Effective and versatile with a wide variety of uses Truck-mounted cranes deliver benefits that can streamline just about any business. But too often the lifting capacity of these cranes is misunderstood. Anton du Plessis, regional sales manager of Palfinger, shared his insights at the annual LEEASA and Lifting Africa conference. To understand the lifting capacity of a truck-mounted crane it’s important to go back to basics. “We talk about a ton meter lifting capacity. In other words, one does not get a 5-ton truck-mounted crane, but rather a 5-ton meter truck mounted crane,” he says. This, however, does not mean there is a lifting capacity of 5 tons. “Very often there is confusion about this. If one had, for example, a 10-ton meter truck-mounted crane, what it theoretically means is that at 1 meter the crane should be able to pick up 10 tons. In practice, however, that is never the case.” Using the example of an 18-ton meter crane, Du Plessis showed delegates attending the conference how the crane was limited to only picking up 5.75 tons. “The reason for that is that there is a much wider working range with different boom angles. So 12
Lifting Africa - Nov/Dec 2019
depending on the reach, the lift capacity reduces.” Also, he says, referring to the theory of lifting any amount of tons at 1 meter, this was not possible. “You are never going to be able to pick up something at 1 meter. You are most likely only going to reach the edge of the truck body. Typically, we look at 3 to 4 meters as a good average working area where we refer to the maximum lifting capacity.” According to Du Plessis calculating the lift capacity of a truck-mounted crane is not as difficult as many people think. “What you need to do is divide the ton meter capacity by the lifting distance in question. For argument sake, a 10-ton meter crane at 5 meters should be lifting 2 tons. Something that is not factored in is the dynamic moments, so it will reduce slightly more. Also, on top of that, as one adds extension booms,
the actual weight of the booms itself has an effect meaning the lifting weight will also drop.” Any new crane, he says, is delivered with a lifting chart and acts as a guide for users to spec a crane. “When deciding what crane you want it is important to first establish how much weight you want to lift at what distance. Based on that the size of the crane most suitable can easily be established.” Important factors When it comes to truck-mounted cranes, the first thing to keep in mind is the vehicle. “You must mount it on a truck that is legally allowed to carry the crane on the road and you also need to have a useable payload.” He said compatibility between the truck and the vehicle was therefore critical. “It must be a practical vehicle in practice and so before investments are made
The Lifting Africa Publication Nov-Dec 2019 Issue with Phakamisa on the cover.