How to Disassemble the InterMountain AC-12 - Mark Watson

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Good evening TrainBoard,

I just accomplished the complete disassembly and reassembly of the InterMountain AC-12 Cab Forward in less than 45 minutes! Edit:*er, well, of the shell, not mech.* This was my very first attempt and I even snapped photos!

Before I began, I was scared to death about this procedure as the AC-12 is the most beautifully detailed N Scale product I've ever known. But during the process I found that many of the detail parts are very flexible and forgiving! I rate this procedure no more difficult than any other N Scale steamer out there!

Well, lets dive right in, shall we?

Step 1:
Carefully pry off the Steam Turret and Feed Water Heater to reveal screws underneath. Two pipes will likely come off with the Feed Water Heater, and a third will need to be lifted and moved aside.


Step 2:
In order to lift the boiler shell, the hand rails and piping must first be slid out from holes in the rear of the cab. The hand rail and similarly sized piping will slide straight out, however on the engineers side is a larger plastic tube which must be kinked away from the boiler in order to slide out. Don't worry, as I said before, this part is quite flexible and forgiving.
To lift the front of the boiler, some detail parts will need to be moved out and around others. Again, these parts are quite forgiving.


Step 3:
To remove the PC board, first remove the screw below the wires. The thin wires are for the forward lights and are extremely delicate, more delicate than any of the detail parts. (And yes, that is RUST on the motor case! )



...continued.

 

Step 4:
In order to gain more slack to remove the locomotive PC Board, unplugging the wires from the tender may be necessary. To remove the tender shell, simply pry the shell along the bottom and lift up. Be extremely careful as more of the delicate wires connect the tender light to the tender PC Board.
Remove the screw to the rear of the tender PC board to gain better access to the plug on the underside. Unplug the plug. (By the way, I noticed the spacer between the PC board and tender floor was an HO sized bearing block! Nifty innovation of part use InterMountain!)
With more slack on the Locomotive PC Board, you can move it out of the way enough to pry the rear of the motor upwards. When the motor is lifted enough, the connecting shaft to the rear drive train will pull out from the flywheel. You can then rotate the motor to position the forward drive set to the desired offset.



Step 5:
With the offset in the position as desired, press the motor back into its clip. Mine made quite a snap that worried me at first, but after inspection, it appears that is just the sound it makes. Next simply re-assemble the locomotive following the reverse of these steps. The only step that was difficult on the reassembly was replacing the details that were removed with the Feed Water Heater, but it was only difficult in getting the parts into their proper place. With patients, I had them set in no time.


Here is a shot of my reassembled AC-12 and it's newly offset drive sets.


I hope this helps anyone with the desire to offset their own drive sets!