Part 1 - Power collection from the track
The idea behind this project is to build a small, automatic tramway that will run up and down, stop at each end, wait for a while and head on back to the other end to do the same thing again, endlessly for exhibition use. Initially this will be achieved using an electro mechanical reversing switch and a couple of diodes. I then plan, with the help of my tame geeky mate, aka
Digital Tim, to add some digital control (using the Arduino) to control the speed and, maybe later, add other features - we will see how it goes.
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| Front and rear pick-ups |
First things first, I need to build something relatively simple and make sure that works. The little tram car is taking shape with pick-ups at either end. Twin pick-ups will ensure the electrical continuity is maintained more reliably than when just using a single collector.
The pick-ups are made from Elektrikit thin brass 2 inch strips. These in fine condition can and do fetch a good price but there are plenty of tatty ones around at lower prices. These can be easily smoothed out using a set of rolling bars. These are intended for bending plates to a smooth curve, and they make a fine job of that, but we used ours far more often to straighten our bent plates.You can see how we build ours
HERE.
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| Flattening out the brass strips |
Here I have just found another use for it. The strips themselves are too thin to track through the rollers on their own but using a flexible plate as a platter the brass strips roll easily and will soon become far more like their original selves. I left them with a slight curvature to press the pick-up 'shoe' against the centre 'live rail'.
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| Perfect - Well good enough! |
The pick-up 'shoe' is in fact a reproduction buffer. I am not sure where these came from as they arrived here at
Laughton Towers in a lot, but similar items can be obtained from Stuart Borrill. A list of his stock parts, including buffers, can be found
HERE.
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| Pick-up mounting and three-point 'suspension' |
Here I have used original Meccano insulating washers to allow a fixing through the double angle strip. The bolt has a 4mm banjo tag fitted under the head that will provide a place to make a solder connection after testing. It also provides a convenient hole to attach the temporary wiring to.
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Insulated washers and solder connection, used her to make a
temporary connection for testing. |
The electrical return is through the body of the tram, through the wheels to the track. If the wheels were all on rigid axles the tram would rock as it traversed the track and at best only three wheels would be in contact at any one time, unless a perfectly flat track section was found. This would assume the axles were perfectly parallel to each other. Neither scenario is likely! By supporting the trailing axle on a central pivot the tram weigh will be on the driving wheels and the pivot will ensure the trailing wheels are always in contact with the track allowing for much smoother running and electrical continuity.
So far so good, next job is to build the reversing mechanism using the new geared motor and reversing switch from the Evolution set... and some track might be useful.
Ralph.
