Most animation comprises three transformations: translation, rotation and scale. Simple animations using just translation and rotation can be used to explore the behaviour of rigid mechanical systems such as this approximation of an internal combustion engine. The translating pistons result in the rotation of the crank shaft via the connecting rods. Rotating the model to the side shows the inline arrangement of the pistons. The addition of a play/pause button allows for further exploration at any point in the cycle. The animation is designed to perfectly loop.