Sherman Crab T147955 “Avalon” Overloon. Regiment? Damage?

[David Herbert]

Originally Posted by Alex van de Wetering

Avalon is somewhat different from most Crabs in that it has a direct vision M4A4 hull, which means the covers for the periscopes are fitted to the hatches rather than fitted on the hull itself.

Alex is quite right here but he is referring to the special covers fitted only to Crab hull periscopes. His first photo shows them both rather well.

With ordinary gun tanks the hull hatches of direct vision port Shermans are exactly the same as later small hatch Shermans. The difference was that the direct vision ports were replaced by a mounting for another identical periscope to the hatch periscope. This second mounting could be adjusted for elevation but not turned sideways as the hatch mount could be. Both mountings had a hinged sheet metal rain cover which was sprung to the closed position. The hatch periscope mount could also have a guard made of about 8mm diameter steel rod fitted to prevent damage to the top of the periscope but this was a later feature and is often missing even on later tanks.

However, on very early Shermans it was possible to open the hull hatches so that they laid flat on the top of the hull if the periscope was not mounted. This was changed at ABOUT the time that direct vision ports were deleted and a stop was added that limited hatch opening to about 135 degrees so that the driver's head was protected a bit from the side and the hatch could be closed more easily in an emergency. Thus if the hatch can be seen to be lying flat on the hull roof, the tank is PROBABLY a direct vision port one. Many tanks were upgraded to prevent the hatch lying flat so it not lying flat proves nothing about direct vision ports.

David

[Alex van de Wetering]

Originally Posted by David Herbert

Sorry Alex but the hull hatches of direct vision port Shermans are exactly the same as later small hatch Shermans. The difference was that the direct vision ports were replaced by a mounting for another identical periscope to the hatch periscope. This second mounting could be adjusted for elevation but not turned sideways as the hatch mount could be. Both mountings had a hinged sheet metal rain cover which was sprung to the closed position. The hatch periscope mount could also have a guard made of about 8mm diameter steel rod fitted to prevent damage to the top of the periscope but this was a later feature and is often missing even on later tanks.

However, on very early Shermans it was possible to open the hull hatches so that they laid flat on the top of the hull if the periscope was not mounted. This was changed at ABOUT the time that direct vision ports were deleted and a stop was added that limited hatch opening to about 135 degrees so that the driver's head was protected a bit from the side and the hatch could be closed more easily in an emergency. Thus if the hatch can be seen to be lying flat on the hull roof, the tank is PROBABLY a direct vision port one. Many tanks were upgraded to prevent the hatch lying flat so it not lying flat proves nothing about direct vision ports.

David

David,

I am talking about the periscope covers specific on Crabs. If you see a head on picture of a crab with the hatches open and the covers attached to the hatches, you know it's a direct vision hull.

[David Herbert]

Sorry Alex, I realized my mistake before reading this and corrected my post. Thanks for the drawings though !

David

[Alex van de Wetering]

David,

No worries; my choice of words might not have been the best.....as what I called periscope covers are actually called "forward station keeping visors" in the manual!

[Chris Suslowicz]

I don't see the third aerial base?

The usual complement (Commonwealth) would be a WS19 with a 'through the turret roof' aerial feed, and Aerial Base No.8 or 10 for the 'A' set (fitted with and 8-ft whip aerial), plus Aerial Base No.9 (on a pillar mounting) for the inter-tank 'B' set. A third aerial base (if fitted) would be another No.8 or 10 for a WS38 to communicate with supporting infantry.

Best regards,
Chris.

[Maurice Donckers]

Chris , can you explain then why there are 3 aerial bases mounted on Avalon , and other command tanks , plus a B set one ?
I know that an additional 38set was fitted in the turret , but where was the aerial mount on the co drivers side used for ?

[Chris Suslowicz]

Originally Posted by Maurice Donckers

Chris , can you explain then why there are 3 aerial bases mounted on Avalon , and other command tanks , plus a B set one ?
I know that an additional 38set was fitted in the turret , but where was the aerial mount on the co drivers side used for ?

Command tanks could have 2 x WS19 + 1 x WS38 and would be rather cramped inside. I think the usual arrangement was:

Standard WS19 in turret bustle, provides A1 set for inter-unit comms, B set for inter-troop comms, and tank intercom. Second WS19 provides A2 set for rear link comms. (Control Units No.12 and No.2 are used instead of No.1 and No.2, with a repurposed WS 38 Mk.2 for communication with supporting infantry. There was a later WS38 AFV that used Control Units 17 and 16 instead of 12 and 2, and I think there was also a No.33 that allowed 2 x WS19 + WS38AFV (or the later WS88 and WS31 AFV variants) for command or artillery OP tanks.

The 'Rear Link' set could be a WS19HP, but I don't think that tanks had enough internal space.

Louis Meulstee has an entire chapter on the WS19 control boxes and their use in Wireless for the Warrior Volume 2.

The Royal Signals Pocket Book section "Wireless Diagrams" shows the standard communications setup for various units up to Corps or Division size, together with the number and type of sets used and how they were allocated.

Chris.