GB1492828A - Brakes - Google Patents

Abstract

1492828 Disc brakes; brake discs; preventing brake noise SOC ANON FRANCAISE DU FERODO 16 April 1975 [18 April 1974] 15682/75 Heading F2E A brake comprises at least one friction surface 11 mounted to rotate about an axis A, and a friction member 13 which has a contact face for engagement with the surface 11, the surface 11 being shaped so that when it rotates the position of the centre of pressure P of the contact face on the surface 11 varies, the width L of the surface 11 being substantially constant and smaller than that of the contact face of the friction member 13. The brake may be a bond brake or a drum brake but the embodiment illustrated is a disc brake having a disc 10 with two flat friction surfaces 11, 12 for engagement by pads 13, 14 respectively. The surface 11 is defined between outer and inner contours E, E<SP>1</SP> of generally elliptical shape with a major axis X. The outer contour E extends between an inscribed circle C 1 and a circumscribed circle C 2 having radii R 1 , R 2 , the length of R 1 being between 0À80 and 0À99 of the length of R 2 (preferably 0À90). Likewise the contour E<SP>1</SP> extends between circles C<SP>1</SP> 1 , C<SP>1</SP> 2 . The pad 13 co-operates with surface 11 over an annulus having a width 0 and L is advantageously between 0À70 and 0À90 of D (preferably 0À80). The surface 12 is of a shape similar to surface 11 but the surfaces 11, 12 are asymmetrical about a median plane perpendicular to the axis A and passing midway between the surfaces 11, 12. The arrangement in use is said to reduce noise due to the fact that zones in the pads 13, 14 are alternately heated and cooled leading to thermal and mechanical stresses and internal damping of the pads 13, 14. The surfaces 11, 12 instead of being elliptical with two points on the inscribed circle and two on the circumscribed circle might have a different number of these points on these circles.