Reverse Loop problems

[tanj666]

Hi all,

 

I have a DCC controlled dogbone style layout, with reverse a Hornby reverse loop module controlling both the return loops.

 

Every thing works fine for normal trains. The problem I have is when I use my GWR Diesel Railcars. They stop dead at the loop entry points every time. The RLM starts flashing and I need to cut power, move the loco by hand, re-apply power and then I can carry on playing.

 

My controller is a Digitrax Super Empire Builder. The trackwork is all standard Hornby, with the little DCC power clip things on the points. All the points are managed by ZTC point controllers. Generally I run one loco round the track while I move something else in the stations goods yard.

 

Anyone got a clue whats wrong? And more importantly, what I can do to make it work better?

 

Cheers

 

Anthony

[Weekday Cross]

It sounds more like a problem wwith the railcars than DCC - are the back-to-backs on the railcar wheels correct? Do they run Ok on other pointwork on your layout?

[tanj666]

It sounds more like a problem wwith the railcars than DCC - are the back-to-backs on the railcar wheels correct? Do they run Ok on other pointwork on your layout?

 

Hi,

 

Yes they run really well everywhere else on the layout, very smooth at all speeds. They don't even seem to notice the things like crossings.

[noiseboy72]

Is the current consumption with them higher than your other locos ? The detection of a short should cause the module to switch, but on occasions they can just shut down. Try the other switch posiiton as it alters the switching sensitivity.

[HLT 0109]

Hi all,

 

I have a DCC controlled dogbone style layout, with reverse a Hornby reverse loop module controlling both the return loops.

 

Anthony,

 

Do you use a separate reverse loop module for each reverse loop or make one RLM work for both loops? In theory you should have one for each loop but I am not sure if that is the answer. You could try disconnecting one of the loops from the RLM and see if the railcar then crosses the entry point of the other; if so, then reconnect that loop, disconnect the other and repeat the exercise. I had three Hornby RLMs in use and had similar problems. Hornby pointed out that the RLMs have a switch to choose either the Select or the Elite controller. They suggested changing the setting as one has a quicker response than the other so that might be worth trying. In my case it made no difference.

 

In the end, I changed all but one of my Hornby RLMs for Gaugemaster ones but I found other contributory causes: if you have any dodgy electrical connections, the RLMs are unreliable (not specifically Hornby's) - eg if you are relying on the fishplates for any rail connections within the reverse loop they could be making intermittent contact. I have found that, if you get any break in electrical contact while a loco (or lit train) straddles the isolating fishplates, a short will be triggered - in fact, a short will be indicated if you stop a loco straddling them.

 

I hope there is something helpful in this.

Harold.

[Suzie]

I suspect that your railcar is not succesfully shorting the reverse loop section break in order to fire the reverse loop module. Improving the pickups on the railcar should help, you really need to ensure that both axles of the leading or trailing bogie have good pickups on all four wheels. If your railcar has traction tyres on one side of the power bogie you may find it will work better when run round the loop the other way, or possibly reversing the track connections of the reverse module might help if it is the type that only detects shorting on one rail. This problem is sometimes seen where steam locos have one side of the pickups on the tender only, the train will stop with the loco in the loop and the tender outside the loop - in this case you need to add extra pickups to the other side of the loco.

 

If your dogbone has just a simple loop fed by a single point you could simplify your wiring a bit by removing the point clips and the insulated joiners on the frog rails. That way changing the point will force the reverse loop module to switch before the train gets there, which should completely eliminate the problem - just remember to change the point before the train exits the loop!

[tanj666]

All,

 

Thanks for the replies. A lot of good suggestions there.

 

I've taken this afternoon of work to try them as they can't all be tried in my lunch break.

 

To answer some of the questions:

 

I'm using a single RLM right now. It does 'click' when the railcars enter the sections, but its a click of motion death not just the relay working. I've read other forum messages about RLM's. I think I may replace the Hornby one with a DCC Specialities model as that's all solid-state. I can use the Hornby on my N gauge layout which actually works a lot better (it's DCC too, using Kato unitrack, all sections individually powered).

 

Get back to you soon with some results.

 

Cheers

 

Anthony

[Glorious NSE]

I think Suzie probably has it - if the railcar has electrical pickups from one side only on each bogie (and lots of Lima stuff was set up like this) then when the first bogie crosses the break there is no complete circuit to the motor on one side of the break, and no circuit to the motor on the other side of the break either, so the motor is not being powered and it stops moving.

 

Add pickups to both sides of one (or ideally both) bogies and it will work.

[tanj666]

All,

 

The plot thickens.

 

I have two railcars, an older one (probably a rebadged Lima though from a Hornby box) which has no tyres. A newer Hornby one which has traction tyres on only one bogey and on one side. Oddly this bogey still gets power despite the tyres. I tested it one bogey at a time on the test track.

 

I tried removing the power clips from all the points that connect the two tracks. That left me with 4 power zones ;-) which didn't help much at all.

 

I shorted two of the isolating section (one either end). That didn't help either.

 

The engines actually started going backwards and forwards on the remaining isolating breaks.

 

Both front and rear bogies pick up power, both also are driven.

 

If I cut another isolating sectio, about as long as the engines themselves and wire this into the RLM as well (I'll add a second RLM to handle these sections) do you think that might work?

 

cheers,

 

Anthony.

[noiseboy72]

Try moving the isolated reversing section away from the point. It should be longer than your longest Train (Not ust the loco), but does not need to be next to the point. Anywhere on the loop is fine.

 

As Suzie says, pickups need to be opposite each other on the loco for any RLM to work correctly.

 

Save your time (And Money!) and look at re-wiring the loco rather than looking for fixes to the layout which is unlikely to work.

[melmerby]

 

Both front and rear bogies pick up power, both also are driven.

 

Anthony.

 

I don't understand what you mean. Surely only one bogie has drive?

I have a Lima GWR DRC and it only picks up on one side of each of the bogies.

 

Keith

[tanj666]

All,

 

Sorry to be away from the topic for so long, lots of problems and not much time.

 

I tested my locos in all directions, with/without traction tyres etc. I even put two module controlled section of track next to each other with the track feeds reversed (so a kind of double reverse if you like)

 

No matter what I did it still would not work. The railcars just stopped.

 

SO I chickened out, and make the layout into a merry g round instead and removed the need for reversing loops.

 

So thanks everyone for the suggestions, I tried everything but it was beyond me and the simple Hornby RLM's I have.

 

Instead I have put the RLM's onto my N Gauge layout which has a working dog-bone. Again the railcars I have on there have a little panic when they reach the RLM sections, but overall the problem solution is simpler - they just need to be going in the correct direction round the reversing loops.

 

The suggestion to remove the traction tyres actually turned out to be the solution to a Hornby 14xx engine that was causing problems, it wasn't getting enough power. Luckily I had another broken 14xx, which I swapped a set a wheels with to leave me with 4 driving wheels with no traction tyres. The loco runs quite smoothly again at last - first time since I converted it to DCC! So big thanks for that suggestion Suzie.

 

Cheers

 

Anthony

[Crewlisle]

On my 00 gauge layout 'Crewlisle' I use the Lenz system with an LH90 controller and on my reversing loop use a Lenz LK100 Reverse Loop Module. When I first tried the reversing loop I found that at the entrance some of the larger locomotives shorted out and shut the whole layout down. As soon as I removed the offending locomotive, everything was restarted. I had noticed that there was a lot of ‘chattering’ of the relays inside the electronic LK100 Reverse Loop Module when this happened. Reading the manual, I found that there was an adjustable potentiometer (a voltage divider) on the side, which is factory set at the 12 o’clock position. With a small screwdriver, I moved it to the 1 o’clock position. Since then, I have had no more shorts on the reversing loop.

 

Has the Hornby unit got an adjustable potentiometer like the Lenz system? I don't think the loco pick ups have much to do with the problem; it appears to be a Hornby control problem. I have 42 locos of which half are steam. They are a mixture of Mainline, Hornby, Airfix, Lima and Bachmann with no mods to the pick up arrangements with Hornby, Bachmann, ZTC and ESU sound decoders and all run smoothly over the whole layout.

 

[HLT 0109]

The Hornby module only has the two-position switch I mentioned in my earlier reply but I found it made no difference. However, last week I installed a further reverse loop in my layout and used a Hornby RLM that I had previously replaced with a Gaugemaster one because of problems - in its new position, it has worked perfectly so I think my earlier problems were imperfect electrical supply to the track. I now have two Hornby RLMs and two Gaugemaster ones working perfectly with NCE Powercab.

[tanj666]

All,

 

It's been a while since I posted about this. I tried various things including a continuous loop of track for a track (boring watching trains go by).

 

I ended up witht the same problem on N gauge with Farish railcars too. Same Hornby RLM's. So I spurged out on the cheaper, smaller, cuter but uncased Digitrax RLM. This is excellent. It has the variable potentiometer mentioned above and can be set for the trigger voltage to prevent double-triggering.

 

It works so well that the Hornby RLM's are now relegated to the turntables as someone said a RLM would be handy there on a DCC system. No problems so far.

 

Cheers for all the helpful comments. I am actually cracking on with my planned layout - which has obviously changed a few times over the months - which is based on the old St Agnes, Cornwall station, the Wheal Liberty Viaduct and some place to play shunting.

 

Cheers

 

Anthony.

[HLT 0109]

Thanks for the update Anthony - it is always interesting to see how a problem has been resolved. Glad you've found a use for the Hornby RLMs too and that you are making progress with the layout.

 

Harold.