Do You Have Crane Tracking Problems?

Is your crane running straight? If it is not what are the consequences? Many people don’t realize the damage abnormal tracking can cause to your crane and your runway. Bad tracking can result in premature wear of your bridge crane wheels, bearings, runway rail,  and cause crane binding or racking, bridge drive breakage, or even causing broken couplings, gearing, and axles. I have seen time and time again where people will just fix these broken components instead of trying to find the cause of the breakage or excessive wear. People will change a bridge wheel and bearings just to find in a year or two later they have to invest in yet again another set of wheels and bearings. If you’re having excessive wear on your wheels or rail, or you are finding yourself replacing bridge couplings, and axles then this could be caused by abnormal tracking. There are several causes of abnormal tracking and finding these issues is becoming easier with new technology.

Crane Rail Alignment Requirements

In order to have correct tracking the runway and bridge system has to be within CMAA Spec 70 tolerances which requires the system to be square. The runway rail must be straight and parallel, and they must also be the same elevation the entire length of the runway. Depending on the span of the bridge the allowable tolerances will change.

•       The distance center to center of rails must be within +- 1/8”
•       The level of the runway rails should be within +- 1/8” of each other at all opposite points
•       The elevation of each rail along its length must be level within +- 1/8”    

Elevation

During the data collecting many crane companies fail to check the elevation of the runway and concentrate on the rail span. Although the rail span is vital for proper tracking elevation is just as important. Elevation problems can cause your tracking to be off center. One possible identifier in elevation issues is when one endtruck is centered straight on the rail and the opposite end truck is off center and against the wheel flange. If your elevation is off you will see premature wheel flange wear, and rail wear. 

Other Crane Tracking Issues

Just because you are having what appears to be tracking issues it is important to rule out certain crane problems prior to analyzing your runway. This could save you a whole lot of time and money if these issues are checked first. There are several crane issues that could cause abnormal tracking that is unrelated to your runway or bridge squareness including the following which should be verified before performing major runway alignment or repair.

•        Different diameter bridge wheels
•       Bent end trucks 
•       Bridge brakes not releasing simultaneously
•       Bad bridge bearings
•       Bad bridge couplings
•       Different RPMs on drive wheels
•       Different torque values on drive motors
•       Out of square bridge wheels

Crane Damage From Poor Alignment

Once these have been verified to not be the issue then we can focus on the runway. If the runway is the issue it is vital to correct the issue as soon as possible. Delaying repair can result in extensive crane issues that will not go away by just replacing the broken component. Your investment will be wasted in useless repairs that will only keep your crane running for a short period. Without the corrective action you will be causing your crane…

• Wheel Flange Wear
•  Railhead Wear
•  Bearing Damage
•  Coupling Damage
•   Axle Damage
•  Gearing Damage
•  Crane Racking and binding

10 Questions to Ask Your Crane Service Provider

There are several ways to fix runways that are out of alignment. However, to do the repair properly you really need to know exactly where the problem is and to what extent of repair is required. The solution of a cost effective repair is only going to be viable if you have an accurate reading of the dimensions of the entire length of runway including the runway area where no repair is required. This enables you to find the best solution for the runway repairs. This typically is a large investment so you want to make sure you have the right vendor finding out exactly where the runway and rail is off and how to correct it. When deciding on a vendor for your crane runway analysis you want to ask the following ten questions…

•         How will you be data collecting?
•        How accurate is your data collecting?
•         How long will my crane be down during the data collection?
•        What qualifies your team to collect the runway data?
•         How will I get my results?
•        Will I get any kind of report?
•        Who analyzes the data?
•         How do you decide what needs repair once the analysis is completed?
•        How long does this process take? 
•        How will you get to all the runway areas to take accurate measurements?
• 
  

     

     
 Once you have asked these questions and have asked more than one vendor, compare them and pick the one you are most comfortable with. Be sure one of the vendors you call is Konecranes. Konecranes has a state of the art runway survey called RailQ. This survey is the most accurate I have ever seen on the market. A robot called Roborail travels the length of your runway collecting data of the span and elevation throughout the length of the runway rail. It is a very fast way to collect all the required data reducing your downtime and no personnel has to walk the rail making it very safe to perform. The data is analyzed by engineers and the reports are in 3D giving you an easy understanding of your runway issues. The additional benefit is that this program will find the best solution to fix the runway reducing your overall repair cost. Find a nearest Konecranes and check out the newest technology on the market.

Bridge Cranes and Hoist Duty Cycles by Guest Blogger Richard Wehrmeister

This week is The LeCrane Chronicles first Bi-Monthly! I want to start the first one with a highly reputable guest blogger. This month I am pleased to have a post from Richard Wehrmeister. Mr. Wehrmeister is the General Manager of AdvancedOverhead Crane out of Houston Texas. Advanced Overhead Crane has been in busy for many years and is highly respected in the Texas area.

I was scrolling through my LinkedIn groups the other day and I came across this post regarding the duty cycles of electric motors. I had thought this gentleman had brought up a good point. Why won’t bridge crane manufacturers label their cranes with the designed duty cycle? Just because you have a H4 duty bridge motors does not mean your trolley is H4 or the duty cycle of the crane itself an H4 rated crane system. It would be beneficial to know what the crane was designed for regardless of the duty cycle of each individual motor on the crane. The hoisting mechanism is an integral part of the crane. Therefore the duty cycle of the hoist should be the same for the crane correct? You would think so, however this is not always the case. So if the manufacture labeled the crane with an overall duty rating, it would help in the future of the crane with decisions for certain retro-fits, and also an increase of crane usage. Lets hear what Richard had to say about this topic…..

Bridge Crane and Hoist Duty Cycles by author: Richard Wehrmeister

For quite some time I have been an advocate of having all manufacturer’s adding the duty cycle designation to both the hoist and the bridge crane nameplate. My reasoning for this is it allows the bridge crane inspector to analyze the actual duty cycle as operated to the manufacturer’s designed duty cycle. It is not unusual to find equipment that is being used beyond the manufacturers designed duty cycle.

Situations that have come up:
• Equipment was sold for one application and over time the application changed to a more strenuous duty cycle.
• Equipment sold did not meet the application requirements from the start.

To give a couple of examples:
• A number of years back we sold a class C crane with a class H3 hoist. The crane was going to be used in a testing lab. The crane/hoist was only being used 3-4 times a day under capacity load. We were trying to save the customers a few dollars with the H3 hoist. Big mistake, after a couple of years the lab was gone and the crane/hoist became a production crane/hoist. While the crane is working trouble free for the operation the H3 hoist would not hold up. In other words the hoist had on going problems with both the mechanical load brake and the hoist motor brake up until we change out the hoist to a H4 classification.
• Not long ago we were asked for a second opinion involving a hoist. When looking at the hoist from the floor, I remarked that it looked like a brand new hoist with the gear cover off. The customer said that the hoist was a few weeks old. I started to question the customer about the application and I noticed a very large lifting magnet sitting at the other end of the shop and looking back up at the hoist I saw a cord reel. Of course my question to the owner was how often did they use the magnet and did they leave the magnet hanging on the hook during a normal shift. This magnet was about the size of a scrap yard magnet and for those of you familiar, they are very heavy. Once I received my answer I told him that the hoist would not work in this application unless he wanted to rebuild the mechanical load brake every few weeks. He was upset and of course I asked him if he addressed the hoist application with the supplier before ordering the hoist. Note: The lifting magnet far exceeded the maximum weight requirements allowed by the manufacturer for a below the hook device on this particular hoist.

The duty service classifications for hoists are listed In ASME HST Performance Standards. ASME lists five duty classifications H1, H2, H3, H4 and H5.

The duty classifications for bridge cranes are listed In CMAA 70 and 74. CMAA lists six duty classifications A, B, C, D, E and F.

Both ASME and CMAA define each classification according to loading groups and the service conditions as close as possible, taking into account the speed, load and quantity of lifts in a time frame.
Getting back to my first paragraph I believe this is a topic that both ASME and CMAA should address when Regulations and Specifications become due for rewrite. A simple change to a name plate is a very small cost when we’re only talking about adding a couple digits to a name plate however the only way these changes can get done is to get more crane inspectors, manufacturers and associations involved in advocating change. You comments would be appreciated.

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What do you think about this?
Do you feel that adding the duty rating to the crane will be a benefit for the manufacturer or owner? 
Please share your thoughts on this subject.

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Calvin LeClair is a representative of Koneranes, A global overhead crane and hoist service company and manufacturer.