Petrol tank inspection lamps from 1931 onwards

[Dave.Barkshire]

I was wondering about the petrol tank inspection lamps from 1931 onwards.

I know of two types. One has a bayonet fitting and the other has a spring which is released by pressing the two protruding domes.

Some are plastic, are the plastic ones reproductions or did the originals also come in plastic?

Are there any other variations?

[Roger Gwynn]

there are 3 versions 1931 in brass retained by a threaded ring
1932-38 brass retained by 2 spring loaded pins
1939-50 Bakelite bayonet fitting.
The brass ones were always in a black finish, never polished brass.

[Dave.Barkshire]

Thanks Roger.

BTW, do you know whether the PA speedo was used after WW2?

[Simon.Gardiner]

My mate's '46 NH (with the WD-spec frame and forks) has a PA in the panel tank. (He's had the bike since 1970-something and we've no reason to believe the tank and speedo aren't original.)

SG

[Roger Gwynn]

Yes, PA were used into at least 1946, the chronometric speedo drive gears have a 1947 number but probably only fitted to gearboxes from January 1947 as Burman seemed to change their models by calendar year not in September inline with the manufacturers. I think that G6,7,8 gearboxes would be PA and G30,31,32 would be chronometric.

[paul.jameson]

I have to disagree slightly with Roger when he says there were 3 varieties of inspection lamp from 1931 onwards because there were in fact 4 types. The one Roger is missing is the brass lamp with bayonet fitting. These are not too common but I have one on my Red Hunter. It is not something which came out of the factory with the bike because it is something I bought at an AOMCC AGM autojumble either in 1990 or 1991. It is not a modified version of the brass lamp retained by 2 spring loaded pins because there are no holes in the rim of it to take the spring loaded pins. It is not easy to spot as being different as the only external indication is the lack of the holes for the pins and the pins within those holes.

Dating it is also difficult but my suspicion is 1938 and / or 1939. The lamps with the 2 spring loaded pins vibrate badly as you ride along so I assume that the bayonet fitting was developed to counteract this. Presumably some bright spark at Lucas (a rare commodity, I know) then came up with the idea that the lamp could be produced more cheaply in bakelite which were used through to the end.

Although I am not aware of having seen another original brass / bayonet lamp, good quality replicas were available through AOMCC Singles Spares for a time so they must have been a standard item.

I agree fully with Roger on the use of PA speedos in 1946 and the gearbox numbering he quotes for them.

[Dave.Barkshire]

Thank you all for your comments. Excellent information as always.

[Karol Burger]

we have these two models of instrument lamps in stock

https://www.arielklub.sk/inzerat-25333- ... DC-40-1931

https://www.arielklub.sk/inzerat-25333- ... el-1932-38

[nevhunter]

How easy is that?. Nev