| 摘要 |
Brake shoe compositions moulded or machined with scooped air passages to assist cooling, esp. where compositions are based on 18.35% novolak (phenolic) resin/1-3% hexamethylene tetramine/20-50% asbestos flocking/0.16% kaolin/5-20% granulated rubber/0-41% carbon (graphite). Wear resistance is 400-600% better than cast iron, the coefficient of friction remains at 0.21-0.25 at all speeds, not moisture sensitive. Particular compositions quoted for (1) trains; (2) trams; (3) automobile brakes.
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