Bonus project no 2The Märklin 7051 Crane converted to DCC
One of the most famous and liked accessories from Märklin is the Stationary Crane that has been in the product line for several decades. It has during the years undergone several minor changes, but is generally spoken still the same. Today there is a commercial kit available for digitalisation, but only to fit the Märklin Digital system.
Since the crane is such a popular item it is logical to try to convert it also for DCC layouts. This bonus project aims at doing that.
The projects is based on the original digitalisation project that you find in book No. 4 and starting on page 62 (English issue). There you will get all practical information on how the crane works in more detail, colour coding of all wires, etc.
Here we exchange the BVE 9105 module from that project with an electronic module from Roco, named RKRAN V1, which you can order from your Roco dealer. It is the original onboard decoder from the Roco digital crane.
Since this DCC module allows you to control more functions, here are some suggestions on how to utilise those.
There is provision to control 3 electric motors via this decoder. The 7051 crane has 2 onboard motors. So with some ingenuity there can be one more motor for adjusting the vertical angle of the arm. There is room for a smaller motor (example; use A Robbe motor with 1:150 gear ratio) in the crane house and wiring down to the decoder in the basement can alternatively use two home-made feeder rings under the house, or simply double prolonged holes which will limit the turn operation to less than 360 degrees.
Instead of a third motor there can be 2 extra light functions, each with a diode in series as shown for the 3:rd motor on the adjacent picture. Then by just turning the speed knob of the cab in different running directions (being in "3:rd motor mode") one of those two light functions will go ON and OFF.