Exercise 10. Analyze the sentences underlined in text A. Find predicates and define their tense and voice form
Exercise 11. Translate the text without a dictionary.
Text B
PULLEY
A pulley is a wheel with a groove along its edge, for holding a rope or a cable.
Pulleys are usually used in sets designed to reduce the amount of force needed to lift a load.
However, the same amount of work is necessary for the load to reach the same height as it would without the pulleys. The magnitude of the force is reduced, but it must act through a longer distance. The effort needed to pull a load up is roughly the weight of the load divided by the number of wheels. The more wheels there are, the less efficient a system is, because of more friction between the rope and the wheels. Pulleys are one of the six simple machines.
It is not known when or by whom the pulley was first developed, but most likely it came from Eurasia. The basic building block of a pulley, the wheel, was unknown to cultures in the western hemisphere, sub-Saharan Africa and Australia. It is believed however that Archimedes developed the first documented block and pulley system, as recorded by Plutarch.
Notes:
groove – желоб
edge – край
magnitude - величина
hemisphere – полушарие
Exercise 12. Translate the text with a dictionary in written form.
Text C
PLAIN BEARING
A bearing is a machine element that constrains relative motion to only the desired motion, and reduces friction between moving parts. The design of the bearing may provide for free linear movement of the moving part or for free rotation around a fixed axis. Many bearings also facilitate the desired motion as much as possible minimizing friction. Bearings are classified broadly according to the type of operation, the motions allowed, or to the directions of the loads applied to the parts.
The term "bearing" is derived from the verb "to bear". A bearing is a machine element that allows one part to bear, i.e. to support, another. The simplest bearings are bearing surfaces. Other bearings are separate devices installed into a machine or machine part. The most sophisticated bearings for the most demanding applications are very precise devices. Their manufacture requires some of the highest standards of current technology
The most common bearing is the plain bearing which uses surfaces in rubbing contact, often with a lubricant such as oil or graphite. A plain bearing may or may not be a discrete device. It may be nothing more than the bearing surface of a hole with a shaft passing through it. With suitable lubrication plain bearings often give entirely acceptable accuracy, life and friction at minimal cost. Therefore they are very widely used.
A suitable bearing can improve efficiency, accuracy, reliability, speed of operation, size, weight, and costs of purchasing and operating machinery.
Notes:
rubbing – трение
accuracy – точность
sophisticated – технически сложный
Unit 3
Grammar:
Modal Verbs;
Degrees of comparison;
Functions of “one” and “that”.
Exercise 1. Work out the following sounds:
[aI] side, apply, design, timing, align, item
[H] loop, groove, improve, solution, two
[I] slip, link, fit, transmit, system, this, many
Exercise 2. Match the transcription to the words given below and define their meanings:
| 1. [sLs] | 1. alignment | 1. круглый |
| 2. [flxt] | 2. side | 2. устройство |
| 3. [slIp] | 3. requirement | 3. скользить |
| 4. [raVnd] | 4. source | 4. требование |
| 5. [q'laInmqnt] | 5. transmission | 5. передача |
| 6. [sq'lHS(q)n] | 6. flat | 6. сторона |
| 7. [rI'kwaIqment] | 7. solution | 7. источник |
| 8. [trxnz'mIS(q)n] | 8. arrangement | 8. решение |
| 9. [saId] | 9. slip | 9. выравнивание |
| 10. [q'reInGment] | 10. round | 10. плоский |
Text A
BELTS
Belts are used to link two or more rotating items mechanically. They may be used as a source of motion, to transmit power at up to 98% efficiency between two points.
Power transmission is achieved by specially designed belts and pulleys. The demands on a belt drive transmission system are large and this has led to many variations.
The earliest was the flat belt. It is a simple system of power transmission that was well suited to its time in history. The Industrial Revolution soon demanded more from the system, as flat belt pulleys should be carefully aligned to prevent the belt from slipping off. The flat belt also tends to slip on the pulley face when heavy loads are applied.
Round belts are circular cross section belts designed to run in a pulley with a circular (or near circular) groove. They are for use in low torque situations and may be bought in various lengths or cut to length and joined, either by a staple, gluing or welding (in the case of polyurethane).
Vee belts (also known as v-belts or wedge ropes) are an early solution that solved the slippage and alignment problem. The V-belt was developed in 1917 by John Gates of the Gates Rubber Company. The "V" shape of the belt runs in a groove in the pulley, with the result that the belt cannot slip off. The belt also tends to wedge into the groove as the load increases — the greater the load, the greater the wedging action — improving torque transmission and making the vee belt an effective solution. They can be supplied at various fixed lengths or as segmented sections, where the segments are linked to form a belt of the required length.
For high-power requirements, two or more vee belts can be joined side-by-side in an arrangement called a multi-V, running on matching multi-groove pulleys.
Timing belts (also known as Toothed) have teeth that fit into a matching toothed pulley. Correctly tensioned they have no slippage and are often used to transfer direct motion for indexing or timing purposes. Camshafts of automobiles often use these belts.
Belts normally transmit power only on the tension side of the loop. However, designs for continuously variable transmissions exist that use belts that are a series of solid metal blocks, linked together as in a chain, transmitting power on the compression side of the loop.
Exercise 3. Answer the following questions:
1. What are belts used for?
2. What types of belts are there?
3. Why should flat belt pulleys be carefully aligned?
4. How was the slippage and alignment problem solved?
5. When was the V-belt developed?
6. Why are timing belts also known as toothed belts?
Exercise 4. Translate the following words into Russian:
Link, design, flat, align, slip, apply, join, wear, cross section, groove, improve, solution, side, arrangement, timing belt, fit, match, tension, camshaft, loop.
Exercise 5. Translate from Russian into English:
Скользить, улучшать, выравнивать, подходить, устройство, петля, ремень привода газораспределительного механизма, соединять, решение, устанавливать, сторона, плоский, применять, изнашиваться, поперечное сечение, паз.
«A»
1. belt
2. ransmission
3. motion
4. slip
5. apply
6. tension
7. align
8. wedge
9. solution
10. wear
«B»
1. the process of moving
2. a force stretching something
3. an answer to a problem
4. a piece of hard material with V-shaped edge
5. a band or strip with no ends, used to drive a machine by connecting two wheels
6. to bring into use
7. the part of a motor car which passes on power from the engine to the axle
8. to move or slide suddenly a short distance out of place
9. to bring or form into a straight line
10. to lessen the quality, value, etc. by using or rubbing
Exercise 7. Translate the sentences paying attention to modal verbs:
1. Students must know the properties of building materials.
2. Bricks can be transported on pallets.
3. Hydraulic devices may also be used in industrial applications.
4. Machines can perform work better and faster than a man.
5. Any mechanism has to be made of strong materials.
6. A new school is to be built there.
7. We will be able to use the new instruments in our practical work in the laboratory.
8. The engineers were to test all the machines before starting work.
9. The workers should use a new powerful equipment.
10. The axles must bear the weight of the vehicle plus any cargo.
Exercise 8. Give the comparative and superlative degrees of the following adjectives:
Many, efficient, small, quick, convenient, little, great, heavy, much, available, expensive, high, large, good, important, far.
Exercise 9. Translate the sentences paying attention to degrees of comparison:
1. Functioning physical machines are always less than 100% efficient.
2. Simple machines are often used in combination as components of more complex machines.
3. The torque of the driving gear produces a larger torque in the driven gear at a lower speed, or a smaller torque at a higher speed.
4. The more wheels there are, the less effective a pulley system is.
5. Gears are more expensive to manufacture than belts.
6. The more powerful engine is installed, the more productive the machine is.
7. Builders should apply the most modern equipment.
8. The best projects of our students were presented at the exhibition.
9. This plant produces the most reliable engines.
10. The new radio tower is the highest building in the city.
Exercise 10. Define the functions of “one” and translate the sentences:
1. A dump truck operated by one driver transports 40 tons of load.
2. One mustn’t press this button. It’s dangerous.
3. Any kind of energy can be transformed into another one.
4. One may use steam engines for locomotives.
5. This construction site is served by one crane.
6. A mobile crane is more widely used on the construction site than a stationary one.
7. For transporting bulk materials one can use conveyors.
8. V-belts were invented later than flat ones.
Exercise 11. Define the functions of “that” and translate the sentences:
1. The engineer says that he will change some details in the design.
2. That old equipment has been replaced by a more modern one.
3. The crane that was shown at the exhibition is the most efficient one.
4. The motor of a giant crane is more powerful than that of a truck crane.
5. That cranes are used on building sites is known to everybody.
6. It is known that machines perform all hard work at plants.
7. It is evident that the mechanical advantage of a jackscrew is greater than that of a wedge.
8. That people used tools in ancient times is proved by many facts.
9. That equipment was designed by our engineers.
10. V-belts are an early invention that solved the slippage problem.
Exercise 12. Analyze the sentences underlined in Text A. Find the function of «that».
Exercise 13. Translate the text without a dictionary:
Text B
RACK AND PINION
A rack and a pinion is a pair of gears which convert rotational motion into linear one. The circular pinion engages teeth on a flat bar - the rack. Rotational motion applied to the pinion will cause the rack to move to the side, up to the limit of its travel.
The rack and pinion arrangement is commonly found in the steering mechanisms of cars or other wheeled, steered vehicles.
This arrangement provides a lesser mechanical advantage than other mechanisms such as a recirculating ball, but much less backlash and greater feedback, or steering "feel".
Notes:
rack – зубчатая рейка
engage – зацеплять
backlash – мёртвый ход
feedback – обратная подача