BOSS®

Physical Background

Today cranes are able to hoist with 180m/min using huge motors up to 1000kW and more. Using huge equipment means also handling huge inertia that must be accelerated and stopped. The energy that has to be controlled by the hoist is increasing with the square of the lifting speed. In a snag case motors and couplings are still rotating for a short period of time whereas the container or the empty spreader has been already stopped.

During this period of time all kinetic energy has to be absorbed by the wire ropes. The rope tension is increasing tremendously what can cause further damage like ripped off rope drums or even worse broken steel structure up to a total crane collapse. An anti snag system must be able to control and dissipate a huge amount of energy within a very short time.

Fast Reaction

When snag has happend motor speeds must be reduced to zero as fast as possible in order to avoid rapid damage of the system. For that reason fast closing brakes are needed. PINTSCH BUBENZER provides SB28.3 services brakes with ultra-fast setting BUEL® thrusters. Closing times of 36ms help to stop the motor rotation within 100 to 200ms. Due to the fast stopping of the motors the amount of energy that will elongate the wire ropes is very limited.

Fast setting emergency brakes additionally help to slow down. Key components like rope tension sensors (load pins) with special, ultra-fast amplifiers guarantee to recognize any overload condition within the shortest possible time. Fast reaction is the key. The BOSS® system combines fast electrical components (hard-wired) with one of the fasted mechanical brakes. The system is limiting the snag load to such a minimum that rope elongation will be within an acceptable range and further damage can be excluded.

How does the BOSS® System Works?