Algodoo

How is this different from a standard crank mechanism (e.g., a crankshaft and piston rod in an internal combustion engine)?

Q: How is this different from a standard crank mechanism (e.g., a crankshaft and piston rod in an internal combustion engine)?
A: If blue link is the crankshaft and yellow link is the connecting rod then the right green block can be (or be glued to) the piston. In this case the piston doesn't need a cylinder to guide it. The idea behind this scene is that the green boxes can be glued to two objects (or ground and one object) and the objects will travel along the same line (or one object will travel along a straight line).

Okay, that makes sense. Thanks!