The Patiala State Monorail Trainways

[Stubby47]

If you are only running one loco , then you only need maybe 3 or 4 switches, connect more or less alternate sections in parallel. Then either sense the loco position and operate switches accordingly, or have the switching linked to the speed/direction of the speed/direction controller.

Ray,

This sounds more complicated. I'm not sure how to 'sense' the loco and have no idea how to link the switches to the speed.

 

As this is a fun project, I want to keep it as low cost and simple as possible - I'm hoping a cheap dc controller and an X04 motor will be sufficient, with the magnets swapping the track polarity whatever speed is used.

Stu

[raymw]

Hi Stu,

 

You could use reed switches to sense the loco position, but they may not be capable of providing the power required to run the loco. If reeds are too insensitive, then hall sensors, photo cells whatever could do the detection. I was trying to make the point that you do not need to switch each section of track individually, which could require a number of more expensive relays, but that you can connect more or less alternate (every third, I think) sections together, which would only require 3 relays.

 

A simple linking to the speed. Have two controllers, (assuming dc, not dcc). Use one to control the loco speed/direction. The other one controls another motor, which, say, turns a rotating disc with a magnet to switch in sequence three reed relays (driving heavier current rated relays if needed) connected to the track sections. You vary the speed by adjusting both controllers. you could possibly connect both controllers together with a simple pulley system/whatever. Trying to avoid anything too complex, here. I am concerned about the price and difficulty in finding reed switches that will do the job as you describe, unless you have them stashed away somewhere.

 

Have you built any of it yet?

 

Best wishes,

 

Ray

[CourthsVeil]

Hi Stu,

 

You could use reed switches to sense the loco position, but they may not be capable of providing the power required to run the loco. …

 

… Trying to avoid anything too complex, here. I am concerned about the price and difficulty in finding reed switches that will do the job as you describe….

 

 

 

Thanks for the clarification, Stu.

 

 

 

 

An intriguing adventure this is! Made me ponder about it quite a while.

 

Me thinks, Ray is correct in analysing the problems, but maybe a simpler solution is feasible…?

 

I see two different setups:

one like you (Stu) propose with the positive charge wandering with the loco around the length:

 

 

 

At another setup the track sections would be charged in an alternating manner: all even sections connected as well as the odd ones (this is similar to Ray's proposal). Each time the loco enters a new section the polarity of all sections would be switched:

 

 

 

Now I imagine the following:

First: use only one loco wheel for power pick up (a 1:35 loco should be heavy enough to ensure good contact). Thus only one section needs to get the correct polarity:

 

 

 

Second: Insert short isolating sections to prevent arcing (in the pic above: grey). Please the loco by providing a hefty flywheel (gold caps etc. could be used, but they are good for them DCC/sound people; we in this topic here are keen on KISS solutions and frown on this electronickery        – mechanics it is!       ).

 

Thirdly: Use just one small magnet near the leading wheel (see pic again). Which requires latching (bistable) switches…

Why that? Because it appears to me to be very difficult to adjust the length of the magnet line to the distance of the reed sensors. Not the physical length, rather the range of its effect… Much more problematic to get the grip on.

If those intervals differ, the polarity changes will be out of sync, resulting in either a short or power off…

Therefore I would prefer a small magnet providing just a pulse to toggle the relay.

 

 

The solution #1 looks like a simple circuit: just one bus connecting the switches (parallel):

 

 

 

Not so nice: all the reed switches must be “Single Pole-Double Throw” variety in order to change polarity. Such switches should be able to manage more than 250mA (Stu wants to run a 1:35 train). Or I would have to attach to each Reed a Relay… Now: the few SPDT-reeds handling more current I found cost a lot more (chea­pest: 2.9 LWT^*)      ! EACH !    Triple the price of simple reed switches)

 

 

This annoyance is avoided by solution #2. All the even reeds are connected in parallel, the same manner the odd ones are connected – this makes one bus. This bus leads to TWO latching SPDT-relays (pink in the following pic) which are wired opposite. Both relays together provide the track cur­rent by means of a common bus: one relay feeds the odd sections, the other the even ones:

 

 

 

This all looks rather complicated, but ImhO it isn’t:

– a row of some 30 simple, cheap reed switches,

– two buses instead of one

– plus two relays.

The additional cost of the latter is much less than the cost of many SPDT reeds.

Oh, nearly forgot that sol. #2 requires a power source for the reed bus – a 4.5V battery will do and that's what the reed contacts like (instead of ~1A track current).

 

 

Hmmmh… … Should I put my current micro layout aside for a while and make a simple experimantel rig to explore what I have concocted?

For example: a length of standard track, one rail cut into sections (the other just to keep the wagon upright). Reeds and relays as above, solution no. 2.

A small (oldish and idle) wagon (metal wheels !) provided with wipers at one side, neodym magnet below.

On top a LED, replacing the motor.

And all powered by a 1.5V battery…

Push the wagon manually along the track – as long as the LED is alight…        

 

Now, this became quite a lengthy article      

I'm curious about your opinions.

 

Regards

   Armin

 

 

 

^*) Laughing water tokens – don't want to argue about/with Sterling or Euro, you know!

 

edit: last drawing could be misunderstood – replaced it.

Edited September 29, 2015 by CourthsVeil

[Guest Lyonesse]

Yep, sectional track with reed switches & magnets.

 

I thought about radio control with batteries and using the road, but the planned solution is, I think, easier...

 

reed_switches.gif

This is similar to the electric go-kart system on the pier at Weston-super-Mare.  That picks up power from steel floor panels, alternatively energised +ve and -ve.  Conection to the traction motors is via a fairly simple arrangement of brushes and diodes.

[Barry O]

Stu

 

having talked to you at Halifax yesterday I now confirm that you need to have a lie down in a dark room!  (can't you just us e the roadway as a second "rail"?

 

baz

[Northroader]

Mumble, mumble, stud contact, mumble....

[uax6]

I agree, either use the road surface or put some small studs in on one side, you will hardly notice them...

 

Andy G

[Satan's Goldfish]

Stu

 

having talked to you at Halifax yesterday I now confirm that you need to have a lie down in a dark room!  (can't you just us e the roadway as a second "rail"?

 

baz

Was about to suggest the same thing but with a slight difference. Make the road out of a nice conductive material, thin coat of paint to make it road coloured, then treat as standard 2 rail DC operation with something like a Relco track cleaning unit. The DC on top of the AC signal should hopefully not see the capacitance created by the paint and keep things running (other RF AC producing devices are available!)

[uax6]

If you chemically blacken the copperclad it should still conduct shouldn't it?

 

Andy G

[raymw]

I think you guys advising stud contact, using road, batteries, etc. are missing the point. That would be too obvious and easy. A bit like wanting to run a marathon, but using a car - the journey is the destination.

[uax6]

Actually aren't we asking the wrong question here? What were the road surfaces actually made of in India back in the teens and twenties? Were they mcadamed at all? This could have a fundimental effect on the way the train behaves too...

 

Maybe for the road surface you could lay blocks of carbon?

 

Andy G

[CourthsVeil]

I think you guys advising stud contact, using road, batteries, etc. are missing the point. That would be too obvious and easy. A bit like wanting to run a marathon, but using a car - the journey is the destination.

 

A shame that it is not possible to hit the AGREE button more than once!

 

Stu has made it quite clear to anybody who can read:

 

It's one of those ideas that's been nagging at me for many years.

When I was at school we built a robot that could follow a single white line on the floor. This railway seems to be in the similar vein, a very simple idea but fascinating at the same time.

I also feel I now have the modellng skills to do it justice, not just the buildings and scenery, but the loco and rolling stock too.

Time will tell....

 

Regards

   Armin

Edited September 29, 2015 by CourthsVeil

[Mike Riley]

Actually aren't we asking the wrong question here? What were the road surfaces actually made of in India back in the teens and twenties? Were they mcadamed at all? This could have a fundimental effect on the way the train behaves too...

 

Maybe for the road surface you could lay blocks of carbon?

 

Andy G

The Patiala monorail was built to replace mules (it was primarily a freight system).  The roads at that time would not have had bituminous surfacings - probably natural gravel or water bound macadam at best.  The preserved example at the railway museum has a concrete strip for the outrigger wheels which the original would certainly not have had.

 

I will be following Stubby's progress on this project with interest.

 

Mike

[awoodford]

Actually aren't we asking the wrong question here? What were the road surfaces actually made of in India back in the teens and twenties? Were they mcadamed at all? This could have a fundimental effect on the way the train behaves too...

 

 

According to the Day article...

 

"The road itself, like many Indian roads in the flat country, was for the most part on a raised embankment to keep it clear of the water when the surrounding land is flooded. According to a sketch provided by Mr Bowles, the embankment was 20ft wide at road level and the centre strip, about 8ft wide, was metalled. This left soft 6ft shoulders at each side of the metalled strip. The monorail was laid on one of these shoulders so that the balancing wheels ran along the edge of the metalled surface, leaving all but six inches or so of it clear for other traffic."

 

The Ambler article mentions there were issues with the road wheels wearing the road surface. Also he says of the closure, "The road seems to have been too good for the health of the monorail and one's guess is that the rapidly-growing competition of road traffic made it not worth while to get over these other difficulties."

 

Alan.

[Stubby47]

Gents,

 

Wow - thanks for all of your posts - very much appreciated.

 

Thanks for all the alternative suggestions for current collection, operation and wiring options - I'm having to re-read several to make sure I understand them (did lightly skim read whilst away at the weekend).

 

Despite all of the options, I'm still not convinced that my reed switch idea won't work.

 

In no particular order, and these are my opinions and have no basis in fact, practical application or anything else ...

 

Stud contacts - I think these will be too obvious, plus when used between two fixed rails the contact distance can be reasonably consistent. As the outrigger wheel will be running on a set of strips of 'stone', even if I add some suspension to the wheel, the contact with the studs would be variable. 

 

Batteries & r/c - I did seriously consider this, but would really want to have a variable speed controller - all the cheap r/c cars I have are on/off. Plus the battery power doesn't last for long (an hour or so continuous running ?? ) so there would need to be a large supply of re-chargeable batteries and a simple way of replacing them in the loco.

 

Ray's idea of sensors and a second controller seems very plausible, but is probably too complex for what I want to aim at.

 

Likewise Armin's detailed explanation & diagrams - you have clearly spent sometime thinking about this. I do need to re-read this again. 

 

Using the road wheel as the 2nd contact - even with both road wheels (the loco and coach), I still feel this is too problematic due to maintaining contact. Also, the stone blocks will not look like stone, which is part of the aesthetics I'm aiming at. 

 

 

Overall, yes, the cost of the SPDT reed switches may be prohibitive in the end. I'm also re-thinking about making sure the sections are not switched negative under the loco wheels, so the length of the magnets is important - I also think this will prevent the coach being the only switched polarity, as the magnets will need to extend back beyond the collecting wheels. I also realise where the magnet is placed in relation to the section (start, middle, end) will have some bearing on the process.

 

As yet, I have not made any physical start - I think the first step will be to use a circle of set track and some reed switches and have a play.

 

But seriously, gents, thanks !!

[uax6]

One thing to be aware of aswell with the reed switches is how you lay them. You will probably find that they will have to lie transversely with the contacts placed dead in line, so the magnets will pull them up properly. Also the amount of current flowing in them will have to be watched too, as they will weld up very easily. (I found both of these out as a teenage when useing them for psudo track circuits...)

The reed system will work, but everything will have to be spot on..

 

How about a bit of lateral thinking. Could you manufacture a rail that has a contact at the top, and then an insulator and then the foot is contact again? Or better a rail that is split down the centre? Then a pair of jocky wheels (or strips) bear on the contact sides. Actually you would have to have the head insulated, so the metal wheels won't short it out. A sort of scalectrix inverted slot...

 

Andy G

[Echo]

There's always live steam! Compared with most solutions proposed so far, it sounds the simplest - and probably the most fun too ;)

[uax6]

A cut up Mamod tracion engine would fit the bill!

 

Andy G

[CourthsVeil]

The last drawing in my post #53 above could be misunderstood (in fact it contradicted to what I had written before). Therefore I replaced it by a correct one.

 

In the meantime it dawned to me that the two SPDT relays could be replaced by a single DPDT relay.

 

Regards

  Armin

[Stubby47]

First batch of reed switches ordered - £8.41 for 10  http://www.ebay.co.uk/itm/like/141745187091?clk_rvr_id=904088060508&item=141745187091&lgeo=1&vectorid=229508&rmvSB=true

 

 

BTW - More loco build stuff here : http://www.rmweb.co.uk/community/index.php?/topic/103277-scratchbuild-loco-challenge-psmt-no-4/

Edited September 30, 2015 by Stubby47

[dhjgreen]

I am eagerly awaiting news of large showers of sparks and clouds of blue smoke!!

[Stubby47]

Wheels have arrived, still waiting for the reed switches.

 

Smoke and sparks on order.

[Stubby47]

The first pack of SPDT reed switches have arrived - I need to swap to my extra-strong glasses.

 

Hopefully I can rig up a short test track this weekend to validate the theory.

[Mallard60022]

Stubbs....there's a challenge for an 'era' ......The Patiala monorail was built to replace mules ......... Now they would be hard to make look/sound realistic. Puts your 'era' into perspective really.

Looking forward to seeing your progress as I stroke a piece of loft timber on Saturday. (Sad boy I am........)

Phil

[Stubby47]

In my world ( don't come in, it's a very strange place) the PSMT is still running ( well, in truth it is again) - I've seen an Airfix kit for a VW Beetle which will look nice rusting in some weeds.