3.2. Calculating Required Boom Length

So, let us see what is the significance of this crane range diagram. As a name indicates if you know what is your working range needed, you can find what is the boom length needed to satisfy the working range in my project site. That is the purpose of the crane range diagram or in the reverse way, for a particular boom length, with this particular boom length, what is the maximum working range, horizontal range and the vertical range I can have? That information I can get it from the crane range diagram.

The crane range diagram serves a crucial purpose. It allows operators to determine how long the boom (the arm of the crane) needs to be based on the distance they need to reach (the working range) and the height they need to lift. Conversely, if you have a set length for the boom, the diagram helps identify what the maximum height and horizontal distance can be achieved. In essence, it aids in ensuring that cranes can operate safely and efficiently by matching the boom length with the task requirements.

Imagine a basketball player reaching for a hoop. If the hoop is 10 feet high (the height), the player must jump high enough (just like the boom must extend high enough). If the player can only jump a certain height, they know how close they need to be to the basket (the working range). Similarly, the crane range diagram helps operators know how far back they should be while still being able to reach the desired height.

So, what you have in this crane range diagram in the x axis is a distance from the centre of axis of rotation of the crane to the load line, distance from the centre of axis of the rotation of the crane and what you have in the y axis is the height of the boom tip above the ground. Say, for example, if you know that your operating radius working radius needed, maximum working radius needed is 20 meters and if we want to, say, for example, I need to reach a height of say 53 meters. The maximum height reach needed is say 53 meters. Then what is the boom length needed for my particular project? I can determine from this range diagram.

The crane range diagram is plotted with two axes: the x-axis represents the distance from the crane's rotation center to the load line (horizontal reach), while the y-axis represents the height of the boom's tip above the ground. For instance, if an operator knows they need to reach 20 meters horizontally and lift something to 53 meters high, they can find the necessary boom length using this diagram. It’s essential as it gives a clear visual guide to ensure the crane can perform the required tasks safely.

Think about a seesaw on a playground. When you sit further away from the center, you have to lean back more to stay balanced. Similarly, the further the crane extends horizontally (x-axis), the higher it needs to go (y-axis) to lift a load. The crane range diagram helps keep that balance between height and reach, ensuring safe operation.

So, the height of boom tip above the ground equal to height at which the load needs to be lifted above the ground, it is 40 meters. Height of the load is 5 meter plus the length of the sling is 8 meters. You add everything; you get 53 meter that should be the height of boom tip above the ground that is what you need for this particular project. And the operating radius, the horizontal radius is 20 meters. So, from the crane range diagram, for these 20 meters and 53 meters, we have chosen the boom length of 55 meter.

To determine the required boom length using the crane range diagram, first, it's necessary to calculate the total height needed for the boom tip to lift the load. For example, if the load is at a height of 40 meters, includes a 5-meter load height and an 8-meter sling length, you'll need a total height of 53 meters. With the horizontal distance required being 20 meters, you can find that a boom length of about 55 meters is necessary to reach this height and distance safely.

Imagine stacking books on a shelf. You need to ensure that you have enough reach (boom length) to get the top book (load height) without straining. If the shelf is 40 inches high and your books add up to about 53 inches when stacked, you’ll have to stretch a bit further to get that top book, just like adjusting the boom length to reach higher.

Determine the maximum net weight of the load that can be hoisted by the crane. If the block, hook, and the sling weight 2200 kg, as I told you when you consider the lifting capacity of your crane, you should include the weight of the hook, block, sling, everything, the rigging device also.

When determining how much weight a crane can lift, it's vital to include not only the weight of the load but also the weight of the rigging equipment, such as the block, hook, and sling. In this case, if the combined weight of these components is 2200 kg, operators must subtract this from the total lifting capacity indicated in the crane load charts to determine the maximum net weight of the actual load that can be safely hoisted without exceeding the crane's capacity.

Consider a person lifting a backpack. If the person can lift 30 kg but the backpack itself weighs 5 kg, then they can only carry 25 kg of additional items. Similarly, the crane operator needs to account for the 'weight' of its equipment to ensure that lifting limits are not exceeded. Without this calculation, it could lead to unsafe lifting conditions.

So, maximum total load permissible is 24040 kg. So, from this, you have to detect the weight of your sling and the hook block everything. So, what is that the maximum lifting load possible from the safety of the crane for this particular boom length for this operating radius, it is 21840 kg.

Load charts provided by manufacturers detail how much weight a crane can lift at various boom lengths and horizontal distances. For example, if the maximum load for a certain radius is 24040 kg, but you must also account for the 2200 kg weight of rigging tools, the actual maximum net load that can be lifted safely becomes 21840 kg. This ensures that the crane operates within safe limits.

Think of a delivery truck. If a truck can carry a maximum of 10,000 pounds, but you load a toolbox that weighs 500 pounds into it, the effective load the truck can deliver is now reduced to 9,500 pounds. Similarly, the crane must account for all its 'additional weight' to ensure it doesn't overextend itself and compromise safety.

--