GB568603A - Improvements in or relating to control devices for constant speed units of aircraft - Google Patents

Abstract

568,603. Linkwork. TAMPIER, R. J. C. May 6, 1943, Nos. 7165/43 and 10641/44. [Class 80 (iii)] [Also in Group XXIX] In a constant speed unit controlling a variable-pitch propeller on an aircraft, which is associated with a device for feathering the propeller, the spindle 3. Fig. 4, of the constant speed unit carries a composite arm 1 which is actuated from the pilot's control lever 19 to rotate through an angle showing a mechanical advantage over the movement from 19a to 19b of lever 19 during the feathering operation. The arm 1 has a cylindrical upper end housing a spring which presses the foot of an L-shaped lever 9 against a stop. The lever 9 is pivoted at 10 on the arm 1 and is formed with a cut. away portion constituting an abutment surface 18 for a stop 17 carried by the connecting rod 15. When lever 19 is moved from 19c to 19a, arm 1 moves'as a whole and turns the spindle 3 through a comparable angle ; this movement controlling the speed of the engine. At point 19a, stop 17 contacts surface 18 and, during the further movement of lever 19 to point 19b, corresponding to the feathering operation, lever 9 will be held stationary relative to rod 15, but will pivot on arm 1 so that the latter is swung through an angle larger than that covered by lever 19. In a modification. Fig. 9, arm 1 is replaced by a lever 22 with a forked upper end in which is pivoted a further lever 23 connected to rod 15. The upper end of lever 23 carries a roller 25 which runs against a cam surface 26 bolted to the casing of the constant speed unit. During the first movement of the operating lever 19, levers 22, 23 move together, but the end part 20 of the cam surface causes them to move relatively to each other during the " feathering " movement of lever 19 to give the greater angular movement of spindle 3.