When performing the brake test at 125% capacity, which performance metric is crucial?

The crucial performance metric when performing the brake test at 125% capacity is the ability to stop and hold. This test is designed to ensure that the braking system is capable of effectively bringing the elevator car to a complete stop and maintaining that position even under conditions of increased load. Since the test involves applying a load that exceeds the rated capacity, it is vital to confirm that all safety systems, particularly the brakes, function correctly under these circumstances. The ability to stop and hold ensures that, in the event of a power failure or emergency situation, the elevator will not descend or move unintentionally, thus protecting the safety of passengers.

Other performance metrics, like the ability to lower and ascend or maintain speed, while important, do not directly address the critical safety requirements that the brake test is intended to validate. The focus here is primarily on the stopping capability and the reliability of the braking system under stress, as any failure in this area could lead to severe safety hazards.