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

Exercise 14. Translate the text with a dictionary in written form.

Text C

TORQUE

Torque is the tendency of a force to rotate an object about an axis, fulcrum or pivot. Just as a force is a push or a pull, a torque is a twist to an object. A force applied at a right angle to a lever multiplied by its distance from the lever's fulcrum (the length of the lever arm) is its torque.

The concept of torque, also called moment or couple, originated with the studies of Archimedes on levers. The rotational analogues of force, mass, and acceleration are torque, moment of inertia and angular acceleration, respectively.

Torque is a part of the basic specification of an engine. The power output of an engine is expressed as its torque multiplied by the rotational speed of the axis. Internal combustion engines produce useful torque only over a limited range of rotational speeds (typically from around 1,000–6,000 rpm for a small car). The varying torque output over that range can be measured with a dynamometer and shown as a torque curve.

Steam engines and electric motors tend to produce maximum torque close to zero rpm, with the torque diminishing as rotational speed rises due to increasing friction and other constraints. Reciprocating steam engines can start heavy loads from zero rpm without a clutch.

To transfer rotating power from a prime mover, such as an internal combustion engine or electric motor, to a rotating driven load a torque converter is generally used. The torque converter normally takes the place of a mechanical clutch in a vehicle with an automatic transmission allowing the load to be separated from the power source. It is usually located between the engine's flexplate and the transmission.

Notes:

flexplate – эластичная муфта

rpm – revolutions per minute

couple – момент сил

Unit 4

Grammar:

Complex Sentences;

Sequence of Tenses.

Exercise 1. Work out the following sounds:

[jH] fuel, pneumatic, use, due

[H] smooth, revolution, tool

[R] start, large, shaft

Exercise 2. Match the transcription to the words given below and define their meanings:

1. [klAtS]	1. truck	1. сгорание
2. [rJtS]	2. heat	2. установка
3. [trAk]	3. combustion	3. преимущество
4. [hJt]	4. steam	4. теплота
5. [stJm]	5. power	5. механический
6. [Instq'leIS(q)n]	6. installation	6. сцепление
7. ['paVq(r)]	7. mechanical	7. мощность
8. [kqm'bAstS(q)n]	8. advantage	8. достигать
9. [mI'kxnIk(q)l]	9. clutch	9. пар
10. [qd'vRntIG]	10. reach	10. грузовик

Text A