DEVICE FOR AND METHOD OF EQUALIZING HEAT STRESS OF DRUM-AND- SHOE BRAKES BY MULTIJET COOLING EJECTORS Russian patent published in 2003 - IPC

FIELD: mechanical engineering. SUBSTANCE: invention relates to drum-and-shoe brakes of road vehicle and road building machinery. Proposed device is made in form of de Laval nozzles installed with gaps between nozzles of bases of brake shoes in two rows and interconnected in zone and heel parts by variable-section rounded off channels to form multijet ejector. Clearances between nozzles communicate with slots in friction linings. Cross section of holes in nozzles increases from zone part of brake shoe to its heel part. Proposed method of equalizing heat stress of drum-and-shoe brakes comes to the following: compressed air supplied along pipeline of air system before check valve of nozzle of multijet ejector of self-pressing and self-releasing shoe has different pressure defined by ratio 1.25-1:4 as ratio of mean stress of self-pressing to self- releasing brake shoe. Length of each nozzle, with due account of curvature of brake shoe base, is such that jet rarefaction borders in each nozzle are close to gap between nozzles, thanks to which amount of air sucked out in form of additional flow from space between brake friction pairs is increased. EFFECT: improved performance of brake, reduced heat stresses in rim of brake drum, increased service life of friction pairs. 3 cl, 5 dwg