Disc brake for motor vehicles

Claim 1

A disc brake for use in a motor vehicle hydraulic brake system having main and auxiliary brake lines through which pressurized fluid is supplied to said disc brake, which disc brake comprises, in combination: 1. a rotatable braking disc mounted to rotate with a vehicle wheel; 2. a hydraulic cylinder positioned adjacent to one side of said braking disc and movable in opposite directions which are substantially parallel to an axis of said braking disc; 3. a piston axially slidably fitting in said cylinder, said piston and said cylinder defining therebetween main and auxiliary fluid chambers into which said pressurized fluid is drawn when a braking action is to be initiated, said main and auxiliary fluid chambers communicating with said main and auxiliary brake lines respectively; 4. inner and outer friction pad assemblies respectively positioned adjacent to either side of said braking disc and forced against opposite sides of said braking disc when said piston and said cylinder are moved by means of said pressurized fluid, said inner friction pad assembly being interposed between said braking disc and said cylinder; 5. a yoke fitting over said braking disc and movable with said piston in the opposite directions which are substantially parallel to the axis of said braking disc, said yoke mechanically connecting said piston and said outer friction pad assembly for carrying the movement of the former to the latter; 6. a pair of spaced sealing means mounted between peripheral walls of said piston and said cylinder for isolating said main and auxiliary fluid chambers from each other; 7. a drain passage leading from a junction between said peripheral walls of said piston and said cylinder and between said spaced sealing means to the outside of said disc brake for permitting said pressurized fluid to be released through said drain passage when at least either of said sealing means fails; and 8. a support structure connected with said cylinder and including a stationary support member, an arm secured thereto and having formed adjacent its free end portion an aperture and a guide pin which is secured to said cylinder and which is axially movably inserted into said aperture, said stationary support member having a recess formed to admit the rotation of said braking disc and to house said inner and outer friction pad assemblies therein.