Plan your service call - Two simple options
Crane and Hoist classifications
Are you planning to replace an overhead crane that has reached the end of its life? Your project may sound simple at first: lift loads of up to 5 tons, at a height of 20' and at a reasonable speed. But now a diligent supplier mentions... crane classifications! What the heck is this about?! Can't we simply replace the current equipment with a newer version? Why should I care about classifications?
Determining the most appropriate class of use is crucial for selecting the right lifting equipment. This concept is relevant for both an existing installation and a new project. A wise selection promotes productivity and profitability. Let's explore why.
Why exactly should the equipment be classified?
Admittedly, lifting equipment is designed to specific standards to begin with, and those standards require appropriate classification (the CSA standard, for example). But crane classification is not just a theoretical exercise. It is also about making the best possible choice regarding usage and operation. This is the main element that should be of interest to future crane owners. Determining the crane classification will make it possible to choose the most economical solution for the application, not only in terms of initial cost but also considering the installation's lifespan. In other words, defining the appropriate classification will ensure a balance between cost and equipment reliability while also helping to determine maintenance needs.
Let's look at this the other way around: if someone buys an overhead crane that's in a lower class than what the company needs, the crane’s price will obviously be lower. However, the crane will require more maintenance, parts, labor and lost productivity. These costs, added to the original purchase price, will result in a higher total cost over the crane’s life compared to equipment of the appropriate class. This option will therefore be more expensive.
Now, why would you apply this strategy for a replacement project too? After all, the equipment you were using was working well overall. Why not just swap it for more of the same? First of all, that solution may have met your needs at the time. But your lifting requirements may have changed over time. It's also possible that the original equipment itself wasn’t appropriate to begin with. If that's the case, you may have spent more than you should have in maintenance and downtime costs! If the analysis was not done then, it certainly makes sense to do it now.
It can even be useful to establish the class of use for an existing crane! In what cases exactly? When you suspect your equipment is overused. In fact, in the medium to extremely heavy classes, maintenance frequency increases. The class calculation will be used to establish the proper maintenance schedule, in order to minimize additional costs.
How is the equipment classified?
In North America, the CMAA standard is the starting point for crane classification. However, since European standards are different, they sometimes have to be taken them into account, for example when some of the parts come from a European country. It is also important to know that a crane consists of several components which may have different classes (class groups). For example, in some cases, a lifting application may require a higher class than the one related to the crane or cart movement. But most of the time, the class is applicable to the entire equipment. So how is the classification done in concrete terms?
Your crane specialist is the best resource for establishing the appropriate class you should be using. To do so, he will request usage-related data, such as the average daily load, how many days a year the equipment is being used, its average lift height, etc. When this information is unknown to the users, it is often possible to collect it from the production data already available. For example, a transportation company will typically know how often it loads and unloads cargo, or how often this cargo is handled. This data can often be used as a source of the information needed to establish the proper class.
You also need to factor in the percentages of use per capacity. To illustrate, let's say you are a strong man who carries rocks all day. You may brag that you can lift 250 kg, but how many times a day will you lift that weight before you collapse and have to take a full month off? Similarly, it's true that the equipment you choose will have to handle the heaviest load in your plant. But how often will it lift that heavy load? What kind of load will the equipment lift most often? All of this analysis goes into choosing the right equipment.
Different uses, different solutions
The following examples help understand the different types of use and the solutions that should be recommended by your lifting specialist.
As a first example: let's say you need lifting equipment with a maximum lifting capacity of 10 tons, which would perform an average of 15 to 20 lifts per day, 5 days a week. Despite the occasional lifting of a 10-ton piece by your equipment, your daily lifts would be between 2 and 7 tons. Moreover, this equipment is vital for you. Nonetheless, it would only be utilized occasionally during the day. We refer to this equipment as a handling tool. What would it be classified as? It belongs to the lower classes. The use of this equipment is common in most industries.
As another example, your future lifting equipment would be included in a production line. It would feed a machine 250 times a day. Even during vacation periods, this production cannot be stopped. Loads would weigh between 7 and 10 tons. It is considered a production equipment, and its classification is part of the higher range.
As we can see, the equipment in the two previous examples must have a rated capacity of 10 tons. But they are not in the same classification because their application is different. It's obvious that the mechanical design of the two devices will be different, as well as their acquisition cost.
A distinction must also be made between the mechanical and electrical capacities of a lifting device. The device's mechanical design may allow for the desired use, but its electrical capacity may be insufficient.
Imagine a hoist with a 10-ton capacity that rarely lifts full load, but lifts 1/2 ton at a rate of 500 times a day. The impact on mechanical capacities may not be significant. However, the motors are likely to overheat, especially as the equipment will constantly be in "stop/start" mode. This could result in a potential overload of electrical capacity. Precautions to be taken in these cases are not outlined in the user manual. To prevent damages to electrical components and production interruptions, solutions must be put in place. Forced ventilation or variable speed drives may be used in these cases. Even ambient temperatures need to be considered when determining electrical requirements. That's why your lifting experts will start by establishing the appropriate classification at the mechanical level, and then check that electrical capacities are also sufficient.
Due to these reasons, it is conceivable that two devices with the same rated capacity could have an enormous impact on investment, with differences as big as adding zero to the bill!
Another important element that is rarely discussed is the expected operational service time of the lifting device. Two customers with the same situation might prefer different classes. Why? Because one may need his equipment for the next 30 years, while the other has a 5-year mandate for his future facility.
In short, the analysis of a class implies expertise. Do not hesitate to contact your crane expert to evaluate the appropriate class for your project.
Please note that Premium uses a chart to evaluate the various parameters, and this chart is available upon request.
Choosing the right equipment, a done deal!
To conclude, we can argue that there are two crucial elements to crane classification. First, productivity is an important consideration in today’s modern industry. By choosing the optimal crane class, the equipment owner ensures maximum productivity, avoiding lengthy and repeated production stoppages. Secondly, a piece of equipment’s cost-efficiency is not only measured by its purchase price, but also by its lifespan and maintenance costs. Your final decision is going to be directly related to these factors when you purchase your equipment. Choosing the correct crane class now will ensure your investment is maximized. Instead of purchasing a piece of equipment that will last a lifetime but generate unsuspected costs and endless concerns, make a class(y) purchase!
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