About this detail of the Tiger
The Tiger could be completely sealed for deep wading. The gun barrel could recoil; therefore a removable seal was required between the barrel and the mantlet.
The gun barrel was carried in a cradle. This is a view of the cradle from above. The box structure contains a lubricated sleeve for the gun.
This view shows how the cradle fit into the mantlet casting. The gun sleeve in the cradle protrudes beyond the body of the mantlet. The designers chose to place the seal here, where it would be accessible by removing the protective sleeve bolted to the mantlet.
But it was not necessary to remove anything in order to activate the seal. That could be done from within the turret. The Cradle Seal ('Wiegenabdichtung') is shown in this sketch from the Turret Manual; a sliding ring on the end of the cradle could be pushed forward by two levers, with force applied by turning a handwheel.
This diagram from the Turret Manual is a left-side profile of the gun cradle and seal. The sliding ring ("Buchse") is made of metal. Ahead of it there is a rubber ring ("Dichtring").
This view from above includes the mantlet and has the sliding ring sectioned. You can see that the sliding ring will squeeze the rubber ring against a step in the mantlet's protective sleeve. This will make the rubber expand laterally, gripping the gun barrel and forming a seal.
This is a cross-section of the cradle, looking forwards. You can see that the levers and arms lie between the cradle sleeve and the recoil cylinders on each side. The sleeve is narrowed slightly to give clearance.
This is the handwheel in the Bovington tank, before restoration. Under a layer of dust, its original colour is black. You can see that the levers pass through slots in the gun cradle. The handwheel carries the legend '5'; this is its number in the sequence of steps for sealing the turret.
Again from the Turret Manual, we have a sectioned profile of the handwheel.
In September 1943, the sealing equipment was ordered to be deleted from the Tiger's design. While the designers were able to stop installing all parts dedicated to sealing, they omitted to make relevant alterations to the drawings for parts that were retained.
As a result, we can find traces of the sealing system in all subsequent Tigers. This is the Late Tiger of Saumur museum. We are looking fowards, along the top of the gun cradle. The slots for the arms, and the welded base for the handwheel, are still present.(The latest version of this article)