1.3 - Effect of Transmission Type on Cycle Time
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Interactive Audio Lesson
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Introduction to Cycle Time
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Today, we'll focus on cycle time in bulldozer operations. Can anyone tell me what cycle time entails?
Does it include the time spent on pushing and returning?
Exactly! The cycle time consists of push time, backtrack time, and maneuver time. Push time is the time spent moving material forward, while backtrack time is the return to the starting position.
What affects the push time specifically?
Good question! Push time is dependent on haul distance and the speed of the bulldozer. Let's remember this with the mnemonic 'PUSH' – P for Push time, U for Underhaul distance, S for Speed, and H for Haul distance.
So, if the haul distance increases, then push time also increases?
Correct! The longer the distance, the more time it takes.
What about the maneuver time?
Hold that thought; we’ll discuss that in the next session!
Variable and Fixed Time
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Continuing from where we left off, let's explore fixed and variable times. Who remembers the distinction?
Variable time changes based on factors like haul distance, while fixed time doesn't?
Exactly right! In our cycle time, push and backtrack are variable, but maneuver time can be fixed based on transmission type.
So what types of transmissions are we talking about?
We have direct transmission and automatic systems. With direct, an operator adjusts gears, leading to longer maneuver times.
And automatic makes it faster, right?
Exactly. Automatic systems, like torque converters, cut maneuver time nearly in half. We can remember that with the acronym 'AUTO' – A for Automatic, U for Unimpeded, T for Time-saving, and O for Operation ease.
That sounds very efficient!
It absolutely is. Keeping maneuver time low is crucial for productivity.
Calculating Speed and its Impact
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Think of speed as the vehicle's 'heartbeat' in relation to productivity.
It helps us find out how fast we can move material, right?
Spot on! You can determine speed from performance charts. What factors influence this?
Total rolling resistance and grade conditions are key!
Exactly! The heavier the resistance, the slower the speed. We can use the acronym 'SPEED' – S for Soil conditions, P for Performance charts, E for Engine output, E for Efficiency, and D for Distance.
Shouldn't we also consider the load of the bulldozer?
Absolutely! The load plays a crucial role in determining efficiency.
Introduction & Overview
Read summaries of the section's main ideas at different levels of detail.
Quick Overview
Standard
This section outlines the relationship between transmission types (manual vs. automatic) and cycle time for bulldozers. It details how maneuver time varies with different transmission systems and emphasizes the importance of calculating push and backtrack times based on haul distance and speed to accurately estimate bulldozer productivity.
Detailed
In bulldozer operations, the cycle time is comprised of multiple components including push time, backtrack time, and maneuver time. The section highlights that while push and backtrack times are variable and depend on haul distance and operational speed, maneuver time is influenced by the type of transmission used—manual or automatic.
Manual transmission requires the operator to manually change gears, which leads to longer maneuver times, while automatic systems like torque converters automatically adjust to load conditions, significantly reducing maneuver time. The text establishes that push time is determined by the haul distance and speed achievable under project conditions, which can be derived from performance charts based on total resistance factors. By understanding these dynamics, operators can better estimate the productivity and efficiency of bulldozer operations, crucial for effective project management.
Audio Book
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Understanding Cycle Time
Chapter 1 of 6
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Chapter Content
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...
Detailed Explanation
Cycle time refers to the total time taken for a bulldozer to complete one full operation cycle, which includes cutting the earth, pushing it to a specified location, dumping it, and returning to its original position to prepare for the next operation. This cycle time is influenced by several factors, including maneuvering time and the distances involved in pushing and backtracking.
Examples & Analogies
Imagine a chef chopping vegetables (cutting), tossing them into a pan (pushing), serving the dish to a customer (dumping), and then cleaning the prep area to start again (backtracking). Each step takes time, and the efficiency of the chef in completing the whole preparation process directly impacts how quickly they can serve a meal.
Fixed vs. Variable Time
Chapter 2 of 6
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Chapter Content
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...
Detailed Explanation
In cycle time, there are fixed and variable components. Fixed time is the consistent amount of time needed for actions like gear changes or adjustments (maneuvering), while variable time fluctuates based on conditions such as haul distance. The longer the distance, the greater the push and backtrack time, making it variable.
Examples & Analogies
Consider walking to a store. If the store is always 5 minutes away (fixed time), that part of your journey remains the same. However, if you decide to walk to a distant location that takes 10 minutes or 20 minutes (variable time), the time changes based on how far you have to go.
Determining Push and Backtrack Time
Chapter 3 of 6
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Chapter Content
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...
Detailed Explanation
To calculate push and backtrack time, you must know the travel distance and the speed. This information allows you to compute how much time it will take for the bulldozer to push the earth and return to its position. Speed can be determined using a performance chart that examines the machine under specific conditions such as resistance from the ground.
Examples & Analogies
Think of a car trip to a friend's house. The distance tells you how far you must go, and knowing your car's speed (like the speedometer readings) helps you estimate how long the trip will take. For instance, a 10-mile trip at 20 miles per hour will take about 30 minutes.
Types of Transmission and Their Impact
Chapter 4 of 6
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Chapter Content
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...
Detailed Explanation
The time it takes to adjust the bulldozer's speed (maneuver time) varies based on the type of transmission. There are two primary types: manual transmission, which requires the operator to change gears manually based on load, and automatic transmission, which adjusts gears on its own. Automatic transmissions typically result in shorter maneuver times compared to manual ones.
Examples & Analogies
Consider driving a car with a manual transmission versus an automatic transmission. In a manual car, you have to shift gears as you accelerate or slow down, which can take extra time. However, in an automatic, the car changes gears for you, allowing for smoother and faster acceleration, just like a bulldozer adjusts speed more seamlessly.
Maneuver Time and Total Cycle Time
Chapter 5 of 6
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Chapter Content
So, depending upon this transmission mode, your maneuver time will change. Say if you are going to go for power shift that is automatic gear change, the maneuver time is 0.05-minute, 0.05 minute in the sense 3 seconds. But your manual gear change that is direct transmission...
Detailed Explanation
Maneuver time is quantified based on the transmission type. For automatic gear changes, maneuver time is 0.05 minutes (or 3 seconds). In contrast, manual gear changes take double that time (0.1 minutes or 6 seconds). This difference in maneuver time is crucial as it directly impacts the overall cycle time of the bulldozer's operations.
Examples & Analogies
Imagine two people setting up for a race: one person has a ready-to-go start button (automatic), while the other has to manually pull a lever to start (manual). The first person is ready to take off quickly, while the second person takes a moment longer to get going, affecting how fast they can join the race overall.
The Importance of Estimation in Operations
Chapter 6 of 6
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Chapter Content
So, if we want to make an accurate estimate, you have to consider all these things...
Detailed Explanation
Accurate estimation of cycle time and productivity in bulldozer operations requires careful consideration of all factors, including push time, backtrack time, and maneuver time. Any underestimations can lead to miscalculations in costs and project timelines, affecting the overall productivity and profitability of a construction project.
Examples & Analogies
When planning a birthday party, if you underestimate how long it takes to prepare the food or set up the decorations, you might end up racing against the clock while guests start arriving, leading to chaos. Similarly, in construction, accurate time estimates are crucial for successful project management.
Key Concepts
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Cycle Time: The total operational time for a bulldozer cycle.
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Push Time: Time taken to push materials.
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Backtrack Time: Time taken to return after dumping material.
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Maneuver Time: Changing of gears/speeds affects cycle time.
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Transmission Type: Manual vs. Automatic effects on operation.
Examples & Applications
In a manual transmission bulldozer, maneuver time is typically around 0.1 minute (6 seconds), while in an automatic transmission, it is reduced to 0.05 minutes (3 seconds).
The speed of a bulldozer can be determined using a performance chart by estimating the total resistance based on site conditions.
Memory Aids
Interactive tools to help you remember key concepts
Rhymes
Push and return as fast as can, time's key in this earth-moving plan.
Stories
Imagine a bulldozer named 'Benny' who always took extra time to change gears; Benny learned that using automatic gears saved him valuable time, helping him push more dirt each day.
Memory Tools
To remember cycle time, think 'P-B-M': P for Push, B for Backtrack, M for Maneuver.
Acronyms
MUTE - Maneuver, Underhaul, Time, Efficiency - helps remember cycle time components.
Flash Cards
Glossary
- Cycle Time
The total time taken by a bulldozer to complete one full operational cycle, including push, backtrack, and maneuver times.
- Push Time
The time required for the bulldozer to push material over a specified distance.
- Backtrack Time
The time taken to return to the original position after dumping the material.
- Maneuver Time
The time taken to change speeds or gears during the operation.
- Transmission Type
The mechanism by which the bulldozer's engine power is transferred to the wheels—can be manual or automatic.
- Performance Chart
A graphical representation that outlines the expected operational speeds based on various resistance conditions.
Reference links
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