Hopefully someone here can clarify some questions about what seems to be a Heywood compressor as fitted to, for instance, Merlins. This is illustrated below.
What I am trying to work out is what type of engine it was actually fitted to. It is marked as a Type SH6/2 Compressor. I suspect with no suffix such as ‘A’, it is an earlier example. Also it is natural metal whereas all others I have seen are finished in black.
It is fitted with unions and seems to have scour marks around the mounting holes, so I assume it is a used example. Presumably, the union at the side is the compressed air outlet, while the chamber at the back with the union at the bottom is the oil route.
In terms of history, it has been lying around at the family home since at least the 1950’s and is a post-war surplus item. I was always told it was from a Merlin, but I am not sure. Additionally, for a smallish item it has what seems a large number of inspection stamps and numbers including a Ministry arrowhead.
Does anyone have any observations? Thanks.
By: Denys Jones - 25th August 2012 at 22:37
Taking advantage of this thread having the focus of people informed on the Heywoods and Merlins I’m appealing for a couple of bits.
For the restoration of one of the Merlins for Mosquito HR339 we need the three parts shown in the attached to mount the compressor we have. Any leads etc much appreciated and apologies for the thread hijack.
By: Creaking Door - 25th August 2012 at 09:40
Although they look simple these are actually two-stage compressors.
It first compresses the air between the piston and cylinder-head, through a one-way valve in the piston crown; the bore of the cylinder is stepped and the valve has an outlet that comes out between the cylinder-wall and the piston. As the piston descends the space formed by the step in the cylinder and the step in the piston compresses the air again and forces it through the second one-way valve that is built into the outlet on the cylinder side.
I love dismantling these sorts of things; the quality and complexity is something to behold.
By: HP111 - 25th August 2012 at 09:06
…..
What are your intentions with it?…… 😀
It very nearly got dismantled once and may well get dismantled sometime in the future, but for now it is just an aviation artifact lying in the garage.
Interesting to see the outline of the cylinder including provision for six rings. Very difficult to turn over manually, but you would expect that from a compressor. I once ran it off an electric motor just to see what happened. Apart from the noise, there was a long plume of oil mist from the outlet. Running it as part of an appropriate engine would be quite interesting, but I don’t think I will go there!:eek:
By: Creaking Door - 24th August 2012 at 18:03
I’d forgotten I’d got this in my desk drawer.
This is what the piston inside one of these compressors looks like…..well, it does if you cut it in half! 😉
By: Creaking Door - 24th August 2012 at 17:40
These are pretty universal compressors; I’ve seen them on Napier Sabre, Armstrong-Siddeley Cheetah and Merlin engines (some early jet engines too). What are your intentions with it?
The way to dismantle it, if you’re interested, is to rotate the brass ring at the base of the barrel (can’t remember which way to turn it but so it moves ‘upwards’ towards the ‘cylinder head’) and that will allow you to split the ‘crankcase’ when you’ve undone all the bolts.
I’ve got a couple of these; I’ll try to post some photographs showing the ‘gubbins’ if you like. 😀
By: pagen01 - 24th August 2012 at 12:05
It’s listed here in conjunction with Lancaster Merlin, http://www.lancaster-archive.com/lanc_ap-list.htm
I think I’ve seen reference to it on Spitfire Merlins, but that might be a /2A.
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August 24, 2012 at 11:34 am