FEW BIG CHANGES.

Auckland Star, Volume LXVIII, Issue 69, 23 March 1937, Page 18

FEW BIG CHANGES.

CAR CONSTRUCTION.

REAR ENGINES DISCOUNTED,

EXPERTS IN CONFERENCE,

DETROIT, January 16.

Few motor changes in the American motor car are in sight, if opinions expressed at this week's meeting of the Society of Automotive Engineers reflect the future trend in motor building. The likelihood of a rear-engined car, such as visioned by the recent patents of

one company, taking the road in large numbers was discounted. There were recurring statements that, with additional increases in engine speed and power output, greater attention will be given to lubrication problems and oil economy. The construction of body and chassis as a single unit came in for a share of discussion. Bus builders have been loud in chanting the praises of the chassisless structure, and there were predictions that the passenger car buyer would quickly accept this type of enclosure.

"Whatever changes may be made in engine design during the next year or two," said Mr. P. M. Heldt, engineering editor of "Automotive Industries," "will be such as to improve the present standard types." Present passenger car engines show, on the whole, satisfactory performance, Mr. Heldt added. He admitted, however, that they are subject to further improvement. Aims of Industry. "Engineering efforts undoubtedly will be directed," he continued "toward increasing the output per \init of displacement and per unit of weight, increasing the fuel economy and increasing the service life. As long as we adhere to the present general chassis layout, the six and eight-cylinder in line and the eight and twelve-cylinder V engines will no doubt retain their present relative positions, at least approximately." "The manufacturing cost increases with the number of cylinders, and, besides, beyond six there is no improvement in the mechanical balance. The smoothness of the torque curve, of course, increases with the greater overlap of power impulses in the multicylinder engine. While an increase in cylinder number probably is conducive to smoother idling, it has little effect on passenger comfort and on transmission stresses at. average driving speeds, as long as the displacement of the engine is the same."

Discussing rear engines, Mr. Heldt expressed the opinion that it is practically impossible to place a conventional in-line engine back of the axle in a fore-and-aft direction, as that leaves too little weight on the front axle. "Another objection to an engine placed too far back," he said, "is that it reduces the aerodynamic stability of the car. To insure such stability, the centre of gravity must be located ahead of the centre of pressure, and this requirement is hard to meet with a car having the

power plant behind the rear axle, except by providing it with a large tail fin, which is certainly not a desirable feature -of a car designed for use on congested roads. Rear Engine Discussed. "The engine can be arranged parallel with the rear axle, either behind or in front of it, but, in that case, too, compactness is desirable, especially if the clutch and transmission are to be mounted in line with the crankshaft. It is also possible to mount the engine longitudinally squarely over the rear axle, but, in that case, a transfer drive must be provided to carry the power to the primary shaft of the transmission, which latter would be placed below the crankcase and bolted to the final-drive housing. Such a construction involves the use of independent suspension for the rear wheels, so that the differential and transmission will be spring-supported. -

"Other alternatives consist in placing the engine with its axis in .the length of the car, ahead of the rear axle, or in using a very short type of engine and placing it at a considerable inclination either forward or back of the axle or squarely above it. In every case, compactness is essential."

In the view of another there is little doubt that the public's attitude toward the integral construction of body and chassis will be favourable. "One of the greatest advantages, of all-steel bodiee," he told.. t&B,^'engineers, ic has been the possibility of building them in completely assembled arid finished units, which can be economically transported to ike assembly plant of the ni'tomobilc manufacturer and asscinb'ed into tbj» Complete body in a period measured

by iniimt.ee. Further development of the integral construction of body and chassis would be an additional step toward simplifying assembly problems and toward realising to the maximum the structural advantages introduced by en all-steel body." Insurance Position. Mr. Howard D. Brown, general attorney for the Detroit Automobile InterInsuranee Exchange, foresaw the possibility, however, that the integral body may compel an increase in accident insurance rates. The cost of making repairs, from an insurance angle, has risen from 15 to 25 per cent in the Inst three years, he said. This increase was not entirely due to an increase in accidents, Mr. Brown added. Part of it was attributable to the fact that certain new parts were not easily repaired.

"A great deal of difficulty is encountered in repairing knee action equipment and also the grill work on radiators," Mr. Brown $aid. "These grills are now constructed so that, in parking, they are damaged and are- not easily repairable. Consequently, the insurance company must entirely replace the grill at an additional cost. "If the modern body is to be so constructed that repairs cannot be easily made and the whole body must be junked and a replacement made, then anyone can reasonably determine that the rate on collision of this type of case would be considerably affected." — (N.A.N.A., copyright.)