Automobiles are typically equipped with hydraulic braking systems.  In such systems, hydraulic brake fluid actuates a brake to stop the automobile.  In these systems, air may become trapped in the braking system to form bubbles in the hydraulic brake fluid.  To reliably produce adequate braking pressure, the hydraulic brake fluid is moved through the braking system during maintenance of the automobile to remove air bubbles. 
The figures are not to scale.  Wherever possible, the same reference numbers will be used throughout the drawing(s) and accompanying written description to refer to the same or like parts.  As used in this patent, stating that any part (e.g., a layer, film, area, or plate) is in any way positioned on (e.g., positioned on, located on, disposed on, or formed on, etc.)  another part, means that the referenced part is either in contact with the other part, or that the referenced part is above the other part with one or more intermediate part(s) located therebetween.  Stating that any part is in contact with another part means that there is no intermediate part between the two parts.