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How Fast?

HauteSaoneFrance

Joined: 2-01-14

Topics: 30

Replies: 106

Posted: Sat 9th Dec 2017, 6:10pm
How Fast?

How fast is your loco going? Useful info for curves and gradients. Has anyone tried fitting bicycle style speedometers that work by attaching a sender to a wheel and a pick up to a fixed point the computer can be programmed once you know the distance traveled for one revelation
 

Replies To This Post

Peter Beevers

Joined: 9-10-01

Topics: 3

Replies: 143

Posted: Sat 9th Dec 2017, 7:22pm

Opinions vary. FWIW mine is - on a decent sized railway, a maxima of 7mph is about right. On a smaller circuit, or a garden, 3-4mph is plenty.
Has anyone used bike Speedos? Of course, but some do not allow wheel diameters as small as ours, so choose carefully. Also remember that they're battery powered and it won't last forever, so mount it somewhere that you can change the battery.
For a future project of mine, I want something better than a bike speedo display, so have obtained a lovely old 270 degree swing meter, and have written code for an Arduino to take an input from a wheel sensor and convert that to a suitable voltage range for the meter. And all that's not half as hard as you'd think.
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 30

Replies: 106

Posted: Sat 9th Dec 2017, 8:10pm

Thanks Peter, I ask because my initial trial on my up to now limited length of track with the CMD Knight class 0-4-0 petrol hydraulic loco has produced frightening speeds of an estimated 10 MPH at much less than full throttle.
 

George Coles

Joined: 4-08-09

Topics: 22

Replies: 107

Posted: Sat 9th Dec 2017, 8:22pm

Cheap bike speedos work fine. Mine come from Halfords. I cross drill an axle and hang the sender (magnet) on a piece of bike spoke fixed through the hole.
George C
4973
 

Xz

Joined: 1-01-92

Topics: 20

Replies: 256

Posted: Sun 10th Dec 2017, 10:07am

The cheap Halfords ones work very well, they do allow you to set to small wheel sizes, and if you are quick you can change the battery and not lose your data. Thumbs up from me.
 

nickburton

Joined: 2-06-09

Topics: 4

Replies: 7

Posted: Tue 12th Dec 2017, 11:34pm

Another option is to use a App, such as a running App, on a smart phone. It is GPS based so not accurate on a minute by minute basis, but will record maximum speed, average speed etc over time such as several circuits around a track. Nick
 

colinedmondson

Joined: 9-08-09

Topics: 3

Replies: 84

Posted: Wed 13th Dec 2017, 9:56pm

If the cycle type speedo won't go down to the wheel diameter that you use, try putting two magnets on the wheel and choosing a wheel size twice what you have, and so on.
 

Peter Beevers

Joined: 9-10-01

Topics: 3

Replies: 143

Posted: Thu 14th Dec 2017, 1:06pm

Err, no. Putting multiple magnets on effectively reduces the 'wheel diameter', not increases it. It will, however, render the speedo more accurate to small changes in speed. For an upcoming project I will use 4 equally spaced magnets to quarter the diameter (but multiply the accuracy by 4). I have chosen this because the wheel diameter (8.5) is quite large and so the speedo would not be great at recording speeds as you set off from rest without this fiddle (sorry, carefully thought out engineering solution).
 

Railrose

Joined: 25-06-07

Topics: 1

Replies: 13

Posted: Sat 16th Dec 2017, 10:22pm

bicycle speedometers work with a magnet. If you put the magnet straight on the steel axle the steel material will "suck up" the magnetic field, thus reducing the strength of the magnet. For optimal function I use a plastic spacer, either a ring around the axle or a plastic pipe clamp to keep the magnet at a little distance from the axle. see picture. 

I use an old type Sigma Sport, sadly the type is not available anymore. The working principle is the same for different brands. The picture is 10 years ago, it still works on my Vliegende Hollander, as ridden at this year's annual Gala at Burnley.

Average service speed is about 8-9 km/h, on a good track tops of about 12 km/h are sufficient and safe. My petrol mechanic 'Panter' can do well over twice that speed, please don't tell the safety guys...
bicycle speedometers work with a magnet. If you put the magnet straight on the steel axle the steel material will "suck up" the magnetic field, thus reducing the strength of the magnet. For optimal function I use a plastic spacer, either a ring around the axle or a plastic pipe clamp to keep the magnet at a little distance from the axle. see picture.

I use an old type Sigma Sport, sadly the type is not available anymore. The working principle is the same for different brands. The picture is 10 years ago, it still works on my Vliegende Hollander, as ridden at this year's annual Gala at Burnley.

Average service speed is about 8-9 km/h, on a good track tops of about 12 km/h are sufficient and safe. My petrol mechanic 'Panter' can do well over twice that speed, please don't tell the safety guys...
 

HauteSaoneFrance

Joined: 2-01-14

Topics: 30

Replies: 106

Posted: Sun 17th Dec 2017, 11:14pm

Thanks for all the replies my guess was right the bike speedo's can be successfully adapted with care an experimentation. Like Railrose my petrol 0-4-0 is frighteningly fast so need to know about safe speeds and although my site is entirely garden private it's nice to put up max speed signs for the various sections to give some authenticity
 

Johng

Joined: 7-06-11

Topics: 1

Replies: 2

Posted: Thu 21st Dec 2017, 4:40pm

Have a look at Magpie Computer Developments site. They make speedos, rev counters etc. I can speak from personal experience, their products are first class. You get a personal service the firm being run by the owner himself.
 

Brian Leicester

Joined: 12-04-18

Topics: 0

Replies: 2

Posted: Thu 19th Apr 2018, 5:48pm

I have used bike speedos on my wife's wheelchairs over the years which travel at similar speeds to miniature trains. I found that setting the wheel size to read ten times faster than actual speed works very well as most won't indicate at speed below 2 or 3 MPH, which means that they will actually start at about a quarter of one MPH. Very easy to see what speed you are doing as 45.6 indicated speed is 4.56 actual.
To get an accurate circumference measurement, measure how far the vehicle travels for several revolutions. X revs = X times more accuracy in measurement, as long as you don't miscount the number of revs...
 
 
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