2. Pusher Cycle Time

Cycle time = LT + HT + DT + RT + ST + TT + ADBT (Where, LT-Load, HT-Haul, DT-dump, RT-Return, ST-Spot, TT-Turn, ADBT- Acceleration, Deceleration and braking)

Cycle time is the total time taken by a scraper to complete one cycle of operation. It includes various components: Load Time (LT), Haul Time (HT), Dump Time (DT), Return Time (RT), Spot Time (ST), Turn Time (TT), and the time needed for Acceleration, Deceleration, and Braking (ADBT). Each of these components reflects a specific activity within the scraper's operating process.

Think of a bakery making cupcakes. The time to gather ingredients (Load Time), mix them (Haul Time), put them in the oven (Dump Time), and then clean up (Return Time) all contribute to the total time from start to finish. Similarly, each part of the scraper's operation makes up its complete cycle.

Cycle time can be split into two parts: fixed time and variable time. Fixed time does not depend on travel distance (loading, dumping, turning, acceleration, deceleration). Variable time depends on haul and return, which are influenced by travel distance and machine speed.

The cycle time can be divided into two categories: fixed and variable time. Fixed time includes activities such as loading, dumping, turning, and adjusting speeds, which remain constant regardless of how far the scraper travels. In contrast, variable time is affected by how far the scraper needs to travel to haul materials and return, as well as the speed of the machine, which changes based on project conditions.

Imagine driving to a store. The time it takes to park your car (fixed time) doesn't change whether the store is 5 minutes or 50 minutes away. But the time spent driving varies depending on traffic conditions (variable time).

The loading time of the scraper is fairly consistent irrespective of size. The loading power is supplemented by a pusher, making the loading time not change significantly.

The loading time required for a scraper remains similar regardless of its size because the use of a pusher helps maintain a consistent loading power. You can obtain actual loading times from the scraper manufacturer, ensuring accurate planning for operations.

Consider a family using the same type of blender to make smoothies regardless of their size. Whether they are making a smoothie for one or multiple people, the blending time remains similar because the blender offers consistent performance.

When loading scrapers, maximizing capacity doesn't always mean higher production. Studies show that loading beyond a certain point leads to reduced loading rates due to material resistance.

The idea that loading a scraper to its maximum capacity will maximize production is a misunderstanding. Research has shown that as the scraper bowl fills, resistance increases — particularly when it reaches around 85% capacity. This resistance slows the loading rate, illustrating a principle often referred to as the law of diminishing returns.

Imagine a funnel pouring water. Initially, the water flows freely, but as the funnel fills with water, it starts to back up, slowing the flow. Similarly, overloading a scraper creates resistance that can actually decrease efficiency.

Haul and return time varies with travel distance and speed, which depends on project conditions. Maintaining the haul route can reduce cycle time and improve productivity.

Both haul and return times fluctuate based on the distance traveled and the speed of the scraper, which is influenced by the site conditions. Proper maintenance of the haul route, such as grading and ensuring good visibility, can significantly decrease these times, leading to improved productivity and reduced costs.

Think of a hiking trail. A well-maintained trail allows hikers to move quickly and easily, while a rugged, overgrown path slows them down, taking longer to reach their destination. Keeping the trail in good shape saves time and improves the hiking experience.

Dump time varies with scraper size and material type—larger scrapers take more time, and sticky materials increase dumping time. Site congestion can also affect how quickly dumping happens.

Dump time is influenced by the size of the scraper and the type of material being handled. For instance, larger scrapers will take longer to unload, and if the materials are sticky, dumping becomes more time-consuming. Additionally, if the dumping site is congested with obstacles or other machinery, the time taken also increases.

Consider a garbage truck. If it's picking up loose trash in a clear area, it can work quickly. But if the truck has to maneuver around parked cars or tight corners in an alley, the time taken to dump the trash increases significantly.

Balancing the number of scrapers and pushers is crucial. If one waits for the other, it can increase cycle times and reduce productivity. Proper optimization is necessary.

To optimize efficiency, it's essential to balance the number of scrapers with pushers. If the scrapers have to wait for pushers or vice versa, it leads to increased waiting times, which can further extend cycle times and decrease productivity. Effective management ensures this balance is maintained.

Think about a relay race. If one runner is significantly faster or slower, it causes delays for the other runners. Ensuring that all runners are properly paced increases the chances of finishing the race as efficiently as possible.

--