3. Approaches to Estimate Productivity

So, this cutting and pushing will go together. So, the time required to push, backtrack and maneuver into position, so that is called as a cycle time of the bulldozer. So, you are going to cut the earth, push the earth, dump it at the required place, then backtrack, backtrack in the sense you are going to return, return back to the original position where you want to do the dosing operation again. So, other things are maneuvering, maneuvering in the sense whatever adjustments you do, like for increasing the speed, accelerating or decreasing the speed, changing the gear, so the time needed for changing the gear, all those things comes under the maneuvering. So, we call this as fixed time, this is fixed time and this one is variable time, your push and backtrack it is called this variable time.

Cycle time for bulldozers includes different components, primarily the time taken to push, backtrack, and maneuver into position. The cycle time is composed of fixed time and variable time. Fixed time refers to the adjustments needed to operate the bulldozer, like changing gears or accelerating, while variable time depends on how far the bulldozer needs to push and the backtrack distance, which alters with the haul distance. Essentially, push and backtrack times vary based on how far you need to move. If you have to move farther, your times will increase, which is why they are considered variable.

Think of the bulldozer as a runner in a race. When the runner has to navigate obstacles (like changing gears or accelerating), that time is fixed irrespective of the distance to the finish line (maneuvering time). However, running between two points (pushing and backtracking) can take longer if the distance increases, just like the bulldozer takes longer to push earth if the haul distance is longer.

So, to know the push time and the backtrack time, I need to know the travel distance or the dozing distance or the haul distance. I need to know the travel distance and I also need to know the speed. So, you very well know how to determine the speed. So, in the earlier lecture, I discussed about how to determine the speed from the performance chart. So, with the help of the performance chart, you can determine the speed.

To estimate the push time and backtrack time for the bulldozer, one must determine two key variables: the travel distance (also known as the haul distance) and the speed of the bulldozer. The speed can be derived from a performance chart, which represents the speed against total resistance. Knowing both the distance and speed allows us to calculate the time required for these operations.

Imagine planning a road trip where you need to know how long it will take to reach your destination. You need to know the distance to drive and your average speed. Similar to using a performance chart, you could look up the average speed based on your vehicle's condition (like how the bulldozer determines its speed based on resistance).

So, now let us see what is this maneuver time? So, already I told you maneuver time is nothing, but the time needed for changing your speed accelerating, changing the gears, or reducing the speed, so that is what is called as a maneuver time. So, this maneuver time will depend upon the type of transmission.

Maneuver time refers specifically to the time taken for adjustments such as changing gears or modifying the speed settings of the bulldozer. This time can vary significantly based on the type of transmission used by the machines. There are typically two types of transmission systems: direct transmission, where the operator manually shifts gears, and automatic transmission, which can adjust gear shifts without manual input.

Consider driving a car with a manual transmission compared to an automatic one. When using a manual car, you have to manually change gears, which can take time and requires attention. In contrast, an automatic car takes care of gear changes for you, allowing for a smoother and faster driving experience. This difference in changing gears affects how quickly the vehicle (or bulldozer) can react to changes in conditions.

Now let us see how to estimate the productivity of the bulldozer. So, we are going to estimate the productivity a lose meter cube per hour. As I told you whenever you express the volume, you should be very specific that whether you are expressing the volume in the loosen state or bank state, that is natural state or in the compacted state.

To estimate the productivity of a bulldozer, we need to express it in terms of volume moved, typically in loose cubic meters per hour. It is crucial to specify whether we're discussing the volume in its loosened state (after excavation) versus its natural state (before excavation) because this significantly influences calculations. The basic formula for calculating productivity is the blade load divided by cycle time.

Think of estimating how much popcorn a popcorn machine can pop in an hour. If you describe it in terms of popped popcorn versus unpopped kernels, it gives a different picture. When measuring bulldozer productivity, specifying whether the material is loose or compacted is similarly important.

Now, after estimating this, you have to take into account the job efficiency. So, one thing you should know that your machine is not going to be operated for the entire 60 minutes in an hour. So, depending upon your project condition, it may operate for 45 minutes or 50 minutes. So, it may even operate only for 30 minutes, it depends upon your project condition.

Job efficiency must be factored into the overall productivity calculation. A bulldozer won't operate continuously for the full hour due to various factors like project conditions and operational inefficiencies. For example, if a bulldozer operates for only 50 minutes out of an hour, the overall productivity must be adjusted to reflect that reduced operating time. This adjustment allows for a more accurate representation of real-world effectiveness.

Think about studying for a school exam. Even though you plan to study for an hour, distractions like phone notifications, snack breaks, or just losing focus can reduce your effective study time to only 45 minutes. You have to adjust your study plan accordingly. Similarly, bulldozer operation needs to account for non-productive time.

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