The forklift lifting system is the direct working device of forklift for loading and unloading. The unloading and stacking of goods are finally completed by it, so it is the most important part of forklift. In use, it is necessary to often strengthen the maintenance to maintain its good technical condition.
Disassembly and adjustment
Inner and outer door frames. There is relative movement between the main components of the forklift lifting system. The inner and outer door frames form a motion pair, and the fork frame and the inner door frame form a motion pair. In order to improve the motion accuracy of each moving pair, reduce the friction between moving components, reduce vibration and noise, and improve the lateral stability of the whole vehicle when forking goods, the inner and outer door frames and the side rollers on the forks are equipped with adjusting gaskets. Through the adjustment of the gasket, the clearance between the side roller of the fork frame and the inner gantry, and the clearance between the inner and outer gantry rollers and the inner and outer gantry shall not be greater than 1mm under the condition of relatively free movement. When the clearance of roller or coincidence gantry exceeds the clearance specified in the design, the roller shall be adjusted or replaced to ensure the clearance of rolling or sliding, reduce the impact sound and prevent the goods from sliding out of the fork. The dimension (thickness) of the flange of the gantry section is reduced by more than LMM or the transverse dimension (vehicle width direction) of the whole gantry combination is greater than the specified dimension by more than 2.5mm. In case of gantry deformation or warpage, the gantry shall be replaced to ensure safe use.
Guide pulley and lifting chain. When assembling the chain, the tension of the two chains shall be equal, the load shall be as uniform as possible without distortion, and the two sprockets shall rotate flexibly after installation. The thickness and length of the two paired forks should be roughly equal. The included angle between the vertical section and the horizontal section of the two forks shall also be consistent. After two forks are installed on the fork frame, the upper plane shall be kept in the same plane. Adjust the maximum length of the lifting chain when the fork rises to the maximum lifting height (i.e. the lifting cylinder piston rises to the upper limit). The adjusted lifting chain should not be too tight. Generally, apply 5on force to the chain at the height of LM, and the maximum deflection deformation of 2omm is qualified. During each maintenance, grease shall be added to the inner and outer portal frame channel steel and the chain sprocket to ensure good lubrication and reduce the friction of each moving pair. In the wide view lifting system, the stroke of two lifting cylinders (oil cylinders) shall be equal, and their oil inlet pipelines shall be unblocked. The upper end face of the plunger rod of the two oil cylinders shall be in contact with the inner gantry and sprocket support at the same time.
Fork frame. As the installation size between the hook and the fork frame has been standardized, all kinds of accessories have the same hook as the fork. Therefore, the plate fork frame can easily replace the accessories. In order to make the fork or accessories can be installed or removed from the fork frame, when the fork frame is equipped with a rack, the fork can be installed and removed by using the gap in the middle of the lower baffle. In order to position the fork or accessories on the fork frame and adjust the fork spacing, several symmetrical positioning holes and positioning slots on the upper baffle can be used for positioning by the positioning pin with spring at the upper end of the fork. When the fork is hinged, the fork frame is made into a sliding rod type. Two left and right circular shafts are installed in the fork frame, and each circular shaft is sleeved with a fork. The fork can slide on the circular shaft to adjust the spacing between the two forks. When loading and disassembling the fork, the circular shaft needs to be removed, and the fork is positioned on the circular shaft with a clamping pin.
Fork. Pay attention to selection when installing forklift. The thickness and length of the two paired forks should be roughly equal. The included angle between the vertical section and the horizontal section of the two forks shall also be consistent. After the forks are installed on the fork frame, the upper planes of the two forks shall remain in the same plane without high and low dislocation.
Maintenance of lifting system
Technical requirements for hoisting system. The gantry shall be free of cracks, defects affecting strength and rigidity, and the deformation shall not exceed the allowable value of the design. The portal frame generally adopts overlapping structure. The inner and outer door frames shall be well matched and slide flexibly without jamming.
The guide pulley frame shall be installed correctly and firmly. The pulley and pulley shaft shall be free of cracks and defects, and the wear of the pulley groove shall not exceed 10% of the original design thickness. It shall be properly aligned with the guide pulley frame to make the pulley rotate flexibly and reliably. The specification and model of the chain shall meet the design requirements. The chain plate and shaft shall be free of crack and deformation, and the transmission shall be flexible and reliable.
The guide wheel frame of the fixture frame shall be intact, free of cracks, well matched with the gantry, and can slide flexibly and stably on the gantry without jamming. The guide surface of the guide wheel frame beam shall be flat and smooth, so that the transverse movement of the fork is stable and reliable. The fork shall have sufficient strength and rigidity and be well matched with the guide wheel frame beam. Generally, the accessory rack shall be equipped with a protective frame made of flat steel and kept intact without deformation. The gantry and tilt cylinder shall be firmly connected with the frame, with good coordination, reliable locking and flexible rotation.
The portal frame shall be free of deformation and weld desoldering, and the inner portal frame and the outer portal frame, the accessory frame and the inner portal frame shall rise and fall smoothly. The fit gap between the gantry and the roller shall not be greater than 1.5mm, and the sliding shall be good without jamming. The rotation of the roller shall be recorded, the roller and shaft shall be free of cracks and defects, and the wear of the wheel groove shall not be greater than 10% of the original size. The tension of the two lifting chains shall be uniform without distortion and deformation, and the ends shall be firmly connected; The fit clearance between the chain link pin shaft and the bearing hole shall not be too large. The sprocket shall rotate flexibly, and the groove depth shall not exceed 0.5mm of the original size; The accessory rack shall be free from serious deformation and weld opening.
The fork surface shall be free of cracks and the welds of all parts shall be free of desoldering. The fork root angle shall not be greater than 93 °, and the thickness shall not be less than 90% of the original size; The height of the left and right fork tips shall not exceed 3% of the length of the horizontal section of the fork; The positioning of the fork shall be reliable, and the supporting surface and positioning surface of the fork hook shall not have obvious defects; The fit clearance between the fork and the accessory rack shall not be too large, and the movement shall be smooth.
Wear and fracture parts and maintenance. In the use of forklift, the common dangerous section of fork is the vertical part near the elbow at the lower part of its vertical section and the vertical part of the welding between the upper end of the vertical section of fork and the upper hook, which are all dangerous parts that are very easy to fracture. In particular, forklift drivers often operate in violation of regulations, use the front end of one fork alone to lift or pick the ground goods, resulting in the bending and deformation of the fork or fork tip, and even the breaking of the root of the vertical section (after the goods are overloaded), which will cause serious economic losses.
Maintenance of common forklift forks. According to the provisions of national standards, the use condition of forks shall be inspected once a year; Forklifts used under harsh working conditions need more frequent inspection to find out any defects or permanent deformation, and take relevant technical measures to eliminate unsafe hidden dangers. The inspection of forklift forks shall be carried out by professional technicians. If the forks are found to have any signs that hinder the safe use, failure, obvious deformation and other defects, they must be stopped from use. They can only be used after being strictly repaired and passing the test and acceptance.
Once the fork surface crack (especially the fork root, upper hook, lower hook and the connection of vertical section) is found, the height difference between the two fork tips exceeds 3% of the length of horizontal section, and the fork must be stopped from use. During use, it must also ensure that the locating pin is in good maintenance and normal working condition. If any fault is found, the fork must be stopped before good repair. The wear degree of the horizontal and vertical sections of the fork shall be thoroughly checked regularly, especially the root of the fork. If its thickness is reduced to 90%, it shall also be stopped from use. The wear, overstock and other local deformation of the upper hook bearing surface and the positioning surface of the upper and lower hooks of the fork increase the gap between the fork and the fork frame, which must be repaired before use.
In the absence of conditions, it is best to replace the broken fork with a new one, and it is not allowed to make do with it. Even after the fork is welded and repaired, it can be put into use only after it has been inspected by strict technical standards and meets the specification requirements of the original factory.
Maintenance of forklift working device
During the maintenance of the chain and pulley, the chain piece shall be free of crack and deformation and shall rotate flexibly. The elongation of every 20 chain links shall not exceed the specified value (8mm). The wear of the chain pin shall not exceed 5% of the original diameter, and there shall be no serious bending, fatigue crack and corrosion. If it exceeds the allowable conditions, it shall be replaced. If uneven wear occurs on the pulley surface, the difference between the outer diameters of the two pulleys is greater than 0.2mm, and steps or indentation appear on the pulley surface, affecting the normal operation of the chain. It should be replaced.
During the maintenance of the main and side rollers, check that the wear marks of the main and side rollers should be uniform. The wear limit is along the diameter direction, and the main roller is 1 OMM, the side roller is 0.5mm. Otherwise, replace it. During the maintenance of the inner and outer door frames, the inner and outer door frames shall be straight, the non straightness in the whole length shall not exceed 1mm, and the service limit shall be 3mm. Otherwise, it should be repaired. Check whether there are cracks by magnetic flaw detection and knocking method. Repair if any. Check for distortion or distortion. When the bending deformation exceeds 1.5mm within the full length, the transverse width difference exceeds 1.5mm, and the bending deformation of the top plate of the inner portal frame exceeds 2.5mm OMM, it shall be corrected. When the overall deformation is serious and the size of the inner opening of the guide rail exceeds the wear limit, it shall be scrapped. When each side of the guide rail on the inner side of the inner and outer door frame is worn up to 2mm, the guide rail shall be replaced or repaired before use.
When checking and adjusting the working device assembly, first check and adjust the front and rear clearance of the inner and outer door frames. Optional use of rollers with a gap of less than 1mm for assembly. During assembly, after obtaining the appropriate clearance, operate the lifting handle to make the inner gantry run up and down stably, and the roller rotates freely and evenly; Second, check and adjust the left and right clearance of the inner and outer door frames. According to the required size, adjust the installation position of the lateral roller by increasing or decreasing the gasket to ensure that the gap between the roller and the inner and outer walls of the channel steel of the inner and outer gantry is met (0.1-1.0mm at the highest position of the inner gantry and 0.1-1.5mm at the lowest position of the inner gantry); The third is the adjustment of the left and right clearance of the fork frame, which is the same as the adjustment of the left and right clearance of the inner and outer door frames, except that the clearance value is 0.1-1 Omm。 After all adjustments are completed, lift the fork frame and inner portal frame to see if the action is stable. When descending from the maximum height, the inner gantry and empty fork are required to fall freely. Otherwise, it shall be readjusted; The fourth is the adjustment of the lifting chain. The lifting chain is too long and the lifting height cannot meet the requirements; Too short will cause a serious accident that the fork frame runs out of the channel steel of the inner portal frame; The two chains are loosened and tightened, resulting in overload and partial load of one chain, resulting in unstable and inflexible movement of fork frame and inner gantry. The chain must be adjusted twice. The method is as follows: stop the forklift on a flat ground, make the gantry vertical, lower the fork to the ground, and lower the piston (plunger) of the lifting cylinder to the bottom dead center. Install the chain. One end of the two chains is connected with the fork frame and locked. Make the chain bypass the pulley, and the other end is connected with the flange of the lifting oil cylinder body or the beam of the outer gantry, and adjust the length of the chain with hinge bolts. Use your finger to press the chain at 1000mm from the ground, subject to 49n, and the moving distance of the chain is less than 20mm. Adjust the other chain in the same way. After the two chains are adjusted, the lifting fork shall check the tightness and length of the two chains to ensure they are consistent.
