5. Fill in the gaps.

1. This detail is (1)_____ on the shaft. 2. The new equipment was (2)_____ in the foundry shop. 3. The motion is (3)_____ through the toothed wheels.4. You may (4)_____ your own venture.

1). a) adjusted, b) made, c) functioning.

2).a) designed, b) assembled, c) installed.

3).a) made, b) got, c) transmitted.

4). a) open, b) establish, c) organize.

6. Complete the sentences.

Gears are 1)____in machines to trans­mit motion and power by means of positive, con­tact between toothed wheels. Three such types are parallel, 2)____, and skewed shafts. Only a portion of the tooth 3)____ the involute form because the lower part of the tooth (flank) must 4)____ adequate clearance. This means that there is no side 5)____ on the shaft. It also means that only a limited number of teeth can be in 6)____ contact at a given time. One special configur­ation of spur gears is called a planetary gear 7)____ . It has been used in auto­mobiles and propeller-8)____ aircraft. Because gear­ing cut at an angle 9)____ a side thrust on the shaft, it is customary to cut such gears double. Large speed 10)____ are possible with this arrangement.

a) intersect, b) operate, c) use, d) resembles, e) provide, f) thrust, g)mesh, h) transmit, i) precision, j) drive, k) engage, l) causes, m) reductions, n) wear, o) removal, p) loading, q) follows, r) train.

7. Group the synonyms.

a) еngage with, b) part, c) impact, d) cross, e) use, f) rotate, g) lock, h) cover, i) oil, n) roll, p)insert, q) deliver, v) element, l) close, r) grease, x) component, y) extract, s) revolve, u) intersect, z) detail, t)application, w) influence, o) lubrication.

LIFTING AND TRANSPORTING MECHANISMS

UNIT 9

1. Learn the notions and their definitions.

Piston A rod or disk that can move up or down within a hollow cylinder.

Crankshaft A shaft driving or driven by a crank.

Efficiency A machine's ratio between work output and energy in­put.

Horsepower A measure used in the English-speaking countries for the work performed by a machine. It was devised in the eigh­teenth century by James Watt and equals 33,000 foot-pounds per minute.

Mechanical Advantage The ratio of the output force of a machine to the input force necessary to work the machine.

Text 1

2. Read, translate and retell the text.

Crane

A). Crane is a hoisting machine widely used for handling materials at building construction sites, factories, warehouses, and shipyards. Cranes move heavy loads by means of ropes or cables that ride over pulleys. Nearly all of them move loads both vertically and horizontally.

Machines that can only raise and lower loads are called hoists, or winches. Small cranes are operated by a hand crank, most large cranes are powered by electric motors or diesel engines. Originally large cranes were powered by steam engines.

Among the principal com­ponents of cranes is the jib, a horizontal or inclined beam with structural supports to pre­vent it from bending.

The jib supports either a fixed pulley system or a movable pulley system that can travel along its entire length. The jib is usually attached to a vertical pillar, or column, or a wall of a building about which it can be rotated. The jib is attached to the wall with brackets. The pulley system of ropes or cables are wound onto a drum, or cylinder, that is turned by a hand crank or a motor. Some cranes are mounted on stationary supports, while others are mounted on movable bases. Special cranes may have a variety of additional features.

B). Portable Jib Crane. The portable jib crane is small and is attached to the columns or walls of a building by means of simple adaptors. Portable jib cranes are particularly useful in various areas of shops and warehouses.

Cantilever Crane. This type of crane has a jib that extends outward from a supporting column that generally cannot be rotated. The jib is usually counterbalanced.

C).Traveling Cranes. There are several types of traveling cranes. One of the most common is the traveling jib crane. Its pulley system is suspended from a trolley that moves along the length of the horizontal jib. Traveling bridge cranes consist essentially of two elevated tracks that are bridged by a girder that travels along the tracks on wheels. Gantry cranes have a bridge that is supported at both ends by vertical columns, or legs. The legs are mounted on wheels or rollers so that the entire structure can move along rails or tracks.

D).Truck Crane. This type of crane is mounted on a truck that moves on large wheels or on tractor caterpillar treads. They are often called crans, but are designed to travel on standard gauge tracks.

Crawler cranes. Truck cranes are quite versatile because they are self-propelled and can be equipped with accessory booms, or jibs, to extend to about 150 feet (46 meters) high. Locomotive cranes are similar to truck

Floating Crane. Hoisting and transporting cargo to and from ships are often done with floating cranes, which are mounted on pontoons or barges. Floating cranes are also used for water work such as driving piles and raising sunken vessels and other objects.

Cable Crane. Materials such as earth and rocks are often lifted and transported by cable cranes. The load is carried in buckets attached to a cable that moves between two towers.