Patent GB-1120947-A (GB)
Title: Improvements in automatic adjusters for vehicle brakes
Inventor: HARRISON ANTHONY WILLIAM
IPC: F16D65/56
Filed: 1964-08-25
Abstract: 1,120,947. Automatic adjusters for brakes. GIRLING Ltd. 19 Aug., 1965 [25 Aug., 1964], No. 34836/64. Heading F2E. In an automatic adjuster for a vehicle brake incorporating friction pads or shoes for engagement with a rotatable disc or drum, the adjuster is actuated by a feeler member which, on application of the brake after wear of the friction pad or shoe lining has taken place, is brought into engagement with the disc or drum with which it is partially rotated through a limited distance to actuate the adjuster, the friction pad or shoe lining being applied to the disc or drum by means incorporating a rotatable thrust member in screw-threaded engagement with another part of the brake. In the embodiment illustrated in Figs. 1-3 inc. a floating caliper type disc brake consists of a caliper housing 10 straddling a portion of the periphery of a rotatable brake disc (not shown) and mounted to swing about an axis 11. A friction pad 12 associated with one side of the caliper housing is adapted to be moved into engagement with one side of the brake disc directly by a piston and cylinder mechanism 14, 15 and another friction pad 16 on the opposite side of the brake disc is brought into engagement therewith by the reaction on the caliper which swings about its axis 11. An automatic adjusting mechanism is associated with the friction pad 16 and consists of the rotatable thrust member in the form of a screwthreaded plunger 18 provided in a recess 19 in the caliper which abuts the backing plate 17 of the friction pad 16, the plunger 18 being moved towards the brake disc relatively to the caliper housing whenever excessive wear of the friction pads takes place. The excessive wear is determined by a finger member 23 forming a feeler member pivoted at 24 to the caliper housing, such that the finger is angularly movable about an axis substantially parallel to the portion of the surface of the brake disc but is normally held by a spring in engagement with a stop 33 in which position the finger is inclined forwardly at a small angle to the disc surface. When the brake is applied after wear of the friction pad 16 sufficient to cause the free end of the finger 23 to engage the brake disc, the finger is rocked over the disc about its pivotal axis in an anticlockwise direction and a one-way acting spring coil 28 (Fig. 3) allows a spindle 24 (Fig. 3) connected to the finger to move angularly within a sleeve 25, the latter being held by a one-way acting spring coil 29 against angular movement to stress a torsion spring 26. On release of the brake the load on the plunger 18 is relieved and the torsion spring 26 moves the spindle 24 angularly in the opposite direction to allow the spring coil 28 to clutch the spindle to the sleeve 25 and the spring coil 29 allows the sleeve to rotate so that the sleeve moves angularly with the spindle and the plunger 18 is moved angularly to advance the friction pad 16 towards the brake disc to adjust for wear of the brake pads. In a modification disclosed in the Specification (Figs. 4-6, inc., not shown), the finger 23 is replaced by a peripherally toothed rotatable disc which is moved angularly about its axis by contact with the disc. Alternatively the member which actuates the adjuster may be a snail cam of which a portion is adapted to engage the disc to move the cam angularly when adjustment is required. The adjusting mechanism may be protected from dirt and water by a boot member 39. The friction pad assemblies may be removed in a radial direction through an opening in the top of the caliper 10 by removal of pins 21.