POWER LOSSES

Wanganui Chronicle, Volume LXXXIII, Issue 20104, 24 March 1928, Page 21 (Supplement)

POWER LOSSES

WIND RESISTANCE VARIABLE GEARS "Wind resistance encountered by a car goes up by about the cube of the. speed. Therefore, the resistance increases much faster than does the speed of the car, and consequently the higher the rate of speed the greater the percentage of engine power which is lost. It has been estimated, with one particular make of car that petrol mileage drops by about 3 m.p.g. for every increase of 10 m.p.h. above a certain figure. For example, if the owner was getting 19 m.p.g. at 25 m.p.h., the consumption would be 16 m.p.g. at 35, and 13 m.p.g. at 45. Once a car is into its stride only a small portion of its power is required to keep it moving at a constant speed on the level. A moderate weight car requires about 6 h.p. for its propulsion at 30 m.p.h. on the level. Immediately a hill is encountered, or if it is desired to accelerate rapidly, a full throttle opening may result in the delivery of 20 or 30 h.p. It is interesting to observe that cars which may sweep along at 35 m.p.h. on the level with the expenditure of only 10 p.h. may be fitted with engines rated as high as 35 h.p. and developing up to 90 brake h.p. It seems a waste to carry this energy in reserve, but there is no alternative with the orthodox gearbox if one wants power for hills and emergencies. The infinitely variable gearbox is an attempt to abolish high-powered engines. With an infinitely variable gear there is little loss in the transmission of power, and a 1000 c.c. motor-cycle engine can be made to propel a sevensetter car with remarkable economy. A Variable Gear