Spitty Compressor - Merlin

[ProudKerman]

Anyone know anything about this is beaut. I know its a air compressor but there seams to be alot of conflicting info out there. Some have told me it powers instruments, other flaps and guns, and other brakes and stuff. Anyone know for sure. Also how would I go about restoring this thing. Doesn't seam to turn over though may just be tense plus I am missing the shaft that connects it to the engine. The guy reckons it was late model Spit but before the Griff change obviously. Pretty sure it could come off anything Merlin, Lincoln would be more likely given me location, right next to RAAF Amberley.

 

[GregP]

Can't identify but HAVE restored many an item of similar sort.

The first thing I'd do is get access to the piston somehow and pour in some penetrating oil, seal it back up, and let it sit for a week or more, maybe several weeks, adding more oil occasionally as required. Then you have to make or get some sort of shaft to turn the crank. The penetrating oil (or old hydraulic or motor oil) breaks things loose MANY times. When it doesn't, we have used a trick on Allisons and other things with pistons in them many times that works.

We first remove the camshaft (I know this one doesnt have one) and rocker arms. Then we use a dead blow hammer to work the valves loose and make sure they are closed. The we took a spark plug, broke off the ceramic end, drilled it out, tapped it, and screwed in a quick disconnet such as you find on 2500 - 3500 psi water sprayers.

Then, you guessed it, connect the water sprayer and turn it on. Voila! It hydraulics the piston out. You DO need to cushion the place where the piston will come out to avoid damage, but we have "rescued" and returned to service over 25 Allisons that way. We used to use a grease gun to hydraulic it out, but that was REALLY dirty and messy when it came out or a valve let go in your face. After we tried water, we never went back.

So ... I'd apply the penetrating oil to the center valve and try to get it unscrewed, and then make up a hydraulic fitting that can connect to a sprayer. But ... I'd try to machine a hub for the crankshaft and try breaking it loose with oil first. You have to have some patience here since the object is to free it up without damaging anything.

There is a compay called Kano Labs here in the states that sells product called Kroil. Absolutely amazing what it can break free. You might try to google it and find some.

Good luck and let us all know how it comes out ...

LOOKS like an aircraft air pump, but so do a few things that really aren't related to aircraft.

 

[Crimea_River]

I flipped through my Merlin 28/29/31 manual and didn't see this part. As you said, it was probably for later model engines. This stuff is good at loosening seized parts.

 

[GregP]

Yup, another pretty good product. Wonder which is cheaper? I'll look it up and find out next time I need some!

 

[Crimea_River]

BTW, to answer the original question, the following paragraph from the Spitfire IX Pilot's Notes explains the function of your compressor:

 

[GregP]

Good info! Thanks!

 

[Crimea_River]

Did some more digging in my copy of a Mosquito FBVI Parts Manual. I think you'll find the manufacturer of the above compressor to be Heywood as the part number SH6/2A appears on your unit. It's listed here int he Mossie Manual, though it was likely mounted on spits as well.

The compressor runs off an auxillary drive off the back of the right cylinder bank at the top as can be seen in the below drawings. The red arrows show your unit.

EDIT: The splined shaft you are looking for is shown below and discussed here: Air compressor query

 

[ProudKerman]

Well a huge thanks to Greg and Crimea you guys are amazing, I've posted this on a couple of forums and no one comes close to you guys. Thanks heaps

 

[Crimea_River]

Any time!

 

[GregP]

Hope you can free it up! If so, maybe you can make some air and let us know how it works after restoration?

 

[ProudKerman]

Will let youse know if I get her running

 

[Airframes]

Great stuff chaps.