Crossing Paths

Crossing Paths
Model Melbourne trams

Thursday 27 June 2013

Cutting Notches

As I have observed with the remaining stock of W class trams in circulation, is that they have a certain characteristic when accelerating.

As these trams run a traditional series/parallel DC controller (7 series, 7 parallel notches) there are a distinct yet subtle 'kick' most times when notching from first resistance series (notch 1) into second (notch 2) and when going from full series (notch 7) into first resistance parallel (notch 8).

A typical W class set up (minus all the vigilance controls that exist on the current

 Melbourne Fleet) photo courtesy Wikipedia.
With DCC and the Decoderpro/JMRI software, I have 'tweaked' the speed curve on all trams to include this feature, it also allows for a visual speed check of the running tram without having to look at the numbers on the NCE Powercab.

Believe it or not the jump from one step to another in running is not as severe as it appears the speed curve.
From under the wires