| 摘要 |
<p>A drum brake assembly has a brake shoe lining friction surface subtending a total effective friction surface arc length between the shoe heel (36,38) and toe (28,32) ends of about 49 DEG on the first, primary shoe (30), disposed symmetrically about the shoe horizontal centre line (48), and about 57 DEG on the second, secondary shoe (34), similarly symmetrically disposed. In some instances the first, primary shoe may have about the same friction surface arc length as the second, secondary shoe, with each preferably being about 50% of the friction surface arc length of the prior-art typical secondary shoe lining of about 117 DEG . Different methods of reducing the effective friction surface arc lengths are disclosed, as well as the effect the invention has on the brake effectiveness variations of brake assemblies, both with the same lining material composition and with different lining material compositions. Background and test graphs are provided, as well as a review of accepted brake design considerations of the past leading the brake designer away from the invention.</p> |
