Torsion bars

The Tiger 1 suspension consisted of 8 swing arms per side. Each one was sprung by a torsion bar (Drehstabfeder) internal to the hull. A torsion bar is simply a spring that is straight rather than curled.

Most of the torsion bars had a diameter of 55mm [1] . The first and last torsion bar on each side were stronger than the rest, with a diameter of 58mm [1] .

Each end of a torsion bar was ridged for better grip. The free end had 51 ridges [2] .

The torsion bars were mounted inside the hull, as close to the floor as practical. This diagram shows the hull at its design height above the ground. The free end of the torsion bar is inside the swing arm, which is carried by two strong bearings. The external part of the swing arm is not drawn.

The fixed end of the bar was slightly larger than the free end, and had 55 ridges [2] . The bar had a threaded hole at each end. Locking discs and waterproof seals were screwed into the ends [4] .

The fixed end of the bar was held in a cast metal socket bolted to the inside of the hull wall.

Both ends of the torsion bar were accessible from outside the tank, thanks to holes in the swing arm and hull wall [4] . After unscrewing the discs and seals, it was possible to remove and replace the bar without entering the vehicle. This diagram shows the hole in the hull wall. Since the fixed end of the bar was larger than the free end, it had to be removed through this hole.

To keep the left and right wheel sets aligned, the designers pointed the right-side swing arms backward and the left-side swing arms forward. This created a significant offset between two sets of torsion bars. Here, you can see the layout of all 16 torsion bars. The stronger bars are indicated.

This CAD model shows the arrangement of the mechanisms. The torsion bar and swing arm were painted the same colour as the rest of the lower hull interior.

Torsion bars are liable to break. High stresses on the surface can cause cracks to propagate. They must be protected from scratches, and the metal studs in the boots of panzer crew were a concern.

Most of the Tiger's torsion bars were hidden under floor panels, but the foremost bar was exposed to the driver's feet. Therefore, a sheet-metal cover was provided for it.

This cover was bolted to the lower nose armour.

Sources

[1] Der Panzerkampfwagen VI und seine abarten, Walter J. Spielberger, Motor Buch Verlag

[2] British drawing of torsion bar, dated 17.5.1944

[3] Survey of vehicle 250122, Bovington, by David Byrden

[4] Russian intelligence diagrams of suspension

[5] Survey of Sturmtiger at Panzermuseum Munster, by Rob Veenendaal

Copyright © David Byrden 1998-2007 except where indicated.

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