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1. Application range of Walking type bridge girder launcher

It is mainly used for lifting of concrete girder in bridge construction of general railway and highway.

2. Main features and advantages of Walking type bridge girder launcher

After researching and analyzing current highway bridge construction machine at home and abroad, combining with our successful experience, we develop and produce the new walking type bridge girder launcher according to practical situation. The main features are following:
● First-made honeycomb girder in China with light self weight, heavy load and strong wind resistance etc.
● The launching crane conforms to the features of construction of present bridge which form is novel and structure is reasonable.
● The main girder and main connecting structures adopt the mature pin connecting mechanism, it is very firm and reliable, and the assembly and disassembly are rapid and convenient.
● It doesn’t need to pave the longitudinal rails. It not only can reduce the stress of bridge, but also can save the cost of construction. It has a wide adaptability for the box girder.
● In order to make the bridge girder launcher can adapt the longitudinal slope and transverse slope, the machine adopts legs which can move forward by it. And the force which the bridge bears should be reasonable and safe;
● Front and middle legs can be adjusted randomly and core plate with adjustable angle which can adapt the erection of curved bridge and Slope Bridge. According to angle of Slope Bridge, the user can adjust the front and middle legs when Slope Bridge is erected. Therefore, it can be used for 45°and less than 45° any angle slope bridge.
● Transverse trolley is added to the lifting trolley, the whole machine traverses with boundary beam which resolve the problem of installation of boundary beam.

3. Main technical parameters of Walking type bridge girder launcher

4. The design basis of Walking type bridge girder launcher

We design the bridge girder launcher according to the rules of the newest machinery and crane in China, the rules are following: 
● 《Cranes--Test code and procedures》       GB5905   
● 《Safety regulations for hoisting machinery》  GB6067     《Code for design of steel structures》       GB50017 
● 《Safety technology specification for special equipment》 TSG Q7002、Q0002    
● 《Code for construction and acceptance of steel structure》GB50205     
● 《Standard for quality inspection and evaluation of steel structure engineering》            GB50221    
● 《Weld Outer Dimensions for Steel Construction》GB10854 
● 《Code for construction and acceptance of electric equipment installation engineering》      GB232    
● 《General technical requirements of assembly》  JB/ZQ400.9  
● 《Mechanical properties of fasteners》     GB3098

5. Main design requirements of Walking type bridge girder launcher

● Technical  index；       
 Safety factor    1.5      
 Using grade：    U3      
 Load state：   moderate      
 Working grade of the whole machine： A3     
 Working grade of the mechanism：M4     
Working condition and requirements of design etc.
● Calculation analysis and check-calculation of the whole structure According to technology condition of design of crane, we confirm the construction condition, and then calculate and analyze the strength, stiffness and stability. 
After the classical calculation, we start the calculating work of design of steel structure, and adopt the finite element analysis, the load applied to models respectively, and then calculating and analyzing beam element and plate element. Finally, the authoritative department will check and calculate again.

6. Main mechanical manufacturing technology of Walking type bridge girder launcher

There are many mechanical manufacturing (machinery-building) technologies; the rules of management are following:    
● Firstly, the technology department reviews the drawing from manufacturability.    
● Drawing up the technology guide book and making  procedure qualification.   
● Making welding procedure card, mechanical manufacturing card, assembly process, camber drawing of box girder according to drawing , rules and criterion ; emphasizing the size of welding angle, geometry size and requirements of assembly etc.
● Designing the assembly technology clamp according to the requirements of drawing.     
● Making the finishing time of manufacture and patrolling card  according to the requirements of drawing; controlling the quality of manufacture strictly.

7. The quality control in Walking type bridge girder launcher manufacturing process

Technology file drawing and project are handed to production department which assorts with related department and quality department to process, manufacture, control, check and accept of product.       
The workshops do the following work according to drawing:
● blanking splicing（technology and requirements of blanking splicing）
● assembling welding（welding procedure card, welding technology qualification and welding record）
● mechanical manufacture（mechanical manufacturing card）
● finishing time of manufacture and patrolling card
● Assembly（assembly technology）
● checking descriptive chart（controlling the geometry size and key part）.

8. Tracing data and leaving factory data of Walking type bridge girder launcher

● The tracing data of product is made up of contract, review file, drawing , calculation book of design, specification, installation project, raw material quality certificate, product quality inspection record, welding inspection report and purchased certificate.
● leaving factory data is made up specification, installation project, certificate and receiving report etc.

9. The installation method and steps of Walking type bridge girder launcher

The bridge girder launcher (launching crane) is the heavy duty hoisting equipment which requires very high safety. A little negligence maybe causes serious accident, therefore, the installation of launching gantry must be directed or installed by professional works, and the steps are following:
● surveying positioning
● paving rails
● assemble two sides main girder symmetrically.
● installing front and rear connecting frame
● installing front, middle and rear legs
● installing lifting trolley and auxiliary trolley
● hydraulic system, electrical system, operating platform and plug in power
● test run and commissioning.

10. Checking methods after installation of Walking type bridge girder launcher

   We should check geometry size, perpendicularity,degree level and deflection etc. after the structures are installed completely:
● Checking connecting parts connect firmly or not.    
● Checking the electric connection is correct and limit switch is reliable or not.  
● Checking  parts of hydraulic system leak oil or not and the lifting is good or not. 
● Checking mechanism and structure parts run successfully or not. 9.5、checking lubricating condition of rotating parts. 
● Checking the oil level meet the requirements or not ,and then making a trial run .
● After all of above checking and adjustments are finished, and making sure every part goes well, and then doing the trial run. 

11. Operating requirements and attention of Walking type bridge girder launcher

● Adjusting the height of transverse rails of front legs and middle legs  when erecting girder or moving from one pier to keep main girder’s longitudinal slope≤0.5%，transverse slope≤0.5%.   
● The normal working wind speed should less than 6 grade when bridge girder launcher works in the open air ; when the wind exceed 6 grade, the bridge girder launcher shouldn’t moving from one pier to next pier, and components should be locked; the machine can’t work in thunderstorm day and must cut off power.  
● check the steel rope is broken or not,  the circuitry leaks electricity or not, the brake is reliable or not, and after the reducers get enough lubricating oil and the oil lubricate the open gears, the machine start to work; the safe circle of steel rope on the drum shouldn’t less than 3;checking the surface and fixed parts after every shift of steel rope and making a specific check every 7～11 days;
● the brake system of winch is allowed to start again after it checked;
● the lifting ,longitudinal traveling and transverse traveling shouldn’t work together; the speed of lifting and translational velocity should be slowly to avoid leaning and side tumbling;
● the goods are prohibited to throw out from bridge girder launcher strictly; it is prohibited to lift goods to pass over head strictly；it is prohibited to lift workers by hook or goods strictly；the inflammable goods are prohibited to put on the launching crane strictly;
● After the legs move to their places, plug the safe pin to prevent the hydraulic cylinder from bearing force for a long time;
● When the tubes of components are fault, the operator should cut off power immediately, and it is checked and repaired by the professional technician; the operator shouldn’t disassemble privately; when checking and repairing the machine , the technician must cut off the power. 

12. The maintenance time and item of Walking type bridge girder launcher

● After construction are finished everyday, the workers must check the following content: if the level of main longitudinal girder meets the requirements or not; the connection of bolts and pins are firm or not; the electrical wires are broken and extruded; hydraulic system is regular or not; the track joints are plain and smooth or not;  the connection of position limiter of crane and trolley are firm or not; the rail clamping device is in the working position or not; bed timber is plain and stable and the size of gauge is right or not etc.     
● The welding lines are checked every month :：upper and down chords of main girder , web plate, vertical welding lines of legs  and the welding lines of connecting frame etc. The operators should stop working when the welding lines are broken or fatigue crack.  When the users find the crack by eyes, but they can’t make sure the dangerous degree, so they should use the welding inspection instrument to test and then adopt reasonable steps to deal with.
● About the painting of structure which should be painted again every two years. The users should clean the primary surface by steel brush and pay attention to the welding lines before the structure are painted.

● The lifting mechanism, traveling mechanism of crane and trolley, reducer of motor and steel rope of winch are lubricated and maintained according the rules of specification. 

13. The disassembly and site-transferring steps of Walking type bridge girder launcher

The machine is disassembled according to the following steps after the erection construction is finished. 
● cylinder jacks up to make the whole machine go up 250—300mm。
● 2.0m sleepers are paved to nearby middle and rear legs respectively.
● take back the cylinder of legs and the put on the transporter.
● two lifting trolley are lifted and then put on the transporter by the special  gantry.
● disassembling front, middle and rear legs and front and rear connecting frame.    
● disassembling the coupling pin from back to front , each beam is carried in order and then the disassembly is finished.
● when disassembling and carrying the parts, brutal work and violent  collision are  prohibited, special hook and lifting tools are used for lifting. Connecting bolts and pins are put in order after they disassembled to avoid disordering and losing; the disassembly and assembly of connecting plates must be in order, and they must be marked clearly before they disassembled and assembled.

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