POWER LOSSES

Evening Post, Volume CXXIII, Issue 67, 20 March 1937, Page 28

POWER LOSSES

A recent review of the- mechanical losses in the engines, transmissions, and auxiliaries of the modern motor-truck chassis indicates how difficult it ,is for automotive designers and manufacturers to achieve any really marked advance in the efficiency of certain functioning parts of a truck chassis. The same remark applies equally to cars. If one considers the energy storedTn a gallon of petrol and the actual energy delivered at the driving wheels, one finds that it is relatively small, being only about 20 per cent, of the fuel value. The greatest loss of energy is caused solely by • the heat dissipated through the medium of the radiator, and this may amount to. 50 per cent, or more. Then there are the frictional losses in the functioning parts which amount to a considerable figure. These include work done.in pumping oil, creating an air draught, generating electricity, etc. The review shows the calculated gains that have been made in the (mechanical efficiencies of motor-trucks dux-ing the last ten years. For instance, it is computed that the efficiency of engines has increased during that period from 18 per cent, to 23 per cent., while rear axle efficiency lias risen from 90 per cent, to 94 per cent., wheel bearings from 98 per cent, to 99.8 per cent., and propeller shafts from 98 per cent, to 99.8 per cent. It will be noticed, says the DunlopPerdriau Bulletin, that whilst there yet remains a big field for obtaining an improved ratio between the power available at the driving wheels and the power obtainable from- a given size engine, other working parts of a chassis are getting very close to being 100 per cent, efficient.