GB618500A - Improvements in and relating to band brakes - Google Patents

Abstract

618,500. Band brakes. SELF-CHANGING GEAR CO., Ltd., WILSON, A. G., and MILLER, A. A. Sept. 28, 1945, No. 25261. [Class 103 (i)] Band brakes of the type comprising at least three brake bands disposed side by side and in which the application force is applied to one end of one of the bands, the reaction end thereof being coupled to the application ends of the other bands, termed secondary bands, the reaction ends of the secondary bands are connected to means for transmitting the reaction equally and in the same sense to the bands at the opposite side of a diametric plane of the brake drum in such a manner that the moments of the forces acting about the drum axis are substantially balanced. The brake drum is thus relieved of any translatory force. According to Figs. 1, 2, the complete band comprises a primary section 4 extending clockwise from a lug 7 to the point 8 where it is forked to form a pair of secondary sections 5, 6 extending on either side of the section 4 to lugs 11, 11a. Equalizing levers 16, 19 fulcrummed to lugs 14, 18 are interconnected at 20 and at their ends 22, 30 to links 21, 29 connected also to the lugs 11, 11a, on the ends of the band sections 5, 6 and to lugs 12 at intermediate points thereof. The brake is applied by a bell-crank lever 36 connected at 35 to a thrust rod 34, at 37 to the link 21 and at 58 to a link 39 extending to the lug 7 on the end of the primary band section 4. To compensate for wear of the band, the links 21, 29 have arms 24, 31 arranged to engage with lostmotion, devices 26, 33 which frictionally engage the levers 16, 19. Each lever comprises a pair of parallel plates and the devices 26, 33 may comprise a length of helical spring compressed between them. The band is thus supported in release by the links and levers with a constant clearance which is maintained by the movement of the devices 26, 33 with respect to the levers when the band is applied, if wear takes place. The band is positioned and guided by T-section members 41, 42, which bridge the band sections 5, 6 and engage in slots in a lug 44 on the casing 3. Similar members 46, 47 bridge the sections 5, 6 at the lower part. The normal direction of drum rotation is counter-clockwise. The brake is less effective with reverse rotation. In a modification, Fig. 4, the application force is applied by a pullrod 54 acting through a floating lever 55, a lever 56 fulcrummed at 58 and links 59, 61 connected to the end of the band section 4 and to an intermediate point thereof. The brake band may have more than three laps. The Provisional Specification states that the brake may be used in multi-speed epicyclic gear boxes. Specifications 424,635 and 618,582 are referred to.