Tatra T815 is a truck family, produced by Czech company Tatra. It uses the traditional tatra concept of rigid backbone tube and swinging half-axles giving independent suspension. The vehicles are available in 4x4, 6x6, 8x8, 10x8, 10x10, 12x8 and 12x12 variants. There are both air-cooled and liquid-cooled engines available with power ranging from 230–440 kilowatts (310–590 hp). As a successor to Tatra T813 it was originally designed for extreme off-road conditions, while nowadays there are also variants designated for mixed (both off- and on-road) use.
The T815 and its descendant models brought the Czech truck racer Karel Loprais to victory six times in the Dakar Rally.
While most other manufacturers derive their trucks from road applications, Tatra T815 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.
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.
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.