Mack 15 Ton Switcher

I came across this locomotive in searching for a host for one of my Kato 11-103 drives.  It is a cool little switcher/critter that would compliment the other HOn30 motive power.  Here are some prototype photos.

15 Ton Mack Switcher Proto 1

15 Ton Mack Switcher Proto 2

15 Ton Mack Switcher Proto 3

While the first three photos are of later prototypes, the next photo is of an earlier prototype.

15 Ton Mack Switcher Proto 4

Here is a Highway Miniatures model.  It models the later prototypes.

15 Ton Mack Switcher

I like the chunky look of this double ended locomotive.  While the model is HO, it should be relatively easy to adapt this to HOn30.  Of course, it is unpowered.  In looking for additional modeling information, I came across a Wiseman version of a similar Mack, also unpowered.

15 Ton Mack Switcher 1

This is a model of the earlier prototype.  In fact the instructions include the prototype photo I posted fourth on this page.   The Wiseman model is mostly white metal castings.  It is a bit more expensive, but higher quality with additional castings.  The front beam is consistent with the look of the other Sonoma Magnesite Company locomotives.

15 Ton Mack Switcher 2

Here’s an exploded parts diagram.

15 Ton Mack Switcher 5

It is likely I will power this locomotive is the Nigel Lawton MPD18 MK2 drive.

MPD18Mk2-314x19615 Ton Mack Switcher 1

Here are takeoffs from both the Wiseman kit and the MPD-18 drive

MPD18 and Wiseman takeoffs

The three major issues that come out of this comparison are:

  • Wheelbase – I’ll need to stretch the wheelbase of the MPD18 drive by 1/4″.
  • Motor diameter – The Midi motor is a hair too large in diameter (8mm) to fit into the cavity of the Wiseman kit and under the hood.  I have two choices.  One is to use a Dremel to rout out the walls of  the hood and cavity.  The walls are thick so this might work.  The other is to switch to the Lawson Mini motor.  Its smaller diameter (6mm) will provide plenty of room.  I have the Mini motor on order along with some smaller drive belts but Nigel can’t guarantee it will work.  Also, the smaller motor will produce less power.
  • Driver diameter – is 0.38″ in the kit and 0.20″ with the Lawson kit.  NWSL has HON30 wheels that convert to 28″, 33″ and 36″.  They convert to 0.32″, 0.37″ and 0.41″ IN HO.  The middle size will be perfect but will cause speed to be higher than in the Lawson design.  I ordered all three sizes.  Speed factors are 1.4, 1.6, and 1.8.

I’m assembling one of the MPD18 drives without modifications.  Once it is finished I’ll treat fit it to the Wiseman kit and see how clearances work out.

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