Water as a lubricant

[nigel jones 5Participant @nigeljones5]

I note that the drawings i have for loco's which dont have superheaters dont have cylinder oil lubrication also – and i remember reading somewhere that saturated steam is ample lubrication for a loco cylinder etc. Any known facts about this? My upcoming project (with the steel boiler under £200 attempt) doesnt have superheaters.

[nigel jones 5Participant @nigeljones5]

[MICHAEL WILLIAMSParticipant @michaelwilliams41215]

Al loco's apart from the earliest had cylinder lubrication whether superheated or not .

Full size ga's often don't show the lubrication system but it will be fitted on the engine somewhere . Early engines had simple oil/grease cups on the cylinders . Most engines after that had displacement lubricators . Mechanical lubricators were introduced randomly but were surprisingly little used except on big engines and in later days .

Saturated steam contains some wet water in practice and gives marginal lubrication but for an actual working engine real lubrication is essential .

Superheated steam is positively abrasive and even some full size engines had lubrication problems when higher levels of superheat were introduced .

[Another JohnSParticipant @anotherjohns]

Nigel;

Certainly some saturated steam models do not require a mechanical lubricator. Look at all the little willesco/mamod engines, and despite being made from brass, they generally run for a long time.

Bob Maynard's "Raritan" does away with a lubricator; squirt a bit of oil in the cylinders via a plug at the end of the day into the cast iron cylinders. My little Tich's lubricator stopped working years ago, and as the "superheater" flue is permanently blocked, it runs saturated steam to the o-ringed gunmetal cylinders. Other than not being oil covered, I have not noticed a difference in the performance of the locomotive.

I'm taking this approach on my next 7-1/4" locomotive – saturated steam, tapped holes for plugs for putting in oil once in a while. It's not a crowd-hauler, so I doubt if it will get too much work. I fully expect to put some kind of model-based hydrostatic lubricator on it as time goes on, though.

Michael – the problem with superheat on full size is that 1) there is no lubrication via water, and 2) the temperatures attained would flash oils, leaving burnt oil to (not) lubricate. Special oils were developed that retained their lubricating properties at high temperatures.

As an aside, if you have ever seen a hydrostatic lubricator work on full size, the amount of oil it puts into the cylinders is really minimal – one drop every minute or so. That's about 10,000 times less than the mechanical lubricators do. (I do have experience on full size; I am licensed by our provincial government to do full size stuff, but have not in a few years)

Another JohnS.

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