How do I create a piston movement.?

Hello, I'm trying to create a piston moving up/down from a rotating crankshaft. I'm tyring to use the parent/child events to bind them together. So far my piston goes up and down, the issue is that the piston shaft rotates with the crankshaft, where I would like it to always look at "0 degrees" if I can't put it that way. So the bottom of the shaft turns with the crankshaft and the top only goes up and down on the y axis.

any tips?

thx!

marc.

Have a look at this. I think it's what you're after, although the piston is moving horizontally in my demo.

1drv.ms/u/s!AkmrWgxeuxlKhIdsNqjrCRCfnOmV4Q

YYYEEESSS!!!! that's exactly it!! Thanks so much!!

cheers!

Marc.