How can I cross the drawbridge?

Hint 1 of 8:

Stop the train.  I want to get off.

Hint 2 of 8:

Take a close look at the chains on the drawbridge.

Hint 3 of 8:

You need something to hook on the lever underneath.

Hint 4 of 8:

Have you checked the back of the train?

Hint 5 of 8:

Go back to the roundhouse and come back, but backwards.