Model Railway Forum

Hi I'm looking for some help, I have a reverse polarity problem on a wye shaped section of track effectively triangle off the main loop., I've fitted a Block Signaling Rev1 autoreverse module . I have a 1 metre isolated track section which my 0-6-0 locos cross without issue. My problem is my 4-4-0 and 4-6-0 locos trip the module before leaving the isolated section. My dcc system is a z21 and I've used 2.5 dial 5amp wiring for both the main bus and wiring the Rev1. I'm at a loss as to why the Hornby TTS locos cause the auto reverse module to trip out.

Hi
With any auto reverse loop or Wye, the length between incoming and exiting pairs of IRJs needs to be longer than the longest complete train (loco and all carriages and wagons) that can pass over that section. Are you running trains or just light locos?

Secondly, the RLM (Reverse Loop Module) must trip at a lower current threshold than the main DCC system e.g. Main system rated at 4.0Amp RLM operates at 3.0Amp or lower. If your DCC system has a low current output, such as around 1.0Amp to around 1.8Amp you will be hard pressed to find many RLMs that will operate satisfactory with the DCC system. This is why the Hornby RLM has a selection switch e.g. Select = 1Amp or Elite = 4.0Amp

Finally, double check there is no other rail feeds to the isolated loop rails other than what comes from the RLM output.

For a Wye configuration your loops section needs to be like this.... https://www.brian-lambert.co.uk/DCC%20T ... wiring.gif
Text not shown in teh link... A Reverse Loop is also formed where a Wye (Y) track configuration is used. Here the easiest way is to feed the single line or tail end of the Y track from a Reverse Loop Module and then install a pair of IRJs at least the longest trains length away from the Y IRJs.
Notes shown in the text for the drawing...
1) Where Insulated frog points are used the two IRJs shown in the straight through track at the bottom are not needed.
2) If the top track is a dead end siding etc the two IRJs and the two rail feeds from the main DCC console are not needed.

Thanks for your reply my z21 is rated at 3 amps the Rev1 module.is quoted at 1.75amps as stated smaller locos are not a problem so I assume that isolators and track work are ok.