In the experimental floating tank K-90 has been implemented a unique assembly diagram: power plant had frontal placement, units boxes located along the longitudinal axis of the body alternately fighting compartment is shifted to the stern. Therefore, when the barrel of the gun was in the forward position, it did not go beyond the boundaries of the body. The crew consisted of 3 people: the commander (gunner), the driver and loader. Branch Office has left the bow of the hull, engine and system of his work — the right. tank commander was placed in the fighting compartment to the left of the gun, the charge — the right of it.
To the members of the crew are in the tower was more convenient to work, the floor of the crew compartment was attached to the turret through the rod, spinning along with it. On a rotating floor on special racks installed seats loader and commander. The driver watched a couple of prismatic viewing devices that are placed in the front part of the roof, in front of the input hatches, gunner — a set in the roof of the tower observation unit MK-4, commander of the machine — through inspection blocks located on the perimeter of the commander's turret.
In the turret mounted 76.2-mm rifled gun LB-76T and 7.62-mm machine gun SG-43 paired with her (in a separate embrasure towers on the right). During the fire of the twin installation used a shortened articulated telescopic sight TSHK-9 (in a separate embrasure towers left). Vertical angles pickup paired installation ranged from -4 to +25 °. Cannon was charged by hand, with all this fighting rate equal to 6-7 shots a minute. Ammunition of the gun was 40 rounds and a coaxial machine gun — 1000 rounds of ammunition. Artillery shots with horizontal placement boeukladki placed around the perimeter of the rotating floor of the crew compartment near the site of the loader.
The tank was bulletproof body armor, made of 4, 6, 8, 10, 12, and 15-millimeter-rolled armor plates. Maximum thickness of the turret and the front part of the body is 15 mm. Housing have faired that provided little resistance while moving through the water obstacles. In the front part of the roof on the left is the body of the driver's hatch, which lockable swivel armored cover, in the middle part of the body — the hatch on the engine having armor covers over the holes through which air enters to cool down, to the right — with the hatch bronezhalyuzi for withdrawal of spent cooling air and fan cooling system. Before the tower in the higher part of the starboard hatch had kitted hinged lid and serving for removal by the bilge pumps water trapped in housing in overcoming the aqua-bottlenecking. The lower inclined portion of the right side there is an opening for discharging fuel. Detachable three-piece volnootrazhatelny shield mounted lever, welded to the bow of the hull. In the bottom of the case were made cut-outs for niche propellers, and the hole (on the right side) serve to exhaust motor.
Conical tower was welded from bent bronelistov which had variable angles. In the roof of the tower has a front flap with bronekryshkoy, opens forward. In her left side was placed motionless commander's cupola, curb observation devices. In the top of the turret for the commander's cupola had an opening for an antenna. Right in front of the roof of the tower fan is installed, disguised armor protection, the right side of the turret hole to the dictates of personal fire guns, which locked up the armor cap. Emergency exit hatch was located in the back wall of the tower.
In the power plant amphibious tank K-90 used 4-cylinder two-stroke diesel YAZ-204 140 hp (103 kW) at speed 2 thousand rev / min and the cooling of the liquid-speed manual. The engine is run with the help of the electric starter ST-25, power 7.5 HP (5.5 kW). To facilitate starting the engine at low ambient temperatures served heater, which consists of the boiler pump and piping systems elektroborudovaniya Also intake air heating device built into the receiver blower motor. Engine lubrication system had a water-oil cooler and air cleaning system — combined type air cleaner, which consists of a 2-inertsionnomaslyanyh baths and a set of cyclones. Fuel capacity — 240 liters .. Progress in store afloat up to 100 km on the highway and 240 km.
Box consisted of: single-disc dry clutch friction head (steel by Ferodo) two-shaft box car type that provides the 5-speed front-running and one reverse gear, transfer case, 2-boxes reversing propellers, main gear (conical reduction gear) , 2-on-board multi-disc dry clutch friction (steel on steel), which are used as a mechanism for turning, 2-tape floating type brake and 2-conventional single-row final drive. The units are connected between the box cardan transmissions.
In cushioning system used by personal automobile torsion bar suspension bump stop balancing on recent nodes. Jigging third rollers in relation to other nodes suspension had counter seating. Caterpillar tracks (one side) consisted of 5 stamped monopitch rollers having an outer amortization (diameter 500 mm) of the steering wheel (standardized to the support roller) Curb track tensioning mechanism; cursor in the progression of the guide, who performed the functions of support rollers and set to 4 fixtures; leading stern-wheel drive has a removable ring gear; melkozvenchatye OMSH tracks with a width of 300 mm.
The movement afloat with 2 propellers with a diameter of 600 mm, placed in niches in the bottom rear of the hull. Drive the screws was performed using reverse box. Reverse Taper had the clutch switch, which was absent in the neutral position. The design of the box units allowed to work directly tracked and amphibious propellers. Afloat turn the tank was carried out using a pair of navigable rudders are mounted behind the propellers. Propellers governed by rope mechanism, smooth and horizontal control wheel. Electrical equipment of the tank produced by a single-circuit. Mains voltage 24 V equated the main source of electrical power is a pair of rechargeable batteries 6STE-140 and 1.5 kW generator HSC-1500.
Tank devices equipped with internal lighting, external lighting and traffic signalization. For external communications used radio 10RT-26 Intercom implemented through TPU-47 (tank intercom). The introduction in the design of K-90 units and units of the car YAZ-200 and M-2 tractor identified cheapness and ease of production. But the tank has certain significant shortcomings in the set are low unreliability of the box and navigable properties, insecure volnootrazhatelnogo panel and insecurity propellers.
After the test, the design of the car chassis and turret improved.
Modifications have been input hatch tower (reducing its size) and the commander's cupola. Now back cover flap unfolded, because the antenna input was moved forward (on the left in front of the commander's cupola). Established reservations loopholes sight with openable from inside the protective cover. Instead of directing the cursor in the suspension were applied three (one side) of all-metal mono-pitch support rollers (diameter 250 mm). In addition, to defend a navigable rudder propellers were made in the form of a 2-drop halves of overlapping niches housing while driving on dry land. As such, the K-90 is stored in Kubinka in the Museum of armored vehicles. On the basis of the most experienced amphibious tank Go to-90 made the most experienced K-78 armored personnel carrier. The base of the tank in the second reference TSNIIII them. DM Karbysheva used in working out the installation of gas-dynamic engineering minesweeper BMI.
The performance properties of the amphibious tank K-90:
Combat weight — 10 tons;
Crew — 3 persons;
Armament — 76.2 mm rifled gun, 7.62-mm machine gun;
Book — bulletproof;
Engine power — 140 hp (103 kW);
The highest rate, 34.3 km / h (highway), 9.6 km / h (afloat).