Duplo Locomotive: What is this inner part used for?

Question

Background

I was forced to completely disassemble a duplo locomotive. My son played with it in a sand box and, guess what, it was not working anymore. I used a small brush to clean every single part (mainly axis and gears). I eventually managed to get rid of all the sand. Then I reassembled the locomotive.

Questions

I ended up with 2 small parts I could not figure out where to put them, neither what they are used for. Everything seem to work without these 2 parts - my son is happy again. These are curved parts, with a spring attached to it. They are on left part of this picture:

So what are these 2 parts used for, and where should I put them ?

Answer 1

Skip on over to YouTube and watch this guy fix one of his toddler's jammed up trains.

Comparing your picture to his video, we can see the general area where the "hip springs" should be, but from my vantage point I can't tell if the pieces snap in somehow, or if they were broken off during disassembly. That's where you'll have to step in to make that assessment.

What are they used for?...

Hmmm... I don't know exactly, but after watching the video we know that the motor sorta floats top heavy, and maybe the "hip springs" help cushion any knocking due to the forward motion at start up. Should they be called "Thrust dampeners" instead? I just don't know. Do you need 'em?...

Depends on individual temperament. How annoying would it be to get back in there?

Answer 2

They are protective locks. If something (let’s say kids hair, or part of their clothes) gets stuck and dragged inside the wheel, these tiny blocks will lock the wheels and make sure it doesn’t keep dragging whatever is stuck. As soon as you pull the stuck part back, the springs unlock.