Lenz BM1

[JST]

I am thinking of fitting the Lenz BM system when I complete my branch line having looked at Everard Junction's installation and liked it. I have looked at the Lenz manuals, but still have a couple of questions before I venture down this path.

 

The first is why does the unit have to be fitted to the right rail? I am happy to accept this but just want to understand why and what is going on. Does it make any difference which rail is positive/negative and does it matter which way the red and black wires to the decoder are connected?

 

Secondly, whereas I understand that Lenz decoders are a requirement (unless you tell me otherwise)  but I do not have a Lenz controller. I am using a Hornby Elite and Railmaster, is this compatible?

 

Any other hints on fitting (or not) would be helpful.

 

Thanks

 

John

[RAF96]

You can use any NMRA compliant DCC controller that can change CVs as you need to do some setting up of the ADCC capable decoder. The Hornby Sapphire decoder also supports ADCC.

 

You can easily make your own BM1 equivalent, its only a set of five diodes in series with a tapping dividing the ring into 1 and 4. I have made several and there is a veroboard scheme in my gallery on this site.

 

The right hand rail rule from memory is to produce a positive bias in the DCC signal when the loco is travelling forward in the direction of travel, which the decoder understands and reacts to. It also allows a loco to back out of a ‘rail-break’ section depending upon the decoder setting being uni or bi-directional.

 

All explained nicely on Lenz ADCC webpage.

 

The BM2 and 3 modules are not as easily replicated.

 

Rob

[Ray H]

You can attach the BM1 to either running rail although if you plan to use more than one with the same trains then it may be advisable to attach them to the same rail. That said, it is a bit horses for courses and dependant on the overall installation.

 

CV 27 on Zimo decoders is the one to set it up.

 

Zimo decoders will definitely work with the BM1 modules - or at least they do with our home made ones.

[NickC]

In my opinion Zimo decoders implement ABC better than the Lenz decoders and work with both BM1 units and home made units.

[JST]

You can attach the BM1 to either running rail although if you plan to use more than one with the same trains then it may be advisable to attach them to the same rail. That said, it is a bit horses for courses and dependant on the overall installation.

 

CV 27 on Zimo decoders is the one to set it up.

 

Zimo decoders will definitely work with the BM1 modules - or at least they do with our home made ones.

 

 

Thanks Ray. For complicated reasons I wanted to fit them to the left rail so if it makes no difference that is fine by me. Also good that I can use Zimo decoders. I suppose it it is irrelevant now but I still wonder why Lenz specify the right rail. I take what Rob says about it but I still don't understand the electronics of it.

[Ray H]

Basically, the voltage across a diode drops by approx. 0.6 volts. Because DCC is similar to an AC signal, where the voltage swings from "+" through 0 to "-", it is possible to moderate the swing either on the "+" or the "-" part of the cycle by using diodes. The fact that the diodes are only connected on one rail means that the swing is moderate on only one rail and the decoders can "recognise" that difference (and which rail it applies to) and re-act to it.

 

Probably not the correct terminology but I hope that gives you an idea of how it works. I'm sure someone will come along in a bit and explain it better than me (and probably correct where I've gone wrong in my understanding).

[Suzie]

You can fit a BM1 to either rail, but it has to go the other way round if not following the Lenz advice. They are just trying to avoid confusion.

[jpendle]

The rught hand rail is determined by the loco’s direction of travel.

 

If your track is aligned north/south and the BM1 is connected to the East rail then trains travelling North will stop, trains travelling South will not stop.

 

I suggest you try the BM1 out on a piece of plain track before fitting it to your layout.

 

Regards,

 

John P

[trevora]

The rught hand rail is determined by the loco’s direction of travel.

 

If your track is aligned north/south and the BM1 is connected to the East rail then trains travelling North will stop, trains travelling South will not stop.

 

I suggest you try the BM1 out on a piece of plain track before fitting it to your layout.

 

Regards,

 

John P

On ZIMO decoders at least you can set left / right or both rails to suit what you need

trevora

[JST]

The rught hand rail is determined by the loco’s direction of travel.

 

If your track is aligned north/south and the BM1 is connected to the East rail then trains travelling North will stop, trains travelling South will not stop.

 

I suggest you try the BM1 out on a piece of plain track before fitting it to your layout.

 

Regards,

 

John P

 

 

 

Good plan!

[colpatben]

The right hand rail is determined by the loco’s direction of travel.

 

Regards,

John P

Is this true if the train is Push/Pull will the same ABC stop the train as direction of travel is the same but the loco is either travelling forward or reverse?

 

Using Zimo decoder and ABC to stop at a station, if the train is travelling with the loco leading and the stop distance is 500mm for it to stop at a platform, when the loco is pushing the train tender first the ABC will still trigger the decelerate to stop sequence but as the stopping distance is still 500mm then the whole train stops further up the platform, or even overun as the loco stops in 500mm

 

How could you make the same train stop within the station in both scenarios?

[Guest]

Some manufacture do support ABC technik like ESU, Zimo, D&H and Lenz.

In theirs decoder there is a CV adress to set the brake by use brake modul.

With ABC you can even use both direction on the same track when the signal show stop one way.

Edited January 13, 2019 by Guest

[Nigelcliffe]

Is this true if the train is Push/Pull will the same ABC stop the train as direction of travel is the same but the loco is either travelling forward or reverse?

 

Using Zimo decoder and ABC to stop at a station, if the train is travelling with the loco leading and the stop distance is 500mm for it to stop at a platform, when the loco is pushing the train tender first the ABC will still trigger the decelerate to stop sequence but as the stopping distance is still 500mm then the whole train stops further up the platform, or even overun as the loco stops in 500mm

 

How could you make the same train stop within the station in both scenarios?

 

With a little more complexity in the design of the stopping module (ie. its a bit more than 50p of diodes).  

Is the question a real one, or just an academic "nit-pick" ?  If its real, I'll outline a solution.

 

- Nigel

[Suzie]

It is the direction of travel that is used - not which way the train is facing.

 

The stopping distance is related to when the last vehicle which links track power in to the stopping section gets in to the stopping section - so if you have a train with lit coaches it should not matter whether it is pushing or pulling. If just the loco has pickups it probably will only work going in one direction.

[RAF96]

I think I already said somewhere that BM2/3 are a bit more than a DIY lashup on veroboard.

There was a guy in France who had reverse engineered the BM2 and demoed it on Utube a few years ago.

Rob

[jpendle]

It is the direction of travel that is used - not which way the train is facing.

 

The stopping distance is related to when the last vehicle which links track power in to the stopping section gets in to the stopping section - so if you have a train with lit coaches it should not matter whether it is pushing or pulling. If just the loco has pickups it probably will only work going in one direction.

Hi Suzie,

 

I haven't tried this but I would have thought that the loco, as it has the decoder, would have to be in the section before the BM-1 (Assymetric DCC) would have any effect, unless the lead coach is connected electrically to the loco?

 

Regards,

 

John P

[colpatben]

With a little more complexity in the design of the stopping module (ie. its a bit more than 50p of diodes).  

Is the question a real one, or just an academic "nit-pick" ?  If its real, I'll outline a solution.

 

- Nigel

Nigel, no this is related to a reply from MarkW Post #4 on a thread that I started yesterday regarding changing to full automation using Digikeijs

 

http://www.rmweb.co.uk/community/index.php?/topic/141240-digikeijs-detection-for-automation/

 

‘An alternative option is to stick with the RocRail time based programming and add a Lenz BM1 or homemade equivalent to give the accurate stopping location.’

 

I hope that this may provide a solution to stopping the trains on this project.

 

https://www.ngaugeforum.co.uk/SMFN/index.php?topic=38977.msg501598#msg501598'> Bexhill West to Crowhurst via Sidley  

 

I thought that this thread was a better place to ask the question, if there is a workable solution then I would seriously consider it.

 

Many thanks

 

Colin

[Nigelcliffe]

Hi Suzie,

 

I haven't tried this but I would have thought that the loco, as it has the decoder, would have to be in the section before the BM-1 (Assymetric DCC) would have any effect, unless the lead coach is connected electrically to the loco?

 

All of the pickups on the train have to be in section before the BM-1 has any effect.   Whilst there are wheelsets with pickups across the electrical rail gap, those wheelsets+pickups are bypassing the BM-1 unit, and setting things to "run normally".  

 

So, for a single loco, as its wheels cross into the section, it only "sees" the BM-1 effect when the last pickup wheels enter the section.  But, if pulling a train with pickups for lighting (or any other purpose, including not-connected, just pickups between wheels), then as the first wheel of the first vehicle enters section it temporarily restores full power (BM-1 bypassed) so the loco goes back to full speed running (cancel brake operation).  As a complete coach gets into section the loco begins braking again (BM-1 is active, nothing by-passing it), until the next coach starts to enter section when the BM-1 is by-passed, etc.(repeat many times).... until the full train is in section. 

Whether full speed is restored on each vehicle entering/leaving section depends on the acceleration settings for the loco, but in most cases it will go back to full running speed.

 

 

(Might be enough for Colin's question as well)   For completely reliable "stops exactly" arrangements, either for push-pull working, or if trains might have pickups on coaches or wagons, it may necessary to place a spot sensor inside the brake section.  Until the train reaches the spot sensor, there is no braking section active.  Once the spot sensor is triggered, the BM-1 is no longer by-passed.  Provided sections are long enough, and the spot far enough into section, the entire train will be in section before the BM-1 is active, thus stopping will be calculated from the spot sensor.      The spot sensor needs to act to latch the BM-1 to "active" until such time as the brake section is cancelled by another operation elsewhere. 

 

 

Hope that helps.

 

- Nigel

[colpatben]

Nigel, AHh Lightbulb moment .

 

In my case the fixed rakes of Dapol Maunsel coaches (light bar ready so bogies are conneced) will each bridge the gaps until the complete train enters the ABC section. So it doesn't matter wether the train is going forward or pushing tender first the braking distance is the same as the whole train has to be past the rail break before the rail voltage drops to trigger ABC.

 

Thank you so much.

 

Colin

[Sir TophamHatt]

So in laymans terms:

 

If I purchase two of these and put them at two ends of a piece of track, program something in the decoder, it'll happily travel between them both?

 

How does the train know how long to wait before returning?

How does the decoder know how fast the train should travel?

[Nigelcliffe]

So in laymans terms:

 

If I purchase two of these and put them at two ends of a piece of track, program something in the decoder, it'll happily travel between them both?

Yes, though they need to be in different rails, and connected the correct way round. Follow the manual about which rail, orientation and direction of train into the stop section.

 

The decoder needs to support the "shuttle" feature, not just asymmetric braking, which means "Lenz" (and just maybe one Hornby decoder).  

You can turn the shuttle on/off by an ops-mode CV change, or if the BM1's are bypassed by a switch they don't influence the train if it is driven manually. 

 

How does the train know how long to wait before returning?

How does the decoder know how fast the train should travel?

 

Delay time at the end is a setting in a CV in the decoder. As are acceleration and deceleration rates.

Speed of train when moving is what you set on a throttle to make the train move.

 

Because of the nasty way Lenz implement constant stopping distance, I found it better to ignore constant stopping, and instead set a suitable deceleration value in CV4, and run the train at about the same speed each time the shuttle is used.

 

 

 

[Sir TophamHatt]

Hmm.

That's a shame as the train I planned to use is now a Zimo

 

Just means I'll have to get another loco I suppose!

Edited January 16, 2019 by Sir TophamHatt