Influence of Braking Strategy on Brake Temperatures in Mountain Descents.

摘要

Findings concerning snubbing (pulsing) versus dragging strategies for braking trucks and buses to control speeds on downgrades are presented in this report. Vehicle tests were performed on a long steep grade (approximately six or seven percent for five miles). A mobile dynamometer was used to study individual brakes. A simplified heat flow model was used in planning the experiments and analyzing the results. The basic findings are: (1) the average temperature per pound of brake drum is practically equivalent whether light dragging or snubbing is used to control speed; (2) the hottest brakes will be cooler if snubbing is used; and (3) on short downhill descents the dragging strategy will cause hot spots to develop to a greater extent. Recommendations concerning the wording of manuals used for commercial driver license (CDL) training are given.