Algodoo

they're not better axles. legacyMode 0 axles have far less strength and are prone to stretch when they connect two objects. they perform better at high speed though

Also note that your chains are crap. Never use the chain tool, make them by hand. Try making one entirely by hand: make a box with an axle, then CTRL+drag and position it close to where the axle has to attach the two objects, then shift + mouse wheel down and move a little bit

Suggestion: When displaying a technical scene such as this one, disable the Algodoo clouds. Clouds are not necessary in a scene like this one, and they can even cause confusion while floating past a moving mechanical device.

To disable clouds -- Right click anywhere on the background. Uncheck the box labeled "Draw clouds".