2.4. Backhoe and Loader Combination

They have poor mobility. So, that is why it is preferable to place a truck very close to the excavator. So, very commonly you can see that the truck is placed at 90 degree. So, the truck is placed at 90 degree, this will be 90 to the bucket position.

In construction sites, trucks often need to be close to excavators for efficient operation. When trucks are positioned at a 90-degree angle to the bucket of the excavator, it allows for easier dumping of materials. Poor mobility of the excavators and loaders means that keeping the truck nearby decreases the time and effort spent maneuvering material.

Imagine trying to fill a wheelbarrow with dirt from a pile. If you are standing close to the pile, you can quickly scoop and dump the dirt into the wheelbarrow. However, if the wheelbarrow is far away from the pile, you will waste time moving back and forth. Similarly, keeping the truck close to the excavator speeds up the loading process.

So, basically angle of swing is nothing but the horizontal angle between the digging and the dumping position. As the truck moves further away, your angle of swing would increase. As the angle of swing increases, you can see that your cycle time will increase, the productivity will decrease.

The angle of swing refers to the horizontal angle formed as an excavator moves its bucket from the digging position to the dumping position. If the truck is further away, the driver has to swing the excavator at a larger angle, which increases the cycle time (the time it takes to complete one loading and unloading cycle). Longer cycle times reduce overall productivity since the excavator is spending more time moving rather than digging and loading.

Think of a person trying to toss a ball into a hoop. If they are standing close to the hoop, they can quickly toss the ball and retrieve it. But if they stand further away, they have to take extra steps back and forth, slowing down their attempts to make it into the hoop. Similarly, increasing the angle of swing and the distance to the truck slow down the excavator's work.

Ideal condition ideal production of shovel is based on 90 degrees swing... based on the angle of swing that is going to depend upon the position of your truck relative to the position of your excavator.

The most productive angle for a shovel or excavator is to operate within a 90-degree swing, which allows for the best loading and dumping efficiency. If the height of cut and swing angle are optimal—meaning they meet the specified conditions—no correction factor is necessary. However, if the truck's position differs from ideal, adjustments need to be made to account for decreased productivity.

Consider a basketball player shooting from the free-throw line. If they shoot from the same position every time, they develop a consistent shot. However, if they start shooting from various distances or angles, they may need to adjust their technique for each shot. Likewise, if the excavator must deal with different swing angles or heights during operation, adjustments must be made to ensure it remains productive.

If the actual height of cut is same as optimum height of cut, it means the percentage is 100%... if your actual project condition is going to differ or vary from the ideal condition, then in that case you have to apply the correction factor.

When the actual height of the cut matches the optimal height, productivity is maximized, and a productivity percentage of 100% is achieved. However, if the actual height is lower or higher than the optimal height, correction factors come into play. This means adjustments to the expected productivity must be made based on how far the actual height is from the ideal height.

Imagine a student studying math problems. If they practice problems that are exactly at their skill level, they may solve them quickly and effectively. However, if they try problems that are too easy or too hard, it takes longer, resulting in less effective study time. Similarly, if the excavator is not positioned at the optimal height, it will take longer to complete work, reducing overall productivity.

Now, note that there should be some space left for the tail swing of the shovel... This is called this truck spotting clearance.

To ensure safety and effective operation, it is essential to leave enough space for the excavator’s tail to swing without hitting the truck. This clear area is known as truck spotting clearance, and not allowing enough space can lead to accidents or inefficient operation.

Think of a swing set at a playground. When swinging, children need enough space on either side to avoid hitting other kids nearby. Similarly, when operating an excavator and a truck, ensuring there is enough space allows for smooth and safe operations.

Another important factor is haul unit exchange time... the total time required for the loaded truck to clear its loading position and for the next empty truck to the position for loading.

Haul unit exchange time refers to the period it takes for a loaded truck to leave the loading area and for a new empty truck to take its spot. Reducing this wait time is crucial for maintaining productivity, ensuring there is always a truck ready to be loaded with materials after the previous one leaves.

Imagine a fast-food drive-thru. If cars take too long to order and pick up their food, the line builds up, leading to longer waits. To maintain a smooth flow, the restaurant needs to process cars quickly to keep things moving. The same principle applies to the exchange of trucks at a work site—keeping the process fast keeps productivity high.

Now let us see how to estimate the productivity of the shovel... adjust the productivity based upon the swing depth factor.

Estimating the productivity of a shovel involves calculating the heaped volume of the bucket and adjusting that figure based on factors like cycle time and swing depth. The bucket's volume is adjusted by a fill factor and divided by the cycle time to find productivity. All modifiers related to the height of cut and angle of swing must also be taken into account.

Think of measuring how much paint you can apply to a wall. If you know your brush size and how quickly you can paint a specific area, you can estimate how long it will take to finish. Similarly, by understanding the excavator's bucket capacity and speed, operators can estimate how much material can be moved over a certain time.

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