About this detail of the Tiger
The gunner's seat was in two parts. It had a fixed base and an adjustable back. Both parts of the seat were attached to the bridge.
There were at least three different designs for the seat back.
The sketch above is from the Turret Manual [1] and it represents the original design of the gunner's seat. It also shows the tube of the bridge. (The top of the tube in this sketch does not resemble the real one.)
The seat back is threaded on the vertical part of the tube. The seat pad can be moved left and right by loosening two screws. Also, the joint on the tube has a lever that allows it to be loosened easily. Then the arm of the seat back can be moved up and down, back and forwards.
Plate 56 from the Turret Manual [1] shows this first design in detail. It illustrates a bolt instead of a lever for adjusting the arm. To allow the gunner to climb in and out, the backrest is short and probably uncomfortable.
This diagram shows more details of the first type of seat back. This type can be seen in the preserved Tiger at Bovington Museum [2] .
After testing of the first turret in May 1942, the design of the seat back was changed. I don't know how many turrets were released with the first design.
In the second design, the pad was put on a longer, tubular arm that could be folded out of the way [5] . This diagram shows the seat back in the folded position.
The preserved 'initial' Tiger (hull #31) has this type of seat back [3] . It is curious that a tank manufactured later (hull #122) has the earlier type of seat.
Here are the dimensions of the second design of seat back [3] .
When the turret was redesigned with a new cupola, the bridge was changed from a 50mm diameter tube to an 80mm tube. The seat back was modified slightly to fit this new tube [4] . This diagram shows the changes.
The seat base was bolted to a support. The support was welded to the bridge and could not be adjusted.
The support carried a footrest for the commander. The original design of this footrest supposedly used 'pegs' [5] but I have never seen them. It was soon redesigned with a metal loop, as shown here. Notice that it is 490mm from the turret center line, so it is lined up exactly with the commander's seat (in the first kind of turret).
In all of the surviving vehicles, the seat is angled 10 degrees from the forward direction. This was necessary because the gunner's pedals were offset to the right.
The seat base was tilted at 5 degrees.
[2] Survey of Tiger 250122, at Bovington museum, by David Byrden
[3] Survey of Tiger 250031, by Stephan Vogt
[4] Survey of Tiger 251114 at Saumur, by Hilary Louis Doyle
[5] DW to Tiger 1