UNIT 17

The Gearbox

1. Read and translate the text:

The object of the gearbox is to provide a means of obtaining the most efficient engine speed in relation to the speed required, at the road wheels.

The gearbox is quite a complicated assembly of gears of different sizes, arranged so that certain combinations of gears can be engaged to enable one to drive another. If a larger gear drives a smaller one, a high ratio is produced, and if a smaller gear drives a larger one, a lower ratio is provided. Most car gearboxes have four “speeds”, which means that by moving the gear lever inside the car one of four different ratios can be selected in the gearbox. A reverse gear is also included, to enable the car to be driven backwards for maneuvering.

To illustrate the gearbox principle in a simple manner, the arrangement of gears in a three-speed box only is shown.

In a low ratio gear the engine runs fast while the car is moving quite slowly. As higher gears are engaged the engine speed drops but the car moves faster. A low ratio is therefore used when greater engine power is needed to start the car from rest, to accelerate quickly and to climb steep hills. For normal cruising along the road, a high gear is selected.

2. Learn the new words:

an object – мета, ціль

means – засіб, спосіб

obtaining – досягнення

efficient – ефективний, продуктивний

in relation – у відношенні

to require – вимагати

road wheel – ведуче колесо

assembly – агрегат, вузол

to arrange – розташовувати, розміщувати

to engage – зачіплюватись, включатись

to enable – давати можливість

a high ratio – високе число передач

a reverse gear – передача заднього ходу

3. Match the word-combinations:

1) a road wheel; 2) a high ration 3) a high gear; 4) an engine speed; 5) a reverse gear.

a) швидкість руху; b) висока передача; c) високе число передач; d) передача заднього ходу; e) ведуче колесо.

4. Answer the questions:

What is the object of the gearbox?

What does the gearbox consist of?

How are gears arranged in the gearbox?

When is a high ratio produced?

When is a lower ratio provided?

How many “speeds” have most car gearboxes?

What is used to enable the car to be driven backwards for maneuvering?

uNIT 18

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