More about Crane Rail Fastening System

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Mar 08,

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Currently, most solution for crane rail fixing is designed according to the standard drawing of crane rail fastening system. But why use crane rail fastening? If a crane has very low running speed, low working frequency, and low wheel-pressure, it&#;s working to adopt traditional rail fixing system. If a crane has high running speed, high working frequency, and high wheel pressure, the traditional fixing system will produce a bad influence on the crane rail. Actually, with the update of technology, the tonnage of crane become more and larger, working frequency also get more and higher. Traditional rail fixing system can&#;t be adaptable for the requirement of crane development, that&#;s why knowing crane rail fastening system is important.

Crane rail fastening market

 

Common problems of rail fastening system for crane rail

1. For traditional rail fastening system, rails are connected by the rail joint. There is a joint between two rails, when crane pass through rail joint, strong vibration, the impact will damage the structure.
2. Due to the load from the track, track bolt and fish bolt often loose, which need nonscheduled maintenance.
3. When rail track is wearing and gnawing, joint will misplace and deform. It is hard to do the lateral adjustment.
4. Sometimes, the concrete bed under the rails is broken, the rail joint will sink.
5. Part of rail track bends into S-shape curve along the axial line.
6. Common rail clips can force the crane rail.

Components of crane rail fastening

Rail rubber pad

 

Crane clips

 
Crane rail fastening system has the strict requirement on the clamping force and lateral force of each set of crane clip. Due to the base should bear huge alternating lateral force from tie plate, Crane clip of GANTREX have the high standard of material and welding of base. In general, crane clip adopts forging process, which has good safety, long service life.  

Continuous welded rail 

 

Grout

 

Why use crane rail fastening system to replace traditional rail fasteners?

Obviously, crane rail fastening is more suitable than traditional rail fastening for crane rail fixing. In a word, crane rail fastening system can make up the shortfall of traditional fastening system.

1. Traditional crane rail fixing is joined by the rail fish plate, there will be a gap between two ends of rails. The rail tracks can&#;t be connected into a continuous part. The gap will produce vibration when the train passes the rail joint. Frequent vibration will lose the crane bolts and fish bolts, also result in much more other damage to crane or crane rail.

Solution: welding method is the most effective way to solve the joint problem. Welding method requires the adjustable crane rail clip.

2. Crane rail is made by the hot rolling, and rail base usually has an uneven surface. In the primary period, the contact surface between concrete and rail track will be same as rail base. While longitudinal extension of rail track caused by the thermal expansion and contraction will form peak When the crane operates, the pressure crushes the particles. Again and again, the concrete bed will be damaged.

Solution: to solve problems above, laying steel plate between rail track and concrete surface. Rail pad of crane rail fastening reduces the positive pressure. Grout of crane rail fastening system also provides protection for concrete. Steel plate and cement bound together with grout. Grout has stable size and good liquidity, which is easy to install and also can avoid plastic shrinkage.  

3. Traditional rail clips for fixing steel plate is directly on the anchor bolt. The lateral force produced by the crane operation through the anchor bolt and pass to the concrete bed. When the lateral force is much bigger than the ultimate strength of concrete bed, the bed will be broken and anchor bolt will lose.

Solution: set the anchor bolt and crane clips separately. The anchor bolt is only used to fix steel plate, the lateral force is evenly passed to the anchor bolt and concrete bed will accept less force. Rail track is fastened by the crane clips.

4. When the crane runs along the crane rail track, the end of rail will be left vertically, and large lifting capacity will appear. The lifting capacity can lose or break track bolts.

Solution: crane rail fastening system have a rubber pad, it can protect crane bolts from loose or fracture. 

Crane rail is a combined field of mechanical engineering and civil engineering. In general, mechanical engineers only focus on the problems of operational outfit, and the civil engineers only care about the safety and reliability of track construction. As for the part in between, due to the short of professional engineering technicians, there always exist some problems of crane rails.Currently, most solution for crane rail fixing is designed according to the standard drawing of railroad track . Traditional method of rail connection adopts rail joint bars , but it is better for crane rail to use. But why use crane rail fastening? If a crane has very low running speed, low working frequency, and low wheel-pressure, it&#;s working to adopt traditional rail fixing system. If a crane has high running speed, high working frequency, and high wheel pressure, the traditional fixing system will produce a bad influence on the crane rail. Actually, with the update of technology, the tonnage of crane become more and larger, working frequency also get more and higher. Traditional rail fixing system can&#;t be adaptable for the requirement of crane development, that&#;s why knowing crane rail fastening system is important.In China, traditional rail fixing system requires low investment, but high maintenance cost. As for the cost of beading for cranes and breakage of transmission shaft, let alone the indirect loss produced by the stop work. GANTREX is a typical crane rail fastening system manufacturer. Nowadays, gantry crane rail fastening system is known as the most reliable and cost-effective type of crane rail fastening. So we analyze the crane rail fastening system according to the data of gantry crane rail fastening system.Rail rubber pad is made of anti-abrasive, pressure-proof, anti-oxidative, uviofast, grease-proof synthetic rubber. There are grooves on the surface of rail pad, which keeps the close connection between rail base and rail rubber pad and reduce the abrasion of rail pad. There is steel disc in the middle of pad for increasing lateral rigidity of pad. The width of steel disc is generally thin, and it is easy to roll for transportation. The width of steel disc is proportional to the width of rail pad.Crane clip of GANTREX is different with normal rail clips. There is a special part of vulcanized rubber, and it vertically compresses the crane rail with elastic force. The crane rail of GANTREX has adjustable lateral and self-locking function, and the base is made by the forging process. Forged metal can improve its structure and mechanical property. Compared to the forged piece of same material, casting piece has lower mechanical property.Crane rail fastening system has the strict requirement on the clamping force and lateral force of each set of crane clip. Due to the base should bear huge alternating lateral force from tie plate, Crane clip of GANTREX have the high standard of material and welding of base. In general, crane clip adopts forging process, which has good safety, long service life.Rail connection adopts welding method, which requires variable crane clips. Welding method is allowed to elongate and shorten when the rail is heated or cooled.Compared to ordinary cement, grout has features of good early-strength performance, good fluidity, and high compressive strength. After molding, grout has no plastic shrinkage.Obviously, crane rail fastening is more suitable than traditional rail fastening for crane rail fixing. In a word, crane rail fastening system can make up the shortfall of traditional fastening system.: welding method is the most effective way to solve the joint problem. Welding method requires the adjustable crane rail clip.: to solve problems above, laying steel plate between rail track and concrete surface. Rail pad of crane rail fastening reduces the positive pressure. Grout of crane rail fastening system also provides protection for concrete. Steel plate and cement bound together with grout. Grout has stable size and good liquidity, which is easy to install and also can avoid plastic shrinkage.: set the anchor bolt and crane clips separately. The anchor bolt is only used to fix steel plate, the lateral force is evenly passed to the anchor bolt and concrete bed will accept less force. Rail track is fastened by the crane clips.: crane rail fastening system have a rubber pad, it can protect crane bolts from loose or fracture.

Let&#;s face it, if you don&#;t have rails, you don&#;t have a crane.  Bridge cranes travel on rails.  If those rails become misaligned, the crane&#;s wheels will begin to wear out sooner than they should&#;and this can lead to acatastrophic failure of your overhead crane in the middle of a time-critical project, not to mention the costs associated with purchasing new crane wheels and potentially new rail. Even if your system does not fail, misalignments will cause your crane system to be inefficient.  Planned maintenance in the form of crane rail and runway inspections and surveys can prevent these types of issues before they become problems.

Let&#;s face it, if you don&#;t have rails, you don&#;t have a crane. Bridge cranes travel on rails. If those rails become misaligned, the crane&#;s wheels will begin to wear out sooner than they should&#;and this can lead to acatastrophic failure of your overhead crane in the middle of a time-critical project, not to mention the costs associated with purchasing new crane wheels and potentially new rail. Even if your system does not fail, misalignments will cause your crane system to be inefficient. Planned maintenance in the form of crane rail and runway inspections and surveys can prevent these types of issues before they become problems.

 

The Problems of Rail Misalignment

When crane rails and runways are not properly aligned, problems are going to develop. Both horizontal and vertical alignment are extremely important. When horizontal misalignment occurs, the crane&#;s wheels will experience excessive wear as the horizontal forces act against them (scraping/rubbing vs. gliding). Vertical misalignment causes the crane&#;s load to be unevenly distributed and results also in accelerated wear to multiple elements in the crane structure. Further, not only are the crane wheels and rail affected when rails are misaligned: we commonly see wear structural element fatigue and failure, as well as bridge couplings and axle wear patterns. Through recurrent misaligned operations, the crane itself can become skewed or flanged and experience binding on the runway, or dislocation of the crane from the rail altogether. In terms of efficiency, skewing and other types of misalignment can cause the crane to use more power to overcome the inconsistencies in alignment, making the crane unnecessarily inefficient and leading to premature failure of other electrical and mechanical components.

Based on these facts, it is safe to assume that ignoring rail alignment issues can prove both costly and dangerous.

 

Causes of Rail Misalignment

Crane rail misalignment can have many different causes, starting with an incorrect installation. When the installation is not performed correctly, the crane may not be fully square, the structure may not be properly aligned or the rail may note be properly aligned or a combination of all.  Immediate issues should begin to propagate, most often illustrating in wheel metal shavings on the top of the beam or on the floor near the runway. Overloading a crane past its rated capacity and sudden impact loads can also lead to issues with misalignment. Settlement in the columns and/or support structure are additional culprits. All of these cases point to the need for regular crane rail and runway inspections.  In the event issues are uncovered, a rail survey is an in-depth evaluation of the issues in order to confirm root causes for ultimate remediation.

 

Signs of Rail Misalignment

There are certain signs you can look for if you suspect your rails may not be properly aligned. These include the following common symptoms:

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• Loud scraping sounds when the crane is in motion
• More power required to move the crane through certain sections of the runway
• Wheels that float or climb over the rails and then crash back down
• Wheel flanges that are cracked or completely broken
• Excessive wear on the rails, wheels, or wheel bearings

If you notice any of these issues, it is important to remember that just addressing the symptom (e.g., replacing a broken wheel or worn-out wheel bearings) will not solve the problem but just result in more repairs. If the issue is alignment, a rail survey needs to be performed to confirm and address with the real problem.

 

How Rail Surveys are Performed

A rail survey is performed using manual or electronic surveying tools to obtain key measurements related to the position of various points along the crane structure.

Rail surveys can be performed using traditional surveying tools as well as more modern 3D laser or camera equipment. The traditional approach uses a theodolite and geometric leveling, with the theodolite more commonly replaced with a laser now. In such an approach, a laser is mounted at the end of a rail and projects a point on a target board attached to a vehicle that moves along the rail. The position on the target board can then be read at specific distances and heights.

A more modern approach to alignment surveys makes use of lasers and automated tools. For example, alignment of high-level tracks can be accomplished using a laser auto-tracking total station at ground level to measure the distance to a robotic survey target (a prism) on the rail. With modern rail survey tools, the alignment, span, and level can all be obtained using the same setup. The rail survey service that you use may also use analytical software to fully investigate the data so that you can get as much information as possible about the condition of your crane rails.

Importantly and often missed, surveys should be performed in a loaded and unloaded crane/runway condition.  Often, issues will not propogate in an unloaded scenario.

 

What to Expect from a Professional Crane Rail Survey?

Rail surveys will typically include the following:

• A visual inspection that includes observation of excessive wear as well as the assessment of rail gaps, rail joints, and rail clips
• Measurement of straightness, alignment, span, elevation, and rail-to-rail elevation
• Measurement of rates of change in structural elements between sections
• Data that shows where your rails are not within tolerances required by the Crane Manufacturers Association of America (CMAA)
• Full written rail inspection and survey report with recommendations

The crane rail inspection and survey report will include measurements, photographs, video footage, and calculations supporting the results presented in the report. In addition, you can expect to see the survey results compared to any standards that apply along with a full set of recommendations for how the crane rail and runway should be realigned for optimum performance. It is also common to see both 2D and 3D representations of the rails. In addition, the recommendations for addressing crane rail misalignment should propose ways to accomplish alignment by adjusting a minimum number of locations on the rail.

 

Conclusion

Proactively evaluating the health of your crane&#;s rail and runway condition will give you confidence in the reliability of your cranes. When properly performed, rail surveys can significantly reduce unplanned downtime and eliminate many costly repairs.  In fact, with today&#;s technology, a service provider can quickly pinpoint potential issues before they happen (many times in real time with the proper equipment), further reducing unexpected downtime and many unnecessary repairs.

At Hi-Speed Industrial Service, you can count on our factory-trained technicians to use cutting-edge technology to perform a comprehensive rail survey for your cranes. In fact, we offer predictive maintenance service plans customized to your facility and its needs so that you can catch problems like rail misalignment before the damage is done.