Unit three. Cars

Pre – reading Activity

• Can you drive yet?

• Would you like to learn? Why? Why not?

• Do you know anyone who had trouble learning to drive? What happened? Do you think some people just can’t drive?

Make sure you know these words:

mileage – відстань у милях

blueprint – проект, план

reciprocate – рухатися вперед та назад

spin (spun, spun) – крутитися

scale down – знижувати

1.Read the Text *** Mercedes Gas Turbine

Mercedes would like to continue making big cars. Engineers there think that maybe they can – by using a gas-turbine engine to acceptable mileage. They calculate that the prototype car in it will go, and on which they are already working, will weigh 3,350 pounds when finished. By comparison a Toyota Starlet weighs 1,730 pounds.

Recently I was admitted inside the Mercedes-Benz experimental design offices and research laboratories to look at work in process. I was accompanied by Dr. Michael Wessels, one of the engineers who works full time on the gas turbine project. Dr. Wessels spread a blueprint on a big table and explained the advantages of the gas-turbine engine:

• Multi-fuel capability.

• Low emission levels – due to continuous combustion with a high proportion of excess air.

• Simplified maintenance – no oil changes are needed.

• Minimal internal friction – low wear rates result in long engine-life expectancy.

• No vibration – because there is no reciprocating motion as there is in a conventional piston engine.

• Low noise level – which makes silencing easy.

Mercedes is looking at the year 2000 as a possible production date. However, before turbine-powered Mercedes start rolling off the production lines, many problems must be overcome.

A turbine’s aerodynamic efficiency is dependent on the peripheral speed of the turbine rotors. To maintain the necessary speed, a small automotive-type turbine has to spin faster. This can cause temperatures and increased revolutions per minute (rpm).

Clearances are a problem. When scaling down a turbine to automotive size, tolerances – which are already minimal – can’t be scaled down proportionally. So the smaller unit tends to operate with disproportional large clearances and loses aerodynamic efficiency.

But the biggest problem of all is temperature, says Dr. Hans Joachim Forster, director of research for Mercedes-Benz. ‘At 2,400 degrees F the gas turbine reaches the same overall efficiency as a good diesel engine under full load, and exceeds the part-load efficiency of a modern Otto-cycle piston engine,’ he says.

Only ceramics can withstand these temperatures. Most promising are silicon nitride and silicon carbide.

2. Reading Comprehension

1. What are the advantages of the gas turbine?

2. When does the turbine-powered Mercedes start rolling off the production

lines?

3. What are the problems connected with the car gas turbine?

3. Vocabulary Focus

A. Find the words in the text which mean the following and write them in the blanks. ***

1. A good or useful quality or condition that something has.

_____________________

2. A gas or other substance that is sent into the air.

_____________________

3. The amount of space around one object that is needed for it to avoid

touching another object.

_____________________

4. Showing signs of being successful or good in the future.

_____________________

5. An engine or motor in which the pressure of a liquid or gas moves a special

wheel around.

_____________________

B. Name the words from which the following derivatives are made. Translate both the derivative and the root-words:

Acceptable, comparison, experimental, accompanied, explained, continuous, maintenance, production, promising, clearance, proportionally, biggest, capability, made, working, expectancy.