Overview[]
The PT-85 (Ob"yekt 906) is a Soviet prototype light amphibious tank developed in the early 1960s.
Development[]
Development of the Ob"yekt 906 project was started at the STZ design bureau under the leadership of I.V. Gavalov with the lead designer being Yu. V. Shadrin, in accordance with the USSR Council of Ministers dated 30 May 1960. On 30 June 1961 the technical project was submitted.
The main purpose of this project was to create a floating vehicle with a more powerful gun than the PT-76B.
Between 1961 - 1962 VgTZ produced six prototypes of the tank, two of which were tested at the NIIBT test site between January - August 1963. The vehicle was not accepted for service.
Design[]
The tank had the classic layout scheme with a longitudinal engine location in the hull, consisting of three crew.
Driver's Compartment[]
The driver's compartment was located in the bow of the hull and it contained the driver's seat, levers and control pedals, two control panels, a lever for the wave splash shield, a DP-3 radiometer, an automatic fire suppression system, batteries, a GPK-59 gyroscopic compass, spare parts and other equipment. To observe, the driver had three different viewing devices installed at the base of the entry hatch, of which, the central device had a hydro-pneumatic cleaning system installed, similar to the one found in the T-55. To drive the tank at night, a TVN-2B night device was mounted instead of the regular viewing port.
Fighting Compartment[]
In the fighting compartment, a cannon with a paired machinegun was placed, stabilizer assemblies and components, a gun loading mechanism, ammunition, commander's seat to the right of the cannon and gunner's seat to the left, day and night sights, communications systems, a fan for the PAZ system, and spare parts. The entry point for commander and gunner was located in the roof of the turret. The gunner used two TNP-165 prismatic viewports to monitor the battlefield and the commander used a combined day-night TKN-2 sight with an OU-3K illuminator and two TNP-165 devices, located in the rotating cupola, which were equipped with a target designation system.
For the crews' convenience, a rotating floor made of aluminium alloy was placed in the combat compartment. Along the floor perimeter, there was a 300mm high mesh to prevent spent casings from falling out of the rotating floor.
Firepower[]
The tank was fitted with an 85mm D-58 cannon and a paired 7.62mm SGMT on the right side. The cannon was mounted on the cheeks of the turret using cradle trunnions and was equipped with a two-plane stabilizer "Zvyezda", an ejection device for gasses, a two-chamber muzzle brake, and a loading mechanism. The barrel's length was 5,670mm with the chamber pressure reaching 304MPa (3,100kgf/cm2). To lock the cannon, a rod was used with an elevation of 15 degrees. The stabilized provided a horizontal aiming speed of 0.05 - 20 degrees per second and a vertical speed of 0.05 - 4.5 degrees per second. To load it, the gun was brought to a specific loading angle after each shot and the turret was rotated using the commander's target designation. The horizontal belt conveyor of the loading mechanism with an electric drive, designed for 15 shots, was located in an elongated housing at the rear of the turret. A special control panel was used for remote control of the reload process. The duration of the reload cycle was 5 seconds, with the maximum being, with a burst of a single type of projectile, 14 rounds per minute and the minimum 9 rounds per minute.
To fire from the main gun, a TSh2B-8A telescopic sight was used during daytime and a TPN-1 with an L-2A1 illuminator was used during the night, which, during daytime the objective was removed and placed inside the tank, with a quick ejection armor piece installed on its place. The vertical aiming angles ranged from -5 to +20 degrees. The turret rotation mechanism had both manual and electric motor drives mounted in a housing to the left of the cannon.
The ammunition of the tank consisted of 40 single-piece shots with 8 armour-piercing and 32 high-explosive shells. The armour piercing projectile, with a muzzle velocity of 1,000m/s, provided penetration of a vertically mounted steel armour plate at 1,000m and 2,000m with a thickness of 185mm and 145mm respectively. The direct firing range of the projectile was 1,170m and the maximum firing range of the high-explosive shell was 13,500m. 25 shots were placed in the rotating part of the fighting compartment (15 in the loading mechanism and 10 in the rear, laying vertically, 6 shots in each of the sides of the hull and 3 shots in the engine partition wall. The ammunition for the machine gun was 2,000 rounds, loaded in ribbons and stacked in 5 cartridge boxes, with one mounted in the frame of the machine gun.
Armour[]
The vehicle uses anti-shrapnel bulletproof armor. The hull is welded by electric arc welding in argon from rolled armor plates of aluminum alloy ABT-101 with a thickness of 8, 10, 12, 20, 25 and 30mm. The frontal armor of the hull provided protection from 14.5mm B-32 bullets at a firing range of over 100m, the hull side was not penetrated by 7.62mm B-32 bullets from ranges over 350m, and its shape provided minimal water resistance while moving during amphibious operations. The turret was made of Grade 2P steel armor plates with a thickness of 8mm and 15mm (two frontal, two side, roof and bottom sheets) and provided protection for the crew and internal equipment from 14.5mm armor-piercing B-32 bullets at distances of 100m to 150m and 7.62mm at all ranges. The design of the waveguide shield, the lifting mechanism, and the driver hatch lifting mechanism was similar to the design of the corresponding units of the PT-76 tank. In a similar fashion to the Ob. M906, the driver's hatch was made of a special steel alloy. In the frontal part of the turret, there was an embrasure for the installation of the cannon, to the right and left of which there were holes for a machine gun and a telescopic sight. From the outside, the embrasure of the gun was closed with a mask, the armor resistance of which corresponded to the armor resistance of the frontal projection of the turret, and encased with a 23M fabric cover, which served to seal the gaps between the mask and the frame. Steel shields were mounted on the inside of the turret to keep lead splashes from bullets that could penetrate through the gaps of the embrasure. The design of the embrasure of the machine gun differed from the embrasure of the PT-76B tank by the presence of an improved seal in it, in the form of a ball bearing, which was attached to the frontal part of the turret through a rubber cuff. The embrasure of the sight was closed with a special protective glass resistant to gamma radiation. In the right side sheet of the turret niche there was an opening for the installation of an exhaust fan, for the release of separated dust from the supercharger. In addition, four hooks were welded on the sides of the turret, intended for dismantling and mounting the turret, as well as handrails for boarding the vehicle.
Engine and Transmission Compartment[]
The MTO was equipped with an engine, transmission, water jet propellers, water pumps, traction control drives, and part of the units of the PPO and TDA systems.
The tank was equipped with a PAZ filter, UA PPO «Rosa», TDA system, and emergency water pumping systems. In order to protect the crew from the shock wave of a nuclear explosion, devices were provided in the combat compartment that automatically closed all the holes during the explosion, as well as locking the turret. For ventilation of the fighting compartment, an axial exhaust fan and a centrifugal supercharger were used, which were installed, respectively, on the right (in the area of the commander's location) and left (behind the gunner) sides of the turret. When the supercharger was operating in a sealed tank, an excess pressure of 0.49kPa (0.005kgf/cm2) was created, which was necessary to protect against the penetration of radioactive dust into the tank. In addition to the RBZ-1M device, a DP-3 radiometer was installed, which allowed measuring the radiation in the range of 0.1 - 500R/h. In addition, in order to protect the crew from the effects of chemical agents and toxic extinguishing agents of the PPO system, the commander's and the gunner's workplaces were equipped with personal protective equipment. The protective kit included a filter from a combined filter gas mask, a hose, a half mask and a switching device.
The PPO system provided manual turning on or off the combat compartment fans. It consisted of an automatic system which signaled for fires and checked how many filled cylinders there are, after which, it stopped the engine, and triggering said cylinders with a delay to the MTO. Seven thermal sensors were mounted in total to the tank, three of which were located in the combat compartment and four in the MTO.
The first of the Ob. 906 vehicles used a 300.5HP 8D6M diesel engine. One ejector and one water radiator with an increase cooling area were used in the cooling system which were located to the left side of the MTO. On further built vehicles, a 300.5HP UTD-20 diesel engine was used. This engine started with the help of compressed air or with the help of a 15HP ST-713 electric starter as an alternative. Four 100 liter fuel tanks were located in the MTO, alongside two additional 50 and 150 liter fuel tanks in the sides of the hull, which let the vehicle traverse over 500km on highway.
A two-stage VTI air cleaner is used in the air purification system. The engine lubrication system is circulating, forced, high temperature. It uses oil heating with coolant from the heating system and oil filtration using a centrifuge mounted on the engine. The consumption capacity of the oil tank was 35 liters (total - 90 liters). The oil tank is also combined with the heater as a single unit. It was placed in front of the engine, on the left side of the vehicle. The oil radiator was installed in the right ejector above the water radiator. To facilitate oil pumping at low temperatures, the oil pump had a water jacket connected to the engine heating system. The engine cooling system is of the liquid ejection, high temperature, closed type. Two ejectors with two radiators of the cooling system were located on the sides of the MTO. Such an installation of ejectors excluded the recirculation of engine exhaust gases. In the right ejector there was an ejection device for automatic removal of dust from the air cleaner.
Transmission[]
The mechanical transmission consisted of a two-disc main clutch, a two-flow gearbox without differential, which provided five forward and one reverse gears, drives to water cannons and an AK-150S compressor and two single-row simple on-board gearboxes. The main clutch was mounted on the flywheel of the engine. In the case of the MPP, it was mounted on three supports (two tow-type supports on the axis of the cargo shaft and one on the axis of the drive shaft). The option of installing the MPP to the side of the engine was considered, but this was abandoned due to the exclusion of possible unification when using it on other machines that were supposed to be created on the basis of this tank. Dry friction belt stop brakes with plastic linings were removed from the aluminum crankcase of the MPP. In order to control them, in contrast to the brakes in the PT-76B, where control levers were used to brake it, a brake pedal was installed. The on-board gearboxes, made according to the kinematic scheme of the on-board gearboxes of the PT-76B, differed from them in the size of the gear ratio (5.09), and their bodies were made of aluminum alloy AL-19. The transmission provided joint and separate operation of the track and water jet propulsion. The drive to the water cannons was carried out from the shaft of the additional drive of the MPP using a gear coupling and did not depend on the number of the included gear. This made it possible for the tank to enter the water non-stop in any gear without necessarily switching to a lower gear, as it was on the PT-76B.
Pump impellers and guiding devices were used in the design of water cannons, the rest of their parts underwent structural changes aimed at reducing weight and improving efficiency (reduced the length of the water jet pipe, brought all its sections to the shape of a circle, increased the radius of curvature to reduce hydraulic losses, and provided straightness of the ejected jet to increase traction, etc.). The estimated durability of the water jet propulsion increased from 75 to 100 hours. To control the tank while its floating, «Syekach» flaps were used, which differed from the flaps in the PT-76B tank by the presence of a remote supports - a bracket attached with two prismatic bolts and receiving an axial load from the water pressure. The diameter of the aft nozzles compared to the aft nozzles of the PT-76B tank was reduced from 340mm to 250mm, which reduced the dimensions of the dampers and their weight. To reduce the spray fountain, a reflective visor was installed on the aft sheet of the hull along the radius of pumping the dampers.
Suspension[]
The tank's spring system used an individual torsion suspension with two-action telescopic piston hydraulic shock absorbers, which were installed on the first, second and seventh suspension nodes. The maximum tangential stresses of the exposed torsion shafts were 953.2MPa (9,720kgf/cm2). When transporting the tank by An-12 aircraft, the front and rear suspension units were switched off using special screw devices included in the spare parts kit of the machine. At the same time, a rigid connection of the balancers of the support rollers with the body of the machine was provided. The peculiarity of the tank's springing system was the counter location of the balancers of the seventh suspension units. Each track consisted of seven support and four supporting single-pitched rollers with external shock absorption, a guide and driving wheels, a compensating device and a caterpillar with an open metal hinge like on the PT-76. In addition, a caterpillar track with a sequential rubber-metal hinges was developed, manufactured and tested. The track track with rubber-metal hinges (stamped, with welded ridges) had a width of 350mm and a pitch of 128mm. The average ground pressure was 43.2kPa (0.44kgf/cm2). The support rollers had the same dimensions and seats as the PT-76B and therefore were interchangeable in the assembly. The disks of the hollow support rollers were made of AMG-6 aluminum alloy which made it possible to reduce the weight of the roller from 59.5kg to 37kg. The guides and driving wheels were borrowed from the PT-76B tank without changes. When using tracks with rubber-metal hinges, driving wheels with removable gear rings cast from KDLVT steel and hubs made of aluminum alloy AL-19 were installed. Their design provided for the possibility of replacing the crowns without dismantling the drive wheel. At the same time, the drive wheel itself could be installed both on the left and on the right side of the hull. The type of engagement of the drive wheel with a caterpillar with a rubber-metal hinge is a pin, and the method of transmitting the force in the engagement is pushing (with a caterpillar with an open metal hinge - pulling). The weight of the set of tracks with rubber-metal hinges (224 tracks) was 1,380kg.
Electronics[]
The electrical equipment of the machine was made according to a single-wire scheme. The voltage of the onboard network was 24V. The main sources of electricity were two 12ST-70 batteries and a 5kW VG-7500 generator. To ensure the normal operation of the tank at low temperatures, electric heating of the sight, viewing devices, the glass of the protective cap of the mechanic and the clock was provided. For road signaling, five marker lamps were mounted on the tank (one of them on the turret). In addition, there were two yellow lanterns for communication of the crew with the infantry. For external lighting, FG-102 and FG-100 headlights with an IR filter were used. The R-113 radio station served for external communication in the tank, and the R-120 intercom device served for internal communication. In the future, they were meant to be replaced with the R-123 radio station and the R-124 intercom.
Variants[]
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| Russian Objects | ||
|---|---|---|
| New System (1959.06.13) | ||
| 001-099 VNII-100 VNIItransmash |
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| 1-99 GAZ |
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| 100-134 UZTM |
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| Redesignations of existing designations | ||
| 134-199 KB-520 UVZ |
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| 160-200 VTZ |
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| 200-299 SKB-2 LKZ |
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| 300-350 Uraltransmash |
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| 352-399 MTZ |
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| 400-499 KB-60 KhTZM |
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| 500 Zavod 174 Omsktransmash |
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| 501-549 RMZ |
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| 550-599 MMZ |
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| 600-649 Zavod 174 Omsktransmash |
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| 650-699 KMZ |
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| 700-799 OKB-200 ChTZ |
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| 800-849 LKZ |
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| 850-899 ZiS / ZiL |
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| 900-999 VgTZ |
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| 1000-1050 KAZ |
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| 1200-1299 BAZ |
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| Old System | ||
| GAZ Zavod 37 |
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| Zavod 174 Zavod 185 |
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| KhPZ | ||
| Zavod 75 | ||
| Zavod 183 | ||
| OKB GIU | ||
| Zavod 112 | ||
| KhTZ | ||
| Ishimbaytransmash | ||
| ATZ | ||
| ZiS (before 1941) | ||
| ZiS (after 1941) | ||
| SKB-200 | ||
| VNII-100 | ||
 Russian FederationLand Vehicles Modern Period (1991 — Present) |
|---|
| Tracked Vehicles | ||
|---|---|---|
| Light Tanks | Light Tank | 2S25 (M) |
| Light Tank, Amphibious | 685 • 906 • PT-76 (A, B, M) • PT-85 • PT-90 | |
| Light Tank, Amphibious Command | PT-76K | |
| IFV | 19 • 911 • 914 • B-10 • B-19 • BMP-64 • BMPT • BMPV-64 • T-15 | |
| IFV, Amphibious | 764 • 765 • 911 • BMP-1 (P) • BMP-2 (D • M) • BMP-3 (F • FK • Fr • K • M • M-3) | |
| Medium Tanks | MBT | 139 • 140 • 167 (T) • 430 (U, 435) • 640 • 785 • T-14 • T-62 (1960, 1972, 1975, D, D-1, K, KN, M, M-1, M1, M1-1, M1-2, M1-2-1, M1V, M1V-1, MD, MD-1, MK, MK-1, MV-1) • T-64 (A, AK, B, B1, B1M, BM2, BV, R, T, U) • T-67 • T-72 (A 1979 • A 1984 • AK • AV • B • B 1989 • B 1990 • B1 • B2 • B3 2011 • B3 2014 • B3 2016 • T-72B3M • BA • BU • BV • M • M1 • M1M • M1V • S • V) • T-74 • T-80 (A 1982 • A 1984 • AK • AKV • B 1978 • B 1980 • BK • BV 1985 • BVK • BVM 2017 • M-1 • U 1986 • U 1992 • UE 1999 • UK • UM 1995 • UM-1 1997 • UM-2 • UM2) • T-90 (1992 • A 2006 • AK • AM • K • M 2017 • MS • S • SK) • T-95 • T-99 |
| Command Tanks | 446B • T-64B1K • T-64BK • T-72 (AK • B1K • BK • K • M1K • MK) • T-90 (K) | |
| SPG | ATGMV | [[]] |
| SPAA | 2S6 (M • M1) • 2S38 • 9K35 • 9K37 • 9K330 | |
| SPATG | 120 • 2S15 • 2S25 (M1) • 2S28 • 2S29 • 2S37BTR-50P | |
| SPG | 2S1M • 2S5 (M • M1) • 2S7 (M) • 2S9 (-1 • 1M) • 2S11 • 2S13 • 2S17 (-2) • 2S22 • 2S23 (M) • 2S31 (Ye • M) • 2S34 (-1 • M) • 2S36 • 2S39 • 2S40 • 2S42 • 2S43 • ISU-152 • Obzhimka • T-62/160 | |
| SPH | 924 • 2A3 • 2A4 • 2S1 (M1) • 2S2 • 2S3 (M • M1, M2 • M2-155 • M3) • 2S18 • 2S19 (M • M1 • M1-155 • M2) • 2S21 • 2S26 • 2S27 • 2S30 • 2S33 • S-103 | |
| Self-Propelled Laser | 1K17 Szhatie | |
| SPM | 2S4 • 2S8 • 2S10 • 2S12 (A • B) • 2S24 • 2S41 | |
| SPRA | 2P16 • 9P139 • BM-24T • Object 280 • Object 634 (B) • TOS-1 • TOS-1M (A) | |
| Explosive Related | Mine Laying | GMZ-3 |
| Mine Clearing / Sweeping | BMR-3 • BMR-3M (A) • UR-07 • UR-67 • UR-77 | |
| Misc Tanks | Ammunition Carrier | TZM-T |
| APC | B-11 • BTR-50 • BTR-50PA • BTR-50PM • BTRV-64 | |
| ARV | BREM-1 (M) • BREM-64 • BREM-72 • BREM-L • Object 447T • BTS-4V • T-62T | |
| Bridge Laying | MTU-72 • MTU-90 | |
| Command | BTR-50PN • BTR-50PU • BTR-50PU-2 • BTR-50PUM • BTR-50PUM-1 | |
| Engineering & Maintenance | BAT-2 • BMT-3 • BTM-4 • IMR-2 • IMR-3M • IRM • MDK-3 • MTP-1 • ZSU-57-2 BTS-55 | |
| Firefighting | SPM | |
| Observation, Spotting & Survey | [[]] | |
| Reconnaissance | PT-76RKh | |
| Transport & Towing | BMO-T • IT-1T | |
| Wheeled Vehicles | ||
|---|---|---|
| Offensive / Defensive | IFV | BMPT-K-64 • VPK-7829 • Object 19 |
| SPAA | 9P31 • BTR-40A • BTR-141A | |
| SPATGM | 2P27 • 2P32 • 9P110 • 9P122 • 9P124 • 9P133 • 9P137 • 9P148 | |
| SPBM | 9P71 • 9P117 • 9P120 | |
| SPH | 2S27 • A-222 | |
| SPRA | 2B5 • 2B17 • 2B26 | |
| Other | APC | BTR-40 (V • B • B (RKh) • ZhD) • BTR-60 (P • PA • PB • PBM) • BTR-70 • BTR-80 • BTR-90 • BTR-141 • BTR-7829 • GAZ-3937-11 |
| ARV | BREM-K | |
| Bridge Laying | PP-2005 • PPS-84 • TMM-3 • TMM-6 | |
| Cargo | GAZ-33097 • KamAZ-5350 • KamAZ-6350 • KamAZ-43501 • MAZ-4370 • MAZ-4570 • MAZ-5336 • MAZ-5337 • MAZ-5432 • MAZ-5433 • MAZ-5434 • MAZ-5442 • MAZ-5516 • MAZ-5551 • MAZ-6303 • MAZ-6317 • MAZ-6417 • MAZ-6422 • MAZ-6425 • MAZ-6430 • Ural-4320 • Ural-5323 • Ural-43206 • ZiL-4334 | |
| CP | GA-39371 | |
| Crane | KS-5571 • KS-5573 • KS-5576 • KS-6571 | |
| Decontamination Vehicle | ARS-14KM • TMS-65 • USSO | |
| Dump Truck | MAZ-7510 | |
| Engineering | EOV-3521 • EOV-3523 • KamAZ-65225 • KS-3574M3 • MAZ-205 • MAZ-500 (A, SH) • MAZ-501 • MAZ-503 (A) • MAZ-509A • MAZ-510 • MAZ-511 • MAZ-516B • MAZ-525 • MAZ-529 • MAZ-530 • MAZ-5335 • MAZ-5334 • MAZ-5549 • MAZ-53352 • PBU-100 | |
| Firefighting Vehicle | AA-60(543)-160 • AA-70(543)-172 • AA-60(7310)-160.01 • AA-60(7313) (160.01 • AA-60(7313)-220) | |
| IMV | GAZ-2975 • GAZ-3937 • GAZ-3937-10 • GAZ-233034 • GAZ-233036 • Iveco LMV | |
| Medical | BMM-80 | |
| RV | BPM-97 • BRDM-1 (RKh • U) • BRDM-2 (RKh • RKhA • RKhB • U) | |
| Security | Lavina-M | |
| Smoke Generating Vehicle | TDA-2K • TDA-3 | |
| Transport & Towing | 9T254 • MAZ-200 (V) • MAZ-502 • MAZ-504 (A • B • G, S • V) • MAZ-508B • MAZ-520 • MAZ-535 (A) • MAZ-5429 • MAZ-7310 • MAZ-7904 • MAZ-7906 • MAZ-79221 • NAMI-020 • NAMI-021 • Ural-375 • ZiL-131 | |
| Utility | MAZ-543 (A, M, P) • MAZ-547 • MAZ-7907 • MAZ-7910 • MAZ-7912 • MAZ-7917 • MAZ-74106 • UAZ-452 • UAZ-469 • UAZ-3132 • UAZ-3163 | |
| Sources | ||
|---|---|---|
| Books | Online | Documents |
| • Отечественные Бронированные Машины - ХХ век - Том 3, 1949-1965. А.Г. Солянкин, И.Г. Желтов, К. Н. Кудряшов (ISBN 978-5-9771-0106-6) • Отечественные Бронированные Машины 1945-1965 гг. - Часть 1 - Легкие, средние и тяжелые танки, М. В. Павлов, И. В. Павлов (ISBN 978-5-85905-623-1) |
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