Fixing Angles SR68JR Basic Mast

Products Specification

Type , Model: Fixing Angles SR68JR Basic Mast

Size: 2M

Use for : L66A1, L66A3 ,L 68A1, L68A3, L68B1, L68B2 , L68B3  mast section , P20A  R20A, P21A  R21A  ,2m L type mast

Materials: Q345B

Process: Blasting derusting, 

Painting:  Under painting , Middle painting, Surface painting.

Our factory produce and supply almost all famous brand tower crane :Mast section, Anchor Frame, Fixing angle ,Adaptor and so on as good quality and price.

Fixing Angles SR68JR Basic Mast

Tower Crane Knowledge sharing：

Cause analysis and improvement of piston fracture of jacking hydraulic cylinder of QTZ125 tower crane

After the cutting observation of the piston, we found that

(1) the whole piston is composed of three parts: the upper piston rod, the piston rod base and the intermediate connecting shaft , and the fracture part happens to be the joint part of the intermediate connecting shaft and the tube wall of the tubular piston rod with thinner and greater stress concentration.

(2) the middle connecting shaft cutting about 3cm2 from the top to the bottom of the fracture cannot be separated from the tubular piston rod, and there is no thread buckle, indicating that the upper tubular piston rod and the middle connecting shaft are not threaded.

Fixing Angles SR68JR Basic Mast

(3) the inner end face of the fracture surface is smooth and smooth, with traces of organic processing .

(4) the fracture surface has pores formed by welding and is accompanied by residual welding slag.

(5) the outside of the fracture part forms an inner depression surface, while the inside is flat, indicating that the fracture surface material is not dense.

 Since the manufacturer of tower crane or oil cylinder could not be contacted, the detailed drawing and processing technology could not be obtained. It can only be speculated that the piston manufacturing process is as follows.

firstly, weld the upper piston rod to the intermediate connecting shaft , and then carry out machining and heat treatment. It can be seen from the phenomenon

Fixing Angles SR68JR Basic Mast

(6) that the obvious non-compliance of welding quality is the main reason for the fracture of the piston rod, but if the design is more reasonable, it will effectively reduce the impact of welding quality and improve the degree of safety essence.

3. Suggestions for improvement measures

In the construction practice, the tower crane jack-up piston hydraulic system failure is rare, as one of the most important parts of tower crane, top quality of parts of hydraulic system is related to the safety of personnel and property.

Whether in design, manufacturing defects or the use of improper maintenance, are likely to people's lives and property caused a huge loss, the author thinks that, this case give us at least three implications

(1) the piston rod design and processing technology of the jacking hydraulic system shall be improved. The author thinks that the simple plug welding (and in thin wall, stress concentration) is not desirable, if the internal thread connection on the basis of plug welding, post-machine processing and heat treatment effect will be better.

Fixing Angles SR68JR Basic Mast

(2) attach importance to processing quality and inspection procedures. From this case, it should be said that the piston rod of the jacking hydraulic system has obvious defects in the quality of plug welding.

 It can be inspected out of the factory and put into use, if there is a major accident, the manufacturer must be culpable.

(1) the user should attach great importance to the key and important parts of the equipment and carry out inspection and maintenance seriously. Even the parts that have never had accidents before or the parts that are not required by the technical specifications and operating instructions cannot be ignored.

How to choose tower crane is one of the essential construction machinery in construction.

Due to its own characteristics and special working mode, the

selection of tower cranes is quite different from other construction machinery.

According to the structure and construction mode determined in the construction process, the selection of different types of tower cranes is the main principle for the selection of tower cranes.

Fixing Angles SR68JR Basic Mast

In addition, transportation road, soil condition, underground structure and other surrounding environment also have a certain impact on the selection.