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Installation Technology of Double Girder Overhead Crane

July 26, 2021

1. Project overview


The roof of the factory building is made of prefabricated concrete, the lower chord elevation is 19.2m, and the crane track length is 40m.


1. Preparing skill files


2. Preparing equipment


3. Unpacking and viewing


(2) The electromechanical equipment should be free of deformation, damage and corrosion, and the steel wire ropes should not be corroded, damaged, bent, looped, kinked, cracked or loose.


(4) The unpacking inspection should involve the personnel of the construction unit, and the records shall be saved after the inspection personnel sign.


(1) The error of the beam centerline orientation to the planned positioning axis is not more than 5mm.


(3) The relative elevation of the beam plane shall not be greater than 10mm at the column, and not greater than 15mm at other places.


(5) The top surface of the leveling layer on the beam must ensure that the top surface level of the bolts within a wide range of 400mm is not more than 2mm; the top elevation difference of each bolt in any 6m length is not more than 3mm; the top of each bolt along the full length of the workshop The surface elevation difference is not more than ±5mm.


5. Set up a 1m wide scaffold on the inner side of the two beams along the full length of the crane beam, and lay a springboard on top to track the equipment.


1. Tracking equipment


Taking the crane beam positioning axis as the reference, use theodolite to hit a point at 60mm on one side of the track center according to the longitudinal direction of the beam, and hit a point at each pillar to release the reference line for trajectory alignment. Track manufacturing is mainly about cutting, drilling, straightening and cutting the track. When straightening, you can use a full-length cable or partly with a steel ruler to find out the tortuous parts, and then use a track straightener to top the protrusions. The top time should be over a bit, and should be stopped for a while and then released. If necessary, use a sledgehammer to hit the protrusion a few times, and it should be adjusted to two directions on the positive side to pass. Put some 20mm thick wooden boards on the crane beam first, then lay out the elastic pads according to the rules, and hoist the manufactured tracks (four on each side) onto the beam with an 8t truck crane. The materials needed for the equipment track, such as bolts, washers, pressure plates, fishplates, etc., are bagged and placed on the crane beam. After the elastic backing board is padded, the wooden board under the track can be pulled out, and then the track can be connected by a fish plate. Note that the gap of the track joint should not be greater than 2mm. According to the alignment datum line that has been placed on the beam, roughly align the full-length trajectory into a straight line, and initially fix the trajectory with a bolt pressing plate. Carry out a comprehensive alignment and stop at the request. At this time, all bolts should be tightened back. After the trajectory equipment is finished, it should be measured and checked to see if it meets the equipment skill quality requirements, and recorded as the delivery data.


Check the track gauge and measure it with a spring scale, steel pan ruler, etc. The gauge is measured every 6m, and a spring balance is used to control the tension of the steel rod. The tension required for the tension is related to the span and the weight of the disc ruler per meter, and is not a fixed value. Calculate the required tensile force according to the difference of the gauge and the disc ruler.


2. Crane body assembly


(1) According to the plant equipment layout drawing, select the center position of the plant for assembly and hoisting.


(2) Pave the temporary track of the assembled car body. The temporary track height is about 300mm, the gauge is 13.5m, and the level is found.


(3) According to the number of the connecting plate, connect the two beams with the crane beam and fix it. When connecting the end beams, level the steel plates at the joints and check whether the bolt holes fit. After the bolt holes are aligned, put on and tighten the bolts, and measure the diagonal of the cart to see if they are equal. In addition, measure the center distance between large and small cars relative to the two wheels and the gauge of the trolley on the big car to make it reach the regular value.


3. The crane is hoisted in place as a whole



The 120t truck crane enters the factory building, and the outriggers stand about 1m away from the car body at the tail end. The truck hoisted the crane off the ground under the condition of 20.4m boom and 7.5m gyration radius. When the crane is lifted off the ground, use human power to shake the body of the cart, and check whether the lifting equipment has any defects, use the cart to adjust the cart to a horizontal position, and fix the cart to continue lifting. When hoisting to a height of 2.5m, put the equipment in the operation room, and adjust the level of the cart again, and then continue to hoist. When to get close? When building concrete beams, pull the ropes tied up in advance to make the cart turn a corner to avoid the concrete beams. When the cart continues to rise, when it is higher than the concrete beam, the cart is reset, and at the same time, it gradually falls, causing the wheels to fall on the track. After the cart is in place, install other accessories and connect the power line.


(1) Preparation before test run



The electrical system, safety interlocking equipment, brakes, controllers, lighting and signal systems and other equipment should meet the requirements, and their actions should be flexible and accurate.



The lubrication and grease of each smooth point and reducer conform to the rules of the equipment skill file.


(2) No-load trial work


The operating direction of the operating organization should be consistent with the working direction of the crane organizations.



When the hook is lowered to the ** position, the number of loops of the wire rope on the drum should not be less than 2 (fixed loops are outside).


None of the above experiments should be less than 5 times.


The static load test is carried out according to the following procedures and requirements.


 Start the lifting organization first, carry out the no-load lifting operation, and make the trolley work reciprocatingly in the whole process. This no-load test work should not be less than three times, and there should be no abnormal phenomena.


 Park the trolley in the middle of the crane, and lift 62.5t load without impact. At a height of 200mm above the ground, the suspension time should not be less than 10min. There should be no instability. Unload the load and drive the trolley to the end of the span. Check the metal structure of the crane's extruded frame. There should be no defects such as cracks, weld cracks, paint peeling, and other damage or looseness that affect safety. This experiment should not exceed three times, and there should be no deformation during the third time. To measure the actual camber of the main beam, it should be greater than 0.7S/1000mm=9.45mm (S is the crane track span.


(4) Test work under dynamic load


Fourth, quality specifications


(2) The horizontal azimuth error between the actual centerline of the track and the reference line of the equipment should not be greater than 5mm. AS=±[3+0.25(S-10)](mm)


(4) The longitudinal inclination of the top of the track to its planned azimuth should not be greater than 1/1000; measure one point every 2m, and the unevenness of the entire stroke should not be greater than 10mm.


(6) The relative elevation difference between two parallel tracks in the same section should not be greater than 10mm.


(8) The rail should be tightly attached to the elastic backing plate. When there is a gap, a backing plate should be added under the elastic backing plate to be firm. The length and width of the backing plate should be 10-20mm larger than the elastic backing plate.


1) The camber (F) of the main beam allows the error -0.1FSF≤+0.4F. In the formula, S—— crane span (mm).


3) The permitted error of the span end gauge of the trolley is 2mm, and the permitted error of the mid-span gauge is between +1mm and +5mm.


Five, matters needing attention


(2) The pressing plate can be made of No. 3 ordinary carbon steel, which can be processed and welded as required. The size of the pressure plate at the fishplate should be changed from 16mm to 6mm in contact with the track.


(4) The screws on the track must be tightened, and spring washers must be added under all nuts. After tightening, the thread should expose 1.5 buckles of the nut, and the length should be less than 10mm below the clearing plate.


(6) The inspection before the test run should be carried out with all the power sources blocked.


1) The brake should be opened and closed flexibly, and the brake should be stable.


3) The brakes of the work organization should not be adjusted too loosely or too tightly, so that the phenomenon of slipping and impact should not occur.


(9) During the construction of crane equipment, there is no construction work in the workshop, and the site is cleaned.


(11) Construction workers working at heights need to wear safety belts, and it is strictly forbidden to throw objects, materials, etc. down from a height.


(13) In order to prevent the binding position from shifting when the crane is hoisted, cut holes of appropriate size in the corresponding position on the platform of the carriage beam. Then choose the ribbed part between the girders to support them with sleepers to avoid the deformation of the girders from bending inward when they are hoisted.


(14) During the transportation and hoisting process, the command and order must be obeyed, and the work position must not be left without authorization. The construction guard area defined during hoisting is marked with a restricted zone, and non-construction personnel should stop the person.


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