Abstract: An improved roller skate includes a shoe portion, front and rear wheels, and a bracket coupling the wheels to the shoe portion. The have a "generally" spherical shape which allows the skater to maintain a rolling surface of each wheel on the floor or ground, while leaning the skate by a relatively large degree with respect to a line extending perpendicular to the floor or ground. Each wheel has a rigid inner core and a softer outer cover. The inner core includes an axle housing connected to a hollow, "generally" spherical, rigid shell by a plurality of radially extending spokes. The bracket coupling the wheels to the shoe portion includes arms coupled to the wheel axles. The shape of the bracket and bracket arms are designed for strength as well as to allow for a high degree of skate inclination (lean or angle) with respect to the ground or floor without contacting and scraping the ground or floor.

Abstract: A master cylinder for a dual hydraulic braking system has two pistons arranged end-to-end in respective bore sections, each piston having sealing valves which close off communication between front and rear brake circuits and respective reservoirs when displaced by operation of a brake pedal to cause pressurization of respective compression chambers connected to the brake circuits. This invention provides two seals in the inner piston between the two compression chambers and an auxiliary chamber defined between these seals into which small quantities of brake fluid escape in the event of leakage from either compression chamber to give visual warning of such leakage.