Image Number 3 for United States Patent #4346791.
An improved brake for a wheel mounted on a spindle is of the type which includes a housing secured to the spindle with a plurality of brake discs carried by the housing for relative rotation therewith. A plurality of reaction plates are carried by the hub of the wheel for relative rotation therewith and the discs and plates are intervened in an alternating fashion to define a pack. The housing has a central bore defined by an interior cylindrical surface and a radially, inwardly extending annular wall. A piston has a tubular portion with a cylindrical outer surface and a radially, outwardly extending wall with an annular surface thereon. The piston is axially, slidably mounted in the bore with the annular wall, the interior cylindrical surface, the exterior cylindrical surface and the annular surface defining an expandable chamber between the bore and the piston. A first, generally U-shaped expandable seal is in the chamber and seated against the annular wall of the bore with a pair of lips making sliding, sealing contact with the cylindrical surfaces. A similar second generally U-shaped expandable seal is in the chamber and seated against the annular surface of the piston to also make sliding, sealing contact with the cylindrical surfaces. Hydraulic fluid is selectively introduced to and discharged from the chamber to produce selective movement of the piston axially relative to the bore to cause it to produce a compressive force on the pack.