INGENIOUS DEVICE

Ashburton Guardian, Volume 58, Issue 187, 21 May 1938, Page 5

INGENIOUS DEVICE

SWITCHES LIGHT ON. THE CHILOWSKI RELAY. The parking lights of unattended ears are switched op automatically by an ingenious apparatus known as the Chilowski light relay. This device depends for its action on the well-known phenomenon that a mixture of hydrogen and chlorine will combine to form hydrochloric acid only when illuminated; in darkness the combination will not take place. This phenomenon is used in the Chilowski relay by half-filling a small glass bulb with aqueous hydrochloric acid and passing a small continuous current through the acid by means of two platinum wires fused into the glass. As a result of the electrolysis of the acid, the chlorine and hydrogen liberated at the anode and cathode respectively collects above the level of the acid, so that in the 'absence of light a considerable pressure js developed inside the bulb. If, on the other hand, the bulb is exposed to light, the gases combine, at a rate depending upon the intensity of the light, and the resulting gaseous hydrochloric acid dissolves in the aqueous solution, so that there is no appreciable pressure rise. To utilise the pressure developed when the bulb is in darkness, the back of the bulb communicates with a space closed by a thin diaphragm, which distends as the pressure rises. The distention compresses the air in a space at the side of the diaphragm and this space communicates with the upper end of one limb of a U-tube containing mercury, so that the mercury rises in the other limb and completes the circuit containing the lamp and battery. The Chilowski. relay is used in automatic car parking-light control apparatus, - the object of which is to switch on automatically the parking lights of a car left unattended when darkness falls.

Another important application of the relay is for automatically switching on and off the electric lamps in railway coaches, and it is understood that it is now being employed for this purpose on certain French railways with entirely satisfactory results.

CHANGES OF DESIGN. REDUCTION OF WHEEL WEIGHT. Somo very important changes have been made in wheel design in the last few years. For many years American ears were fitted with, hickory wheels having detachable rims, while British makers favoured the steel artillery type with the manufacturers of expensive and sports models using the wire type, then the strongest type known. The revolution started \ujth the gradual reduction of wheel diameter to make room for tyres of larger section, artel it was aided by the gradual disappearance in America of the hickory forests from which came the wood employed. In America, the first step was to adopt the wire type, a very smart wheel, hut an appalling thing to keep clean. English makers followed suit. An early, short-lived attempt to alter wheel design was to adopt the disc wheel, but this acted as a diaphragm, and so exaggerated chassis noises that it was dropped very quickly. After the wire wheel came the pressed steel artillery wheel, light, strong, and good-looking, and this has been followed in the last two years by a revival of the disc wheel, but with perforations around its periphery to help stop drumming, a fault which in any case would not be so apparent in these later types, as they are practically only a hub with a very fat tyre attached. As the wheel as such is gradually disappearing, a writer in an English periodical puts forward a suggestion that the tyre should be attached directly to a rim formed on the brake drum. This would aid brake cooling, but, more important, reduce the weight of the wheel and brake gear. -•

It is pointed out that very light wheels, having practically no Hv-wheel effect, are most important for quick getaway, while they also, improve a car’s suspension.

THE WHITE LINES. PAINTED ON HIGHWAYS. Now that white linos are being painted on highways with the object of defining the two lines of traffic, the legal position as regards motorists who deliberately leave their own side of the road will ho hound to arise in this country sooner or later. In London recently the Lord Chief Justice decided that a white lino indicating the centre of the road is “not a. traffic sign or device.” It is therefore, according to British law, an offence if a motorist’s wheels cross the white lino. However, if on a blind corner or curve in a road a motorist deliberately leaves the correct side of the road, he may be guilty of an offence, and the fact that he crossed the white lines might be accepted as evidence of the dangerous manner of liis driving.