Earth-moving machines are used for a wide range of earthworks, including laying foundations, grading soil, removing dirt and rocks, digging trenches and various demolition works. The demand for construction equipment has grown exponentially over the last few years, due to infrastructure growth plans in African countries. Zimbabwe is no exception, especially when one considers, for example, the massive road development and upgrade plans in the country’s Vision 2030 objective.
Alongside all of these changes will be the availability of modern earth-moving equipment for use in such roadway projects and other areas of urban development in cities and towns needed to accommodate the burgeoning population.
IS EARTH-MOVING EQUIPMENT ONLY USED FOR SHIFTING SOIL?
Construction zones vary from commercial and residential to civil projects, such as new buildings, generation of supplementary roads or repair of existing ones, as well as laying of pipelines for water and sewage and electrical construction.
As technology develops, machinery has become more specialised, allowing greater efficiency and sharpened effectiveness in attending to the task on hand, which is a far cry from even as recently as a decade ago.
Heavy equipment is essential for construction jobs of almost any size, from home building to large-scale commercial and civil projects. Earth-moving equipment covers a broad range of machines that can excavate and grade soil and rock, along with other jobs. Earth movers and other heavy equipment help to speed up not only earth work, but also materials handling, demolition, and construction.
There are several distinct types of earth-moving equipment, each with its own set of uses. While some pieces of equipment only serve one specific purpose, there are others with overlapping functionality, so it’s worthwhile knowing how best to add to construction fleets.
WHAT ARE THE DIFFERENT TYPES OF EARTH-MOVING MACHINERY?
TRACK AND WHEEL DOSERS
Bulldozers (the original name for these heavy-duty vehicles) are the most prolific on a construction site. Their most common function is moving huge volumes of dirt or soil from an excavation. The large metal plate or blade is operated hydraulically, moving in a rather limited range of angles or simply up and down. Not only can they move piles of earth, but they can also assist with rough or fine grading.
There are two different types of dozers: track dozers and wheel dozers. Both provide the same function, but the way they navigate around the site is different:
- Track dozers spread their own weight evenly over the tracks which lessens the pressure on the ground, making this model suitable where the ground may be softer.
- Wheel dozers have large tyres in place of tracks and can move up to three times faster than their companion machine.
These machines consist of an operator’s base cabin and a long extending arm with a bucket attachment. From his cabin, the operator can hydraulically control the excavator through a full rotation of 360 degrees. The cabin sits on a supporting structure with either wheels for quicker access in the operating area, or tracks that can move over various terrains and earth conditions. Hydraulic excavators are widely used on both small and large construction sites and are purpose-used for medium to heavy jobs, such as excavation, demolition, heavy-lifting, grading, landscaping, mining, dredging and more.
Komatsu’s range includes mini, medium and large excavators, with the choice being made depending on the size of the task and the available footprint area.
WHEEL LOADERS OR FRONT-END LOADERS
Other names for wheel loaders are a ‘bucket loader’ or a ‘shovel loader’ and can be used for construction, mining, and agricultural purposes. It can lift, push and move, but on a large scale and with a large capacity. This makes them comparable to a backhoe loader, just without the backhoe. The wheels provide the operator to undertake tasks at a fast pace, but they do leave more marks on a job site than loaders fitted with tracks.
Motor graders (also called road graders) are using in the mining, construction, and agricultural industries. This equipment is used for fine grading and moving small amounts of dirt. The long blade underneath the housing is located between the front and rear axle. It can be adjusted to certain angles and creates a flat surface when the vehicle is moving. For specialised use, they can be fitted with a second blade in front of the forward axle. This grader is typically used in roadworks to fine-grade dirt or gravel roads or to prepare the road base before placing asphalt.
A motor grader can also be used to:
- create a sloped surface or drainage ditch with shallow V-shaped cross-sections
- move small amounts of soil from one place to another
- eliminate a layer of soil from a surface.
DUMP TRUCKS – ARTICULATED OR RIGID
Dump trucks or haulers are used both in the construction and mining industries and are needed on almost every large job site. Although their functionality may appear limited, these machines carry out the all-important task of moving and dumping many types of heavy material.
Articulated dump trucks have all-wheel drive enables access over rough terrain and they can even be used for short trips on public roads, when material needs to be brought into or out of construction sites. They are relatively simple to operate, with steering assisted by hydraulic arms to pivot the front cab or tractor in relation to the rear section or dump body.
Rigid dump trucks (RDTs), also known as Rigid Haulers, look completely different to their articulated cousin, but perform the same kind of task, being able to handle pay loads from 36,5 tonnes to an enormous 369 tonnes. When combined with high horsepower and good engine retardation, RDTs offer outstanding fuel efficiency for their size. Downhill travel speeds can be effectively governed with advanced transmission systems. Komatsu’s models have traction and automatic retard speed control so are safe even on the steepest of inclines under the weight of a full payload.
Utility machinery – backhoe loaders AND skid steer loaders
Backhoe loaders, or backhoes, are tyre-mounted machines which can move effortlessly over difficult terrain and are best used for light to medium duty jobs, such as excavation, digging trenches, placing pipes and filling up trenches. They are capable of working in limited spaces, using the adjustable shovel at the front and either a digger or bucket attached to a jointed arm at the rear.
Being wheel-driven, they can be used in urban areas and driven to the job site. Their design is a combination of three different machines – a tractor, loader and backhoe. They can rotate 200 degrees and can be retro-fitted with different attachments to make them a versatile addition to a construction fleet.
As the name Skid Steer Loader suggests, this machine is tyre-mounted and being quite small, can move easily on its own axis when space is at a premium on a construction site. They have good traction in muddy conditions with tyre treads that have minimal impact on finished construction sites. It is important to remember that whilst this loader is recognised for being an excellent utility machine and very versatile on site, a small skid steer (ideal for interior demolition) cannot tackle large excavating projects for which a larger loader should be used.
Skid steer loaders can also be retro-fitted with different attachments to enable them to move mud, manage some excavation works, compacting soil, drilling holes, lifting loads and more.
Hydraulic mobile crushers (or rock crushers) are track-mounted machines used to reduce the size of large rocks and stones into smaller rocks, gravel and sand. They work well in aggregates production, construction material recycling applications and in mining operations and are also known as mobile crushing plants. Although this equipment has been in use for a long time, they were always very heavy and not very mobile on site, but thanks to product development across multiple construction machinery brands, crushers’ mobility has improved remarkably. Operating conditions crushers are relatively severe so the quick-wear parts tended to have short working lives. Of late, high quality, high-manganese steel casting is used to extend the service life of core parts, thus effectively avoiding too many shutdowns and maintenance tasks.
A CONSTRUCTION RENAISSANCE IN AFRICA
The booming construction industry in many African countries signals a good opportunity for companies that manufacture construction machinery, as well as companies which sell used and refurbished equipment. New civils projects have created demand for concrete mixers, excavators, backhoes and earth-moving equipment. Industry analysts believe that in the next few years the main areas of growth in the African construction machinery market will be in excavators, loaders, bulldozers, dump trucks and cranes.
Many governments, development authorities and companies in some African countries have begun investing in infrastructure development projects, irrigation and mining projects. The face of the African construction industry is changing and the continent’s engineering projects are getting bigger and more complex.
Komatsu is a global leader in the supply of Japanese-engineered mining, construction, earthmoving and utility equipment in Southern Africa. The official Komatsu dealer for Zimbabwe is MMI (Pvt) Ltd, part of MoJo Motor Industries. Their team comes with over fifty-four years of combined experience in the automotive, construction and mining equipment sales and support. Please direct all your pre-sales or equipment enquiries on earth-moving machinery for construction use to our friendly staff.