DCC K1 Beyer Garratt

[009bernard]

 I have built a K1 Beyer Garrett in 009 scale using Two Fleischmann 7000 chassis to power the loco ,I wish to fit a DCC decoder (Digitrax DN136D ) to wire the two chassis together or will I have to use Two decoders and connect then in the control unite in consist (double heading )

 

[JST]

I would have thought that it depends on how many amps the motors pull. The DN136D (I have used al few of them for older locos) have a high loading but being a very cautious person I would use two. Why not just give the two decoders the same address?

[009bernard]

I would have thought that it depends on how many amps the motors pull. The DN136D (I have used al few of them for older locos) have a high loading but being a very cautious person I would use two. Why not just give the two decoders the same address?

 

I think you are right what you say, is probably the easiest way to go it will save linking the wires to both ends I will probably use two DZ126 decoders as they are smaller.

[John K]

I have a 7mm scale LMS Garratt and I have gone the other way with a single decoder driving both motors wired in parallel.

The decoder has a peak output of 1.8A.

It's worked well for 10 years.

John K

Edited September 27, 2017 by John K

[DCB]

If it works on adequately on DC on a feedback controller or resistance controller then try a single decoder.   Don't test it on a high quality DC power unit like a Morley or H&M Variable transformer as that will run almost any pair of chassis at similar speeds.  I would connect the  pickups together to give 8 wheel pick up if you want smooth running, though perhaps this wiring should have been installed earlier in the build, but my feeling is two decoders will be needed and quite a lot of fine tuning to get max haulage without one chassis slipping.

Ffestiniog Fairlies had separate regulators for the two power bogies.

As K1 is a compound the HP power bogie can only slip for a short period before back pressure from the LP power bogie chokes the slip or the LP bogie slips as well.

A big motor in the boiler and drive as per a BoBo Diesel would have been much easier electrically and mechanically....

[009bernard]

Thank you for your replies ,I have fitted two DZ126 decoders and matched the power to each on the front chassis I increased the start voltage  (CV02) to 015 so that on speed 1 the wheels just start  then isolating this from the track I set the rear chassis (CV02 ) to 010 so that on speed 1 the wheels just started to move ,then with both chassises on the track I found that they both started at the same time I then set the mid voltage on both decoders (CV06) to 020 and the maximum voltage (CV05) to 060 as these loco will not run fast like an express train.

When I was happy with the way it performed on the rowing road I renumbers the decoders to 143 to match the engine number of the K1 Garrett on the welsh hi land railway.