Patent GB-1326470-A (GB)
Title: Disc brakes
IPC: F16D55/224
Filed: 1971-10-07
Abstract: 1326470 Spot-type disc brakes; fluid or mechanical operation; wear-adjusting AIRHEART PRODUCTS Inc 7 Oct 1971 [15 Oct 1970] 46610/71 Headings F2E and F2F A spot-type disc brake assembly including a plunger in a cylinder responsive to fluid pressure acting as a primary brake-applying force has a plunger extension and a wedge element providing wedge coupling between the plunger extension and a ram body to accommodate relative shifting of the plunger-and-extension toward the disc as the pad wears while maintaining the ram body coupled to the plunger extension, the ram body being provided to transmit in auxiliary brake-applying force (e.g. mechanical) to the plunger when necessary, and the ram body having an opening through its outer surface which exposes the wedge element, enabling it to be manually uncoupled from the plunger extension and ram body (for re-setting). As shown, a caliper 46, Fig. 1, is slidable on shafts 50 secured to torque arms 51 projecting from a heel 52. Two actuators 55, 56 are housed in the caliper body and one is shown in crosssection in Fig. 3. For fluid-pressure operation, pressure fluid from a source 59, Fig. 2, is applied to two spaced faces 134, Fig. 3, of a plunger 116 whereby pad 58 is brought into engagement with disc 45, Fig. 2, return spring washers 135, 136 being meanwhile compressed by the plunger through the agency of ring 138 and annulas 137. Sleeve 140 is maintained in the position shown, if pad wear is not excessive, by a drag ring 144a frictionally engaging the sleeve. If pad wear is excessive, washers 135, 136, will have collapsed before pad 58 reaches disc 45, so sleeve 140 is urged, by continuing fluid pressure application, to the left, thereby overcoming its frictional engagement with drag ring 144a until the brake is applied. Upon brake release, washers 135, 136 resume their normal configurations as in Fig. 3, while drag ring 144 maintains sleeve 140 in its new position. By reason of engagement of flange 139 on sleeve 140 with flange 142 on stem 116b, secured to the plunger 116, the plunger also occupies a new position after the above-described wear adjustment, and, in consequence, a tapered extension 116a, Fig. 4, on stem 116b, has been pulled a certain distance from between two wedges 129 frictionally engaging the extension and tapered walls 126 of a ram body 131. In the absence of fluid pressure from the same source in a bore 148, Fig. 2, in the caliper body, the brake is applied by a spring 145 through lever 130, ram body 131, wedges 129, stem 116 and plunger 116. Because of the wedges 129 and ancillary structure, the lever movement is invariant, i.e. independent of pad wear. The wedges are urged rightwards by a spring 144; shoulder 181, Fig. 4, on fixed insert 106a, is engageable with stop shoulder 180 on ram body 131 to limit leftward travel of the ram. When pressure is restored, cable 152, Fig. 2, may be pulled to restore lever 130. For re-setting, a tongs 183, Fig. 6, is inserted through a hole 184 in the ram body and manipulated to force wedges 129 leftwards, permitting plunger-extension 116a to regain the Fig. 4 position. Fig. 8 (not shown) despite a simpler arrangement where, as alternative to fluid pressure operation, a cable-operated lever acts on the ram body.