What are the structures of marine cranes? What does each structure represent on the drawing? How does the crane boom accomplish the telescoping action? Don't understand the structure when installing the crane? This article will take you to a detailed understanding of the important structure of the marine crane. Please read the following.
Overview of Crane
The folding and telescopic crane has a more comprehensive structure, which is more helpful for us to understand, so we take this crane as an example to introduce the crane structure.
As shown in the picture, this is our customized 1.5T12M folding and telescoping marine crane structure (CCS certified) for Chilean customer.
It was shipped in April 2022 and arrived at the customer's site in mid-June. The customer has installed and successfully operated it.
(Are you interested in this crane? You can customize it to us if you need it!)
As the cornerstone in the crane structure, the pedestal is a circular cross-section welded structure. It is used to bear all vertical forces, radial forces and overturn moments of the crane.
The upper flange is used to connect the slewing bearing. The pedestal is welded to the base seat.
As you see, the tower body is a box cross-section welding structure. It has the features of high strength, easily fabricated, etc. The lower flange is used to connect with the slewing bearing.
The upper support A-frame is used to connect with boom and the support in front is used to connect luffing cylinder. We fit the side of the tower with an operating platform.
This is a very popular design with ship owners, and the knuckle and telescopic crane structure can effectively save space on board.
This 1.5t@12M crane, the maximum length of the boom is 12m with a minimum length of 5.29m.
A sheave block is located at the boom head and the main boom, the boom is connected with the tower body by a boom shaft.
We mounted the hoisting winch on the main boom for safe use.
Hoisting winch is mounted on the main boom, equipped with a hydraulic motor, reducer, brake, bearing support, drum and frame, etc.
The brake is normally closed when it is not in working condition, the friction plates are on-position by spring force.
When in working condition, oil pressure will compress the springs and the friction plates will loose to unlock the on-position condition. It all means that it has a reliable mechanical braking system.
It has a reliable mechanical braking and has many outstanding features of low-speed stability, high transmission efficiency and lower noise because frictional loss is reduced in the structure and sealing performance is improved as well.
The reducer is mounted inside the drum, and the bearing support is mounted at the end of drum.
A self-aligning bearing is mounted inside the bearing support for preventing the drum from axial moving.
The hydraulic motor on the winch is driven by oil pressure to lift and lower the hoisting hook.
The frame that used to support the drum and the reducer, and it is connected with the hoisting winch by bolts.
The end of the wire rope is fixed on the drum by a clamp plate. We should fill the hydraulic oil into the hydraulic system before using to prevent any kind of damage.
The slewing bearing is suitable for many types of loads, such as axial force, radial force and overturn moments simultaneously.
The slewing bearing is suitable for above mentioned loads in both left and right directions smoothly and reliably.
The Slewing bearing type for this crane is type 013.40.1120
The rolling track of the slewing bearing is made of 42CrMo steel and the hardness of the track is higher than HRC50. And there is nylon isolation between the rollers and diminish friction.
We set dust rings between inner and outer track to prevent dust from entering the roller track.
The inner track of the slewing bearing is fixed on the pedestal and the outer track is fixed under the tower body, each connecting bolt has a performance rate of grade 10.9.
The slewing mechanism is mounted on the tower body.
It is used to control the slewing speed of the crane.
It consists of one hydraulic motor with planet reducers, brakes, transmission pinions, etc.
The pinion engages with the inner gear of the slewing bearing to drive the crane to rotate 360° (full rotation).
Luffing and Telescopic Cylinders
Installed during the building phase of the crane. The luffing cylinders are double effect with a single piston. Chrome treatment and buffing are carried out for the surface of the piston rod and it has high solidness to prevent the surface from rusting.
The luffing cylinder type one is HSGL-300/160-945-1465, the piston has a diameter of 300mm and the piston rod has a diameter of 160mm. The cylinder stroke is 945mm, and the rated pressure is 25Mpa.
The luffing cylinder type two is HSGL-280/160-943-1583, the piston has a diameter of 280mm and the piston rod has a diameter of 160mm. The cylinder stroke is 943mm, and the rated pressure is 25Mpa.
Along with the oil pressure, the piston rods will move back and forth and they control the movements for the boom up and down.
The telescopic hydraulic cylinders have a double-acting piston rod and the cylinder is made of seamless steel tube.
Chromate treatment and buffing are carried out for the surface of the piston rod and it has high solidness to prevent the surface from rusting.
Along with the oil pressure the piston rods will move back and forth and they control the movements for retracting and extending the boom parts.
Wire Rope and Hook
A galvanized non rotation wire rope type is used Verotop 35K7 WA 1960-18mm-RHLL(Gal) for hoisting, it has a diameter of Φ18mm and breaking load of 296.2 KN.
The type of the hook is made according to marine hook standard CB/T3758-1995. The hook has a safe working load of 5t.
We mounted the Platform on one side of the tower body. The operator can clearly see the hook movement and nearby conditions.
The operating system is composed of five operating handles and remote control, which is used to control hoisting, luffing one, luffing two, rotary and telescopic parts respectively.
There is a pressure gauge to indicate the working pressure.
Oil Pump Unit
The oil pump unit consists of marine electric motor, pump, coupling, etc. The motor has a protection class of IP56 and insulation class of grade F.
The coupling can compensate axial errors between pump and electric motor to prevent the pump from damage.
The oil suction pipes should be kept sealed to prevent noise.
The oil pump unit is installed behind the crane to provide hydraulic oil for the hydraulic system of the crane.
The oil lever gauge, air breathe and return filter are mounted on the oil tank.
Honestly, the crane structure may be a bit complicated, getting a satisfactory marine crane often requires a long communication process.
According to our project experience, some customers do not provide us with detailed information, which reduces efficiency.
This is the main reason why OUCO insists on bringing you crane related knowledge.
Have any clues or ideas? Contact us now to order a fully satisfied marine crane!