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Types of tyres

QUESTION: What is the difference between radial and ordinary tyres?

J. Nedumaran, Doha, Qatar.

ANSWER 1: Ordinary tyres or cross-ply tyres are the oldest type of tyre and has a case made of two or more layers of fabric. A tyre's strength and load carrying ability were at one time indicated by its number of plies. Modern materials and man made fibres such as polyester and glass fibre embedded in the rubber are much stronger than the cotton fibres originally used.

Radial tyres give the impression that they have low inflation even though the air pressure is as recommended by the manufacturer. This is primarily because of the soft sidewalls. The physical difference between the radial and cross-ply tyres and in their behaviour on the road is governed by the difference in their individual carcass construction.

Carcass is the rubber-bonded cord structure of a tyre integral with the bead and contains the inflation pressure. The radial ply has a stiffness and resistance in its tread area, so that in motion the tread in the contact patch retains virtually all of its pattern and grip.

Radial tyres normally give twice as much mileage as cross-ply tyres and the difference in cost is not more than 30 per cent sometimes even less and gives a marginally harder ride but are safer at high speed.

Radials make the steering a little harder than cross-ply tyres, but provide better braking performance. The carcass of cross-ply tyres consists of textile cord ply fabric, but in a radial tyres it consists of steel belted cord laid substantially 90{+o} to the centre line of the tread.

J. John Silas, Chennai.

ANSWER 2: Tyres consists of layers of cord called `plies'. Plies are shaped on a form and impregnated with rubber. There are two ways to apply the plies on the bias and radially.

In bias type (ordinary) tyres the plies are criss-crossed. One layer run diagonally one way and the other layer runs diagonally the other way. The arrangement makes a carcass that is strong in all directions because of the overlapping plies. However the plies tend to move against each other.

This movement generates heat, especially at high speed. Also the tread tends to `squirm' or close-up as it meets the road. This increase tyre wear. Tyres with radial plies were introduced to remedy these problems.

In radial tyres, all the plies run parallel to each other and are vertical to the tyre bead. Belts are applied on top of the plies to provide added strength paralleled to the bead. The radial tyre gives better fuel economy & lesser tyre wear.

R. Shihab, Kerala.

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Speech synthesizer

QUESTION: What is a speech synthesiser? How does it work?K. P. Kurian, Kerala.ANSWER: A speech synthesizer converts computer based text (usually ASCII _ American Standard Code of Information Interchange) into the spoken word. Text-to-speech technology transforms ordinary text into natural-sounding, highly intelligible speech.Speech synthesis is widely used by blind and other handicapped persons to make us of computer technology; Now, synthesized speech is also used in a wide range of commercial applications to tell us the phone numbers we request when we dial Information, to announce station stops, to vocalize instrument readings, and so on. The speech synthesizers used to give instrument readings and to make brief informational announcements vocalize pre-stored speech.A speech synthesizer converts ASCII text into speech in real time, by stringing together phonemes according to an algorithm that encodes rules for the relation of English spelling to English pronunciation. Such algorithms can be extremely sophisticated. It first parses sentences and words, then checks for any matches in a stored dictionary; if no match is found, it invokes rules for converting letters to phonemes, then applies prosodic rules for speaking in phrases and finally applies rules for converting phonemes to speech.It provides the highest level of speech quality and accuracy, producing clear, correct pronunciation of single characters, words even homograph pronunciations, phrases, and proper names.

K. Kamalakkannan, Doha, Qatar

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