1. Cycle Time of the Bulldozer

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 refers to the total duration of a complete work process performed by the bulldozer, which includes cutting, pushing, dumping the material, and returning to the start position to repeat the operation. Each of these actions contributes to the overall time, reflecting the bulldozer's efficiency and effectiveness. Cutting involves using the blade to slice into the earth, pushing is the movement of the earth to a dumping site, and backtracking is the bulldozer returning to the starting point for another round of work.

Think of a bulldozer like a chef preparing a meal. The chef first gathers the ingredients (cutting), cooks them (pushing), serves them on a plate (dumping), and then cleans the kitchen before starting again (backtracking). Just like the chef has a routine that includes all steps, the bulldozer follows a routine to efficiently complete its task.

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, why do we call this push time and backtrack time as variable time? 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.

Cycle time consists of fixed and variable components. Fixed time includes the constant duration required for actions like maneuvering (speed adjustments, gear changes). Conversely, variable time changes based on the distance the bulldozer must move materials (haul distance); longer distances require more time to push or return than shorter ones, making the push and backtrack times variable.

Imagine you are running to deliver messages in a neighborhood. If your house is close to your friend's, it takes you less time (variable time) to deliver the message than if your friend lived across town. However, no matter how close or far, adjusting your shoes or running speed (fixed time) takes the same amount of time. Similarly, the bulldozer's cycle time is affected by these fixed and variable factors.

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.

Understanding the push and backtrack times requires knowledge of both the distance to move (dozing distance) and the bulldozer's speed. The distance traveled directly influences how long the bulldozer takes to push material and return. Additionally, the bulldozer’s speed must be determined based on specific project conditions, including both rolling and grade resistance, which can affect performance.

Consider riding a bike. If you know how far you need to go (distance) and how fast you can ride (speed), you can estimate how long your trip will take. For bulldozers, just like in bike riding, knowing distance and speed helps determine the time required for each cycle.

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 is the time required for important adjustments made during the operation, like changing gears or speeding up. The type of transmission (manual or automatic) affects this time. In a manual transmission, the operator must do it manually, which takes longer than with an automatic transmission that adjusts itself, thereby making the bulldozer more efficient in its cycle time.

Think about driving a car. In a manual car, you must press the clutch and change gears, taking extra time. In contrast, in an automatic car, the gears shift on their own, allowing for a smoother and quicker driving experience. Similarly, bulldozers with automatic transmission save maneuver time compared to those with manual transmission.

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. So, in the performance chart, you will be having the speed in the x-axis and you have the total resistance either in percentage or in rimpull in kg it is given.

Performance charts are valuable tools that illustrate how a bulldozer's speed relates to the resistance it faces. By consulting these charts, operators can find the optimal speed for different working conditions, considering factors like terrain and load. This knowledge allows them to make informed decisions to enhance efficiency and safety during operation.

Imagine looking at a map of a hiking trail. The map shows you how steep the trail is—steeper sections will slow you down. By using the map effectively, you can decide how fast to walk to conserve energy. Similarly, bulldozer operators use performance charts to determine the best speeds for efficient work, based on the terrain they are operating on.

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.

Estimating productivity involves calculating how much earth the bulldozer can move in a given time frame, typically expressed in cubic meters per hour. It is crucial to clarify whether this measurement refers to the loosened state (after excavation) or bank state (before disturbance). Such specificity ensures accurate assessments of performance capacity during actual operations.

Think of how you measure flour when baking. If a recipe calls for a cup of packed flour versus a cup of sifted flour, each volume is different. In the same way, when measuring productivity, it's essential to specify the state of the material being moved (loosened or bank state) to assess the bulldozer's capability accurately.

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. It is nothing but your hourly cost associated with the machine divided by the hourly productivity.

The unit cost of production determines the cost of moving one cubic meter of earth using the bulldozer. This is calculated by dividing the total hourly cost of operating the bulldozer by the hourly productivity rate. Understanding this cost is vital for budgeting, bidding on projects, and making informed financial decisions related to earthmoving operations.

Imagine running a lemonade stand. To find out how much each cup of lemonade costs to make, you divide your total costs (lemons, sugar, cups) by the number of cups sold. Similarly, in construction, knowing the unit cost for moving earth helps managers determine expenses accurately and ensure they stay within budget.

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