Describing his Primus 1550 HERE @Nils Stephenson said, Valve/generator/fuel pickup assembly. In the jet pricking position (arrow on control wheel uppermost) the extension to the pricker rod below the eccentric disengages with the sprung-loaded seal cup in the component resembling a non-return valve at the base of the fuel pickup tube, shutting off fuel flow. The seal cup and operating rod tip. The annular seal with the bearing surface for the control rod in brass ensures there’s no slippage of the ‘timing’ of fuel shut-off down to elasticity or wear of the bearing surface if it were the seal itself and not that brass centre. Fuel filter gauze in the pickup tip component. HERE in the Fettling Forum I went into more detail of the Optimus-pattern pre-heater and how it might malfunction. Pre-heater in action. Lantern in action. John
Interesting observation (and a great lamp too) - as a kid in the boy scouts we had "Primus stoves" and "Tilley lamps" - regardless of what was written on them.
I chanced upon the tank, generator and pre-heater of an Optimus 1550. Fuel tank stampings, Primus .. ... and Optimus. The fuel shut-off in the lower end of the fuel pick-up has an annular seal with a central brass mating surface for the pointed extension rod operated by the fuel valve eccentric. No such refinement in the Optimus set-up, with a regular ‘pip’ seal ... ... and a blunted tip to the operating rod.
It's quite likely that the Optimus parts are from a later production. The Primus version existed up until at least 1976 (last catalogue entry I have), whereas the Optimus lasted into the 1990s. I havn't looked at this part for the various variations, but it is quite likely that Optimus was trying to save costs in the 80s. Another small detail to try and keep an eye on.
