Variometer mounting to underside of Aerial Base

[Patrick Johnson]

Hello,
I believe the attached line drawing image came from an ebay auction within the past year or so. Does anyone have a scan of this document at higher resolution? On my scan I can make out a description of the parts but not the actual part numbers.

Also included is a photo of some of the parts making up the 19-set Installation Kit for a tank. I am looking to buy the following parts used to attach the variometer to the aerial base:
1) Plates, Packing No. 1 ZA 2948 This is the thick rectangular plate centered in the photo, the Aerial Feeder Assembly No. 4 fits through the large hole and the small hole is for the variometer's guide pin.
2) variometer adapter washer, no part number available.
3) variometer adapter plate, ZA/CAN 1231. This is the square plate with the round hole, shown on the right hand side of the photo.
4) Also looking for two examples of the microphone loops shown in the attached photo
As usual, any assistance would be greatly appreciated!
Regards, Patrick

[Chris Suslowicz]

Originally Posted by Patrick Johnson

Hello,
I believe the attached line drawing image came from an ebay auction within the past year or so. Does anyone have a scan of this document at higher resolution? On my scan I can make out a description of the parts but not the actual part numbers.

Also included is a photo of some of the parts making up the 19-set Installation Kit for a tank. I am looking to buy the following parts used to attach the variometer to the aerial base:
1) Plates, Packing No. 1 ZA 2948 This is the thick rectangular plate centered in the photo, the Aerial Feeder Assembly No. 4 fits through the large hole and the small hole is for the variometer's guide pin.
2) variometer adapter washer, no part number available.
3) variometer adapter plate, ZA/CAN 1231. This is the square plate with the round hole, shown on the right hand side of the photo.
4) Also looking for two examples of the microphone loops shown in the attached photo
As usual, any assistance would be greatly appreciated!
Regards, Patrick

Ah, right... that explains the washer in the Pershing (T26E1) installation kit - it's to cover the large hole for a U.S. aerial feedthrough in the turret roof, and the "Plates, Packing" is to centre the aerial feeder in the hole.

As to part numbers, from the top:

ZA.1763 - Aerial Base No.8
ZA.1868 - Connector, Pigtail, No.1
ZA.1825 - Aerial Base No.8, Mounting No.1
ZA/CAN.1232 Variometer adapter washer (centres the aerial feeder in the hole and sits on top of the adapter plate, I think)
ZA/CAN.1231 Variometer adapter plate (supports the adapter washer and covers the large hole up)
ZA.2948 - Plate, Packing, No.1 (to adjust for thickness of turret roof)
ZA.2957 - WS No.19 Aerial Feeder Assembly No.4

Hmmm... on the Pershing kit list, I have:

5 ea. 17G59 Hooks (for microphone and headgear) ZA/USA1052
1 ea. 57G512 W.S. No. 19 Variometer Adapter Plate (WA-623) ZA/USA1051
1 ea. 93G767 W.S. No. 19 Variometer Adapter Washer ZA/USA1053

and on a cautionary note:

6 ea. Screws, Hex. Hd. Cad. 1/4 BSF x 1/2" (Aerial Base No.8 to Mounting No.1)

So beware: the mounting bolts are cadmium plated (as well as the microphone hooks)!

Finally, ZA/CAN.1232 - the adapter washer - is described in FZ256/3 as: WASHERS, Steel, 2-in. OD, 3/4-in ID, 0.125-in.
(This is from the Grizzly installation kit section)

Hope this is some help,

Chris.

[Johnny Canuck]

Hello Patrick
Does this help?



Geoff

PS "Ah, right... that explains the washer in the Pershing (T26E1) installation kit - it's to cover the large hole for a U.S. aerial feedthrough in the turret roof, and the "Plates, Packing" is to centre the aerial feeder in the hole"
Perhaps the hole in a US tank was larger than on a British tank as mentioned, but the washer centres the Variometer in the hole and the Plate, Packing, No.1 keeps the Variometer from spinning as the window was set at Position 8 (Vario was to the drivers side of the WS19 set).

PPS There were also 2 metal channels included with the parts mentioned. They were bolted to the radio shelf, with the shock mounts bolted on top and then the wireless set, creating a space under the set of about 3".

[Patrick Johnson]

Thanks Chris for the careful listing of the parts, which helped to better understand what parts and descriptions to look for in the EMERs manual. Then Geoff takes it one step further and not only provides the line diagram which clearly shows every part in the assembly, and how it all goes together in detail, but tops it by providing the dimensions of the shelf and the internal measurements of the M4 Sherman! Thank you very much for sharing this information jewel, made my week!
Regards,
Patrick

[Johnny Canuck]

A nice shot of the USA type Aerial Base No.8 Mounting No.1
Haven't acquired one yet, but this picture shows most of the parts discussed above



Geoff

[Patrick Johnson]

Hi Geoff,
If it interests you I would be happy to post some pictures of the Aerial Base No.8 Mounting No.1 that I have in my collection. There seems to be 2 or 3 variations on this mount but the one I have has only a 3/4" opening for the variometer's aerial feeder. My example also appears to have remnants of the C-broad arrow stamp on it which is nice.
I want to thank you again for posting the Radio Bracket details for an M4 Sherman, it allowed me to build the shelf (see picture) for my turret bustle project. Now that I have the drawing, I realize some of the proportions I used to build the "armour" surround need to be revised. A small re-build is in order, but at the end of the day with the turret shape rebuilt to the measurements shown on the line drawing, I'll have a reasonably accurate take on a Sherman turret.
As an aside, can someone please confirm whether the 69" turret ring diameter for the Sherman turret is for the interior ring I.D., or for the overall outside diameter of the turret casting? I can't find a line drawing on the web which shown this and this confirmation from a Forum member would be much appreciated. To date I have assumed this would be the clear inner dimension available to the crew.
Thanks again, Patrick
P.S. rotate photo 90 degrees clockwise for best reading of the shape. The holes in the shelf are based on the line diagram, and the spacing of the holes on the shelf were drilled based on 1) the mounting holes in the rails of the No. 21 carrier, used to attach the shock absorbers, and 2), the distance between the slots in the shock absorber mounts. Although I only have one shock absorber at the moment, I'd like to find three more. I plan to use wood blocking underneath the carrier (hidden from view) to keep all loading off the mounts, as these will be installed for appearance only.

[tankbarrell]

69" is the internal diameter of the turret ring. The turret basket upper ring fits inside that but any reduction in diameter is localised and fairly minor.

[Chris Suslowicz]

Originally Posted by Patrick Johnson

Hi Geoff,
If it interests you I would be happy to post some pictures of the Aerial Base No.8 Mounting No.1 that I have in my collection. There seems to be 2 or 3 variations on this mount but the one I have has only a 3/4" opening for the variometer's aerial feeder.

That mounting is specific to a "through the roof" fitting with the WS19 Aerial Feeder No.4 or No.5. (The No.5 is a longer version for thicker armour.)

There's the original British version with straight sides, the slightly tapered US/Canadian version, and a late/post WW2 all metal version like a steel donut (made from two stampings with the edges seam-welded). I believe they share the same stores code.

Later on, there was an adapter for use with other sets, consisting of a plate with a length of 3/4" tubing that dropped into the "donut" and was secured to the underside of the roof with a nut and washer (the reverse of the variometer feeder arrangement). This was used with the WS88AFV, WS31AFV and possibly other sets.

Chris.
(I'd like to thank Geoff for that diagram too; it explains some of the odd bits in the Pershing and Sherman installation kits as being there to allow a British (3/4") aerial feeder to be fitted to an American tank intended for a 2" feeder. That drawing (or its equivalent) was not in the Pershing kit and there's a blue-pencil line through it on the kit-list.)