Rails and Wheels of Lifting Machinery: Installation Standard, Selection & Scrapping Guide
I. Crane Rails
Crane rails are running tracks paved with steel rails. Their primary function is to provide a specified traveling path for cranes and transfer wheel pressure to the foundation. Rails shall be firmly installed without horizontal or longitudinal displacement and allow convenient adjustment.
Core requirements: All metal fasteners shall be free of cracks, loosening and corrosion. Any cracked parts must be replaced immediately, and other defects shall be handled in a timely manner.
1. Rail Selection and Technical Parameters
- P-type Rail: Widely used for the main and end carriage rails of small- and medium-tonnage cranes, one of the mainstream options currently.
- QU-type Rail: Special heavy-duty rail for cranes, designed for heavy-load scenarios such as large gantry cranes and container gantry cranes.
Common models include QU70, QU80, QU100 and QU120.
| Model | Theoretical Weight (kg/m) | Typical Application |
|---|---|---|
| QU70 | 52.77 | Medium to large cranes |
| QU80 | 64.41 | Large gantry cranes |
| QU100 | 89.05 | Heavy-duty & large-tonnage cranes |
| QU120 | 118.5 | Extra-heavy duty cranes |
- Standard length: Generally 9m to 12.5m; customised length available on request.
- Material & Performance: Common steel grades include U71Mn, U75V, etc. Alloy elements such as Manganese (Mn), Chromium (Cr) and Vanadium (V) are added to enhance structural strength, toughness and wear resistance. For instance, the tensile strength of U75V is ≥ 980 N/mm².
- Marking: Raised markings are stamped on the rail web every 4 meters, including manufacturer, model, steel grade, production date and other information for traceability and daily management.
2. Allowable Installation Deviation of Rails
Concrete Foundation Rails
- Center line position deviation: ≤ ±5mm
- Top surface elevation deviation: ≤ ±5mm
- Center distance deviation between two rails:
- Crane span ≤ 10m: ±5mm
- Crane span ＞ 10m: ±[5 + 0.25 × (Span S – 10)] mm (Unit of S: meter)
- Elevation difference of two rails at the same cross section: ≤ 10mm
Steel Beam Foundation Rails
- Center line deviation of crane beam relative to the design axis: ≤ 5mm
- Rail center line displacement: ≤ 1/2 of crane beam web thickness
- Center distance deviation between two rails: ≤ 3mm
- Top surface elevation difference:
- At support points: ≤ 10mm
- Other positions: ≤ 15mm
- Lateral displacement & height difference of adjacent rail ends: Both ≤ 1mm
II. Crane Wheels
1. Wheel Scrapping Standards
- Surface cracks or defects that affect structural performance
- Flange thickness wear reaching 50% of the original thickness
- Flange bending deformation reaching 20% of the original thickness
- Tread thickness wear reaching 15% of the original thickness
- Excessive roundness error:
- Operating speed ＜ 50m/min: Roundness ≥ 1mm
- Operating speed ≥ 50m/min: Roundness ≥ 0.1mm
2. Features & Causes of Wheel Rail Biting
Typical Features of Rail Biting
- Bright friction marks on rail side with burrs in severe cases
- Obvious wear spots on the inner side of wheel flange and rail top surface
- Dramatic gap change between wheel flange and rail within a short traveling distance
- Crane deflection and torsion during operation, especially starting and stopping
Main Causes
- Substandard rail installation accuracy
- Inconsistent motor speed and unsynchronized start for separately driven devices
- Different driving wheel diameters or excessive wheel installation deviation
- Deformation of crane metal structure
III. Summary of Parameters for Typical Crane Rails
Reasonable rail selection (QU-type rails for heavy loads), precise installation and regular wheel inspection form the three key factors for safe and efficient operation of lifting equipment.
It is essential to control installation deviation in accordance with industrial standards, select matched rails based on actual working conditions, strictly implement wheel scrapping regulations, and eliminate abnormal problems such as rail biting in a timely manner. This effectively prevents operational accidents and ensures stable and safe on-site operation.
