Excavators and Earthmoving Equipment: A Comprehensive Guide

Posted on Aug 31, 2024 in Other subjects

ITEM XIII – EXCAVATORS

1. Bulldozer Blade Adjustments

Tilt

Lateral tilting of the blade allows for an angled cut into the land. This hydraulically controlled movement is used for:

  • Forming V-shaped trenches
  • Creating gutters
  • Constructing inclined planes
  • Digging canals

Pitch

Pitch refers to the blade’s angle of incidence. The blade can be tilted as needed by activating hydraulic cylinders located on the straps. The first movement digs, while the second moves the excavated material.

2. Angledozer Blade Adjustments

Similar to the bulldozer, the angledozer offers Tilt and Pitch adjustments. However, it also features an additional ground attack angle. The angledozer’s blade is less rigid than the bulldozer’s due to the bucket’s greater separation from the tractor.

3. Types of Ripper Tractor Trailers

Rippers, typically hydraulically operated, attach to tractors and come in various types:

  • Articulated Parallelogram: Maintains a constant tooth tip attack angle at all working depths. Offers superior penetration as the ripper remains upright, allowing for stronger application of force to both bracket arms.
  • Amended Parallelogram: Allows for adjustments to the attack or incident angle.
  • Rotating Hinge: Features a bar with a 30-degree swing angle, which can be fixed or unfixed.
  • Vibration Impact: The driver uses the ripper to strike the ground like a hammer, either automatically or manually.

Ripper teeth, typically made of exchangeable manganese steel, come in three forms:

  • Straight
  • Curved
  • Fairings

4. Ripper Teeth Types and Applications

  • Straight: Suitable for materials that form blocks or slabs.
  • Curved: Facilitate the lifting of less compact materials.
  • Fairings: Combine features of both straight and curved teeth.

The tips are typically made of replaceable manganese steel.

5. Motor Grader Blade Movements

  • Raising or lowering to adjust the grading level
  • Lateral displacement
  • 180° rotation in the horizontal plane on each side of the chassis length
  • 0° to 90° rotation in the vertical plane on each side of the chassis’s longitudinal axis
  • Turning within a given sector along its longitudinal axis (Pitch movement)

Graders can be towed or self-propelled.

6. Earthmoving Machine Definitions and Applications

  • Bulldozer: Excavates and transports material in a cyclical pattern, involving excavation, removal, and return trips. Used in construction, road building, dam construction, canal cleaning, quarries, mines, and snow removal.
  • Angledozer: Similar to the bulldozer but better suited for hillside earthworks, moving material laterally.
  • Ripper: Breaks up the ground without requiring blasting.
  • Grader: Essential for moving, transferring, spreading, and leveling land. Used in road construction, ditch and slope leveling, light clearing, and more.
  • Loader: Loads material onto transportation elements, excavates less consistent land, assists in quarrying and concrete control, clears land, spreads and levels land, and aids in demolition.
  • Scraper: Crucial for earth dams, roads, and airports. Prepares soil, moves earth, compacts soil, levels surfaces, and is also used in mining and quarrying.

7. Motor Grader Frame Types

  • Straight Frame: Suitable for long, straight paths.
  • Articulated Frame: Ideal for curved paths.
  • Toggle Frame: Offers better resistance to side impacts.

8. Loader Types

Loaders can be wheeled or tracked:

  • Wheeled: Feature four-wheel drive, allowing for significant power transmission to both front and rear axles.
  • Crawler: Designed for rocky terrain, offering low resistance and a low center of gravity.

9. Tipping Load on Tire Loaders

Tipping load refers to the minimum weight the loader can lift with its rear wheels on the ground. This measurement is taken on a flat, horizontal surface with the bucket at its maximum separated height.

10. Loader Arm Movements

Loaders, versatile machines used for loading, transporting, and storing materials, can be wheeled or tracked and are typically equipped with a bucket. Their hydraulically operated arms enable the following movements:

  • Elevation
  • Descent
  • Tilting about its longitudinal axis

11. Basic Parameters of Wheeled Loaders

  • Tipping Load: The maximum weight the loader can lift with its rear wheels on the ground while stationary on a level, smooth, and hard surface, with the bucket in its separated position.
  • Maximum Operational Load: Similar to tipping load, but measured while moving at a speed below 6.5 km/h. Should not exceed 50% of the tipping load.
  • Hydraulic Lift Capacity: The maximum weight the hydraulic cylinders can lift while the machine is anchored at the rear. Exceeds the tipping load.
  • Breakout Force: The vertical lifting force measured at the bucket blade’s edge, indicating the machine’s digging power.
  • Discharge Height: The distance from the ground to the bucket edge when the arms are at their highest position and the bucket is at its final discharge point.
  • Reach: The distance between two vertical lines, one tangent to and one passing over the bucket edge, with the bucket dumped and at its highest position.

12. Bulldozer vs. Angledozer: Key Differences

While similar in construction, the angledozer’s blade is longer and adjustable to various angles relative to the tractor’s longitudinal axis. This design prevents the blade from being mounted as close to the tractor as a bulldozer blade.

Here are some key differences between bulldozer and angledozer blades:

  • Size: Bulldozer blades are shorter (15-20%) but taller (25-30%) than angledozer blades.
  • Material Accumulation: The taller bulldozer blade allows for greater material accumulation in front, while the narrower cutting length of the angledozer blade reduces excavation resistance.
  • Curvature: The slightly curved top of the bulldozer blade prevents excavated material from falling back or deforming excessively during movement. The angledozer blade’s curvature is more pronounced, preventing soil from piling up too high in front of the blade.

13. Excavator Bucket Arm Adjustments

The excavator’s bucket arm, which can be single or double, supports the bucket at one end and allows for the following movements:

  • Translation (forward and reverse)
  • Rotation around a horizontal axis
  • Sliding in relation to the boom (using a rack, chain, or cable system depending on machine size; smaller machines use a rack, while larger ones use a cable)

Minimizing downtime due to arm adjustments is crucial for optimal efficiency.