(1) Disassemble and inspect the hooks, shafts, beams, pulleys, and bearings, clean and lubricate them. The hooks, beams, and pulley shafts must not have cracks. The threaded parts should not be loose. The bearings are in good condition. If there are knife marks or cracks in the knife groove, it should be replaced;

(2) Check the wear condition of the dangerous section, if the wear of the dangerous section exceeds 10% of the original height, it should be replaced;

(3) The test of the hook, after the overhaul, the hook should be tested and checked, suspended for 10 minutes at 1.25 times the rated load, the elastic opening of the hook should not exceed 0.25% of the size of the hook, and should not be unloaded after unloading. There are permanent deformations and cracks;

(4) Overhaul of the plate hook. After the plate hook is riveted, the gap between the plate and the plate should not be greater than 0.3mm.

2. Maintenance of wire ropes for crane accessories

(1) Broken wire inspection: If the number of broken wires in one twist exceeds 10% of the total number of wires, it should be scrapped according to the standard;

(2) Radial wear amount: if the radial wear of the steel wire exceeds 40% of the original diameter, the whole wire rope should be scrapped;

(3) Deformation inspection: if the diameter of the wire rope is reduced to 70% of the rope diameter, the rope core is exposed, and the broken strand should be scrapped and replaced with a new wire;

(4) Lubrication of wire rope: Before lubricating, use wire brush, kerosene, etc. to clean it, and dip-coat it with wire rope hemp grease (Q/SY1152-65) or synthetic graphite calcium base lubricating (SYA1405-65) for saturation.

3. Maintenance of pulley block for crane accessories

(1) Disassemble and clean the pulley block, check for cracks, the pulley shaft must not have cracks, the journals must not wear 30% of the original diameter, and the taper should not be greater than 5%. If the value exceeds this value, it should be replaced;

(2) Overhaul of the pulley groove, check the pulley groove shape with a sample plate, the radial wear should not exceed 30% of the wall thickness, otherwise it should be scrapped. Those that do not exceed the standard can be repaired. After overhauling, use a sample plate to check. The bottom and side gaps should not be greater than 0.5mm. The deviation between the centerline of the wheel groove and the centerline of the pulley should not be greater than 0.2mm. The deviation should not be greater than 1mm;

(3) Inspection of the shaft hole, after overhaul, the shaft hole is allowed to have a defect of not more than 0.25CM2, and the depth should not exceed 4mm;

(4) Assembly, after assembly, it should be able to rotate flexibly by hand, and the lateral swing should not exceed D/1000. D - Nominal diameter of pulley.

4. Reel maintenance of crane accessories

(1) The rope groove of the drum, if the rope groove wear exceeds 2mm, it should be re-machined. After the overhaul, the rope groove should meet the requirements of the drawing, but the wall thickness of the drum should not be less than 81% of the original thickness;

(2) On the surface of the reel, there should be no cracks on the surface of the reel, there should be no obvious out-of-roundness, and the platen screws should not be loose;

(3) There should be no cracks on the reel shaft. After major repairs, it should meet the requirements of the drawings. When the wear exceeds 5% of the nominal diameter, new parts should be replaced;

(4) For assembly and installation, the center line of the reel shaft should be parallel to the supporting surface of the trolley frame, and the deviation should not be greater than 1mm/m.

5. Wheel maintenance of crane parts

(1) The wheel tread is worn out. If the wheel tread wear exceeds 15% of the original thickness, it should be replaced with new parts. If it does not exceed this value, it can be re-machined and heat treated for repair. The diameter of the wheel should be within the tolerance range, the surface quenching hardness should be HB300~500, and the thickness of the quenched layer should be greater than 20mm for the diameter of the wheel larger than Φ400mm; when it is less than Φ400mm, the thickness of the quenched layer should not be less than 15mm;

(2) The diameter deviation of two mutually matched wheels, the diameter deviation of the driving wheel should not exceed 0.1% of the nominal diameter, the driven wheel should not exceed 0.2%, and the diameter deviation of the electric hoist wheel should not exceed 1% of the nominal diameter %, the driven wheel should not exceed 0.2%; the diameter deviation of the electric hoist wheel should not exceed 1% of the nominal diameter;

(3) Wheel rim wear and tear, deformation: the wear amount of the wheel rim reaches 50% of the original thickness or the broken area exceeds 30mm2, which should be scrapped, and the rim thickness should be scrapped when the bending deformation reaches 20% of the original thickness;

(4) Wheel cracks: If the wheels are found to be cracked, they should be scrapped;

(5) Tread ovality: Wheel tread ovality up to 1mm should be scrapped;

(6) Wheel assembly assembly: The installed wheel assembly should be able to rotate flexibly by hand. Several wheels installed on the same balance frame are in the same vertical plane, and the allowable deviation is 1mm.

6. Repair of axles and bearings of crane parts

(1) Overhaul of the journal: The ovality and conicity of the journal after overhaul should not be greater than 0.03mm;

(2) Repair of cracks: Check the shaft with a magnetic or ultrasonic flaw detector. There should be no cracks on the shaft, and the scratch depth should not exceed 0.03mm;

(3) Overhaul of rolling bearing: Axial clearance within the range of 0.03~0.18mm is allowed between the inner and outer rings of the tapered roller bearing. The adjustment gap of the bearing gland should be within the range of 0.5~1.5mm.