant, the new ZIL-2906 was compared with the previous ZIL-4904. The GAZ-71 tracked transporter also took part in comparative tests. In different conditions, the three machines had certain advantages over each other. For example, when measuring the maximum speed on virgin snow, the small-sized auger-rotor all-terrain vehicle bypassed its larger predecessor. At the same time, he significantly lagged behind the tracked competitor.
In the first half of 1978, the ZIL-2906 all-terrain vehicle underwent minor revisions. The helm station, built with the use of a steering wheel, was changed to a "traditional" one. Now the operation of the two onboard power units and the rotation of the augers were controlled by the levers. The rest of the control systems have not changed.
In July-August, new tests took place, during which the modified control system was tested. First of all, the testers were interested in the characteristics of maneuverability and controllability when using levers. Such improvements, in general, justified themselves. Nevertheless, they could not outweigh the existing shortcomings of the machine associated with the not very perfect power plant. After summer trials in 1978, the ZIL-2906 was returned to the plant.
Even during the first checks, it was found that the existing MeMZ-967A engines do not differ in high performance, and do not fully correspond to the tasks assigned to them. The introduction of a new power plant, in turn, was associated with the need for the most serious processing of the entire all-terrain vehicle. In a not very successful configuration, the existing ZIL-2906 entered new tests, and the designers of the SKB ZIL, meanwhile, began to develop its updated version that fully meets the requirements. The new version of the auger-type snow and swamp-going vehicle for the search and rescue service was named ZIL-29061. Unlike its not very successful predecessor, it was able to reach mass production and full operation.
