Some fast – assembly lower – slewing tower cranes with telescopic tower – body structures and horizontal booms (such as the QT16 – type tower crane) mostly complete the erection and installation according to this method. The installation procedure is as follows:
(1) Setting up the Outriggers
Pull out the four outriggers and lower the outrigger jacks so that the tires are lifted off the ground. Adjust the chassis beam to be level, and ensure that the base plates under the outriggers are firmly placed. The stability of the outrigger system is crucial for the safety of the subsequent installation operations. Uneven or unstable outrigger settings can lead to the tilting or instability of the crane during the erection process, which may cause serious accidents. Therefore, careful adjustment and fixation are necessary to ensure that the outriggers can bear the weight of the crane and maintain its balance.
(2) Straightening the Boom
First, pull out the connecting pins between the connecting rod and the boom head to disengage the boom head from the connecting rod. Rotate the boom head to align it with the boom tail in a straight line. Use bolts to firmly connect and tighten the lower chords of the boom head and the boom tail. Then, remove the connecting rod from the boom tail. This step is essential for preparing the boom for the subsequent erection and extension operations. Proper connection and straightening of the boom ensure its structural integrity and stability during the lifting and slewing processes.
(3) Adjusting and Fixing the Tower – top Struts
Pull the tower – top struts downward to make the lower struts form a straight line and fix them with pins. The proper connection and straightening of the struts are important for supporting the tower – top structure and ensuring the stability of the crane during operation. Any looseness or misalignment of the struts can affect the overall structural strength of the crane.
(4) Checking the Stay Cables of the Bracket
Check whether the stay cables of the support frame are placed on the upper chord of the boom tail. Incorrect placement of the stay cables can lead to improper stress distribution on the boom and the support frame, which may affect the normal operation and safety of the crane. Therefore, careful inspection is necessary to ensure that the stay cables are in the correct position.
(5) Preparing the Lifting Trolley
Pull out the fixing pins that connect the lifting trolley to the boom, tighten the front and rear adjustment bolts on the lifting trolley, and tension the trolley towing rope. These operations are to ensure the normal movement and operation of the lifting trolley on the boom. A properly adjusted lifting trolley can move smoothly along the boom, which is essential for the lifting and transportation of loads.
(6) Releasing the Hoisting Wire Rope
Release about 20 meters of the hoisting wire rope. Adequate release of the wire rope is necessary for the subsequent erection and lifting operations. Insufficient wire – rope length may limit the movement range of the crane components during installation, while excessive release may cause entanglement and other problems. Therefore, accurate control of the wire – rope length is required.
(7) Laying the Sliding Tracks
Slant – lay a steel plate about 500mm wide on the front – axle towing beam of the crane, and lay a 400mm×6000mm steel plate along the longitudinal axis of the crane in front of the boom to serve as the sliding track for the boom head during tower erection. The smoothness and stability of the sliding track are crucial for the smooth movement of the boom head during the tower – erection process. Any irregularities or instability of the sliding track can cause the boom head to deviate from the intended path, which may pose a risk to the installation operation.
(8) Tower Erection
Through the lower console, operate the double – drum winch. First, erect the tower and then pull up the tower and lift the boom. As shown in the schematic diagram of the erection process (QT60 – type tower – crane installation process), when the crane is transported to the construction site and ready for erection:
Start by slightly lifting the tower body by tightening the wire rope of the tower – erection pulley block. Remove the transportation connecting rod that supports the upper part of the tower body on the turntable. Then, continue to operate the winch to gradually erect the tower body. As the tower body is erected, the head end of the boom lands on the ground, and the rollers at the boom head slide outward along the steel – plate sliding track until the tower body is completely upright.
Align the pin holes at the bottom of the tower body with the corresponding parts of the turntable, drive in the connecting pins, and install the shaft – fixing plates. Tower erection is a key step in the installation process. Precise alignment and firm connection of the tower body and the turntable are essential for the stability and safety of the crane. Any misalignment or loose connection can lead to the instability of the tower body during operation.
(9) Installing and Checking the Cables
Install and straighten the boom stay ropes, tower – top support – frame stay ropes, telescopic – adjustment stay ropes, and luffing ropes. Check whether the four screw jacks at the upper end of the outer tower body are loosened. Proper installation and adjustment of these cables are crucial for the normal operation and safety of the crane. Tight or misaligned cables can affect the movement and stability of the crane components.
(10) Preparing for Inner – tower – body Extension
Operate the winch to lift the inner tower body by 20 – 25mm. Remove the shaft – fixing plates on the connecting pins of the inner and outer tower bodies, slightly pull out the connecting pins outward to disengage them from the inner – tower – body structure, and then fix the connecting pins with screws. This step is a necessary preparation for the extension of the inner tower body. Precise operation and proper fixation of the connecting pins ensure the smooth extension of the inner tower body.
(11) Extending the Inner Tower Body
Operate the winch to make the inner tower body extend upward. During the upward extension of the inner tower body, the boom head slides inward, climbs onto the front axle along the inclined steel – plate sliding track, and approaches the tower body. At this time, pay attention to using the guy ropes to hold the boom head to prevent the lifting trolley from colliding with the tower body. Subsequently, the boom automatically unfolds. Untie the guy ropes and continue to extend the inner tower body until the limit – switch activates and cuts off the power supply. When pulling out the inner tower body, also pay attention not to scratch or break the cable. The extension of the inner tower body is a complex operation that requires careful monitoring and control. Precautions such as preventing component collisions and protecting cables are necessary to ensure the safety and normal progress of the installation.
(12) Connecting the Inner and Outer Tower Bodies
Loosen the positioning screws of the connecting pins of the inner and outer tower bodies, push the connecting pins inward to connect the inner and outer tower bodies. Operate the winch to lower the inner tower body and fix the connecting pins with shaft – end baffles. This step restores the connection between the inner and outer tower bodies after the extension operation, ensuring the structural integrity and stability of the tower body.
(13) Tightening the Jacks
Tighten the four small jacks at the upper end of the outer tower body against the inner tower body. First, tighten the two inner jacks and then the two outer jacks. The tight – fitting of the jacks helps to further strengthen the connection and stability between the inner and outer tower bodies, ensuring the normal operation of the crane under various working conditions.
(14) Connecting the Pulley Frame and Checking the Wire Rope
Operate the winch to loosen the installation wire rope, drive out the shaft of the outer – tower – body pulley frame, and then use this shaft to connect the pulley frame with the luffing rope. Check whether the wire rope is out of the groove. Proper connection of the pulley frame and the luffing rope is important for the normal operation of the luffing mechanism. Checking the wire – rope position can prevent potential accidents caused by wire – rope derailment.
(15) Lifting the Boom to the Horizontal Position
Continue to operate the winch to loosen the installation wire rope and pull the boom to the horizontal position. At this time, the boom stay ropes are under stress, and the head of the boom should be about 300mm higher than the tail of the boom. Adjusting the boom to the correct horizontal position is the final step in the installation process, ensuring that the crane is in a proper working state for subsequent operations.
In conclusion, the installation process of the tower crane is a complex and meticulous task that requires strict compliance with the installation procedures and safety regulations. Each step is interrelated and crucial for the overall installation quality and safety of the crane. Operators need to have professional skills and rich experience to ensure the smooth progress of the installation. Regular inspections and maintenance after installation are also necessary to ensure the long – term safe and reliable operation of the tower crane.
