Types of excavators

Excavators are the main machines used for stripping overburden and excavating mineral. An excavator is a power-driven digging machine, usually mobile, designed for digging solid ground or broken rock and for moving it in its bucket to a discharge point.

Two main types of excavators exist: single-bucket type and multy-bucket type. The first type is self-explanatory. In the second type a number of buckets are fixed either on an endless chain or on a wheel.

The working cycle of an excavator includes the following operations;

(1) The bucket cuts into the face and fills itself;

(2) The loaded bucket moves towards the discharge point;

(3) the bucket discharges;

(4) the empty bucket returns.

Single-bucket excavators operate cyclically, i.e., with interruptions, since all these operations are consecutive. Multi-bucket excavators work continuously, and all the operations, including the travel of the excavator, are simultaneous.

Vocabulary:

overburden -

power-driven digging machine

- електроекскаватор

bucket – баддя

discharge - розвантаження

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Single-bucket excavators are the most widely used type in opencasts, particularly the face shovel and the dragline.

The face shovel has the following front-end equipment the bucket, with its crowed and jib. The bucket is rigidly fixed to one end of the arm which is hinged on the jib. The bucket is also hung by its bail block from the hoisting rope passing over the end of the jib.

The powered equipment, including the crowd device, enable the bucket to dig in, to lift and fill, to move the full bucket to the discharge point and to return amply to the face. The excavator during digging can travel under power as the face advances; it can also move to a new face.

The working motions of the face shovel are: digging, slewing to discharge, discharging, slewing back to the face, and lowering of the bucket.

The excavators of the smaller type are made universal or semi-universal and are used mainly for building work, but on opencast sites they are subsidiary equipment.

The larger excavators are the main machines used on opencast sites.

For rock excavations with underloading on to transport, at the lowest level of the opencast, ЭКГ-4 and ЭКГ-6 excavators are used.

Vocabulary:

Shovel - ковш

Crowed – навантажувач

bail block – круглий блок

hoisting rope – канат

slew – повертати, прокручувати

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1. What are the larger excavators the main machines used on?

2. What kind of excavators are the most widely used in opencasts?

3. What are the working motions of the face shovel?

4. What is the bucket hung by?

5. What are the excavators of the smaller used for?