Mechanical lubrication

[Fred Graham 1Participant @fredgraham1]

Alternatives to displacement lube for hard worked engines

[Fred Graham 1Participant @fredgraham1]

Hi Folks,

I have not been active on the site for a while but keep busy despite age 74.

I was wondering if anyone had any clever ideas as to how much 'pumped' oil would be required to maintain a smooth friction free engine when running at high speed or pushing a heavy load.

I note that there are exponents who race round poles with flash boats ( e.g. Bob Kirtley and Paul Windross) and they are very concerned about good lubrication.

I have not seen any enlightening articles which describe how to determine the pump size and how much it should deliver over a given time span.

I have had a go at calculating an amount based on surface area of swept volume and film thickness but data is scant on steam engines big or small

I realise that it is more common to use displacement lubricators although I believe the flash men use hydrostatic lube systems.

Someone is bound to be able to point me to a load of data for which I would be grateful especially if it is not full of differential equations and lots of mathematical and flow complexities.

Cheers, and happy steaming Fred Graham

[mrsgogginsParticipant @mrsgoggins14041]

I made and fitted a mechanical lubricator to my Borderer twin. It has proved most satisfactory and delivers a minimal amount of oil. I doubt you will find any credible method of calculation as there are so many variables.

For what it is worth my pump delivers a (calculated) 0.001 Cu in "lump" of oil every 3.6 revolutions of the crank. I say "lump" because it is a piston pump driven through a reduction gear.

I run the engine at 60/70psi in a tug and would say that if anything it is over lubricated. Engine bore is 0.5" and stroke 0.625".

Hope this is of some use.

Keith

[mrsgogginsParticipant @mrsgoggins14041]

Woops, forgot the effect of the roller clutch. This reduces the calculated flow to 0.001 cu in per 30 crankshaft revolutions or about 0.000035 cu in per rev. I have a feeling I further reduced the flow but can't find the relevant notes.

Keith

[Fred Graham 1Participant @fredgraham1]

Hi Keith,

Thank you very much for your response and the data you have included, it is most helpful.

As it happens some time ago I found an article in a very old Model engineer Magazine entitled 'Model Marine notes' from the 1920's or 30's (I don't recall exactly) and based on the authors engine size, the oil pump size and gear ratio used, the amount of oil you have calculated corresponds closely with the figure which I calculated from his data. The author described the oil delivery as, 'more than adequate.'

The article was my reason for canvassing comment from others such as yourself

Once again thank you and it may well be that such data will help others to determine the oil demands for their engines. Model loco fans may well have such data as they usually pump oil into their engines so it may also be a source of pertinent data.

All the best and happy steaming, Fred Graham

[mrsgogginsParticipant @mrsgoggins14041]

Hi Fred,

Thanks for your follow-up. Interesting correlation.

May you steam long and hard.

Regards,

Keith

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