Algodoo

Chains and ropes are two of the more difficult items to work with in Algodoo. In your particular scene, the chain falls off the pulleys because the chain has no collision layer. Do the following things, and then your treadmill should work:

1. Select the chain and make it collision layer A.
2. With the chain still selected, change the chain values as follows:
Strength = 50000
Impulse Break Limit = 9999
3. Select the stone block and change its collision layer from A to B (this is needed so that the chain on collision layer A doesn't collide with the stone block.

After making those changes, your treadmill should work.