Tell you more about Marine Crane

Marine Crane

Marine crane is ship's heavy deck equipment ,for a long period of use suspender device, but in the 40 years of 20th century has begun in some ship using a crane, after the Second World War to gradually promote the use . at the beginning of the 1960s, with large ships and high speed, more eager to want shorten the time to stop in port and fast speed of loading and unloading of ships, has the advantages of compact structure ,convenient and reliable operation, large lifting capacity crane appear.

advantage

(1) loading and unloading efficiency is high. Because the positioning ability is good, the reduction of cargo in the cargo hold handling, do not have to be like the hanger device to adjust the position of boom to stop work. At the same time crane can take into account the operation of two cabin.

(2) easy to operate. Almost no preparation work before use. Operating personnel in the higher position of driving room operation, broad vision, strong operation.

(3) the deck layout is simple and use deck area is small.

(4) the hoisting large cargo is particularly suitable. Container ship as long as the lifting equipment will be a crane.

shortcoming

(1) Heavy, high center of gravity and large volume, effect the ship's stability and ship's sight

(2) the price is more expensive, the initial investment is high.

(3) large power, high requirements for the ship power station.

(4) the mechanization and automation of the crane is high, and the technical requirement for overhaul is high.

Type of ship crane

There are many type of ship cranes. According to the characteristics of crane loading and unloading of goods, can be configured to grab, container spreader. For the common grab, dynamical grab and dynamic container spreader crane need add support cable winch

Ship crane although due to the type structure, driving mode and the manufacturer's different varieties and different, but no matter what form the crane must meet: the rated lifting speed lift rated load, according to the requirements of operator, convenient and flexible cargo handling; can according to different situation lift like heavy cargo, light cargo, empty hook and goods, in a wide range of regulating speed, and has good acceleration and deceleration characteristics; in landing and unloading process, according to need can be stopped at any time, and hold the heavy cargo.

1.Classification by structure

Rotary crane is the most common form of ship crane, and its structural form has two kinds.

(1) Hanging arm end with luffing that crane cable leading to the upper part of crane tower, and with performance of horizontal luffing means hanging arm luffing, hook position remained horizontal motion. This crane is widely used.

(2) the rotating end of lifting arm is at the top of tower, working radius is changed with the aid of variable amplitude cylinder.

2.According to drive classification

Crane according to the driving mode is divided into two kinds of electric and electro-hydraulic drive.

(1) the efficiency of the electric crane is high, speed correct, operation simple, maintenance few and easy to control. Electric cranes are commonly used in two kinds of generator motor system and silicon controlled control system. The former uses three output modes, respectively to lifting, luffing and slewing motor power supply, with less motor units, small volume and advantage of small capacity, preserving the DC motor start-up, good speed performance characteristics; the latter in handling, efficiency and scale better, this form of great weight electric hoist is gradually being used in large ships. The starting weight of the series is 5~40t, the maximum working radius is 12~36m.

(2) electro-hydraulic drive crane smooth operation, light weight, small volume, stepless speed regulation, with the characteristics of constant power, empty hook high speed and heavy load slow speed, due to the continuous improvement of hydraulic technology. At the same time, electronic control, also retaining advantages of electric crane, so electro-hydraulic driven cranes has been widely adopted.

Hydraulic pump group is used one motor to drive three hydraulic pumps, respectively driven lifting, luffing, rotate motor. High voltage electro hydraulic drive crane is usually used axial plunger type hydraulic pump and hydraulic motor. The transmission mechanism of the winch is a planetary gear, mounted on winch drum with a hydraulic motor, structure is compact. Luffing device 2 forms of hydraulic cylinder and variable amplitude winch.

Medium voltage electric-hydraulic drive crane often adopts vane pump and hydraulic motor or high torque low speed hydraulic motor.

Electro hydraulic crane capacity series for 5~50t, maximum working radius of 32m, full play rise speed generally is about 12m / min and high speed can be more than 20m / min, empty hook speed normally one time of full capacity; rotary speed is generally about 1 R / min and ship floating state with different change; from maximum working radius to the minimum radius of the amplitude time is about 1 minute.

Selection of ship crane

1 the driving form often depends on the choice of owner;

2. The lifting capacity, depends mainly on the loading and unloading of goods species (container ships are usually used 36~40t). At the same time also should consider the cost factor.

3. The span size, usually outboard span should not less than 6m, must also meet the requirements of cabin loading, in addition to considering the boom stalled position;

4.rane’s rotary, luffing and lifting speed etc. These parameters have been marked on the product samples of each manufacturer. Designers can choose according to the requirements of owner.

Arrangement of ship crane

The ship's crane is usually arranged on the center line of the ship's hull. Cargo handling operation both forward and after cabin lifting, this arrangement forward and after two cranes can be combined loading and unloading heavy cargo.

For container ships, the layout is not ideal, because in the crane will affect container stacking. So the development of slender type crane, it accounted for only a box and the minimum radius of work of this kind of crane only 2.4m, even side container pile can be lifted, so the container ship mostly used slender type crane and arranged at the side of the ship. This arrangement can increase the number of containers, and improve the economic efficiency. However, it should pay special attention to the horizontal balance of ship when ship is too small.