Braking resistance elevators work by using a mechanical braking system to control the descent of the elevator car in the event of a power outage or emergency situation. 

When the elevator is in operation, the motor drives a hoist that raises and lowers the elevator car along the vertical shaft. In normal operation, the braking system is not engaged and the elevator moves freely. 

However, in the event of a power failure or other emergency, the braking resistance system is activated. This system consists of a mechanical brake that is applied to the hoist drum, preventing the elevator car from descending too quickly. The braking resistance system slowly lowers the elevator car to the nearest floor, allowing passengers to safely exit the elevator. 

Overall, braking resistance elevators provide a safety mechanism to prevent free-falling in emergency situations and ensure the protection of passengers.