CAR OPERATION.

Hawera Star, Volume XLVI, 1 May 1926, Page 11

CAR OPERATION.

SILENCE AN ASSET. Always a serious problem for designers, quietness of operation has proved one field of activity in which striking developments have been mad© in recent years. Silence is one of ■ the most yaluabio assets of th© modern automobi'e, and one of the most insisted on demands bv purchasers. 'The Bells -Royce attracted the wealthier clientele from its earliest appearance, primarily owing to its quietness. To-day. if cars were as noisy as those of even the late pre-war days, the noise of congested traffic would be insupportab’e. . Of recent steps taken to quieten cars the most- .striking relate to the. valvi systenis, and the gears operating in tile gear box, timing casing and final drive.

The former —the cans© of most engine noise—have been considerably silenced by the use of lighter parts, lighter springing, and the lining with felt of

flio cover p'ates, which havo been thickened to prevent noise amplifier tion. „ , . ... In some cases the felt lining, which serves \also as an oil retainer for the working gear (particularly in the case of overhead valves), deadens valve noises completely. Tills accomplished, the designers are now (seeking bo eliminate all tappet noises, particularly those existing between the tappet rods and cams, and the rods and overhead rocker arms. Most success, so far, has been achieved by oil-cushioning, ball and cup abutments being used, as may lie seen on many 1926 engines between tappets and the other working members they operate.

The cups in. each case are- occasional ly or continuously fed with oil, a typical continuous feeding system being provided by grooving the irocKer arm, so that oil shot from a, t-uhe running along, or inside, the pivot rod of the rockers, runs down the rocker arin, arid thence down the tappet, filling both oil cups. Concerning gear silencing, this is being best accomplished bv better lubrication devices; the use of helical con-stant-mesh pinions ; fabric composition gear wheels, and the scientific forming of the gear teeth so that they engage over the whole area, thus eliminating chatter. Anotfier system is the use of silent chains, even within the gear box, to replace wheels, though this depends for success on the suitability of the chains-’ tension-adjustment provisions. In the gear boxes also the elimination of shps by the use of shorter shafts or by the introduction of central hearings," has had a marked si’encing effect, while the shapes of the gear-box mid clutch flywheel housing have been carefully studied, and the newest designs made to largely eliminate resonance and amplification of noise. Other innovations for the silencing ;of the transmission have been fabric 'universal joints, an the use of spiral ibevei or worm final drives-.