Monday, January 11, 2021

A keep-alive for Maerklin 37180 (094 232-6)

Maerklin's 37180 model of BR94 in early era IV livery is a beautiful model. In addition, it's lettered for BD Stuttgart, Bw Crailsheim which makes it perfect for use on the projected Murrbahn layout.
Even though I don't have any photographic evidence that a BR94 was operated between Backnang and Gaildorf/West in the early 1970's, the opportunity to pick up a model that could have been running at least nearby was too good to pass up.

Meanwhile, it's a great switching engine for sessions on the Welztalbahn. There's only one catch: The power pickup seems to be a bit finicky and there is minimal run-out distance on my model, despite the motor having an -- admittedly small -- flywheel.  Other modelers reported not having any problems, so maybe I'm particularly picky, or the pickup shoe needs some love. In any case, I want to use this engine in situations that require slow switching moves and nothing is more annoying than the locomotive getting stuck on a yard ladder turnout. Hence, I looked into what it would take to install a keep-alive, in addition to a mechanical review of the pickup shoe. 

This is a tender locomotive, which are not exactly blessed with space, so I searched for really small keep-alive units. Tams usv-mini have a nifty way to hardwire with any decoder, so that the keep-alive is turned off during programming, which I would have preferred for this application. However, the TCS KA2 is much easier to source in the U.S. Since the locomotive has a MTC21 connector, the KA2 can be hardwired to pins 16 and 20 of the plug. No modification of the decoder is needed.

Contrary to my 10 year old BR86, with this locomotive Maerklin managed to keep the view through the cab open. This allows me to install figures for engineer and brakeman, as well as hide the KA2 in the rear of the cab. With a size of only 9 x 9 x 15.5mm the unit is truly tiny.

I spent most of the evening carefully disassembling the cab, plotting where to install the KA2, and painting the unit black. That's good enough for tonight.

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