Archive for the ‘excavator’ Category
Sunday, March 1st, 2009 |
Excavators are heavy equipment used in civil engineering and surface mining. An excavator, also called a 360-degree excavator or digger, sometimes abbreviated simply to a 360, is an engineering vehicle consisting of a backhoe and cab mounted on a pivot (turntable is a more apt description) atop an undercarriage with tracks or wheels. The term excavator is sometimes used as a general term for any piece of digging equipment.
Roles of Excavators
Excavators are used in many roles:
1- Digging of trenches, holes, foundations
2- Demolition
3- General grading/landscaping
4- Heavy lift, e.g. lifting and placing of pipes
5- River dredging
6- Mining, especially, but not only open-pit mining
7- Brush cutting with hydraulic attachments
Varieties of Excavators
Excavators for sale come in a wide variety of sizes. The smaller ones are called a mini-excavator or compact excavator. One manufacturer’s largest model weighs 84,980 kg (187,360 lb) and has a maximum bucket size of 4.5 m³ (5.9 yd³). The same manufacturer’s smallest mini-excavator weighs 1470 kg (3240 lb), has a maximum bucket size of 0.036 m³ (0.048 yd³) and the width of its tracks can be adjusted to 89 cm (35 inches). Another company makes a mini excavator that will fit through a doorway with tracks that can be adjusted to only 70 cm (28 inches) wide.
Often the bucket can be replaced with other tools like a breaker, a grapple or an auger. Excavators are usually employed together with loaders and bulldozer equipment. Most smaller excavators have a small backfill (or dozer-) blade. It’s a horizontal bulldozer like blade attached to the undercarriage and is used for pushing removed material back into a hole.
Examples of Excavators
1- Compact excavator
A compact hydraulic excavator is a tracked or wheeled vehicle with an approximate operating weight of 6 metric tons (13,228 lbs). It generally includes a standard backfill blade and features independent boom swing. The compact hydraulic excavator is also referred to as a mini excavator.
The compact hydraulic excavator is somewhat unique from other used construction equipment in that all movement and functions of the machine are accomplished through the transfer of hydraulic fluid. The compact excavator’s work group and blade are activated by hydraulic fluid acting upon hydraulic cylinders. The excavator’s slew (rotation) and travel functions are also activated by hydraulic fluid powering hydraulic motors.
2- Dragline excavator
Dragline excavation systems are heavy equipment used in civil engineering and surface mining. In civil engineering the smaller types are used for road and port construction. The larger types are used in strip-mining operations to extract coal and these are amongst the largest mobile equipment (not water-borne), and weigh in the vinicity of 2000 metric tonnes, though specimens weighing up to 13,000 metric tonnes have also been constructed.
A dragline bucket system consists of a large bucket which is suspended from a boom (a large truss like structure). The bucket is maneuvered by means of a number of ropes and chains. The hoistrope, powered by large diesel or electric motors, supports the bucket and hoist-coupler assembly from the boom. The dragrope is used to draw the bucket assembly horizontally. By skillful maneuver of the hoist and the dragropes the bucket is controlled for various operations.
3- Bucket-wheel excavator
Bucket-wheel excavators are heavy equipment used in surface mining and civil engineering. The excavation component itself is a large rotating wheel mounted on an arm or boom. On the outer edge of the wheel is a series of scoops or buckets. As the wheel turns, the buckets remove soil or rock from the target area and carry it around to the backside of the wheel, where it falls onto a conveyor, which carries it up the arm toward the main body of the excavator. Additional conveyors then may carry it further; in some cases, several long conveyors are placed end-to-end, each supported by a large vehicular base.
Especially large bucket-wheel excavators, over 200 meters long and up to 100 meters in height, are used in German strip-mining operations, and are the largest earth-movers in the world. These tremendous machines can cost over $100 million, take 5 years to assemble, require 5 people to operate, weigh more than 13,000 tons, and have a theoretical capacity of more than 12,000m³/h. Specifically, the RB293 bucket wheel excavator manufactured by MAN Takraf is recognized by Guinness World Records as the largest land vehicle.
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Monday, January 19th, 2009 |
Building construction equipments vary from the heavy, large equipment to the mobile, lighter equipment. Hydraulic excavators, cranes, and concrete mixers are among the basic, hardworking equipments that any heavy construction equipment company cannot function with.
Hydraulic Excavators
Hydraulic Excavators (also known as diggers or earth movers) are extremely large equipments utilized for multiple operations. They are utilized in applications such as construction of large structures and roads as well as in the mining industry. As one of the first equipment to be applied for readying the construction place, excavators level the land by burrowing and cutting ground. Excavators equipments are very functional for certain confined work sites which are less receptive to traditional construction equipment.
The excavator is made up of four basic parts-hydraulic cylinders, arm, bucket, and boom-all involved in loading and excavating. Interestingly, their movement is similar to that of a human arm. The boom acts similar to the upper part of an arm, together with shoulder and elbow. The excavator’s arm’s movement is likened to a human arm beginning at the elbow to the wrist. And, the bucket is likened to a cupped hand.
Hydraulic excavators consists of loaders, tippers and crawlers (bulldozers). A crawler is a very robust tractor fitted with a dozer blade. Most excavators feature crawlers since they’re more functional for operations on mud-covered, rough terrains as compared to wheeled ones.
Cranes
Cranes are equipped with pulleys and levers to haul up and lower sizeable weights. Basically, a crane has a telescopic boom or steel truss that hoists its portable base. Both the levers or pulleys lift the boom, and the boom typically has a hook hanging on it. There are several kinds of cranes including loader cranes and tower cranes. Loader cranes feature hydraulic power booms attached onto trailers. Booms load up materials onto the trailer and may be collapsed after use. Certain types of loader cranes feature telescopic boom for easy operation. Tower cranes are usually the tallest of all cranes. However, they do not feature portable base and parts need to be assembled. These cranes equipment are largely applied to build tall structures and skyscrapers. Primarily exploited for the cutting down of workload, cranes can also perform lots of jobs including moving, digging and creating.
Concrete mixers or processors
Concrete mixers or processors are powered equipment used for mixing cement, water, sand, and gravel to create concrete. A concrete mixer is made up of a rotating drum, a motor, and a trough. The elements applied to create concrete whirls around thus mixing everything consistently.
Concrete processors come in various sizes from the extremely large industrial mixing truck to the smaller, handy concrete mixer. A small concrete mixer is ample for smaller amounts of concrete, up to 2 cubic yards. It’s normally run by electricity and features a wheeled base for easier transfer. Its drum can be tilted at an angle so that concrete can be easily dispensed onto the spot that needs to be cemented. A large industrial concrete mixer truck on the other hand, is applied for mixing as well as carrying big amounts of concrete for use on a construction place. These mixers are computer encoded for constant, accurate mix.
Technology indeed creates modern construction equipment to function efficiently, dependably and quickly.
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Sunday, October 19th, 2008 |
It is important to select the right heavy construction equipment for the job to be performed. Incorrect selection will result in underutilization of machine or is inappropriate for the job. These resulted in wasting time and resources. Furthermore the progress of the job or project will be affected.
What are the factors to consider then during the selection process? The two basic factors which should be taken into consideration are: -
1. The cost per unit of excavation and
2. The job condition the machine will work in
Lets discuss more in details these two factors. The meaning of cost per unit of excavation means how much does it cost to excavate per unit volume of the material found in the job site. The factors to take into account when working out the cost per unit of excavation are :-
* The size of the job, as a larger job may justify the higher cost of a large machine.
* The cost of transportation ( larger ones more cost)
* In quarry works, there is the combined cost of drilling or blasting to be considered. If a large excavator is used, these costs may be less than if a small one as a large machine will handle bigger rocks better than a small one. Hence a large machine may permit savings in drilling and blasting costs.
As for the job considerations, this determine the type of bucket or the size of machines to be used. There are different types of buckets in terms of size and make. Hence if the material to be excavated is hard and tough, the bucket of a large machine which can exert higher digging pressure will handle the material more easily. If blasted rock is to be excavated, the large-size bucket will handle bigger individual pieces better and easily. Then if the project time is short and a high production is required, either multiple small machines or a single large one can be used.
Another factor which is often missed is the type of hauling units available. If small hauling units are used then the size of the excavator equipment should be small, where as if large or heavy hauling units are used then a large excavator should be used. Finally it is also important to take into account the maximum dumping height of the excavator when loading hauling units.
As for backhoe loader equipments, beside the above, there are additional factors to consider and these are:-
* Maximum digging depth required
* Minimum digging depth available
* Working radius for digging and dumping
* dumping height required
* digging width required ( trench operation)
* clearance for carrier, superstructure and boom
* hosting capability.
If the work is a trenching operation, then the primary concern is to match the hoe’s ability to excavate linear length per unit of time with the pipe / cable laying production. Usually, the volume of material moved is not the question.
Thus the above are factors to be taken into when selecting the right excavators for the work and it is also advisable to always consult manufacturers specification in the planning and selection.
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Tuesday, October 14th, 2008 |
An excavator is defined as any of a number of power-driven machines used to dig, move, and transport earth, gravel, etc. Excavators are used by builders, concrete contractors, paving companies, excavation crews and utility contractors just to name a few. These heavy construction equipments for sale are designed to handle all of the hard, heavy jobs where men’s strength can’t be used. Places such as dams are built using these machines that specialize in digging and hauling away dirt and concrete. If someone where to try and rebuild a ancient monument such as the pyramid in Giza, an excavator would be the best building tool.
About Excavators :
There are several Excavator brands on the market that vary in price and functionality. Prices for new excavators can reach well into six figures, weighing many tons. Do to the price, renting excavators isn’t an uncommon option. Buying used excavators isn’t uncommon either, which can be expected. For repaving your driveway or during other small constructions jobs to homes, renting is the best choice. Common excavator features may include an optional cab, rubber tracks, blade, air conditioning, and counterweight.
Excavators Brands :
BADGER, JOHN DEERE, CATERPILLAR, KOBELCO/KOBE STEEL LTD,DAEWOO, KOEHRING, SAMSUNG, NEW HOLLAND, KOMATSU, TAKEUCHI MFG. CO. LTD., GEHL COMPANY, KUBOTA TRACTOR CORPORATION, VERMEER, GRADALL COMPANY, LIEBHERR, VOLVO CONSTRUCTION EQUIPMENT, HITACHI, LINK-BELT CONST., YANMAR, HYUNDAI, MELROE COMPANY and JCB.
Excavators Uses :
One of the many uses of excavators is digging for tree planting and removing excess dirt and debris. In addition to that they can be used to excavate large areas for construction. These machines come in very handy when it’s time to build and develop land as well. Its strength and power make moving extremely heavy objects simple and speed up the building process. Demolitions go rather quickly with excavators. As does digging out soil, excavation, loading up, sewers repair, demolishing, materials handling, recycling, elevating, destruction and construction site preparation.
Mini Excavators :
Mini Excavators are merely compact sized excavators that perform the same functions as their larger, heavier counterparts. Other differences may include the depth at which the machine can dig, the amount of weight it can handle and the overall machine weight. Weights generally tend to be around two to six tons overall. Drive speeds are usually less than five miles per hour for excavators. Mini excavator gas tank sizes are predominately eighteen gallons
Excavator Fueling :
You may think that the bigger the vehicle the lower fuel efficiency you’ll get. However, fuel efficiency of large excavators does play a role in the overall cost. The gas tank amount and the type of fuel the excavator needs determines fuel amounts. Diesel based fuel is almost always used for excavators no matter the size. Fuel efficiency is very important with any many and diesel is used because it burns slower than gas. Large size excavators can have up to a thirty six gallon tank for fuel.
Excavators Conclusion :
As you can see from the above information, excavators provide a wide range of uses. Various brands, sizes, weights, fuel tank sizes and features need to be considered if you plan on buying or renting an excavator. Although they can be quite expensive to buy new or used and to rent, there is no substitute known that can perform the functions of these machines.
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