Dragline excavator: specifications, description and reviews

Excavator is a digging and transportation machine of cyclic action, intended for separating the soil from the massif, its moving and loading. The main working body of special equipment is a bucket, which is loaded, moving relative to the developed rock with the help of the traction forces of the machinery mechanisms. The excavator can be of the "direct shovel" type (designed to develop the rock above the site of standing), "backward shovel" (used to extract the ground mass below the support surface) and a dragline excavator with a "scraping" bucket. The latter type is indispensable for the development of a large volume of soil, during stripping, in land reclamation and hydraulic engineering, for cleaning the bottom of rivers, lakes and other water bodies.

Excavator-dragline

The first schematic diagram of the dragline excavator was developed in the 16th century by the great scientist of the Renaissance, Leonardo da Vinci. On an industrial scale, this type of equipment has been used since 1884 in the United States. In Russia, this type of earth-moving transport vehicles first appeared in the post-war years. They were used to develop mineral deposits. Dragline excavator, unlike other models of special equipment, separates the rock from the massif by dragging the bucket over the surface, and not by the action of a hydraulic or cable-block system. Due to the flexible rope attachment of the bucket to the boom, the dragline performs its work at a much greater distance and greater depth from the traction mechanism than other types of machines. This is both an advantage, and the main difference of this type of earth-moving equipment.

Design and operation principle

The dragline consists of several basic systems - a machine that generates pulling force, boom, rope system and bucket. The rope system consists of traction and lifting cables, which are attached to the ladle by means of chains. The first is necessary for moving the working element in the vertical plane, and the second pulls the bucket to the machine, which causes both cutting of the rock and loading of the soil. After this, the dragline excavator simultaneously pulls both the lifting and pulling cables, because of which the distance between the tilting block and the connecting link rises, the unloading rope stretches. As a result, the front edge of the bucket is lifted upwards, which does not allow the soil to accumulate.

After the movement of the soil mass to the unloading place, the force on the traction and lifting ropes is sharply reduced, due to which the tension of the unloading cable is weakened - the bucket loses balance, is turned over, the rock is shipped.

Features of operation

Deepening of the bucket into the ground occurs only under its own weight. Therefore, in order to ensure a high digging force, the rocks must be sufficiently loose. Therefore, dense and hard rock, which is planned to be developed using a dragline excavator, is first loosened by wedge disintegrators or blasting operations.

During operation, both the traction and lifting ropes must be in constant tension, which is necessary to avoid overlap. Lifting and lowering of the boom is also due to the operation of the cable mechanism. Therefore, when working with hard and dense ground rocks, smaller size buckets are installed, so as not to exceed the maximum load capacity.

Advantages and disadvantages

Unlike conventional excavators, in which tractive effort is created by hydraulic or cable-block systems, and the bucket is rigidly connected to the boom, the dragline body moves freely relative to the main machine. This allows you to lower it to a greater depth (several times larger than conventional models can).

Thanks to a light and long boom, the development of the soil with a dragline excavator can be carried out at a considerable distance from the standpoint. This increases the productivity of this type of equipment and reduces the cost of excavation. In addition, judging by the feedback, a simple and durable bucket control mechanism allows you to reduce the costs associated with the current maintenance of machinery.

Minuses of the dragline excavator are due to the flexible suspension of the bucket. Because of it, the accuracy of digging and unloading is reduced. As a result, shipping of rocks directly to vehicles is difficult. Most often, the ground is poured into the dump - from where it is moved to dump trucks. Therefore, the development of a land mass without additional special equipment - conventional excavators, forklifts - is impossible.

Technical features

In order for the excavator with dragline equipment to show the maximum productivity, the site of soil development must be located directly in front of the machine. Moving the bucket to the face can be a pendulum way - an experienced machinist, swinging the working equipment, can "throw" it to a greater distance than the arrow allows.

Depending on the model of this type of earthmoving equipment, the characteristics of the machine will be in the ranges:

• Length of the boom - from 15 to 100 meters;
• Capacity of the main bucket is from 6.3 to 168 m3;
• The maximum radius of digging is 15.3 and more meters;
• The pressure on the ground is 0.06-0.255 MPa.

The distinguishing characteristic of the dragline excavator is the working mass. The weight of the lightest machines is several times larger than special equipment with a hydraulic drive or a cable-block system. This greatly limits the scope of their application.

Application area

Reviews say that dragline excavators are most often used in places of large-scale development of a soil massif. They are actively used during overburden mining, as well as mining and the creation of quarries of large radius and depth. Dragline with a perforated bucket is used to extract rocks from the bottom of water bodies, as well as to clean rivers, lakes or during the construction of hydraulic structures. They are also widely used in land reclamation. In urban conditions, such digging machines are very rarely used.

Excavator drive type

More recently, walking dragline excavators have been used more and more often . They are delivered to the work site in disassembled form, where their subsequent assembly takes place. This machine is mostly located on a flat area. If you need to move to a new place , the dragline excavator operator lowers the special shoes, which take the weight and raise the car.

After that, the support pad moves, and the technique again "sits" on it. Shoes are installed in a new place, and the whole process repeats. As a rule, walking excavators have a large mass that can not be sustained by a caterpillar engine. Crawler or pneumowheel dragline excavators are almost never found. Usually they are small machines with low productivity, which is why it is not advisable to use them on construction sites. Virtually all representatives of this species are displaced by hydraulic and cable-block machines.

World producers

Uralmash is a domestic machine-building company, which has a dragline excavator in different parts of the world. The technical characteristics of the models are in a wide range, which allows each customer to pick up the machine according to their needs. Judging by the reviews, this is one of the most reliable step-by-step representatives of special equipment.

The competition of the domestic company is only a multi-sectoral Japanese concern that promotes caterpillar models on the world market. Typically, this is an easier technique, which is used in the development of relatively small tracts of soil.