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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.

BOSS® Innovation

The BOSS® sytem has been developed based on the experience with the SOS system that has been already installed in more than 200 container cranes world wide. Conventional hydraulic anti snag systems have only one fixed tripping point (pressure relief valve).

The BOSS® system is working with variable tripping points (each corner individually) depending on the actual corner load measurement and hoisting speed. The BOSS® PLC is pre-calculating the perfect tripping point for each load condition. Working with the best tripping points leads to faster snag detection and less stress in the wire ropes as well as in the crane structure.

What is a Snag?

What Is A Snag

A snag occurs when a spreader or container jammed in the cell guides or hiding an obstacle during upwards motion. The worst case happens under high speed conditions with empty spreader full speed up due to the high amount of kinetic energy in the system.

How to detect Snag?

How To Detect Snag

Four two-channel load pins are installed in the boom tip or backreach, monitoring continuously the rope forces.

How does the BOSS® System Works?


How Does Boss System Work

  1. Two-Channel load pins with integrated high speed amplifiers
  2. BOSS® PLC
    • Special designed components for snag detection

    • Integrated overload weighing system

    • Profisafe Interface to crane (based on Profibus / Profinet)

  3. SB and SF brake with BUEL® H and BUEL® G thruster
    • Five times faster compared to other systems
Key Componenets

Boss 01

Boss 04

  • Profisafe Interface
  • Fastest reaction time
  • Precise control
  • TÜV certified
  • Cross-check of both channels
  • Simple calibration and set-up
  • Fully integrated
  • Closed wired system
  • Dynamic snag trip point setting depending on corner load and speed
  • No maintenance time required
  • No nuisance tripping after e-Stops
  • Easy retrofitable



We are an international manufacturing company and your specialist for high quality braking systems. PINTSCH BUBENZER develops and produces in the headquarter in Kirchen, Germany high quality braking systems for both static and dynamic applications. PINTSCH BUBENZER is a german brand. It is therefore obvious for us to face the increasing challenges of the markets.

Our brakes are used in:

  • Container Cranes, Overhead Cranes
  • Steel and Aluminum Mills, Foundries
  • Mining Applications, Conveyors, Stacker/Reclaimers
  • Motor and Gearbox Mounted Brakes, Offshore Winches
  • Movable Structures, Lift Bridges, Dam Gates
  • Wind Turbines, Power Plant Equipment

Our experts will be pleased to advise you. Local and 24/7.

PINTSCH BUBENZER products leading all markets. With first-class customer support and always on-time.

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