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Turret ring bearings
The Tiger had a fully rotating 11-ton turret that was significantly out of balance. It was carried on a circular ball-bearing race. As was normal German practice, the turret bearing ring was carried on the inner walls of the turret.
This diagram, from Plate 65 of the Tiger Turret Manual, shows a simplified view of the ball-bearing race as originally designed. The inner steel ring is fixed to the hull top; the outer steel ring is fixed to the turret. The overall diameter ("Außendurchmesser") is exactly 2100mm.
The centers of the balls lie on a circle of 1990mm diameter. There are 158 ball-bearings. One half of them are load-carrying, with diameter 40mm. The rest are spacers, with diameter 39mm [4, see page 9] . (The diagram exagerrates the size difference.)
When assembling the ring you drop the balls in through a hole, visible at the top right of the diagram. But balls cannot escape unless the inner and outer races are aligned exactly as shown to form the hole.
This diagram shows the a profile of the steel rings and a ball bearing. Compare it to the left side of the German sketch. The ring carries two rubber seals, which I have also shown.
The Tiger's turret was redesigned and simplified in July 1943. The requirement to travel submerged was dropped shortly afterwards. The rubber seals were therefore omitted from the ball-bearing race, and the steel rings were made smaller.
The diagram shows the new profile of the parts. An example of this ring exists in the surviving Late Tiger at Vimoutiers in France. However, in the wreck of a Late Tiger at Snegiri in Russia, the inner ring is of the earlier kind, but with the rubber seal removed; it may be an old part used for repairs.
Another simplification in this new turret is that the spacer balls have been eliminated. There are now 113 load-bearing balls, each one carrying a spacer ring of 55mm diameter [4, see page 9] .
This 3D model shows the new ball-bearing race fixed inside the turret wall, as per the redesign. The bearings and spacer rings can be seen.
Sources
[1] Survey of vehicle 250122, Bovington, by David Byrden
[2] Survey of vehicle at Saumur, by Hilary Louis Doyle
[5] Survey of vehicle 251114, at Saumur, by Jean-Charles Breucque
[6] DW to Tiger 1
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Copyright © David Byrden 1998-2007 except where indicated.
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