Special Usages of Emergency Crane Hoist Brake

Emergency brakes are typically redundant systems with a spring-applied fail-safe mechanism that is held in the released position while the hoist is in operation. Unlike the service brakes on the input shaft, they are not cycled on and off for each lift. In the event of an emergency stop, hoist overspeed fault, or power outage, the emergency brake is immediately set on the output (or slow speed) side of the system.

Emergency hoist brakes prevent accidents by stopping loads from falling in the event of a crane hoist mechanism failure. Root causes of hoist failure include input shaft breakage, input shaft brake failure (often due to improper adjustment or no automatic lining wear compensation), and various types of gearbox and low-speed shaft failures. In any situation that relies solely on the motor brake, there is a chance that the connection between the motor and the hoist rope drum will break. 

This catastrophic failure can create a hazardous situation, resulting in equipment damage or, even worse, loss of life. The solution to this dangerous situation is to install an emergency safety brake on the output side of the system, either on the gearbox output shaft or on the hoist rope drum flange.