1.5. Estimating Productivity

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 a 90 degree angle. The angle of swing is nothing but the horizontal angle between the digging and the dumping position between the loading and the dumping position.

Placing the truck close to the excavator is crucial because excavators have limited mobility. A 90-degree angle between the truck and the excavator allows for optimal work efficiency because the excavator can swing its bucket to load the truck without much delay. The angle of swing defines how far the excavator has to move its bucket to transfer material from the digging site to the truck. A smaller angle means less movement and faster loading.

Imagine a waiter serving food at a restaurant. If the waiter is standing right next to the table, it’s easy and quick to serve the food. But if the waiter is far away, he has to walk a longer distance, which takes more time. Similarly, keeping the truck close to the excavator speeds up the loading process.

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, and the productivity will decrease.

When the truck is placed farther from the excavator, the swing angle increases. This larger angle means more movement is needed for the excavator to dump the load, consequently increasing the time taken to complete each cycle (the time taken to dig, swing, and dump). This longer cycle time negatively impacts productivity because the excavator completes fewer cycles in the same amount of time.

Think of a person throwing a ball. If they throw the ball directly in front of them, it’s quick and straightforward. However, if they have to twist and turn to throw it to someone further away, it takes much more time and effort. The same concept applies to the excavator; the more it has to swing, the less it can do effectively.

Ideal condition of shovel production is based on a 90-degree swing that is what I told you; the truck will replace it. The actual height of the cut in your project site should be the same as optimum height of cut.

For optimal productivity, both the angle of swing and the height of cut must meet ideal conditions. The ideal swinging position (90 degrees) allows the excavator to operate efficiently, while the actual height of cut should match the optimal height set for the machine. Ensuring both these conditions are met maximizes the output and efficiency of the excavator.

Consider a professional athlete training under perfect conditions—optimal weather, proper gear, and ideal training space. When all these factors align, the athlete performs at their best. Similarly, having the ideal conditions for an excavator leads to maximum productivity.

Now, let us see what are all the adjustment factors, we have to apply while doing the productivity estimation based upon the height of the cut of material, and based upon the angle of swing.

Adjustment factors are necessary for estimating productivity when actual project conditions differ from the ideal. If the actual height of cut is lower or higher than the optimum height, or if the angle of swing varies from 90 degrees, these factors need to be accounted for to assess how they affect productivity. This ensures more accurate predictions and planning for operations.

Imagine trying to bake a cake. If you use the wrong temperature or incorrect ingredient amounts, the cake might not rise properly or might take longer to bake. Similarly, when digging, if the machine isn’t set optimally, it affects how efficiently it can work.

If the actual height of cut is the same as optimum height of cut, it means the percentage is 100%. If this percentage is going to be 100%, it means actual height of cut and optimum height of cut are the same. So, in that case, you need not apply any correction factor.

When the actual height of cut matches the optimum height, no correction factor is needed in productivity calculations, allowing for straightforward estimates. If the height of cut is less than the optimum, it reduces productivity, prompting the application of a correction factor to adjust the estimated output.

Think of a school assignment. If you meet all the criteria for assignment length and quality (the optimum height), then you don’t need to make changes. But if you write less or exceed the required length, you might need to adjust what you've written to ensure you meet the requirements adequately.

When the angle of swing is higher than 90 degrees, the correction factor decreases, indicating reduced productivity. If the angle of swing is less than 90 degrees, the correction factor increases, suggesting improved productivity.

The angle of swing is directly correlated with productivity. When the swing exceeds the ideal 90 degrees, it contributes to inefficiencies, which lower productivity. Conversely, a swing angle of less than 90 degrees allows more efficient movement, thus enhancing productivity through a favorable correction factor.

Consider riding a bicycle around a curve. If you take a sharp turn (akin to a wide swing), it’s harder to maintain speed as it requires more effort. But if you take a gentle curve (less than 90 degrees), you can keep going faster. This is similar to how an excavator performs better with smaller swings.

Another thing to be noted is truck spotting clearance. There should be some space left for the tail swing of the shovel.

Truck spotting clearance is the necessary space between the truck and the excavator to allow for safe operation. The excavator needs room to swing its tail without risking collision with the truck. Maintaining this clearance is critical for safe and efficient productivity.

Think of a large revolving door in a busy café. If people stand too close, the door won’t turn properly and can get stuck. Leaving space ensures smooth operation, just like ensuring enough clearance for the excavator tail allows for efficient loading and unloading.

The time needed for the loaded truck to leave its position and for a new empty truck to take the position is called haul unit exchange time.

Minimizing haul unit exchange time is essential because it directly affects overall productivity. If trucks are not readily available, it can cause delays and increase the cycle time for the excavator as it must wait to load the next truck. Efficient coordination of truck arrivals reduces wait times and improves productivity.

Imagine a busy café where a new waiter needs to quickly serve new customers as fast as possible. If the previous customers take too long to leave, the new customer has to wait for their service. By ensuring smooth transitions, like promptly clearing tables, the café can serve more customers effectively.

Now let us see how to estimate the productivity of the shovel. The production of the shovel depends upon the heaped volume of your bucket, adjusted with the bucket fill factor, then divide it by the cycle time.

Estimating shovel productivity involves knowing the bucket's heaped volume and adjusting it with the fill factor based on material type. Then, dividing this adjusted volume by the cycle time gives an estimate of productivity. This calculation informs how much material can be moved effectively within a certain timeframe.

This is akin to measuring how much water you can pour from a pitcher before it runs out. If your pitcher has a certain capacity (bucket volume), and you know how fast you pour (cycle time), you can easily calculate how much you can serve in a given amount of time.

If the actual height of cut and angle of swing differ from the ideal condition, then you have to choose the correction factor accordingly.

When the actual conditions deviate from the ideal setup for height of cut and angle of swing, adjustment factors must be applied to the productivity estimate. These factors correct for inefficiencies caused by less-than-optimal conditions, leading to a more accurate productivity forecast.

Think of a car traveling in ideal conditions—smooth roads and no traffic. If it drives into a construction zone (less than optimal conditions), its speed drops, and you’d need to estimate the new time based on this slower speed compared to the ideal. Similarly, adjustments in the estimating process account for real-life challenges.

Multiply the production of the shovel with the job efficiency. How much time your machine is going to work in an hour.

To find the actual productivity, it is essential to multiply the calculated shovel production by the job efficiency factor, which reflects the actual working time in an hour. This factor accounts for downtime or inefficiencies, allowing for a more realistic estimate of productivity over an hour.

It's like preparing food for a party. If you plan to prepare a dish in an hour but only realistically work for 45 minutes (efficiency), then you multiply the amount you can make in that time with the actual working time to understand how many servings you can prepare for your party.

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