IN the discussion of automatic devices in motor cars presented in this paper, special emphasis is placed on fully automatic and semi-automatic clutches, drives, and transmissions.
Two methods of attack are being used to eliminate the clutch pedal: power operation of the mechanical clutch and the fluid coupling. Three fundamental types of control for vacuum-operated clutches are discussed:
  1. 1.
    Position or follow-up type valving.
  2. 2.
    Balanced or pressure-sensitive type.
  3. 3.
    Balanced cushion with variable bleed.
In a review of the merits and demerits of the fluid coupling, fuel economy and the shock loads on the driving mechanism are stressed. An appraisal of the operating principles and characteristics of various fully and semi-automatic transmissions compares the following: overdrive; four-speed semi-automatic transmission with fluid coupling; three-speed fully automatic transmission; and four-speed fully automatic transmission with fluid coupling.
In his conclusion the author predicts that sliding gears will not be used in the final version of a generally satisfactory automatic gear box; that the clutch pedal and driver operation of the clutch will soon be eliminated in all but the lowest-price cars; and that the final design of automatic transmission must be torque- and speed-responsive and should have at least four gear ratios or their equivalent.


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