New to me. Any thoughts on its purpose? It looks like it would shut things down when the pressure was below some critical amount, so I suppose it would minimize leaking kerosene when the stove was just sitting around; but that seems rather mundane. I don't get the filler cap stuff at all.
A problem I have with my brassies is that I have to leave them with their air screw open. If the air screw is closed, then on high pressure days air goes into the tank via the burner and then on low pressure days it drives fuel back out and into the spirit cup. I have had to clean up more than one oily mess because of this.
Can you show the filler cap thing from more angles? Does it have a hole at the tip? Is there an O-ring on the rod? Could it be a paraffin depth gauge? That's the one thing I would expect there. Yonadav
It's for adding paraffin to the spirit cup wick for priming. You are looking at the Monitor Regal. https://classiccampstoves.com/threads/178
A couple of pictures that I forgot to put on earlier. The link to the other Monitor that I put on some time ago. Note there are differences between the filler cap and the pump bits. https://classiccampstoves.com/threads/14103
It also has a patented "over pressure " valve which you can see in the first photo, directly above the "T" in the embossed Monitor logo on the tank. This relieved pressure if over pumped, or if the stove got to hot in use and the pressure built up.This is a particular favourite stove of mine and I have posted on it before