While most other manufacturers derive their trucks from road applications, the 815 was purposely designed for extreme off-road conditions, and its road versions are derived from the off-road original concept. The principle consists in a
central load-carrying tube with independently suspended swinging half-axles bolted as one whole. This gives Tatra vehicles outstanding driving qualities in the most difficult terrains. The concept allows higher off-road speed compared to
classical rigid axle design.
Central load-carrying tube The primary structural feature of Tatra trucks is the central load carrying tube, also called a backbone frame. All other parts of the truck are mounted to this rigid assembly. The inherently high torsional and flexural rigidity of this layout protects superstructures from the motions and forces on the axles. Torque distribution to the axles is also carried within the backbone.
Differential Tatra differentials are a unique design that uses two opposing spiral bevel gears instead of the usual single set. The differential gears are part of the input drive shaft rather than between the output axles as in a
conventional differential. All versions of the Tatra differential have locking pins that can force the differential gears to rotate together, "locking" the differential. This arrangement had two distinct advantages. The first is that the dual output bevel gears allow the axles to swing around the drive axle without the need for universal couplings. The second is that the input drive shaft goes essentially straight through the differential housing, allowing simple coupling to a second set of swing axles. This modular design enables configurations of 2, 3, 4, 5, or even 6 axles with all axles driven. The whole assembly is part of the backbone frame.
Suspension Front • Mechanical suspension of load capacity up to 8 tons per axle by torsion bars – for versions with one steered front axle (4x4 and 6x6) or by leaf springs – for versions with two steered axles (6x6, 8x8, 10x10 or 12x12). • Air-bellows, with a load capacity of 9 tons per axle and a possibility of a ground clearance regulation.
Rear • Mechanical – by leaf springs, with a load capacity of up to 11.5 tons per axle • Air-bellows with a load capacity of 10 tons per axle and a possibility of a ground clearance regulation • Tatra
King Frame suspension system - combination of an air-bellow with a coil spring placed inside, with a load capacity of up to 11.5 tons per axle or combination of air-bellows with leaf springs, with a load capacity of 13, 15 and 16.5 tons per axle. All suspension types are equipped with telescopic shock absorbers; some versions also have stabilizer torsion bars.
Engine The Tatra engine There is a basic version, extended version with room behind seats used for a berth and especially for fire-fighting applications, and a long four-door cab enabling transportation of up to six persons. There is also special low cab version used mostly for cranes and other special applications. The cab is situated in front of the front axle.
Equipment • Trucks equipped with air-bellows suspension have possibility of a ground clearance regulation. • Special protective surface finish •
Central tyre inflation system enabling deflation/inflation of tyres during the drive in boggy terrain (standard for military versions, on demand for civilian) • Multi-fuel engines for military version (on demand) • Vehicle radio-shielding as per NATO standards for military version • Possibility of additional cab ballistic protection through a supplied and subsequently installed additional armouring set intended also for windows for military version ==Variants==