OK @mouradOo_ned , you’re onto something here. Now, have a look at this video ( https://www.youtube.com/watch?v=NDyukh08jIQ ) and watch how Andrew Davis has handled pendulums. Then imagine two pendulum clocks lying sideways with their swinging pendulums right where your pistons are located. Offset by just the right amount and properly masked, you could get a realistic working engine effect. Let’s surprise Andrew when he gets back from vacation by turning his pendulum world sideways. You game for it? It’s gonna be a streeeettttccchhh!
I can’t seem to locate Andrew’s original clock post for you to take apart directly, but he scaled a version of it down and used it with Santa here: https://plus.google.com/+AndrewDavis-the-omnipotent/posts/QGaTFc3W8hC