R7277 - reverse loop advice

[Matthew -1221193]

Hi all,

First post on here :)

I’ve seen a number of posts related to the reverse loops in R7277 but all the links have stopped working.

Any suggestions?

[Chrissaf]

The whole Hornby website and the forum was recently transferred and remodelled on a new hosting company service. Many links in old historic posts and threads have become broken as a result. This website transfer particularly affected historic posts that had images in them, no historic image has so far been reinstated on the new forum. Given that the transfer was performed nearly a year ago, then the likelihood that the historic images and broken historic links will be repaired is very low indeed.

The R7277 corner layout is indeed full of 'reverse loops'. The historic posts you refer to made extensive use of images to describe the issues, thus that historic information should now be considered lost.

If used on a DCC layout, then the R7277 layout needs to use electronic "Reverse Loop Modules [RLMs]" to resolve the created short circuits. At the same time that Hornby released the R7277, they (in their wisdom) decided to discontinue the Hornby R8238 RLM, which just did not make any sense at all and just proved that Hornby Marketing did not seek any advice from Hornby Engineering when launching the R7277.

At the top of the "Hornby DCC" forum, you will find some 'sticky threads' one of these threads will lead you to a downloadable 'Reverse Loop Tutorial' PDF which will assist.

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[Matthew -1221193]

Thank you Chrissaf, really useful document.

I think I’ve worked out the placement for the RLM. Got to work out if it is better to upgrade to 4amp Select connection and get the Gaugemaster or stay at 1amp and go with the Lenz.

[Flashbang]

As Chrissaf states, the R7277 track design is full of Reverse loops. AFAIK more than one RLM is needed! Other makes of RLMs are available and most work well. But cost of so many needs to be factored in as well as their placement, you need to be working on the understanding that the longest possible train (Loco and all carriages or wagons) must fit inside the RLM section - between entrance and exit Insulated Rail Joiners that make the isolated section.

[Chrissaf]

I highly recommend that a 4 amp supply for the controller should be used as the RLM needs to have a switching current ideally about 2 amps [i.e 50% of the controller supply current]. If a 1 amp controller PSU is used then the controller is very likely to trigger into short circuit protection mode before the RLM is triggered. This is all explained in my tutorial document. I use the TamValley RLMs configured for 1.7 amp triggers and these work flawlessly with my 4 amp controller supply.

The R7277 needs four Reverse Loop Modules. I will try to recreate my original image [now lost] and post it back here as an edit.

EDIT: My R7277 RLM solution as promised. I now have this freshly created image stored on my PC should it need to be posted again.

Other Reverse Loop solutions that use less than four RLMs can be made to work but with operational limitations. This solution is the 'Rolls Royce' solution, but will provide the most effective solution with the easiest implementation. Remember, as a DCC layout all the Hornby points will need as a minimum R8232 DCC point clips fitted, but given the size and complexity of the layout I would recommend implementing a full DCC BUS power distribution system instead of R8232 point clips.

The Turn Table near RLM1 will also generate short circuits if it is the Hornby R070. I wrote a FAQ tutorial [FAQ3] that details how to modify the Hornby R070 TT for DCC operation. FAQ3 can be found in the 'FAQ Index' sticky thread at the top of the 'Hornby DCC' forum.

[Matthew -1221193]

Again, thanks for the advice.

I've ordered a 4amp power transformer and a single Tam Valley RLM so I can understand and test it on a simple loop - the manual itself isn't too great!

[RDS]

@Matthew

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