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7. Cycle Time of a Scraper

Cycle time is a crucial aspect of scraper operations, encompassing fixed and variable time components. Fixed time components include loading, dumping, turning, and acceleration, while variable time is primarily influenced by haul and return distances. Proper loading practices and haul route maintenance significantly impact efficiency, with the aim of optimizing productivity and reducing costs.

Sections

Cycle Time of a Scraper

This section explains the calculation and components that make up the cycle time of a scraper, emphasizing the importance of load, haul, dump, return, spot, turn, and acceleration/deceleration times.

1 Section Overview

Start current section content and materials

1.1 Components of Cycle Time

The cycle time of a scraper consists of several components including load time, haul time, dump time, return time, spotting time, turning time, and acceleration, deceleration, and braking times.

1.2 Loading Time

This section discusses the cycle time of scrapers, including various components such as load time, haul time, and the effects of machine speed and terrain.

1.3 Load Growth Curve

This section discusses the cycle time components of a scraper and introduces the concept of the load growth curve, emphasizing the importance of not maximizing payloads beyond optimal levels.

1.4 Haul and Return Time

This section explores the components of cycle time in scrapers, focusing on haul and return times, and highlights the significance of maintaining optimal loading practices.

1.5 Dump Time

The section outlines the various components and calculations involved in determining the cycle time of a scraper, highlighting the significance of load time, dump time, variable and fixed times.

1.6 Turn Time

This section discusses the cycle time of scrapers and its various components, emphasizing the significance of optimizing loading, hauling, dumping, and turning times.

1.7 Estimation of Cycle Time

This section discusses the components of the cycle time for scrapers, emphasizing the division between fixed and variable times for operations.

Pusher Cycle Time

This section discusses the components and calculation of the cycle time for scrapers, emphasizing the distinction between fixed and variable time and the significance of loading techniques.

2 Section Overview

Start current section content and materials

2.1 Components of Pusher Cycle Time

The cycle time for pushers consists of various components that include loading, haul, dump, return, spotting, turning, and acceleration related to their interaction with scrapers.

2.2 Loading Methods

This section discusses the cycle time components of scrapers and loading methods, highlighting the importance of timing and efficiency in loading operations.

2.2.1 Back-Track Loading

This section discusses the components of cycle time in scrapers, including fixed and variable times, and elaborates on the loading method known as back-track loading.

2.2.2 Chain Loading

This section details the concept of cycle time in scrapers, including fixed and variable components, optimal loading strategies, and the importance of haul and return times.

2.2.3 Shuttle Loading

This section elaborates on the various components that determine the cycle time of a scraper, including fixed and variable times, focusing on loading dynamics and the importance of optimizing loading practices.

Learning Objectives

  • Cycle time consists of both fixed and variable components.

  • Optimal loading practices enhance scraper productivity.

  • Haul route maintenance is essential for reducing cycle times and enhancing productivity.

Key Concepts

Cycle Time

The total time taken for a scraper to complete a loading, hauling, dumping, and returning cycle.

Fixed Time

The component of cycle time that does not vary based on travel distance, including loading, dumping, and turning times.

Variable Time

The component of cycle time that varies depending on travel distance, specifically including haul and return times.

Load Growth Curve

A graphical representation that illustrates the relationship between loading time and payload percentage, highlighting the diminishing returns when overloading the scraper.

Pusher

A machine that assists the scraper during the loading phase, which reduces the loading time and thereby impacts the overall cycle time.

Practice Exercises

Total Questions

2

Estimated Time

4 min

Passing Score

70%

Instructions

  • Read each question carefully
  • You can use hints if you need help
  • Complete all questions before submitting

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