Complete the following sentences with the appropriate word or phrase.

Date: 2015-10-07; view: 551.

LANGUAGE PRACTICE

1. Jacks are _______________, hand-operated devices for moving heavy loads through short distances.

2. Hoists for coal mines are principally of the __________________ type, for operating in balance from one level.

3. The operation of hoists may be controlled manually, _________________, or semiautomatically.

4. Elevators are widely used to transport ____________________ and freight vertically or at an incline in buildings and structures.

5. Escalators have the advantages of continuity of motion, great capacity, and small amounts of space __________________ and current consumed for each passenger carried.

2. Translate the following extract into Ukrainian:

Chain, because of its energy absorption properties, flexibility, and ability to follow contours, is a versatile medium for lifting, towing, pulling, and securing. Chain can be divided into two main groups: welded and weldless. Welded chain is further categorized into grades by strength and used for many high-strength industrial applications, while weldless chain is used for light-duty low-strength industrial and commercial applications.

The most widely used variety is hoist load wheel chain, a short link style used as the lifting chain in hand, electric, and air-powered hoists. Some roller chain is still used for this purpose, but its use is steadily declining because of the higher strength per weight ratio and three-dimensional flexibility of welded link chain. Wire rope is also sometimes used in hoist applications. However, it is much less flexible than either welded link or roller chain and consequently requires a drum of 20 to 50 times the rope diameter to maintain bending stresses within safe limits. Welded link chain is used most frequently in hoists with three- or four-pocket wheels; however, it is also used in hoists with multipocket wheels. Pocket whells, as opposed to cable drums, permit the use of much smaller gear reductions and thus reduce the hoist weight, bulk, and cost.