In order to animate the wheel, I had to change the structure of the wheel and pistons. I switched the positions of the two wheels, so that the vertical piston can moves with the smaller wheel up and down while the wheels are rotating.

I moved the components followed one by one, which is the parent and child. So when I select the first wheel and move, everything will be moving or rotating together. I also created two locators at the joints for doing the constrains. I moved the locator1 under the joint here so I don’t need to do constrains, instead, the locator which is a child of this joint will moved with it.

Before doing the constrain, the most important thing is to make sure everything is zeroed out and they are in the right position. I did a point constrain and aim constrain for the vertical piston with the locator to make it follow the movement of the locator when the wheels are rotating.