N Scale North American Locomotives

Step 1: Bodyshell Removal

With your hands based against a table or some other hard surface (leverage will be key in this step), grip the fuel tank of the locomotive in your thumb and forefinger of one hand, while placing your thumb and middle finger of your other hand UNDERNEATH the catwalk at the back of the locomotive. Gently rock the shell side to side until it comes loose, allowing you to pull it away from the mechanism. Note that sometimes the engine leads will catch the side of the body shell through small gaps on either side of the body... if this happens, take a small object such as the tip of a pen and push them in to free the shell.

Step 2: Removing the Circuit Board

The circuit board on top of the locomotive is held in place with a slide lock. To remove it, while still gripping the locomotive by the fuel tank with one hand, place your fingers on either side of the copper flaps that hang down and slide the board towards the back of the locomotive. When it will no longer slide, grip it at the back of the board (pictured), and angle it up very slightly, continuing to slide it back until the board comes free of the mechanism. It is very important that when removing and reattatching the light board that you DO NOT press on LEDs on the front or the back of the board. Also note that it's possible that during this process the copper flaps may come loose from the board... this is common and they can simply be slid back in place.

Step 3a: Truck Removal

The N scale SD40-2 has been designed with a screwless truck connection. The trucks themselves are held in the mechanism by two clips, accessible through a hole on each side. To release the truck, take your small flat bladed screwdriver and push the tabs inward, pulling gently down on the truck on each side as you do so. The entire truck assembly should come free, with the wormgear still contained within. If you notice the worm gear assembly is exposed, then one or both of the tabs was not freed and the top half of the truck assembly is still inside the mechanism.

Step 3b: Truck Disassembly

Pictured here is the correctly removed Truck assembly. Note the locking tabs holding the upper cover in place over the worm gear assembly. To access the worm gear or gearing mechanism for the SD40-2 trucks, turn the truck over so that the wheels are on top, grip the sides of the truck in one hand, and gently rock the gear covering from side to side until it pulls free. Take care to keep the truck upright and not to jerk the truck during the process as the worm gear may fall out if you do so.

Important Note: When reassembling the truck, the gear cover has two "arms" which extend outward and press against the brass pickups on the wheels. Use your flathead screwdriver to gently push the brass tabs on the wheel mount outward when replacing the cover so that the arms slip inside them and do not press down on the tabs, potentially damaging the truck.

Step 4: Fuel Tank Removal

The fuel tank is clipped to the mechanism in three locations: at the fuel tank itself, and on each end. All three are snap fit connections; first loosen the end caps by pressing gently on the plastic nubs that extend beyond the ends of the mechanism. Then grip the fuel tank firmly and wiggle it from side to side, pulling away from the mechanism at a 90 degree angle until it comes loose.

Once the fuel tank is removed, the two halves of the mechanism will be freely separated, allowing access to the motor and truck mounts. Take care to notice the orientation of the motor when disassembling the mechanism as they will only fit in a certain way when it comes time to put it all back together.

Step 5: Review Your Work

Behold! You now have a collection of associated parts that used to be a train. Marvel at their craftsmanship and then see if you can remember how it all goes back together. If it seems that you have to force something to get it to fit then be careful! You might have something in the wrong way, so check to make sure everything fits snugly and looks like it should be where it is... you don't want to damage something trying to make it be somewhere it shouldn't!