How can I motorize the Hogwarts Express (76423)

Question

I'd like to motorize this train set:

What is the best way to accomplish this?

Answer 1

There are number of ways to accomplish this. The locomotive traditionally provides the power for a train, so that is a natural place to start. Unfortunately, this locomotive is difficult to motorize directly for a few reasons.

Powered Locomotive Challenges

The wheel type and spacing makes it difficult to directly use the very simple City train motor:

This is typically used with the smaller train wheels, and the spacing doesn't align properly with the larger wheels used in this locomotive:

These wheels can be motorized using Technic gears and axles along with a small motor, but I couldn't find an easy way to hide that setup inside this locomotive.

We'd also still need to find a place to house the battery box.

Powered Coaches

Another option could be to motorize one of the coaches. This would be awkward on this set, as they are relatively small and use only a single wheel at each end. The train motor works best when driving a pair.

There would also still be the challenge of stowing the battery box which would necessarily cut into the interior space in the coaches. I didn't want to mess with the interior of the coaches as they provide interest and play value for the set:

Powered Tender

The approach that worked for me was to modify the tender to house both the battery box and the train motor. Here's the tender from the set:

In order to add a motor and hide the battery box, the tender needed to get about 3 plates taller, so this does change the look of the set a bit. I don't think it changes things too much, especially since it allows the locomotive and coaches to remain unchanged.

Here's the basic process of building the tender:

The parts list and more detailed instructions can be found on Rebrickable.

I don't apply stickers generally, but I assume that this would look a bit more authentic with the stickers applied. I did leave the open hub port facing the coaches, so light could be added to these fairly easily if desired. Overall, I found this solution to be fairly simple, and it works quite well: