A purchase from an online auction. No other bidders, but not surprising since most of the stove's missing and the control knob, although a Primus component, is a later addition and not the metal type correct for the 1936 date of the stove. The date stamp ('AA' for 1936) is ... ... there My reason for buying it was to check out a feature mentioned in the Primus 77 instruction manual (HERE on CCS) but not mentioned in any of the existing Stove Reference Gallery entries for the Primus 77 or the larger Primus 80 here on the site. It's certainly worth a mention I believe and is too important a safety device for the user to overlook. The feature I was intrigued by is Primus's answer to the potential hazard of having a conventional non-return valve in a gasoline stove. Their solution of a locking non-return valve is depicted in the sectioned illustration on this page of the instruction manual. Coleman set a high standard for safety with their metal ball 'check' valve (no rubber or cork non-return valve 'pip' to perish) locked shut by a twist of the pump knob, in addition to incorporating a narrow air tube leading from the check valve to the top of the fuel tank above the fuel level, so that even if the check valve were to fail and were the user to overlook the secondary locking device, only pressurised air and not fuel would be forced into the pump tube. Though lacking that last refinement, the Primus's locking non-return valve safety device works well. It relies on having an oversized non-return valve to cope with the additional mechanical stress of having the conical end of the pump rod forced into the air inlet hole when the threaded pump knob is screwed in the locked position. This action. The pump knob, screwed down in the valve locking position. Comparison of the beefier Primus 77 non-return valve compared to the equivalent component for most pressure stoves. Pump bore is the same (or very nearly so) to that of a Coleman pump, on the left. The generator has a larger bore than anything short of a Handy Gas Plant and since the pricker rod carries the regulating valve seat towards its tip and not at the base as with a Coleman 500 Sportster, it is a substantial 5 millimetres diameter section to prevent flexing. A remaining detail to pick out, the priming flame device. A control tap releases pressurised fuel to emerge as atomised fuel from the small outlet hole. When the tank assembly is clipped on the stove the primer tap outlet nipple is inserted in the end of a metal tube which has its outlet under the generator. John
It's unique to the '77' of course, but a Frankie of some sort is not too remote a possibility Trevor. John
Thanks Tony, Trevor. Your comments vindicate my posting the information here in the Stove Reference Gallery to add to an understanding of these stoves' operating features. The arrangement to eliminate the potential hazard of a conventional non-return valve in a gasoline stove merited special mention I felt, particularly since it could easily be overlooked by someone using a 77 or 80 stove and they'd lose out on a safety feature. Hopefully they'll read this and the instruction manual! John
John, I was also intrigued by the safety feature on this Petrol/Coleman Fuel/Aspen stove. Primus had obviously considered the Coleman safety features and thought it worthwhile building their own version into this stove. I think it is strange that they did not do a smaller version on later petrol stoves such as the 111B. Maybe it was all down to costs.
Just a thought John, but perhaps you could bring that assembly to Newark with you. We could get it running on my also incomplete 77, as I have the case and burners but my stove lacks jet and cleaning needle. Nice write up on the safety feature, it was one I was unaware of. Guess I've never pulled the pump out of mine.
@Matthew92 I'll take it along to Newark, Matthew, certainly. I've yet to make a detailed comparison of dimensions and thread form but the jet is of Coleman pattern on looks alone. The jet pricker needle is like a heavier-built Primus lantern type, unsurprisingly. John
@Matthew92 I was being a bit dull-witted when I wrote the above. No reason for me to hang onto a jet and pricker needle when you'd have a complete stove if I gifted them to you, so I shall. Send me a 'conversation' with your address. Cost to you is agreeing to post some photos of the stove running. John
@MrAlexxx Oh yes, I see it would be relevant to your complete No.77. Great find, looks in fine shape. John
@presscall John...we'll see. Long thick pricker rod still lodged in the generator. I'm pretty sure this is all from a long time many years of storage so am hoping to get some movement in the near future. From what I can see the pricker wire also looks to be missing or at least partly broken but am not 100% certain of that yet. I think this is going to take some time.
Hard to tell but is that pricker rod threaded at the end near the jet? The "regulating valve seat"...Is that what you are saying? Lovely...that would explain why the pen oil wasn't too keen on flowing into the generator. Certainly a different duck than a Coleman type generator.
Yes it is threaded ... You'll see the conical tip to the rod too in that shot, which mates up against a valve seat near the tip of the generator to regulate the flow of vapourised fuel. You can see here the rod in position in the generator tube, the conical tip of the rod against the valve seat. The pricker. You're welcome to it if needed. Matthew92 has the jet tip anyway and there's no frankenstove in prospect. One day I'll maybe get my hands on a complete stove.
@presscall John...that is most gracious of you. I'm almost certain that I'll need it. You have done me more than a few favours now. I can only hope to return a favour some day. Poor quality picture but it sure looks to me like the pricker tip is gone. I will PM you.
Just acquired a 77 and this was very helpful, it took me about an hour or so of changing washers and cleaning before it was up and running, a bit younger than the vaporiser you have mine is a 1940.
Hello Brian - new member from New Zealand here. Total beginner with these stoves. Have owned and used a no.77 for 10 years. It now needs some work. It's date code is AU 3Z, so 1955? Are there instruction or parts manuals for this stove that I can get? Any help hugely appreciated. Will post photos soon.
Lke most of us, find something slightly more interesting to do than old jigsaws with several pieces missing. Or cardoard modelling, or making Airfix planes. Great times ahead.
