Three tower crane accidents in two weeks! Have you mastered the key points of tower crane safety management?

Recently, a netizen broke the news: On March 18, 2023, a tower crane overturning accident occurred during the dismantling operation of a bridge tower crane under construction in Qiannan, Guizhou.

, In the process of lifting steel pipes by tower crane in the first bid section of residential project of Block A of Hanyang Steel Wire Rope Factory in Wuhan City, some steel pipes loosened and fell, causing two steel bar workers on the ground to be injured by steel pipes and died after rescue. In

such a short period of time, so many tower crane accidents have occurred, which makes Xiaobian suspect that tower crane accidents are really so easy to happen? Is the tower crane really so fragile? Is the tower crane really so easy to collapse? This is a reflection of many mechanical principles in practical application.

1. Its main structural components include tower body, tower cap, balance arm and boom. The balance arm and the suspension arm are connected with the tower cap through a pull rod.

2. The working principle of the tower crane is to lift or lift the lifting hook or other lifting devices to move the heavy objects.

3. Mobile tower cranes can be divided into four types according to different traveling mechanisms: wheel-rail type, tire type, truck type and crawler type.

4. The flat tower crane is a new type of tower crane, which is characterized by canceling the tower tip and its front and rear pull rods on the basis of the original tower tip structure, thus enhancing the structural strength of the large arm and the balance arm, and directly connecting with the balance arm.

(2) The working principle of the tower crane rotation mechanism is to ensure the working coverage of the tower crane through the rotation of the boom.". The inner and outer rings of the rotary support are respectively installed on the inner and outer rings of the upper and lower rotary supports, the rotary mechanism drives the pinion, and the pinion is meshed with the big gear of the rotary support to drive the upper rotary support to move relative to the lower support. Safety measures for

tower crane:

1. When the tower crane operator walks on the tower crane, he should pay attention to the platform, corridor, skirting board, ladder, handrail, guard ring and other channels and protective facilities.

2. The counterweight is the balancing component to maintain the stability of the tower crane and realize its lifting performance. It should be noted that the lifting mechanism with different lengths corresponds to different counterweights.

3. The ballast is an important part to improve the stability moment of the tower crane and ensure the stability of the whole machine, and its quality and quantity are directly related to the stability of the tower crane.

4. When the big arms of tower cranes intersect together, in order to ensure the height of safe construction is staggered, the height difference of tower cranes in each building should be kept at least at the free height. 7.

Precautions for inspection of tower cranes:

01. Check whether the roadbed of tower cranes meets the requirements of the instructions. Clean track and roadbed. No obstruction.02.03

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(2) The tower crane machinery must be operated according to the specified lifting performance of the tower crane, and it is not allowed to overload or lift objects of unknown weight.". When overload is required under special circumstances, it must be checked, technical measures to ensure safety must be taken, approved by the technical director of the enterprise, and supervised by a special person on site before lifting, but it shall not exceed 10% of the load limit. Key points of

tower crane inspection:

the top of the tower body is inclined to one side or both sides in any state. Reasons for tower body deflection:

1. Lateral deflection and shaking (on both sides of the front and rear arms):

1) Influence

of lateral verticality 2) Influence

of wind force 3) Operation

of the driver to turn around and reverse the vehicle 4) Operation

of the driver to pull and hang obliquely 2. Deflection and shaking of front and rear arms:

1) Influence

of counterweight 2) Influence

of lifting load 3) Influence

of driver's operation 3. Factors affecting overall deflection and shaking:

1) Looseness of connecting bolts or pins (tower body, Slewing bearing, slewing tower body, tower cap, etc.)

2) Standard section damage, corrosion, aging, fatigue

3) Foundation settlement

4) Driver operation

In summary, By monitoring the deflection, shaking range and track of the top of the tower body, the following major hazard sources of the tower crane can be checked:

1) Whether the counterweight is matched: judge whether the installation of the counterweight of the tower crane is normal, and quickly diagnose whether the counterweight is too heavy, too light or normal.

2) Whether the lateral verticality error exceeds the standard: whether the lateral verticality is normal after the tower crane is installed or the section is added for jacking or the attachment frame is added.

3) The bolt (pin shaft) is loose or the main limb is seriously damaged: the tower crane deflection caused by the damage of the main limb of the tower crane or the loose bolt can be found in time. And

4) jud whether that tow crane foundation has settlement or not. And

5) jud whether that standard section of the tow crane is seriously damaged or not. Common dangerous operations and major hidden dangers in tower crane work at

construction site:

2. Oblique pulling and oblique lifting:

," Loose high-strength bolt:

when the high-strength bolt is fastened, the plane of the main limb end and the casing end is connected up and down, and the friction force between the planes bears the shear force caused by the torque during operation; However, when the bolt is loose, the so-called friction does not exist, and the shear force caused by the torque can only be borne by the loose high-strength bolt, which is easy to shear or damage, and the tower crane may topple at any time.