From the Rolls-Royce experimental archive: a quarter of a million communications from Rolls-Royce, 1906 to 1960's. Documents from the Sir Henry Royce Memorial Foundation (SHRMF).
Brochure on the Chrysler Automatic Overdrive, detailing its operation and advantages for the Airflow model.
| Identifier | ExFiles\Box 125\2\ scan0111 | |
| Date | 2nd November 1936 guessed | |
| File 1054 [Left Page Text] overdrive in operation, or within .6 miles per gallon of the figure for 20 miles an hour without Chrysler’s latest exclusive device. It is a matter of common observation that oil consumption increases very rapidly with car speed. There are two basic reasons for this. In the first place, the higher the engine speed, the greater the amount of oil circulated by the pump. This means an increased throw-off from the crankshaft; also, because of the greater centrifugal force with increasing speed, more of the oil is thrown into the cylinder bores. The amount of oil that is pumped past the pistons depends upon the ability of the piston rings to scrape the oil off the cylinder walls and back into the crank case. The higher the piston speed, the greater is the pressure on the oil built up ahead of the rings. This means that more oil will leak past the rings into the combustion chamber. The result is not only increased oil waste but greater carbon deposition from the burning oil. ADVANTAGES IN OPERATING COMFORT The outstanding impression of the passengers of a Chrysler Airflow car is the complete absence of engine noise at high speeds when the overdrive is operating. If we analyse the origin of noise, we find that it represents the dissipation of energy. Thus, just as the waste of power due to friction is dissipated in the form of heat, so do the forces which produce friction generate noise and vibration, which are other forms of energy dissipation. A typical example is the case of fan noise which may be said to increase in very much the same proportion with speed as does the power required to drive it. Reduction in engine speed, which the overdrive achieves, especially at high car speeds, by eliminating so much of the power losses, at the same time cuts down the volume of noise tremendously. No small part of this contribution to quietness is due to the inherent silence of the overdrive mechanism itself. Instead of being conscious that the overdrive gear is engaged, the passenger gets the impression, in going from conventional to overdrive, that he is going from gear drive to direct drive. The addition of this simple overdrive mechanism puts the finishing touch to the Chrysler Airflow car, which marks the greatest recent advance in the art of individual transportation. At one stroke it makes possible greater speed at lower cost and the elimination of all strain and fatigue both to passengers and engine, and can be used at will by the driver without any addition of physical effort. In other words it is humanly automatically controlled. • 12 • [Right Page Text] The CHRYSLER AUTOMATIC OVERDRIVE HOW TO USE THIS EXCLUSIVE FEATURE HOW IT OPERATES What it means to you in . . . . finer performance, in fuel and oil saving, in conserving engine life and in generally promoting the enjoyment of your Airflow Chrysler. | ||