About this detail of the Tiger
The tracks of the Tiger 1 were tensed by adjusting the position of the rearmost wheel (Idler wheel or Leitrad). The idler was mounted on a short swing arm (Leitradkurbel).
The arm is shown above. It was very strong because it literally pushed the tank along. The axle within the hull could be rotated to adjust the tension. Rotation was by turning a threaded shaft. Access to this shaft was through a small cover on the rear plate.
Two metal bumps (Einstellmarken) were welded to the bearing ring on the hull side. Another was welded to the top center of the swing arm. These showed the recommended limits of adjustment for the arm. As you can see in the photo, they seem to allow movement through an arc of 60 degrees.
The bump on top of the arm was a pointer. It did NOT physically touch the bumps on the hull. The photo above shows the arm from the Bovington vehicle.
In January 1944 the swing arm was slightly modified. Lubrication taps were added to the top and bottom  . The metal bump was deleted, presumably because the upper lubrication tap could do its job.(The latest version of this article)