There are certainly lots of photos of Mk IVs and Vs Female and Male with the sponsons retracted and I have one of a MK IV supply tank with its mild steel sponsons retracted but I've never seen one of them in the process of retraction (or extrusion). I would imagine the trailers were used around the workshops and tankodrome rather than for shipping as these tanks were entrained with sponsons fitted but retracted. one thing that has puzzled me is how the male sponson was pushed in with the 'wedge' step below the sponson dooe protruding. Did these detach?
Is it possible that more expert members can explain the mechanisms from MkIVs where the sponsons could be folded into the tank for transportation?
The photographs I have seen appear to show that for male tanks the sponson was slid into the void, effectively just pushed back.
For female tanks, it appears that the sponson did have the centre plates hinged to let the sponson recess into the body of the tank is this correct?
Is its possible someone has a diagram showing how the sponsons were stored?
Thank you
Andrew Robertson
The sponson on the trailer is the type fitted to Mk I - III male tanks. It is probably the one originally fitted to 785 "The Flying Scotsman".
The Mk IV female tanks did have a central division of the sponson to allow them to be folded back into the body. The sponsons on Mk III females did not have this division and could not be retracted.
I have read but can't remember where right now that another tank was used somewhat like a bulldozer to push the male sponsons into the tank.
The Mk IV female sponson was hinged front and back. When the centre section was unbolted, it could be swung into the tank on the hinges. See this picture on the Landships website to see the hinges.
The Mk IV male sponson was bolted into it's aperture and would have to be unbolted. The top and bottom of the sponson were (relatively) smooth (see this picture and this picture) and would slide in. The rear of the Mk IV male sponson was angled forward to allow the sponson to be pushed into the tank. The sponson door looks as if it would foul on the edge of the aperture; perhaps they were removed before the sponson was pushed in. It would not have been a difficult task to remove and replace the door.
Some photos of retracted sponsons. The female Mk IV is being delivered to Japan The Male Mk IV is on a railway train in Scotland (near Edinburgh). The Supply Mk IV sponson is part retracted. The Mk V male is being delivered to Revel (not the kit manufacturer).
Apparently there was a problem with the males Mk IVs as an enemy hit on the sponson could cause the retaining bolts to shear and the sponson to be pushed into the tank (see accounts of the siege of Frey Bentos).