Introduction of Knowledge on Tower Crane:

(1) Classification of tower crane:
According to position of slewing support, tower crane can be classified into upper-slewing and below-slewing tower cranes.
According to mode of arm support structure, can be classified into amplitude type and movable arm amplitude type tower cranes.
According to installation mode, can be classified into split mounting type, ready-package type, jack-up type and climbing operation type tower cranes.
According to if under-frame is movable, can be classified into stationary type and walking type tower cranes.

(2) Naming Rule and Identifying Method of Tower Crane
According to professional standard ZBJ04008 Programming method for Model of Construction Machinery and Equipment, diagrammatic representation of tower crane model programming of our country is as following:

But aforementioned method of programming model just shows lifting moment, but cannot clearly show what the maximum working amplitude of one tower crane is and how much it can lift under the max amplitude. While such data usually can more clearly express the working capability of one tower crane, which is concerned further by consumers. So now there is a new method of programming model as following:

Operative Details of Tower Crane:

Operation of lifting mechanism should be smooth and precise and prevent from impacting and overloading. So operator must know the structure and capability of the tower crane he operating, especially the timing mode of lifting mechanism.
For the operation of slewing mechanism, the general requirement is smoothness and precision. When tower crane slewing, inertia is very large, while static inertia is large when starting, so it is difficult to start, besides, too large moment is easy to form counterpunch, when stopping vehicle, the dynamic inertia is large, so it cannot be stopped and will swing if stopping fast, and the slewing linear speed of arm end is also large, thus it is more difficult to take the suitable place. Accordingly, operator is required to know how to accumulate experience and grasp skill.
Amplitude mechanism only makes horizontal movement, load is lighter and linear speed is not fast, thus it is convenient for holding and operation. However, amplitude comes down to the change of lifting moment, if stopping crane untimely, it is possible to happen super-moment. Therefore, the main requirements on amplitude operation is stable stopping and precise on-site.
Because tower crane is higher and sling hanging is longer, so when running, hook is easy to swing, which is objective phenomenon. As operation with stable hook, it refers to how to quickly stop the swing hook or make hook moving along with crane starting running, namely, operation method to decrease swing to the full, which is the operating skill what operator should grasp.

Maintenance Proceedings of Tower Crane:

•  Do not pay attention to the maintenance of load-lifting limiter, or use directly without adjusting well load-lifting limiter, additionally, someone even doesn't use it intentionally, or increases its limit degree, making it cannot serve the protective function.
•  Lifting system arrester is not adjusted well, being too loose. When descending with high speed under conditions of overload, tower crane will not be controlled because of inertia, causing sliding and falling.
•  Automatic multiplying power exchanging mechanism makes inaccurate switching form 2 multiplying power to four, if do not pay attention to inspect such conditions or do not add spur guard, in the course of hoisting, movable pulley will fall down abruptly, leading to grave accident.
•  Under conditions that steel wire twists and is in disorder, if do not settle it orderly in time but use forcefully.
•  Because the hook falling to the ground, steel wire looses and rebounds, then bounces out of hoist drum or pulley and gets serious crushing damage and section breakage, at that time, if do not replace it timely, the wire will be broken and then fall down when lifting under conditions of full load or over load.
•  If the rope fastener nut at the end of steel wire isn't locked tightly, wire head will slide out from it.