VIII. Read and translate the following text.

COMPACTORS

Compactors are used to compact loose soil when building an earth bed. They are also employed to compact undisturbed soil, for example at the bottom and on the slopes of cuts to reduce water loss at the expense of filtration. Compactors are also employed when building roads.

They are classified as follows:

a) by the principle of operation: rollers which compact soil by rolling, tampers which operate on the percussion principle, vibrators and machines combining rolling with tamping and vibration;

b) by the mode of movement: trailer, semi-trailer, self-powered and pendant;

c) by the kind of energy used: with internal combustion engines, electric motors, explosion-acting machines.

Rollers compact soil by the pressure exerted by their rolling wheels on the surface. They may be smooth, sheep-foot, air-tyred and vibrating.

Smooth steel rollers are no longer used today because they do not compact deeply in proportion to their weight.

Vibration rollers compact cohesionless soil quite well, but they are very complicated in design and cannot compact cohesive soil very well. They are consequently little used as yet in earthwork.

Sheep-foot rollers are most widespread at present, although air-tyred rollers are gaining increasing popularity.

Air-tyred towed roller is composed of several sections, each moving independently in a vertical plane together with its wheel. This greatly improves the quality of the compacting process as the compacting is uniform everywhere, tyres are also equally loaded.

Each section consists of a box, a tyre, a tubular axle and bearings. A section with ballast weighs 10 tons. The roller may be composed of three or five sections. In the first case, it is towed by a C-100 tractor, and by a T-140 tractor in the second.

IX. Connect the sentences according to the contents. Translate them.

1. Compactors are used to compact a) although air-tyred rollers are gaining

loose soil increasing popularity.

2. Compactors are also used to b) because they do not compact deeply.

compact undisturbed soil c) when building an earth bed.

3. Smooth steel rollers are not d) in order to reduce water loss at the

used today expense of filtration.

4. Vibration rollers compact e) but they cannot compact cohesive

cohensionless soil quite well soil very well

5. Sheep-foot rollers are most

widespread at present

X. Insert the verbs in the proper form. Translate the sentences into Russian.

1. Air-tyred rollers … increasing popularity.

2. The roller may be … of three or five sections.

3. A section of the roller … of a box, a tyre, a tubular axle and bearings.

4. A section with ballast … 10 tons.

5. Compactors … by the mode of movement.

6. Compactors … to compact loose soil when building an earth bed.

7. An air-tyred roller … of several sections.