Deck cranes provide safety functions in case of list up to 5°
Vessel deck cranes equipment gives the possibilities of loading and unloading cargo without help of port equipments ensuring efficiency in any port of call.
Deck crane should be capable of following:
- Ensure high productivity and working range of the crane to cover all the required jobs;
- Safety functions in case of list up to 5° and not be influenced by the marine environment;
- Provided easy access to the enclosed machinery for ease inspection and maintenance.
Safe lifting capacity or safe working load is the maximum load that the crane can lifted. Most of the cranes the SWL (safe working load) is inscribed on the cranes jib.
Deck crane comprises the following parts:
• Foundation column
• Crane house
• Crane-man cabin
• Crane jib
• Hoisting winch
• Luffing winch/luffing cylinder
• Slewing machineries
• Slip ring unit linking the crane network with the shipboard network and is mounted at the bottom of the crane-house. The unit could be bolted either to the top or bottom of foundation. On newer crane variants the slip ring unit is bolted to the top of the foundation.
• Electrical cabinets and other various components included in the electric equipment.
Functionality of the cranes I most worked with:
Handling cargo or lifting the load is carried by the hoisting winch. The hoisting winch through the hoisting wire rope maneuvering the hook block. The winch has two speed ranges –low speed and high speed. The lifting capacity of the hoisting winch at high speed range will be reduce by 40% of the capacity in the standard speed range.
The function of the jib (lowered and raised) is handled by the luffing winch. General design of the winch is similar with the hoisting winch. It is mounted inside the crane-house. The jib angles are restricted by electric limit switches. Also wire slack switches are provided for both hoisting and luffing winch.
Slewing of the crane is made with the help of a rotating gear which transmits motion through a pinion gear on the slewing bearing. The crane can be turn 360° but if required the slewing range can be limited on customer needs.
For protection against overload the crane is provided with a pressure limiting valve.
The sheaves for the hoisting and luffing wire ropes are mounted on top of the crane-house and on the jib head.
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