Vac Cylinders - Wagons

Currently we are working on a 1930s Lowmac which is fitted with 2 Vac Cylinders, one each end.
These are of an approx outside Diameter of about 20"
We then compared this with a cylinder removed from a Walrus ballast hopper and this had a diameter of approx 24"

How many varying diameters of cylinder are there for wagons?

 

AFAIK, there are only two variants for normal* vac cylinders - 18" & 21" (Piston size), so it sounds like you've got two 18" cyls.

Additionally, 18s come in two main flavours - Sliding Band or Rolling Ring. Anything on the bottom like 'E1'?

*i.e. not the GW Dean version.

Pete S
C&W Dept.,
GWS Didcot,

 

There are four sizes that I know of: 15", 18", 21" and 25". The measurement is internal. The Walrus I have looked at had a 25" cylinder (rare) so your 24" external one is probably a 21" cylinder and might not be original for a Walrus, or maybe it is from a different batch. The 15" cylinders are used on some Conflats and as the second cylinder on some 16T mineral wagons. 18" are most common on wagons and 21" on coaches, but we do have a large Weltrol with two 21" cylinders (which are a 'special' design with the lifting lug omitted, from memory). So, quite a few variations. I'm not sure if you can get sliding band ones in all these sizes though.

 

The Walrus cylinder I mentioned, I did say approx figure so quite possible it is 25"
Will be checking tomorrow.