dampens (smooths out) a movement or a vibration. The spring, not the shock absorber, absorbs road shocks. How it works: the shock body is filled with oil. The shaft has a piston attached to the end inside the shock body that controls how fast or slow it moves through the oil. By altering the internal valving, you can achieve the optimum performance of your shock for its application. As the piston moves up and down in the shock body, this creates heat. By pressurizing the shock with nitrogen, this suppresses the tendency of oil to cavitate, or foam, which will hinder shock performance. Here is a diagram of the shock components, and below is a list of what some of these parts do.