can anyone identify the fitting shown in the photo, its on my old compressor and I dont know what it is to look for a replacement

[toolster]

 

[brightspark]

its a decompressor for the valve. you wont get one of them its ancient is it not working or just leaking see if you can strip and repair it if it is

 

[Barking Mat]

Welcome to the forum.

Which fitting exactly ?

 

[Pete.]

Presumably you mean the bit covered in chemical metal? As Brighspark said it's an unloader.

 

[bourbon]

If it's not working, your compressor will struggle to start (if it starts at all) Repair or replace. The fitting will have seized onto the thread, so bear that in mind before giving it large with the spanners

 

[wyn]

It will probably be operated by centrifugal weights on the end of the crank.
a bit like this ingersol rand one.

 

[Windy Miller]

iT works on a centrifugal switch on the end of the crankshaft. I had one on my big old Ingersol Rand compressor back in the 80’s.

Mine went wrong one day but at that time I managed to get a replacement from a local place very easily, but like I say, that was back in the 80’s.

Edit:
Crossed post with wyn! But there ya go - now you can see how it works!

 

[Windy Miller]

Thinking on it, if you CAN’T get a replacement, you might be able to use one of these:

https://amzn.eu/d/bgeWoT2

You could ignore the electrical aspect, and just use the unloader part to dump the pressure in the head when it wants to restart on load.

Just leave your existing valve in situ to stop oil leaks etc, and re route the pipework to plumb in the new one.

Might get you out of a hole…

 

[Erie Fred]

Looks like a Quincy pump with the head unloader.
A bit different animal than the standard unloader, note the air cylinder/diaphragm
on top of the head.

 

[toolster]

It seems to work, just leaks, so now I know what it is I can try stripping it and repairing. Thanks all for your help

 

[frank horton]

just take it apart and clean.....prob find just a corroded sealing washer...

 

[bourbon]

The liquid metal concerns me. The housing may well be cracked. still, nothing to be lost by taking it apart

 

[Erie Fred]

The liquid metal concerns me. The housing may well be cracked. still, nothing to be lost by taking it apart

Looks like JB weld.
Looks like it might have just been splashed on, maybe to just fix a problem with the brass cap to the right.