How do I get the chariot working?

Hint 1 of 5:

You should try putting the wheel back on the chariot.

Hint 2 of 5:

But it will fall off.  You need something to hold the wheel in place.

Hint 3 of 5:

Have you looked at the axle?

Hint 4 of 5:

It looks like the chariot is missing a key part that fits in the axle.

Hint 5 of 5:

There is something in the Gladitorium that will do the trick.