Idea: Speed limiting brake van

[Crayfish]

I've discovered I have an unplanned gradient on my line. This causes issues with running as both of my locos are manual. They either come to a stop on the incline or they run away on the level sections. At some point I expect I will have to lift the track in the problem section and try and get it more level.

Now to the point of this post. My "runaway train" experiences led me to wish for some type of built in speed limiter on my locos. So that got me thinking about how something like that could be installed in a 16mm scale loco. My conclusion was that you would probably need a governor attached to a brake and a fairly large void somewhere for it to be housed. An enclosed space, probably about the size of a van where the braking mechanism could be put...

So that's what brought me to the idea of a speed limiting brake van. This would be a piece of stock that runs quite easily at slow speeds but builds up resistance as its speed increases. The design would be something like this:


I'm not an engineer so please forgive the crude drawing, hopefully it conveys the general idea well enough. The final design would probably have brakes on both axles of the van.

Does anybody know if such a device has been made? Does anybody have any opinions on whether this would actually work in practice? Is there a better or easier way to get the same result?

[IrishPeter]

The short answer is yes, but not by me.  Also your design follows one of the three basic themes for such vehicles in that it uses a governor to apply the brakes. Personally I think it best not to put such a mechanism in the brake van due to the risk of 'cording' on a curve causing a derailment. As a train s essentially a necklace of wagons when you exert pull on both ends it will try to take straight line between the two opposing forces. It is better if the governor is mounted in a closed wagon close to the front of the train.

I have a fairly steep gradient on my line and use manual locomotives, but I do not seem to have a run away problem mainly because the gradients from the top of the garden to the bottom is consistently down, so it is light steam downhill.  What is messing things up for you is not so much the grade, but the fluctation meaning it is difficult to set the manual regulator to take account of the road.

Peter in AZ

[Crayfish]

The short answer is yes, but not by me.  Also your design follows one of the three basic themes for such vehicles in that it uses a governor to apply the brakes.

What are the other two themes. if you don't mind me asking?

[IrishPeter]

One variation is using the governor to engage a braked drum inside the wagon, rather than shoe brakes on the wheels; the other one I have forgotten. I think it somehow involved compressed air!

Peter in AZ

[IRON MAN]

There is the John Turner way of speed regulation. ... An Exhaust regulator. There are many John Turners in my local group and they cope with gradients very well.

The regulators on JT's beasts are mounted on the smokebox door with a wheel where the darts would be.


Just a thought....

[Keith S]

I think that's a brilliant idea! A brake van that actually brakes! Although I do agree with Peter about the possible effects of hitting the brakes at the end of a long train, surely the trains could be kept short and the braking kept subtle enough that this would not happen? In any case it's very clever. I saw someone post a video of a brake van with radio-controlled brakes; he had manual engines and just used the radio to apply brakes at the crest of a hill. I thought that was clever, but I like the governor idea even better.

[Keith S]

 I think it somehow involved compressed air!

Peter in AZ

Peter, I think they call that particular system "Westinghouse"..

[IrishPeter]

The engineering department at the Skebawn and Castleknox has heard of Westinghouse brakes from our colleagues at the Castlederg and Victoria Bridge Tramway. Apparently they were the first in Ireland to use it. It must have been moderately hellish fitting two locos and about thirty pieces of stock with the equipment in the workshop (read: blacksmith's shop) at the back of the engine shed in Castlederg.

I seem to think the compressed air method used the regulator out of a wind-up phonograph. An axle drive air pump pushed air into a cylinder which operated a brake drum inside a box van. Clever - but if you ask me a bit too clever!

Peter in AZ

[MDLR]

Instead of a centrifugal governor, you could use a pair of vanes on a shaft (like they use on musical boxes to get them to run at a constant speed) - this would be a lot easier to make!

[mhlr]

In one of my books, I think 'Garden Railways in Focus' or something, I read a discription of a Roundhouse Bertie with a tender, and the tender housed the mechanism out of a rotary dial telephone to limit the speed. That sounds like a good idea, and thinking about it, when you try to turn the dial on the telephone too fast it doesn't let you...

[garrymartin]

In one of my books, I think 'Garden Railways in Focus' or something, I read a discription of a Roundhouse Bertie with a tender, and the tender housed the mechanism out of a rotary dial telephone to limit the speed. That sounds like a good idea, and thinking about it, when you try to turn the dial on the telephone too fast it doesn't let you...

I recall this too but it didn't give an account of how to construct it. Old phones are not so easy to find too, at least not at prices where you would sacrifice one, but the basic idea must be able to be reproduced.[/img]

[Keith S]

I have a magazine which shows how to build a "skype" phone out of one of those old bakelite rotary phones. If I find one, that is what I will do.

I don't think a Watt's governor would be all that difficult to build. It wouldn't need to have the same degree of precision or "fiddliness" that a steam one would.

If you were too clever for your own good, and had a "computer" radio with the ability to mix channels, you could even build one into a tender that would signal the loco's regulator servo, instead of brakes.

Of course, my engine is manual and I like it that way so I would go with the brakes. It's more elegant. (to me...)

[Crayfish]

In one of my books, I think 'Garden Railways in Focus' or something, I read a discription of a Roundhouse Bertie with a tender, and the tender housed the mechanism out of a rotary dial telephone to limit the speed. That sounds like a good idea, and thinking about it, when you try to turn the dial on the telephone too fast it doesn't let you...

You're right. After googling rotary dial governors they seem like the ideal part to use for such a device. It could be mounted vertically so you would simply need a chain from the axle to the governor mounted just above. I will have to keep my eyes open at car boot sales for old rotary phones.

[METHSSNIFFER]

Why not fit radio control to your locos!

[IrishPeter]

Some of us just plain old don't like R/C. For me it makes the experience of running a garden railway too much like running electric rats inside. Also R/C has a habit of 'dumping' at unfortunate moments, even though it is more reliable than it used to be.

Also, if you go back to meths days, which your name suggests you do, you will know someone who has given a servoa Viking funeral!

Peter in AZ

[Narrow Minded]

Some of us just plain old don't like R/C.  For me it makes the experience of running a garden railway too much like running electric rats inside.  Also R/C has a habit of 'dumping' at unfortunate moments, even though it is more reliable than it used to be.

Also, if you go back to meths days, which your name suggests you do, you will know someone who has given a servoa Viking funeral!

Peter in AZ

Words from a fellow "Burned Finger Brigade" member - I don't want to spark this one off again (though I'm sure it will, if not now, then before too long), so I won't add my comments other than "ditto"