Peter's Model Railroading | Articles | N-scale | Arnold S2
Motor Replacement

In January 2001 I ordered a replacement motor from Hans Starmans. It's made in Switzerland. The motor was not cheap. It came with good instructions.

The Arnold model itself comes with two diagrams in the box (if you bought the original unit). One shows how to take the locomotive apart, and the other side shows an exploded diagram of all the parts. These were very helpful. The Starmans' motor comes with textual instructions on how to take the locomotive apart. Both of the sets of instructions together made for a complete and easy-to-follow road map. My article adds photos. The first thing to do is to take the fuel tank off. With a very small screwdriver pry between the body and the fuel tank part.

Once the fuel tank is out, there are two pieces of plastic that slide toward the middle of the locomotive. This frees up the wheel assembly.

Push the plastic locks back slightly and pry them up using a small screwdriver in the direction shown in this photograph.

Removing the cab was a bit of a challenge. There is a lip that slips in between the walkway and the printed circuit board. Also, before loosening that, pull out the handrails that are attached to the cab from the main body. They snap loose, but require a little effort with a pair of needle nose pliers.

On the front of the locomotive you will find a small screw. This holds the walkway to the main frame. When you remove the screw, the printed circuit board can pop loose and the V clip that holds it in place can fall out, so be careful not to loose that clip.

Here is a photograph of the body, frame, and motor with worm gears. This is an important picture. I actually used this photograph to re-assemble the new motor and worm gears. The worm gears are really extracted springs - an ingenious (but potentially flawed) system (some people have reported problems with this drive system; I never had any problems). Follow the instructions that came with the motor for taking the worm gears off of the motor - very important.

Here is the old motor removed from the main body.

I placed the motor in the vise grip just tight enough so that it wouldn't slip. I placed a bag over the worm gear to catch it coming off the motor. The first one went flying off, and so for the second one I came up with this contraption. Needless to say I found the first one again, but it did generate an increase in heart rate! ;-)

The following photos shows how the worm gears are placed on the new motor.

The motor comes with a piece of brass foil. This needs to be placed in the body before inserting the motor. Be careful because when you press it in too far, it becomes like a spring and it will jump out (again, speaking from experience!). Warning: I received an e-mail message from Hans Starmans, who saw my article on my web site, stating that the brass foil was supposed to go in length-wise, not the way I did it (i.e. turn it 90 degrees from the way it is shown in the photo). It seems to work just fine, so I left it the way I did it.

The next step is to assemble the unit again.

The finished product. Before final assembly I tested the locomotive. I placed it on a test track with the cheap starter set transformer and it ran great. In the forward direction it made a slight noise. I removed the wheels, inspected the worm gears, and replaced the wheels. After finishing the complete assembly, I tested the locomotive again. It made no noise at all this time. Well worth the money and the effort, if you like slow-moving switchers. It runs great and makes little to no noise. Both of these features are a great improvement over the stock behavior.