Just read this "surprise" which comes with the digital version: A lowerable coal heap in the tender
(translated from the PIKO website)
The digital version (# 37241) of the BR 50.35 is equipped by the PIKO designers as a surprise with a yet unannounced, another highlight:
The function "Lower coal heap with locomotive interference" was developed specifically for this locomotive for digital operation. The coal pile is lowered by a motor in the tender of the locomotive.
When the loco is idle, no coal is being consumed. Once the lowest coal level is reached, the locomotive speed is reduced to a low speed step and the locomotive can then only be controlled up to the maximum of this step.
The coal is "refilled" via the special function key F7. In addition, the locomotive offers several adjustment options to adapt this operation to your own needs.
Thus, the duration of the lowering of the coal and the locomotive speed according to the "coal consumption" can be adjusted individually via the CVs.