Return springs for tandem master brake cylinder - consist of strong spring between pistons and weaker spring between input shaft and main piston

摘要

The tandem master brake cylinder has the main and subsidiary pistons linked by a first spring which is compressed when the first circuit fails and the two pistons operate in mechanical contact. The pistons are further linked by a link which limits the spacing between them. The first piston is pressed directly by the input shaft and has a weaker spring which holds the shaft and piston together. This spring is not a return spring but allows the piston to return at a slower rate than the brake pedal. The semi-floating springing of the main piston prevents the formation of sudden voids in the brake lines. It also results in a braking force which is only modulated by the spring between the pistons. The weaker spring has no effect on the manual brake force.