3.2. Estimating Using Thumb Rules

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.

Cycle time for a bulldozer includes all the time spent in completing a push operation. This operation involves cutting the earth, pushing it to a designated area, dumping it, and then returning to the starting position. All these activities need to be done efficiently to minimize the cycle time, which directly impacts productivity.

Imagine a chef preparing a dish. The total time taken to chop vegetables, cook them, plate the dish, and then prepare for the next dish is similar to the cycle time of the bulldozer. Just as a chef needs to optimize their cooking process for efficiency, a bulldozer operator must minimize the cycle time.

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.

Maneuvering time refers to the adjustments made during operation, such as changing gears or adjusting speed. This time is categorized differently from the variable time taken to push or backtrack. Understanding this distinction helps in calculating the overall efficiency of the bulldozer’s operation.

Think of riding a bicycle. The time spent changing gears or adjusting your speed as you navigate traffic is akin to maneuvering time. Just like in biking, where sharp corners or inclines require you to adjust your gears and speed, bulldozer operators must adapt their controls to maximize efficiency.

Because it is variable depending upon your haul distance. So, greater your haul distance greater will be a push time and return time or backtrack time. So, this is solely dependent upon your haul distance, so this is dependent upon your haul distance, so that is why we call it as variable obviously it depends upon the speed also.

Push and backtrack times are variable as they depend on the distance the bulldozer needs to cover. The greater the haul distance, the longer it will take to push and return. Moreover, the machine's speed plays a crucial role in determining how long these processes will take.

Imagine driving a car. The longer the distance you need to travel, the more time it will take to get there. Similarly, the speed of your car will also affect how long your journey takes. The same logic applies to a bulldozer's push and backtrack operations.

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.

To effectively calculate push and backtrack times, one must understand both the travel distance and the speed of the bulldozer. Speed can be obtained from performance charts that outline different conditions and performance metrics, emphasizing how project-specific factors can affect operational efficiency.

Think of a runner who wants to calculate how long it will take to finish a race. They need to know both the distance of the race and their running speed from previous training sessions. Similarly, a bulldozer needs to assess both distance and speed to optimize its work.

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 consists of the time taken to adjust the machine's operational settings, such as speed and gear changes. This time can vary based on the type of transmission system used in the bulldozer, whether it's a manual system requiring operator input or an automatic one.

Consider a car with a manual transmission versus an automatic one. The manual car requires the driver to change gears, which takes time and attention, while the automatic car shifts gears on its own, allowing the driver to focus on the road. This difference significantly impacts how quickly a driver can maneuver.

So, we are going to estimate the productivity a loose 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.

When estimating productivity, it's vital to clarify the state of the material being measured, whether it's loose, bank, or compacted. The productivity calculation itself is derived from dividing the blade load by the cycle time of the bulldozer, allowing for a clear metric of efficiency.

Think of measuring flour. If you weigh it loose, packed tightly, or sifted, each method gives you different volume measures. Similarly, when assessing earthmoving productivity, specifying the material's state is crucial for accurate calculations.

So, 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.

Job efficiency refers to the actual working time of the bulldozer in an hour, which will likely be less than a full hour due to various factors like breaks or delays. Calculating productivity should involve multiplying the estimated output by this efficiency factor to get a more accurate representation of what the machine can accomplish.

Imagine working on a group project. Even if you have an hour to meet, distractions or delays might mean you only work effectively for 45 minutes. It's important to consider this when measuring overall productivity, just as it is for a bulldozer.

So, for that you need to know unit cost is nothing but cost per loose meter cube. Say I am going to find it in the loosen state cost per meter cube of earth moved, I need to calculate.

To determine the cost of earthmoving operations, one must understand the unit cost per loose cubic meter. This is calculated by dividing the total costs associated with machine operation by the total productivity, thus allowing for accurate bids and cost assessments.

Think of budgeting for a party. You determine your total expenses by dividing the overall cost by the number of guests. This gives you a clear estimate of how much you are spending per person, similar to calculating unit costs for earthmoving projects.

So, there are some thumb rules available provided with equipment manufacturers. So, if you know the horsepower of the tractor and if you know the dozing distance, one-way push distance you can directly estimate the productivity of the bulldozer, these are thumb rules.

Equipment manufacturers often provide thumb rules that allow for quick productivity estimations based on known factors like horsepower and dozing distances. These guidelines simplify the calculation process and help operators make rapid estimations.

Similarly, when cooking, experienced chefs often use heuristics or rules of thumb to estimate ingredient quantities based on dish servings. For instance, knowing that a particular recipe yields four servings might help them determine how much of each ingredient is needed for a larger group.

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