Early rev counter

[Asquith]

An old steam engine rev counter, or rather stroke counter.

I’d seen a lot of these on engines, and only recently looked inside one. I wonder if these inspired the ‘Enigma’ machine?

The first clickable thumbnail view is subtly different, the shaft having been turned slightly.





I’d previously decided it wasn’t interesting enough to post, but changed my mind when I saw Rich Carlstedt’s stunning model engine (link below), and decided that someone might wonder about the little odometer on the engine’s ‘instrument panel’.

http://bbs.homeshopmachinist.net/sho...166#post334166

[Evan]

I wonder if the owners of the steam engine would try turning them back before selling the engine?

[oldtiffie]

Odo-meter

It is similar to an Odo-meter/trip meter in your car/truck.

The mechansim is similar in operation to a type of geneva wheel.

Each "drum" turns over 1/10 of a turn at the tenth turn of the one preceding it so it starts at 10>1,000>10,000>100,000>1,000,000 etc.

As input is from the engine shaft, the revs/min can be intregrated/differentiated to give speed and distance by using a constant velocity "potters wheel" device over which a steel ball/s contrained within a cage move accross the disc and so drive a roller which is also in permanent contact with the ball/s.

http://message.snopes.com/showthread.php?t=24654

Silas Sparkhammer Join Date: 22 September 2000
Location: San Diego, CA
Posts: 20,369

----------------------------------------------------------------

I love old computer museums! There's one close by to where I live. They have a Digi-Comp II, and I am so envious! I always wanted one of those, but they went out of production so quickly. They also have a Curta calculator (the one that looks like a pepper grinder!)

They don't have a Digi-Comp I -- and I do -- and I have offered to lend it to them for display, but they won't accept it other than as a donation, and I'm not gonna give it up. (And they won't pay what it's worth.) Oh, well...

Old 'puters are so nifty!

By the way, here's one you might find groovy: take a large flat plate of metal, like a wheel, that turns slowly on an axial axle. Like a potter's wheel, sort of. Take another, smaller wheel, with a rubber rim, that sits on the first wheel, at right angles, so that when the first wheel rotates, it causes the smaller wheel to rotate. If the second wheel is close to the center of the big wheel, it rotates slowly. If the second wheel is out near the rim of the big wheel, it rotates more rapidly.

If the rotation of the big wheel is taken as the independent variable x, and the distance of the little wheel from the big wheel's center is taken as f(x), then the rotation of the little wheel is the integral of f(x) dx. i.e., you can do analogue numerical integration with only two moving parts.

Silas (well, I think it's way kinky!)

[Evan]

Bah. The integrator assumes the position of the driven wheel may be changed. As a strictly engineering consideration that will require more than two moving parts. Besides, you can do integration with just two non moving parts, a resistor and a capacitor.

[oldtiffie]

Mechanical integrator/differentiator

Bah. The integrator assumes the position of the driven wheel may be changed. As a strictly engineering consideration that will require more than two moving parts. Besides, you can do integration with just two non moving parts, a resistor and a capacitor.

The basic idea as said in a quote by another in my post was OK even if the details were a bit sketchy.

The pic at the end of this post will suffice as an example of a mechanical integrator which can also be used a differentiator as an example of the way it was done in the "olden days" when most things were not electronic or digital but were mechanical or analogue.

This was very common in weapons/gunnery fire control and prediction systems on naval vessels.

I am aware that there are electronic and digital systems that can and do the same job more efficiently in every way.

[kendall]

Bah. The integrator assumes the position of the driven wheel may be changed. As a strictly engineering consideration that will require more than two moving parts. Besides, you can do integration with just two non moving parts, a resistor and a capacitor.

Yeah, but resistors and caps just don't have the same eye appeal as spinning mechanisms!

Ken

[Peter S]

I wonder if the owners of the steam engine would try turning them back before selling the engine?

Not quite in reply to this quip, but nevertheless interesting, because it is part of the story of James Watt and his great developments of the steam engine. Boulton and Watt offered a much more efficient engine than the Newcomen engines of earlier years, and they offered them on the basis of sharing the savings their engine would make over a Newcomen engine. Thus, it was vital that the some tamper-proof counter was placed on each of their beam engines to record the number of strokes, and thus allow the premiums payable to be calculated.

A ratchet and pawl counter was used in 1774-75, but soon a pendulum-operated counter was contrived.

Mathew Boulton wrote to James Watt around 1777:

"We have got an excellent Counter that goes true, & can't committ a mistake, for 30 years. It may be hermeticaly seald up in an Iron Box & it hath no external communication whatsoever. You may even exhaust ye Box of air and I think it will be proper to annex one, on our own acct., to every great Engine we make, & wch shall only be opend when we visit the Engine and a Book to register the storkes & ye day of ye Month."

(from James Watt and the Steam Engine" by H.W. Dickinson & R. Jenkins).

The engine owners made large fuel savings when they installed a Boulton & Watt engine, but human nature being as it is, it wasn't long before they became reluctant to share those savings with Boulton and Watt, hence the importance of tamper proof counters, and also explains one reason for the rise of the "pirates" who in every way possible tried to evade the Watt patents.

Asquith,

Thanks for the view inside a counter - it looks like impressive made-to-last quality. I think I have seen counters used to record gallons of water on old pumping engines (may be mistaken) - I wonder if they calculated this from pump strokes, or some actual flow measurement?

BTW, the thumbnails (04 & 02) don't enlarge for me, I wonder if it is just me?

[Guido]

Swing by your local Caterpillar dealer, to check out the latest in modern, engine rev counting. Sealed and mounted on their larger engines for use in record keeping, leasing arrangements, maintenance, etc.

Anyone here have an idea of where/when/who installed the first oilbath air cleaners on their engines?

G

[oldtiffie]

Geneva

An old steam engine rev counter, or rather stroke counter.

I’d seen a lot of these on engines, and only recently looked inside one. I wonder if these inspired the ‘Enigma’ machine?

The first clickable thumbnail view is subtly different, the shaft having been turned slightly.





I’d previously decided it wasn’t interesting enough to post, but changed my mind when I saw Rich Carlstedt’s stunning model engine (link below), and decided that someone might wonder about the little odometer on the engine’s ‘instrument panel’.

http://bbs.homeshopmachinist.net/sho...166#post334166

Thanks Asquith.

You are a wonderful source of knowledge and absolutely marvelous pics of - among other "goodies" - of things "old engine" and "steam".

I really do enjoy your posts and thoughtful insights.

Thank you.

But back to your OP.

When I said it was a type of Geneva wheel/mechanism, I thought I'd better follow up with an example and/or explanation.

See: http://en.wikipedia.org/wiki/Geneva_drive

[Asquith]

Tiffie,

You are too kind!
Thanks for the link for the Geneva mechanism - the animations are just the job. I must go and study the hardware more closely.

I was slow to realise that the clock was placed close to the stroke counter on Rich Carlstedt's engine to allow the RPM to be measured. I've just looked at an 1875 steam engine book, and that has an engraving of a 'Marine Engine Register', which features a clock and a stoke counter combined in one convenient unit. There's also a mercury manometer either side for steam pressure and vacuum. Rich's engine has one of those new-fangled Bourdon pressure gauges.

[John Stevenson]

We used to buy a similar thing that was fitted into a hub cap and bolted onto semi trailers so you could keep track of the mileage travel for maintainance purposes.

In the early days some hire car firms used to also fit them in their hub caps when they used to make a mileage charge as people used to take the speedo cables off

Nearly got caught out by that one once :d
was going to do the prescribed 100 miles and take the cable off but it was absolutely pissing down with rain so decided to not bother.

Took the car back a young lad took the speedo reading then took the hub cap off and checked the mileometer. I think he should have done it out of sight but it was enough.

After that the cable came off and all the bloody hub caps

.

[tony ennis]

They don't have a Digi-Comp I -- and I do

Ha, I have a Digi-Comp I in a shoebox in my attic. I even have the manual for it somewhere. Got it when I was about 8, so that would be around 38 years ago.

[Evan]

I have one of the very first electronic LED display calculators made by Commodore, which started as a calculator manufacturer. It will operate for perhaps 30 minutes on a very expensive battery.

Now one of the techniques used for engine run time accounting is a solid state unit somewhat like a battery. It works by plating material from one plate to another when power is applied. The amount of exchange of material is directly proportional to the number of hours of operation.

[J Tiers]

Now one of the techniques used for engine run time accounting is a solid state unit somewhat like a battery. It works by plating material from one plate to another when power is applied. The amount of exchange of material is directly proportional to the number of hours of operation.

Which is also how very early electric meters operated (on DC, obviously). Actually measured the coulombs of charge passing through the installation, so probably a very good method. Useless on AC.

[Peter S]

I saw an apparently simple rpm counter/hour meter (I think both) a couple of years back - a friend fitted it to a new 3 cylinder diesel engine in his yacht. The sensor clamped to one of the injector pipes, and a wire went off to the digital rpm/hour meter. Seemed like a great idea, as this sort of detail can be a hassle when doing a re-power and nothing is provided on the engine.

Getting back to Asquith's original post - I am curious why that counter is built so heavily. I wonder if it is the work of an engine designer, rather than say a clock or instrument maker? I guess the application is quite different, with no need for particular precision, lightness etc and maybe non-ferrous metals and casting was cheap in those days. Not that I am being critical - top marks for a long-lasting job and I like those cast-in numbers (and no doubt other details are as-cast, not machined all over).