In 2007, an elevator began moving upwards while passengers were exiting, trapping and injuring an occupant. A drum brake intended to hold the elevator stationary failed, resulting in the unexpected movement. Subsequent investigation revealed that a solenoid responsible for opening and closing the brake had deteriorated, causing the brake linings to drag on the drum and wear prematurely. When the solenoid was not engaged, normal brake shoes would have pushed against the drum, preventing elevator motion. Excess brake shoe wear caused the brake to fail to hold, leading to the accident. Figure 1 shows a CAD model of the brake, where the brake arms are pivoted at the bottom and spring loaded to maintain contact with the drum.
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