Crane Rail alignment is a crucial yet often overlooked aspect in overhead (OH) crane operations. It is more imperative than it is considered. Properly aligned crane rails ensure efficient and safe travel and improve the crane’s lifespan. Why? Misaligned rails can increase wear and tear, unexpected breakdowns, inefficiency, structural damage, and unsafe operating conditions.
So, understanding your crane rail’s tolerances and standards is critical. Any deviations from the standards should be identified and addressed. Even the slightest deviations could cause skewing, derailment, flange wear, and load fluctuations, i.e., excessive loads. A Runway Rail survey in Crane rail alignment gives precise data to assess the condition, positioning, and rail’s silhouette on which an overhead crane travels. The runway rails must be properly aligned for the overhead crane to travel safely and efficiently.
Runway Survey analysis, particularly using 3-dimensional measurement, provides more accurate crane-rail conditions including elevation variances, span differences and rail straightness. Corrective strategies can be developed with this data; for example, misalignment could be corrected through rail grinding, shimming, or, if the damage is too extensive, a decision to replace the full rail.
In one way or another, investing in regular crane surveys and proper alignments is also a proactive approach to a crane’s longevity and operational efficiency. A well-maintained and regularly inspected rail system ensures smooth crane travel and operations, and is directly proportional to reducing cost and downtimes.
In this blog, we will explore crane rail alignment, its essentiality, the consequences of poor rail alignment, advanced tools and other interesting topics related to crane rail alignment.
What is Crane Rail Alignment?
Crane Rail alignment is the accurate positioning of the rails on which EOT or gantry cranes operate. The rails these cranes run on are susceptible to wearing out and misalignment. These issues can cause a crane jerk, skew, or drift, leading to wear on wheels, motors and bearings, structural stress on the crane and beams, and inherent hazards like derailment or load swing. Here are some important aspects concerning rail alignment:
- Crane Span accuracy: The horizontal distance between the two rails must be consistent along the entire runway; however, slight deviations are tolerable. For instance, a crane with a 50-foot span can have rails that vary by ±3/16 inch from the nominal span, and for cranes between 50 and 100 feet, the tolerance level could be ±1/4 inch, and it will be ±3/8 inch for crane that spans over 100 feet and can still be acceptable. Too much deviation can cause the crane to jam or derail, causing fatalities.
- Straightness: Crane rail straightness measures how straight the crane rails are along the crane travel and how much they deviate from the intended line, i.e. without lateral shifts or bends. Straightness is measured over a specified length, usually ±1/8 inch over 10 feet. From analysing rail straightness, the area with curves or bulges can be detected, which aids in re-alignment procedures, shim adjustments, or grinding.
- Elevation Levelling: Crane rail elevation is the vertical height of the rail compared to a set point (e.g, crane runway support structure). For safer crane operations, rails must be level with each other; their elevations should be close. Across the runway, the height or elevation of each rail is allowed for a deviation up to 3/8 of an inch, more or less than the nominal level. The level of change in elevation shouldn’t be spontaneous; It must be gradual. If one rail is higher or lower than the other, the crane is prone to tilt or lean on one side, wheels may lift off on one side, and load distribution becomes uneven, leading to structural stress, wheel wear and derailment.
- Rail head wear: The top surface of the rail is the rail head, where the crane wheels roll on. The rail head and gauge wear due to continuous operations causes flattening and pitting in the rail head. Worn rail heads lead to poor traction and abrupt crane movement. Uneven surfaces cause vibration, stress and increased noise levels. Regular checks ensure the rail surface is not worn and is within tolerance levels.
Improper crane rail alignment and tracking cause premature component wear, leading to probable repair costs, downtime, or even replacements. Generally, misaligned or worn rails and pads, incorrect installation, manufacturing defects, bent components, and corroded parts cause a crane to move wobbly.
Common issues caused by poor rail alignment include rail misalignment, uneven wear, crane skewing and vibration while running, increased energy consumption, accidents and derailments, and reduced crane life. Proper crane installation, maintenance, and regular alignment checks are essential to keep the crane working effortlessly.
Benefits of Proper Rail Alignment
Here are some reasons why proper rail runway alignment must be done:
- To ensure smooth crane movement.
- To prevent excessive wear on wheels, rails and motors.
- To reduce derailment possibilities.
- Improve operational efficiency.
- Reduce repairs and replacements.
- Improve the life of the EOT Overhead or Gantry cranes.
Crane Rail Alignment Process
Previously, rail alignments and inspection were done using optical surveys, which had their share of hurdles and difficulties. For one, using optics in rail survey involves difficulty in confined and complex areas and may require complete obstruction of the operation due to multiple lock-out runways. Other reasons include inaccurate measurements, environmental factors, cumbersome steps, lack of 3D data, and the requirements of skilled operators. Modern crane rail alignment has evolved greatly with the help of advanced high-precision instruments and digital tools, replacing the older, manual inspections like theodolites or spirit levels. The following are the steps involved in how crane rail alignment is generally done:
- Initial Investigation: Technicians and engineers review the runway composition, crane tolerances and specs and set reference points on the structure as the baseline for measurement.
- 3D Laser Scanning and 3D Total Station: A 3D laser scanner captures innumerable data points from the rail and the nearby area, providing a highly detailed 3D layout of the rail alignment, wear and elevation. 3D Total station is a high-tech surveying instrument that combines a theodolite, an Electronic Distance Meter (EDM), and a software system to find the exact position of any points in 3D.
- Data Collection: The technicians collect the data concerning rail straightness, elevation, gauge width, span variances, rail head wear, etc., and measurements are considered at regular intervals along the entire runway.
- Crane rail Alignment: The collected data is thoroughly analysed, and based on the analysis, corrective alignments are planned, such as shimming, re-levelling or grinding, re-spacing for gauge correction and re-anchoring sections of rail.
- Verification: A final 3D check is carried out to ensure all adjustments are within the tolerance levels and standards. A compliance report is created for quality assurance and reporting.
Best Practices for Crane Rail Alignment
The following are the best practices for effective Crane Rail Alignment:
- Schedule regular inspections and measurement checks of the crane rails.
- Incorporate laser-based alignment tools to improve precision.
- Comply with the manufacturer’s specs and standards on installation and maintenance procedures.
- Ensure rails are supported and secured by strong structures.
- Maintain detailed records of alignment data and monitor changes on time to detect signs of stress and anomalies.
Advanced Crane Rail Alignment Tools:
- Laser Trackers and Total Stations:
- Measures precise positions in 3D space.
- Captures exact coordinates (X, Y, Z) of rail runway points.
- Highly accurate and ensures the rails are level, straight and within tolerance
- Total stations are generally used for routine inspections, while laser trackers are desired for higher-precision and longer span applications.
2. EOT crane survey:
- It is a detailed inspection of the Electric Overhead Travelling (EOT) crane system.
- Inspects the crane wheels, end trucks and span alignment with the rail runway.
- Ideally detects concerns like skewing, wheel misalignment or abnormal wear.
3. Crane Rail/ Girder Survey:
- This survey will help benchmark and measure the anomalies on the crane rails, crane girders, column flanges and supporting beams to ensure even elevation, accurate gauge and efficient structural support.
- This survey detects twists, or deflection in the rails or girder, that could affect the crane’s running and alignment.
- Crane rail and girder survey is crucial during initial installations, upgrades or major repairs.
5. Crane Rail Alignment Drawings:
- Crane rail alignment drawings are the technical drawings generated using data collected.
- Visually represents the existing alignment layout to contemplate the gap between the actual and required tolerances.
- Helps in developing corrective strategies and alignment procedures.
- Generated commonly through special software and systems.
Crane Rail Alignment Services with Ocean
Being the leading engineering company in Oman, Ocean TMS offers our clients the best and specialised crane-railway survey and alignment services because we focus on ensuring optimal care for your Overhead or Gantry cranes and a hassle-free experience. We understand the mechanical stresses and structural demands in crane maintenance and operations, which is why we have developed our services to align with your crane’s requirements and preferences.
We use the most modern tools available in the industry to carry out complex and comprehensive crane surveys and alignment, be it on runways, rails, and supporting girders. We have got you covered! Our expert engineers and technicians analyse and evaluate key metrics on the crane components to create detailed digital representations and strategies to fix even the smallest anomaly. We continually work on minimising downtime, enhancing safety and crane lifespan, and ensuring untroubled crane operations. Level up your crane operations. Get your crane survey done with OCEAN! Contact us to learn more!