Tatra 813


The Tatra T813 was a truck produced in Czechoslovakia by the Tatra company. It was produced from 1967 to 1982. The basic representative of this series was a military version of the 8×8 Kolos, which was able to pull trailers up to a total weight of 100 tons. Tatra also produced a civilian version in either 6×6 or 4×4. After fifteen years of production, 11,751 vehicles were built in all modifications. Many units were exported to the USSR, East Germany, Romania and India.

History

The first prototype which was made of Tatra 138 parts was built in 1960. It had permanent 4 × 4 all-wheel-drive. After the initial trials however the designers decided to develop and expand the concept to an 8x8 all-wheel-drive all-terrain vehicle. The basis of the design thus became the modular chassis of the Tatra 813. In 1983, it was succeeded by the Tatra T815.

Design and technology

A tubular backbone construction was chosen for the T813. The main advantages of the central load carrying backbone tube are the high torsional and bending stiffness protecting the truck's body from forces caused by the payload. Further advantages are that it houses all important parts of the drivetrain and that it allows a concept of modular construction where designers and customers can choose between two, three and four axle versions and various wheelbase combinations. A new cab-over-engine design was implemented, as were the wide profile super single tyres and central tyre inflation/deflation system.

Engine

The naturally aspirated V12 engine T-930 was created by adding four additional cylinders to the existing T-928 75° V8 engine, used in the Tatra T138. The crankshaft consisted of six individual journals bolted together with front and rear pins all running on the main roller bearings and located on the axial friction thrust washers. The military version was multi-fuel capable, running on any mixtures of diesel fuel, petrol and kerosene aviation fuel.

Chassis

The chassis is a full-length backbone tube with independent swing half axles available as either 4×4, 6×6 or 8×8 model. 4×4 models had a front axle suspension system with adjustable torsion bars, in the 6×6 and 8×8 models front and rear axles had longitudinal semi-elliptic leaf springs. For the 4×4 configuration the rear axle had air suspension. Permanent all-wheel-drive, front twin steer drive via homo-kinetic drive shafts, lockable differentials, inter-axle differentials with locks and planetary hub reductions were standard for all models. Unlike many six-wheeled vehicles, which have a single front axle and tandem rear axles, 6×6 versions used twin steering front axles- as with the 8×8- and a single rear axle.
The main gearbox was located behind the cabin and connected to the engine clutch housing via a short cardan shaft The main gearbox was bolted to an auxiliary gearbox, to a transfer case and then to a backbone tube and formed the main part of the chassis structure. A rear power take off and a winch drive were available as a factory option. Main and auxiliary gears were fully synchronized except the first and reverse gear. The new feature was a unique 2-speed planetary overdrive system bolted between the front and rear axles.
The overdrive could only be selected manually while the vehicle was not moving. The auxiliary gearbox had a neutral position which allowed the winch and a power take off to use the main gearbox gearing for variable speed operation. From the backbone tube the torque was transmitted to the wheels via Tatra gear differentials with differential locks, offset drive shafts and planetary hub reductions.
Full triple circuit air "S" cam drum brakes acting on all wheels drums via slack adjuster, all brake cylinders were remotely vented. First brake circuit acts on front wheels, the second on rear wheels and the third controls trailer service brakes. Unique design feature was remotely mounted brake valve which was operated via hydraulic master and slave cylinder principle on the Hauler 6x6 or via mechanical linkage on 8x8 models.

Bodywork

Cabin is all steel construction of COE design but not tiltable, the access to the engine was provided via removable engine cowlings inside the cabin compartment. The cab came in two versions, the "short" two-seater two-door version and in the "long" "crew cab" seven seater four-door version. The military specs cabs included the roof hatch or two in the case of the crew cab. All cabs were equipped with self-contained diesel cab heater which could also be used in the winter to warm up the engine before starting it. Another military feature was CTI central tyre inflation system controlled from the cab for each wheel independently and an ability to pressurize gearbox and differentials housing during water crossing. The 8x8 models had abilility to cross trenches up to 1.4 metre wide and vertical obstacles up to 0.6 metre high. Water crossing depth was up to 1.4 metre. The vehicle top speed was 92 km/h, 80 km/h, 70 km/h, 60 km/h @ 2000 engine rpm.
Tare - 14,000 kg, 21,050 kg, 11,200 kg, 15,000 kg, 7,000 kg
GVM - 22,200 kg, 22,000 kg, 36,000 kg, 36,000 kg,
Max Trailer Mass - 65,000 kg, 100,000 kg, 32,000 kg, 121,050 kg, 39,000 kg

Production

Production of Tatra T813 began in 1967 and was superseded by Tatra T815 in 1982. Models were available in the 4x4, 6x6, and 8x8 drive configurations for civilian and military use.
T813 has become extremely popular after the fall of the Iron Curtain in the West as an extreme off-road truck, participating at the various truck trials held across Europe.