Light Engine Shuttle wiring

[jamie92208]

Can anyone help me with a problem that I need to solve. On my Lancaster Grren Ayre layout I am trying to construct an operating sequence that follows the working timetable. I have discovered that there were far more light engine movements on end end of the layout than the other. My solution will be to have a pool of 10 or 12 locos that spend their time shuttling between the loco shed and one end of the fiddle yard in sequence representing these movements. On arrival in the Fiddle yard they will go onto a centre track that rises up to a second level. My plan is to take out the existing turntable (I am reusing the fiddle yard from Long Preston) and replace it with a simple run round loop as in the diagram below.

 

 

I would like the sequence to work as follows:-

1) Incoming loco turns on Point A and stops behind loco 1.

2) Loco 4 moves forward to be ready to work back on shed.

3) Loco 3 moves forward to where Loco 4 was.

4) Loco 2 moves forward through point B into headshunt then reverses to where loco 3 was.

5) Loco 1 moves forward to where loco 2 was.

6) Incoming loco moves forward to where loco 1 was.

 

Ideally I would prefer this to happen automatically in order to reduce the workload on the Fiddle Yard Operator who will be quite busy with other things going on.

 

Points are operated by 12v motors, either tortoise or fulgurex so switching is easy.

 

Can anyone help with a wiring diagram or is there a commercially available unit that does this.

 

This will NOT have to cope with DCC EVER.

 

 

I use conventional 2 wire feeds to track sections and not common return and am quite happy wiring up latching relays if necessary.

 

Than ks in advance

 

Jamie

[Engineer_London]

Bit nervous [and surprised] at being the first responder to your question!

 

I believe the functionality you're after is quite reasonable and achievable with DC.

 

There are some key elements to the solution you seek - one is the automatic progress through the plain track sections, second is the automatic reverse in the headshunt, and third is the management of movements of incoming and exiting locos through point A - this may need some manual supervision of priorities through the single track approaching point A.

 

I know very little about commercial products, but there are certainly commercial electronic units which detect a vehicle and control its progress through track sections. One brand of control units uses infa-red detection and I've witnessed this working quite successfully. The Model Railway Electronics Group [MERG] has some detection units too, which are available to its members as kits.

 

I've seen at close hand an end-to end automatic sectioned shuttle, built for a display by a trader at model tramway exhibitions. The layout is identical to the one shown in your post. This uses MERG Superbloc control units for individual track sections on the double-track, plus some additional circuitry to do the automatic reversal at each headshunt. In this example, the points were sprung rather than explicitly operated. This setup runs quite a number of trams at modest speed, back and forth.

 

A few years ago, I wanted an automatic test track and demonstration for model trams and built a dogbone circuit which is fully automatic, 2-rail powered with 24 sections. It allows a queue of trams to follow one another at low speeds without intervention. I used well-established methods for detection and relay switching. I'm overdue to devise an end-to-end version, someday, so haven't done the extra piece of circuitry for headshunt reverse, but I'm confident it's not a big obstacle.

 

I would be happy to declare the circuits and principles I've used so far, if you're interested.

 

My caveat is that I'm not too familiar with steam locomotives, their pickup arrangements and drive, etc., and these factors will influence how the particular solution might work for you, especially governing section length and position of insulated joints.

[jamie92208]

Thanks for that I'll investigate the MERG I liked the look of the stuff they had on show at Warley last year. Management of the incoming and outgoing locos will be by the fiddle yard operator as he/she works through the sequence. I envisaged some sort of isolating section before point A where control would pass to the shuttle unit when the opertor initiated it and then the sequence would run automatically and loco 4 would end up on the isolating section ready to be despatched at the appropriate time. The locos geing mainly ex Midland ones will all be approximately the same size and most of the tender locos have tender pick ups. Operating the points via a lathing relay isn't a problem. The anology with tram layouts is one I hadn't thought of and fits perfectly. If the control voltage is set at the right constant level the locos will all start and stop virtually instantaneously. I will have to do some playing. It will be several months before I start constructing this part of the layout but I just want to find out what's acheivable.

 

Thanks again

 

Jamie

[Engineer_London]

Thanks, Jamie.

 

Sounds like you're well on top of the design issues, and absolutely right to get the control scheme worked out before starting construction.

 

Similar size locos and tender pickups is good news for this sort of control. Definitely check out MERG Superbloc as the basic control unit.

 

Thinking ahead, it may turn out that the only manual control needed will be on the berth occupied by loco 4 in the diagram. If the entry route through A is free, the automatic sections will simply accept a loco driven in, then take it through the cycle. Stop in the 'loco 4' berth [clear of the fouling point] by default, then manual override when the exit route is available. After it clears, all locos behind will shuffle up by one.

 

Would be interested to hear how you get on. In a few months, I might have got round to my own headshunt reverse circuit!

[Prof Klyzlr]

Dear Jamie,

 

It's not exactly what you're looking for, and it involves wiring adjacent loco-length "blocks" in opposing polarities, which is really counter intuitive,

 

but the posted pic below _does_ allow 2 locos to "shuttle past" each other on regular analog DC,

using a basic throttle and simple "dumb timer" reverser, as described on Rob Paisley's "Misc Electronics for Model Railroads" site

 

http://home.cogeco.c...toRevCheap.html

 

 

This schematic assumes you are using Electrofrog (metal frog) points,

but the same basic technique can be achieved with insulfrog points.

(just needs an additional diode on the "stop block")

 

For another application of diodes and dumb reversers, check this Youtube

 

 

and a PDF version of a now-collapsed geocities site

 

http://tinyurl.com/2g7rhfc

 

Hope this Helps...

 

Happy Modelling,

Aim to Improve,

Prof Klyzlr

[Brian]

Hi Jamie

You are asking for quite a lot of dc (analogue) automation!

 

You will need to divide the tracks into sections with insulated rail joiners fitted between sections.

To control each section and stop the approaching train in the required section and then start off the next train and set points etc. will involve several modules working together.

 

It is likely different locos / trains will not stop in exactly the same places. As variations in motors, gearing and the load being pulled will be different train to train making stopping different per train.

 

I would suggest you visit the Heathcote electronics web site and see what is available ready made and then possibly contact Clive Heathcote direct and ask him for his profession opinion on what he produces and could be used?

 

Heathcote Electronics

[Gordon H]

You are asking for quite a lot of dc (analogue) automation!

 

You will need to divide the tracks into sections with insulated rail joiners fitted between sections.

To control each section and stop the approaching train in the required section and then start off the next train and set points etc. will involve several modules working together.

It can be done with rather less hardware than you might think.

As this is a fixed sequence of movements, with essentially only one engine moving at a time, it becomes a matter of energising the individual sections in a particular order, with a detection circuit responding to the arrival of the loco in its next position each time. This only requires one shuttle/shuffle type unit and a few relays.

As a requirement, it is very similar to the demonstration unit I built last year for the MERG demo stand, which has three locos shuttling back and forth around a scissors crossover giving four headshunts, with one always empty for the next move.

 

It is likely different locos / trains will not stop in exactly the same places. As variations in motors, gearing and the load being pulled will be different train to train making stopping different per train.

There will certainly be some variation, but as these are light locos only, it should be manageable.

With a reasonably intelligent control system, the possibility exists for the system to measure and record how long each individual loco takes to make a particular move, so a certain amount of compensation can be employed if necessary.