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A ROLLING ROAD ?

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noel shelley17/12/2021 17:09:16
1298 forum posts
21 photos

Before I try to reinvent the wheel Has ME or anybody else published a design for a rolling road ? Intended for an 0-6-0 in 5" I would aim for it to suit almost any wheel plan and spacing although even the gauge could be made universal. I would not try to make it a dynamometer - to start with. Your thoughts or advice gentlemen ? Noel.

Brian H17/12/2021 17:58:30
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2312 forum posts
112 photos

Hello Noel, I found this in a search;

ME 4122 19 May 2000 - Universal Rollers for Model Locomotive Static Steam Trials by Gordon Helps.

Brian

old mart17/12/2021 18:14:39
3728 forum posts
233 photos

I remember seeing film of a full scale rolling road in use at a locomotive works, I have no idea how the spacings were adjusted for different engines.

Tim Stevens17/12/2021 18:38:47
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1589 forum posts

There are several ways to absorb the output of a wheel (or two) - favourites in industry include driving a friction brake, stir water or oil, whirl a fan, or generate electricity. The last is probably the easiest to measure, as the current and voltage are easy to measure, just multiply them for Watts. With modern belts, arranging a variable pulley system would also be simple, for the fairly low power outputs involved.

And it is much easier to compare outputs, than to be sure what the output is, as none of the stuff involved is 100% efficient.

Hope this helps - Tim

Edited By Tim Stevens on 17/12/2021 18:40:10

Bazyle17/12/2021 18:56:52
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6301 forum posts
222 photos

Did you try googling eg 'locomotive rolling road' ? then looking at the pictures.
In seconds I found this which is an ebay link for 0 gauge but you see the principle. Make one unit with 4 ball bearings (skateboard ones) per axle using whatever angle iron is to hand. With a little thought at the planning stage you can make it adjustable for all gauges but use nylocks so it doesn't rattle loose in use. The weight of the loco keeps the units in place so you don't need a longitudinal spacer. Obviously make the units identical and so do 5 at the same time ready for your 2-10-0.

A couple of precautions, Use shielded bearings to keep the coal dust at bay. Make a big metal drip tray to hold it all in to avoid messing up wherever you are doing the demonstration / test. Make a buffer or trapping system so if a bearing locks up or a kid pokes a stick into the wheel and it launches itself off the bearings it doesn't head for the floor. (eg a large block of wood only 1/4 inch under the buffer beam so it lands with wheels in mid air)

Jeff Dayman17/12/2021 20:46:33
2223 forum posts
47 photos

Noel- Model Engineers Laser do rolling roads for various gauges. A link to their 2 1/2" gauge one below - maybe you could scale it up for 5" gauge? just a thought. I have built MEL's O gauge rolling road kit and it was excellent.

http://www.modelengineerslaser.co.uk/kitpartspage.aspx?kit=156&locotype=13

noel shelley17/12/2021 22:20:31
1298 forum posts
21 photos

Brian, went to the library(back bedroom) and got out the relavent edition and studied it - thank you . Jeff, Thanks but I have a good workshop including oxy cutting gear and though not quite as clean as a laser it's pretty good. Whilst I have a box of flanged bearings of the right size and ample stock of steel - heavy sections and all. One thought is to use a toothed belt, with toothed wheels under the C/L of the axles and at each end - think inverted tank track with the loco sitting on top ! Given that the wheels are free of oil then the adhesion should be good and a simple water cooled band brake or gear driven alternator would not only be a rolling road but also a reasonably accurate dynamometer ? Needless to say the engine would be secured against a buffer stop at the front end and  rear and if a tender engine then the drag box would be held !   Noel

Edited By noel shelley on 17/12/2021 22:26:43

duncan webster18/12/2021 00:23:18
3947 forum posts
63 photos

Depends on the efficiency of the alternator, probably not all that good and dependant on speed. However, if you just use the alternator to absorb the power and measure the drawbar pull with one of those load cells off ebay you get the real power (db load * speed)

I fear I don't understand your inverted tank track. I'd just have big rollers direct under the wheels with central tooth belt pulleys and the alternator underneath. If it has more than 4 driven axles (I note OP's has 6) then an idler between 2 axles to get some belt wrap. I'll try to do a sketch tomorrow, but it's getting late and the dog has his legs crossed.

The SMEE has/had a rolling road dyno for locos, someone might be able to find some info.

Edited By duncan webster on 18/12/2021 00:24:12

Nick Clarke 318/12/2021 07:49:58
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1397 forum posts
61 photos
Posted by Jeff Dayman on 17/12/2021 20:46:33:

Noel- Model Engineers Laser do rolling roads for various gauges. A link to their 2 1/2" gauge one below - maybe you could scale it up for 5" gauge? just a thought. I have built MEL's O gauge rolling road kit and it was excellent.

http://www.modelengineerslaser.co.uk/kitpartspage.aspx?kit=156&locotype=13

As do CMD Engineering CMD Engineering

Edited By Nick Clarke 3 on 18/12/2021 07:50:52

noel shelley18/12/2021 12:14:15
1298 forum posts
21 photos

Duncan, My thoughts are as follows ! I will talk on the basis of 0-6-0 or 6 coupled wheels. A simple rolling road of 12 bearings on a frame to suit the wheel plan would work and better than skid marks on the kitchen table ! The inverted tank track idea was based on the following :- To get any real idea of power or draw bar pull one has to achieve adhesion between the wheels and the receiving components, rollers etc. The point of contact will be very small, to the point that at heavy load, slip would defeat the whole experiment. Using tooth belt and pulleys to suit, one pulley under the C/L of each wheel, an idler at one end and a driven pulley at the other, one can remove the power and measure it by one means or another, an alternator with variable load would come to mind and seem the easiest ! A load cell could be used to restrain the vehicle to give a reading of draw bar pull/push.The accuracy may be questionable but it would give good readings for comparison if carrying out modifications or tests. Why a toothed belt ? The belt trapped between the pulley and wheel will deform and increase the contact area hopefully stopping slip or at least reducing it, needless to say the belt and wheels MUST be clean - no oil. Each pulley would have a flange on the outside to prevent the belt trying to escape. The reference to an inverted tank track was in the context of having a carrying or load roller under the C/L of each wheel, the return run would be at the bottom !. Any thoughts on this anybody ? Noel.

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