Speedometer

[Keith Stewart 5Participant @keithstewart5]

Has anyone ever successfully made or adapted a speedometer for use on their loco?

I know some people have adapted cycle speedos but I was thinking of more of a traditional analogue scale and maybe including a odometer.

Any thoughts or suggestions?

Thanks

Keith

[Keith Stewart 5Participant @keithstewart5]

[not done it yetParticipant @notdoneityet]

Analogue speedos were either mechanically driven or (effectively) a well damped ammeter, in the case of the electric versions. 270 degree movements were usual and currents were in the micro amp range, I would think.

[Neil WyattModerator @neilwyatt]

Back in the 70s my day made an anemometer using a milliammeter, a long wire and a DC motor. He calibrated it by driving back and forth on still day on a disused airfield with it sticking out the sunroof of his Wolseley 6.

Using a bicycle speedo may be easier, you calibrate them for diameter so you may be able to bodge it to read scale speed.

Neil

[Paul LousickParticipant @paullousick59116]

One of my friends who owns a full size Fowler traction engine has fitted a cable driven tachometer (same as a speedometer) to monitor the crankshaft speed.

The input shaft of a small 90 degree bevel gearbox is attached to the end of the crankshaft and the output attached to the cable from the tacho. The bevel gearbox is a standard unit, used on car speedo cables. Very useful on road runs to maintain a constant speed and not over rev the engine

Paul.

Edited By Paul Lousick on 01/03/2017 22:14:53

[vintagengineerParticipant @vintagengineer]

Mechanical speedos are either chronometric or magnetic. Most are magnetic drive. All you need is a speedo and workout the number of turns per mile.

On a Smiths speedo at the bottom of the face should be a four digit number or the last four digits of the model number, this is the number of turns per mile.

[Peter KroghParticipant @peterkrogh76576]

Posted by vintagengineer on 01/03/2017 22:26:30:

On a Smiths speedo at the bottom of the face should be a four digit number or the last four digits of the model number, this is the number of turns per mile.

Now that's some great information!! Thanks.

Pete

 

Edited By Peter Krogh on 02/03/2017 08:35:41

[not done it yetParticipant @notdoneityet]

Now that's some great information!! Thanks.

As long aas it does not happen to be a metric speedo?

[vintagengineerParticipant @vintagengineer]

Then obviously it would be in turns per Kilometer!

Posted by not done it yet on 02/03/2017 09:50:22:

Now that's some great information!! Thanks.

As long aas it does not happen to be a metric speedo?

[duncan webster 1Participant @duncanwebster1]

Ideal project for Arduino and little stepper motor. Loads of info on the interweb. Modern car speedos are stepper motor driven

[BazParticipant @baz89810]

Minimag do a speedometer that they claim is suitable for locos and traction engines.

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