Sunday, July 25, 2021

(Still) In The Diesel Shop

Just over halfway into 2021 and, as usual, not as much model work as desired was accomplished for all the usual life reasons.  Nevertheless, the diesel shop crew did find some time to make progress on rebuilding the MP15DC.

I decided to re-truck and re-motor it, the latter with Faulhaber gearhead motors.  The goal is to provide super slow-speed control and remain extremely efficient with as little draw on the battery as possible.

As of July, the new trucks are re-gauged to P:48 and are installed -- albeit currently backwards.  One can clearly see the difference in wheel profile from the original P&D Hobby Truck Kit and the replacements for P:48 from Right-O-Way.

The brass truck kits are nice, but are mechanically very delicate with working leaf and bearing springs that make assembly a good challenge.   More work is needed to accommodate what seems to be longer axle endpoints on the Right-O-Way wheelsets to ensure reliable operation.

Adapting the underframe for mounting of the new trucks was the next item to tackle.   The original high mounting plates for the Atlas gearboxes were removed and new ones fashioned out of 0.064 brass bar stock with a second layer as a spacer off the underframe.   This resulted in a scale deck height off the rail of 66" -- real close to the prototype's 64 1/2".   Minor adjustments may be made later when the pilots are updated and new coupler boxes installed.

The trucks are currently installed backwards during the bolster rebuild phase shown here as more frame milling is needed to allow for the gear tower to swing and then they'll get turned around to the correct orientation. 

Following that, the motors will likely be installed on new custom-mounts extending up from the outside edges of the fuel tank area so that the motors mount above the inside axles of the trucks.  This will leave the center largely free to accommodate the battery and electronics.

I'm also contemplating a neat feature to add a battery charging plug where the fuel filler would go to avoid having to remove the battery each time.  Look for that update when it moves over to the electrical shop for final outfitting.

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