Sign in to follow this  

Emerald Night, drivetrain failure...

Recommended Posts


Seems someone at LEGO didn't thoroughly test the Emerald Night. I uncovered what I think is a considerable flaw in the drivetrain design of the engine, which leads to a breakdown when it starts to pull or push heavy loads - something mine gets to do a lot.

The flaw is the axle that holds the bevel gear that transfers power to the wheels - this axle is too short, and only reaches half-way through the gear. This is sort of critical considering how thin the gear is to start with; when the engine is put under strain, the gear will simply pop off, the engine will stop and all you will hear are some nasty grinding noises.

Thankfully, it is an easy problem to solve. The axle in question is a dark stone 5.5 axle with stop, that is used already at step 1. This should be replaced with an axle of at least 6 studs length, to ensure that the bevel gear is properly secured. I've myself used a seven studs long axle, just to illustrate how it can be fixed:


Again, the light grey axle I've used replaces the 5.5 axle with stop used in the first step. And so far it's worked OK.

Share this post

Link to post
Share on other sites

Yet another design flaw in the magnificent Emerald Night. :sceptic: I discovered the problem when my Emerald ran over a small toy penguin causing friction along the drive train. The small vertical gear slipped out of the short technic beam. I remedied the problem by sliding the existing beam more toward the gear, and have not had the problem since. Now I just have to keep the toy penguins off the track of my Train Town. :grin:

Thought for the Day: I suppose all great things are not perfect.

Share this post

Link to post
Share on other sites

Sorry to bump an old topic but I saw this thread and wanted to point out something.

I bought 2 ENs just before Christmas. My intent is to MOD them into one with battery & motor built into the engine but that is another topic. I came across this thread while reading past threads on the EN. I couldn't see how there would be a problem with the bevel gear popping off given the way mine is build. Then, I noticed that both my ENs have 2 extra bricks in drivetrain compared to Freddie's pics. I checked the copy of the instructions on and found that step 5 on page 6 is different in my copy of the instructions. I'm assuming Lego recognized the problem and corrected in later runs. I thought I'd share this solution for any who have not come across it.

Here's page 6 from Brickfactory


Here's step 5 from the copy of the instructions I have -- NOTE the 1x1 brick threaded on the axle.


When I was building my EN I thought this was an odd place for a brick but it does serve to keep the bevel gear in place. I've ran it for some time with not issues. If you're having trouble with popping a gear you may want to try this. It butts up nicely against the drive gear. I'm guessing that the brick will get some circular wear over time but I took my engine apart and didn't see any yet.

Share this post

Link to post
Share on other sites

Create an account or sign in to comment

You need to be a member in order to leave a comment

Create an account

Sign up for a new account in our community. It's easy!

Register a new account

Sign in

Already have an account? Sign in here.

Sign In Now
Sign in to follow this  

  • Recently Browsing   0 members

    No registered users viewing this page.