Tower crane dismantling personnel after professional basic theoretical knowledge training, but also for more than (d) months of internship operation, by the relevant departments of the assessment, obtain the qualification certificate of special operations, can work at his post.

A. 1

B.2

C.3

D.6

Brief introduction of tower crane:

Crane mainly includes hoisting mechanism, running mechanism, luffing mechanism, slewing mechanism and metal structure. Lifting mechanism is the basic working mechanism of crane, which is mostly composed of suspension system and winch, and some lift heavy objects through hydraulic system.

Running mechanism is used to move heavy objects vertically and horizontally or adjust the working position of crane, and generally consists of motor, reducer, brake and wheel. The luffing mechanism is only equipped on the jib crane, and the amplitude decreases when the jib rises and increases when it falls, which can be divided into two types: balanced luffing and unbalanced luffing.

The slewing mechanism is used for slewing the boom and consists of a driving device and a slewing support device. Metal structure is the skeleton of crane, and the main load-bearing components such as bridge, boom and gantry can be box structure or truss structure, or web structure, and some can use section steel as supporting beam.

Crane used in bridge construction can be generally divided into four categories according to their different structures and performances: light and small lifting equipment, bridge crane, arm crane and cable crane. Most of the bridge girders of single-beam bridge cranes use I-beams or composite sections of steel and steel plates. The lifting trolley is usually assembled by chain block, electric hoist or hoist, which is an integral part of the lifting mechanism. The characteristics of jib crane are basically the same as those of bridge crane.

It can be used in and over circular fields, mostly for outdoor loading and unloading and installation, including portal cranes, floating cranes, mast cranes, wall cranes and deck cranes. Boom crane includes: lifting mechanism, luffing mechanism and rotating mechanism.

Depending on the synergy of these mechanisms, heavy objects can be lifted and transported in a certain cylindrical space. Boom crane is usually installed on vehicles or other forms of transportation (moving) tools, which constitutes a rotating crane running boom. Such as truck cranes, tire cranes, tower cranes, portal cranes, floating cranes, railway cranes, etc.