Balance lever coupling

Have you ever played on a seesaw with a friend? That's kind of like a balance lever coupling.

Imagine there are two long sticks that are connected in the middle but can move up and down like a seesaw. You can sit on one end and your friend on the other.

If you are both the same weight and sit in the middle, the sticks will be balanced and you will both be at the same level. But if your friend moves closer to the middle, they will become heavier and the sticks will tip toward them.

Now imagine that instead of a friend, there's a big heavy engine sitting on one stick and a lighter cart on the other stick. The balance lever coupling helps make sure that the weight of the engine doesn't cause the cart to tip over.

The coupling keeps the two sticks connected and working together to keep the weight balanced so that the engine and cart can move smoothly along the tracks without falling over. It's like a teamwork between the sticks to keep everything in balance!