Does anyone know what this is

[steveteeParticipant @stevetee]

I have come by this extremely complex piece of equipment. I'm told it may be to do with steam engines. It has BSP adapters , various springs a spring loaded rotating drum with a pawl to hold it in place a piston with mechanism attached to it which can rise and fall, there is a string with a hook and a pulley . I'm baffled…………… Anyone?

[steveteeParticipant @stevetee]

[Neil WyattModerator @neilwyatt]

It's a steam indicator, they are lovely things!

It records the pressure in a steam (or possibly big, low-revving internal combustion) engine over a full cycle as a lopped line on a card wrapped around the drum. The drum rotates back and forth with piston movement (via the string) and the dashpot raises and lowers the pen in line with the pressure.

Neil

[MetalmuncherParticipant @metalmuncher]

Its a diesel engine indicator, this video will explain it better than me. Its 5 and a half minutes in about it.

[Neil WyattModerator @neilwyatt]

I found a similar one by the same maker in the National Museum of American History:

schaeffer & budenberg indicator

[Speedy Builder5Participant @speedybuilder5]

I would guess that the SteamBoatAssociation GB would be very interested in it.
**LINK**
BobH

[Tim StevensParticipant @timstevens64731]

There is an article which explains this tool in the Model Engineer which arrived yesterday. Pages 868 to 869.

Regards, Tim

[mechman48Participant @mechman48]

It's a steam / diesel engine indicator; measures efficiency of the engine for best fuel economy… see Neil & metalmuncher's comments. Used to have to use one every watch, mainly operated by the engineers on watch & usually analysed by the Chief for fuel efficiency; once got caught in the proverbials when dropping the op' lever onto the cams miscalculated when to drop the lever,… an old engine…Sulzer, built in the early thirties… when I was in the MN 1969 – 71, Blue flue & ED's sailing out of Albert dock, Liverpool,…long gone now.

George.

Edited By mechman48 on 06/06/2016 10:46:00

[Tim StevensParticipant @timstevens64731]

Just to avoid misunderstanding, an indicator like this does not 'measure efficiency' exactly. It allows you to calculate efficiency, but other kit is needed for this. What it does is to draw a graph of the pressure in the cylinder in relation to the piston position. Power is produced when the pressure going down is greater than that coming up, and this graph gives clues to the power produced in the cylinder. This is related to efficiency, but other things (which the indicator cannot measure) can use up power before it gets to the outside world. Friction and drag in a gearbox, for example.

That is why 'indicated power' – measured with an indicator like this – is always greater than 'brake power' which is measured by applying something (such as a brake) to use up the power and so allow it to be measured.

Its not that mechman48 is wrong, exactly, he is just using the word 'efficiency' in a loose or everyday sense rather than in a precise or scientific sense.

And it's no use rushing out to buy one of these things to see how efficient your motorbike engine is. They only work at low speeds (rpm in the low hundreds) and you need an extra hole in the cylinder head to connect it.

Modern ways to do this involve pressure transducers, perhaps built in to special sparking plugs, and oscilloscopes to draw the graph, and they need the engine to be under load, so lots of other kit is also required – including a scientific calculator.

Regards, Tim

[mechman48Participant @mechman48]

… 'Its not that mechman48 is wrong, exactly, he is just using the word 'efficiency' in a loose or everyday sense rather than in a precise or scientific sense'…

… exactomundo… it's been well over 40 years since I had my hands on one of those set ups.

G.

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