5.1. Principle of Fulcrum

So, what is this principle of fulcrum states? For the beam to be in the balance condition, deliveries on both the sides of the fulcrum should be equal.

The principle of fulcrum is fundamental in understanding how cranes operate. Imagine a seesaw; if both kids sitting on either side weigh the same, the seesaw stays balanced. Similarly, for a crane to maintain stability while lifting, the forces (or 'deliveries') on either side of its fulcrum (the tipping point) must be equal. This balancing act ensures that the crane does not tip over while maneuvering loads.

Think of balancing two grocery bags on either end of a stick held in the middle. If one bag is heavier, the stick will tilt towards that side. To balance it, you need to adjust either the weight of the bags or their distance from the center. This principle applies to cranes when they lift loads.

So, what is leverage? Leverage is nothing but the product of the object weight multiplied by the distance of center of gravity of the load from the fulcrum.

Leverage plays a critical role in crane functionality. It refers to how effectively a load can be lifted based on its weight and its distance from the fulcrum. When lifting a heavy object, if the load is far from the fulcrum, it requires more strength to lift it. Conversely, if it is closer, it's easier to lift. Cranes use this concept to balance the load effectively.

Consider trying to lift a heavy box. If you're standing right next to it, it's straightforward. But if you're trying to lift it from far away using a long pole, it becomes much harder. The closer you are to the load (the 'fulcrum'), the easier it is to lift.

So, here also, I am going to apply the principle of fulcrum and balance this model. I have to balance the two leverages here. One is the load leverage and other one is a crane leverage.

In crane operation, two types of leverages must be balanced: load leverage and crane leverage. Load leverage involves the weight of the load being lifted, the weight of the boom, and any other external forces such as wind. Crane leverage, on the other hand, involves the weight of the crane and its counterweights. For a crane to remain stable and avoid tipping over, these two leverages must equal each other.

Imagine a person on a seesaw. If one side (the load side) has a heavy person, the other side (the crane side) must have enough support or weight to keep it balanced. If not, the seesaw will tip. Cranes operate on this same balance; if the load outweighs the support of the crane, it tips.

As you change the angle of inclination of your boom, your load leverage will change accordingly. Your distance will change accordingly.

The boom angle is crucial for crane stability. When the angle increases, the distance from the fulcrum to the load decreases, which can enhance stability but limit reach. Conversely, lowering the boom angle increases the load's distance from the fulcrum, potentially decreasing stability. Operators must adjust the boom angle carefully to maintain lifting capacity while ensuring safety.

Think of a basketball player trying to shoot a ball. If the player bends down closer to the ground (increased boom angle), they can shoot higher but have less distance to throw it effectively. Alternatively, if they stand straighter, they can throw the ball further but need to ensure they don’t lose balance.

So, there are 2 moments acting basically you know that. One is your overturning moment. Other one is your resisting movement or the stabilizing movement.

In crane operations, there are two significant forces at play: the overturning moment, which is caused by the load being lifted, and the resisting moment, provided by the crane's weight and counterweights. Balancing these two moments is crucial to maintain stability and prevent the crane from tipping over under load.

Imagine trying to balance a long stick on your hand with a weight at the end. The weight pulls the stick down (overturning moment), but if you push up with your hand (the resisting moment), you can keep it stable. If the weight gets too heavy, you can no longer resist, and the stick falls.

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