Heavy equipment

"Heavy machinery" redirects here. For the album by Anders Johansson, Jens Johansson and Allan Holdsworth, see Heavy Machinery (album).
"Earthmover" redirects here. For the EP by Once Nothing, see Earthmover (EP).
Further information: Equipment (disambiguation)
Heavy equipment vehicles of various types parking near a highway construction site
Caterpillar D9L bulldozer, excavators and other heavy equipment vehicles parking near a quarry in Israel.
Bulldozer, excavators and other heavy equipment vehicles parking near a quarry.
Bucket wheel excavators in Garzweiler surface mine, Germany

Heavy equipment refers to heavy-duty vehicles, specially designed for executing construction tasks, most frequently ones involving earthwork operations. They are also known as heavy machines, heavy trucks, construction equipment, engineering equipment, heavy vehicles, or heavy hydraulics. They usually comprise five equipment systems: implement, traction, structure, power train, control and information.[1] Heavy equipment functions through the mechanical advantage of a simple machine, the ratio between input force applied and force exerted is multiplied. Some equipment uses hydraulic drives as a primary source of motion.

History

The use of heavy equipment has a long history; the ancient Roman engineer Vitruvius (1st century BCE) gave descriptions of heavy equipment and cranes in ancient Rome in his treatise De architectura. The pile driver was invented around 1500. The first tunnelling shield was patented by Isambard Kingdom Brunel in 1818.

From horses, through steam, to diesel

Heavy equipment circa 1922
horse-drawn scraper digging water-supply ditch

Until the 19th century and into the early 20th century heavy machines were drawn under human or animal power. With the advent of portable steam-powered engines the drawn machine precursors were reconfigured with the new engines, such as the combine harvester. The design of a core tractor evolved around the new steam power source into a new machine core traction engine, that can be configured as the steam tractor and the steamroller. During the 20th century, internal-combustion engines became the major power source of heavy equipment. Kerosene, ethanol andengines were used, but today diesel engines are dominant. Mechanical transmission was in many cases replaced by hydraulic machinery. The early 20th century also saw new electric-powered machines such as the forklift. Caterpillar Inc. is a present-day brand from these days, starting out as the Holt Manufacturing Company. The first mass-produced heavy machine was the Fordson tractor in 1917.

The first commercial continuous track vehicle was the Lombard Steam Log Hauler from 1901. Tracks became extensively used for tanks during World War I, and after the war they became commonplace for civilian machinery such as the bulldozer. The largest engineering vehicles, and the largest mobile land machines altogether, are bucket-wheel excavators, built from the 1920s.

"Until almost the twentieth century, one simple tool constituted the primary earthmoving machine: the hand shovel - moved with animal and human powered, sleds, barges, and wagons. This tool was the principal method by which material was either sidecast or elevated to load a conveyance, usually a wheelbarrow, or a cart or wagon drawn by a draft animal. In antiquity, an equivalent of the hand shovel or hoe and head basket—and masses of men—were used to move earth to build civil works. Builders have long used the inclined plane, levers, and pulleys to place solid building materials, but these labor-saving devices did not lend themselves to earthmoving, which required digging, raising, moving, and placing loose materials. The two elements required for mechanized earthmoving, then as now, were an independent power source and off-road mobility, neither of which could be provided by the technology of that time."[2]

Container cranes were used from the 1950s and onwards, and made containerization possible.

Nowadays such is the importance of this machinery, some transport companies have developed specific equipment to transport heavy construction equipment to and from sites.

Types

These subdivisions, in this order, are the standard heavy equipment categorization. Some contractors place numbers on the side of their equipment corresponding to the category - Grader '02' - followed by a sequential number that usually corresponds to the number it was purchased, for example, 02-112, is the 112th grader a company has purchased since their founding. This allows for easy recognition of the equipment type and the relevant age.

Track-type

Grader

SkidSteer

Excavator

Backhoe

Timber

Pipelayer

Scraper

Mining

Articulated

Compactor

Loader

Track Loader

Material Handler

Paving

Underground

Hydromatic Tool

Highway

Images

Implements and Hydromechanical Work Tools

Traction: Off-the-road tires and Tracks

Continuous track (circa 1909)
Caterpillar track (circa 2009)

Heavy equipment requires specialized tires for various construction applications. While many types of equipment have continuous tracks applicable to more severe service requirements, tires are used where greater speed or mobility is required. An understanding of what equipment will be used for during the life of the tires is required for proper selection. Tire selection can have a significant impact on production and unit cost. There are three types of off-the-road tires, transport for earthmoving machines, work for slow moving earth moving machines, and load and carry for transporting as well as digging. Off-highway tires have six categories of service C compactor, E earthmover, G grader, L loader, LS log-skidder and ML mining and logging. Within these service categories are various tread types designed for use on hard-packed surface, soft surface and rock. Tires are a large expense on any construction project, careful consideration should be given to prevent excessive wear or damage.

Structure

"This system connects components, transmits loads, provides attachment points for implements, and allows the machine to travel over uneven ground. The machine’s frame, articulation, and steering for wheeled equipment are the major parts of this system."[1]

Powertrain

Control and Information

"The control and information systems. These systems enable the operator to direct and control all the other systems and provide information to guide operations or to monitor the performance and health of the equipment."[1]

Heavy equipment operator

A heavy equipment operator drives and operates heavy equipment used in engineering and construction projects.[3][4] Typically only skilled workers may operate heavy equipment, and there is specialized training for learning to use heavy equipment.

Much publication about heavy equipment operators focuses on improving safety for such workers. The field of occupational medicine researches and makes recommendations about safety for these and other workers in safety-sensitive positions.

Equipment cost

Due to the small profit margins on construction projects it is important to maintain accurate records concerning equipment utilization, repairs and maintenance. The two main categories of equipment costs are ownership cost and operating cost.[5]

Ownership Cost

To classify as an ownership cost an expense must have been incurred regardless of if the equipment is used or not. These costs are as follows:

Depreciation can be calculated several ways, the simplest is the straight-line method. The annual depreciation is constant, reducing the equipment value annually. The following are simple equations paraphrased from the Peurifoy & Schexnayder text:

m = some year in the future

N = equipment useful life (years)

and Dn = Annual depreciation amount

Dn = purchase price / N

Book value (BV) in year m

BVm = purchase price - (m x Dn)

example:

N = 5

purchase price = $350,000

m = 3 years from now

BV3 = $350,000 - ( 3 x $350,000/5) = $140,000

Operating cost

For an expense to be classified as an operating cost, it must be incurred through use of the equipment. These costs are as follows:[6]

  • tires
  • 3rd party service contract
  • replacement of high-wear items

The biggest distinction from a cost standpoint is if a repair is classified as a major repair or a minor repair. A major repair can change the depreciable equipment value due to an extension in service life, while a minor repair is normal maintenance. How a firm chooses to cost major and minor repairs vary from firm to firm depending on the costing strategies being used. Some firms will charge only major repairs to the equipment while minor repairs are costed to a project. Another common costing strategy is to cost all repairs to the equipment and only frequently replaced wear items are excluded from the equipment cost. Many firms keep their costing structure closely guarded as it can impact the bidding strategies of their competition. In a company with multiple semi-independent divisions, the equipment department often wants to classify all repairs as "minor" and charge the work to a job - therefore improving their 'profit' from the equipment.

Models

Die-cast metal promotional scale models of heavy equipment are often produced for each vehicle to give to prospective customers. These are typically in 1:50 scale. The popular manufacturers of these models are Conrad and NZG in Germany, even for US vehicles.

Notable Manufacturers

The largest manufacturers based on 2011 revenue data as published by KHL Group:[7]

Other manufacturers include:


Wikimedia Commons has media related to Construction vehicles.

See also

References

  1. 1 2 3 C. B. Tatum et al., J. Constr. Engrg. and Mgmt. 132, 987 (2006)
  2. ↑ William R. Haycraft "History of Construction Equipment" Journal of Construction Engineering and Management / Volume 137 / Issue 10, Accepted 14 February 2011; published online 15 September 2011 http://dx.doi.org/10.1061/(ASCE)CO.1943-7862.0000374
  3. ↑ U.S. Department of Labor - Occupational Outlook Handbook
  4. ↑ V. J. Davies, Ken Tomasin (1996). Construction Safety Handbook. Thomas Telford. ISBN 0-7277-2519-X.
  5. ↑ Peurifoy & Schexnayder "Construction Planning Equipment, and Methods" McGraw Hill 6th edition ISBN 0-07-232176-8, 2002.
  6. ↑ Bartholomew, S.H. “Estimating and Bidding for Heavy Construction” CSU Chico, Upper Saddle River, NJ: Prentice Hall, ISBN 0-13-598327-4, 2000
  7. ↑ "Forklift manufacturers lead Yellow Table Top 50". KHL Group.
Wikimedia Commons has media related to Construction equipment.



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