Anti-two-block switch for crane hooks (Ship & Offshore)

On cranes it is necessary to monitor the upper hook position for safety reasons. This prevents the crane hook from crashing against the boom head when the load is being pulled up. Emergency pull wire switches with a special design including a counterweight are able to fulfil this task perfectly. The counterweight keeps the switch contact closed. When the hook block reaches the uppermost point, it hits the counterweight which then rises, opening the contact.

Anti-two-block switch for crane hooks


Because this is a safety-related task, the switch must be extremely reliable. The switch is exposed to all types of weather and must be resistant to saltwater. Due to the rough environment it also has to be shock and vibration-resistant. Mechanically, the switch must be designed to cope with the permanent tensile strain of the counterweight. In addition, explosion protection regulations must be adhered to on offshore rigs and gas tankers.


This specification can only be met by a pull wire switch with a special design completely encapsulating all the electrical components. The anti-two-block switch housing is corrosion-resistant. In this way, reliable limit switching of the moving cable winch is achieved. steute has been manufacturing customised versions of this switch type for many years.

Customer benefit

Anti-two-block switching is one of the safety features of mobile and stationary cranes. steute develops solutions which provide high availability in adverse environments.


Anti-two-block switch for crane hooks