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Mack 15 ton loco project

The Jordan kit #302 is a tempting project, but so far I have not found any chassis that will fit.

The kit is inexpensive with a MSRP of $9.98, and available from several sources, including Walthers and eBay.

Side view, not to scale

Front view, not to scale

Two obstacles remain to be resolved, the long wheelbase and the large drivers. Also, the hood is relatively narrow.

12 ton prototype, photo from the official website of Mack locomotives #4 & #5

You can read more about the Mack history at the the official website of Mack locomotives #4 & #5 here.

A video of the Mack in standard (HO) gauge. Possibly powered by a Bachmann “Gandy Dancer” mechanism with details removed. The instructions suggest this as an option to get it up and running.

Most of the Jordan parts, together with some measurements:

  • A, wheelbase = 24,8mm c/c
  • B, hood width = 10,6mm
  • C, hood heigth = 10,8mm
  • D, cab length = 12,25mm
  • E, hood length = 13,5mm
  • Wheel dia. 9,4mm
  • Height from wheel center to bottom of deck = ~6mm

Jordan parts

Body partially assembled to get some more measurements. Parts are small and need some adjustments before assembly. The floor inside the shell will be removed later. It is needed during assembly for positioning the hoods properly as it has some small guides.
Maximum dimensions for the mechanism is 37.5mm L x 12mm W with some extra space in the cab if needed.

Body partially assembled

One possible supplier for a mechanism:
L.G. Thek Brasswork

And another source,
DU09xxSeries from Brian Madgefirst sketch.

And yet another source:
Hollywood Foundry mechanisms.

Update, 1.Dec.2011
Another approach from Brian – this looks promising – brass chassis drawingand assembly:

Brass chassis

Update, 13.dec.2011
I received a prototype chassis from Brian Madge today, and so far it looks very promising. The chassis is made of 0,45mm nickel silver, and the weight is 12g. Very nice for such a small chassis. Slow running is very good when you take in consideration that this is a prototype. Pickup is also good with no weights added. Wheel dia is 7,5mm on the prototype. Replacing the belt looks like a simple task as the motor / lay shaft assembly is attached with screws.

Prototype mechanism from Brian Madge

Prototype mechanism from Brian Madge

Side view

Side view

Front view

Front view

Update, 14.Dec.2011
After some measurements I found that the chassis fit almost perfect under the deck. Making room for the mechanism to stay level with the top of the deck looks like a good compromise. With styrene added on top of the deck, the chassis is a good fit.

Bottom view

Bottom view, the extra space is for the motor

There is a lot of space for more weight, I started with approximately 10g before adding the hood tops.

Body with weights added

Body with weights added

Top view with mechanism

Top view with mechanism from Brian

Side view with recessed mechanism

Side view with recessed mechanism

More details, maybe a bit low on the chassis here, but with 8.5mm wheels it will be perfect.

More details added

More details added

Performance has improved a lot with the added weight. Coupler pockets have to be moved as they are way too high now.
For now, most of the parts are only tacked on with a tiny amount of glue – just in case..

Update, 15.Dec.2011
Trying to find a place for the coupler. An MT 1015 1015/1016 fits inside the chassis with some narrowing, but the layshaft on the prototype is occupying some of the space needed, so the coupler sits a bit low right now. I will try to chew off a bit on top of the coupler later. With 8,5mm wheels this may not be an issue.

Some styrene glued to the chassis and perhaps a small frame around the coupler will hide the mechanism nicely.
This looks very promising as the coupler will be well recessed and not protruding too much, a common problem with small critters.

The original coupler pocket is way too high and will be removed.

Coupler, top view

Coupler, top view

Coupler, side view

Coupler, side view

Update, 15.Dec.2011
Looks like I selected the wrong coupler yesterday, an older 1015/1016. Too many variations.. The newer 1015-1 fits completely outside the chassis, and allows for a plate at both ends of the chassis as suggested from Brian. Some quick pictures with the new coupler, temporarily attached with Blu Tack ® (I love that stuff..).

New 1015-1 coupler

New 1015-1 coupler

New 1015-1 coupler, side view

New 1015-1 coupler, side view

The question now is if this shourter coupler is able to handle sharp curves, next step will be to mount it properly and give it a try.

Update, 20.Dec.2011
Mounting the couplers turned out to be a simple task (in theory..), as a 3.2mm (.125″) styrene square rod looked like a perfect spacer with some of the support guides under the deck scraped off with a sharp knife. This is of course much easier to do before assembly.

I found that an old Egger-bahn box was ideal as a jig for this task.

Frame support removed

Frame support removed

Chopping supports

Chopping supports

Supports mounted

Supports mounted

Checking the height

Checking the height

Mounting a coupler

Mounting a coupler

Done

Done

Yess..

Yess..

Update, 28.Dec.2011
The step supports were a bit low, so I cut about 1mm off each. Then some patience is needed to get it all straight. Using a tiny amount of old styrene glue will give you some time to adjust the steps properly.
The roof assembly is still a bit of a mystery to me as the connection to the tank on top is not quite precise. I wanted the roof to be removable, so I started with assembling the panels and glued some styrene support under the tank. The tank is still loose, and some careful adjustments are needed before the roof sides can be glued to the tank.

Steps added, roof assembly started

Steps added, roof assembly started

Stay tuned..

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