Patent GB-881601-A (GB)
Title: Mechanical remote control systems
IPC: B64C13/00
Filed: 1959-12-30
Abstract: 881,601. Controlling aircraft. CURTISSWRIGHT CORPORATION. Dec. 30, 1959 [Jan. 22, 1959], No. 44308/59. Class 4. [Also in Groups XXIV, XXV and XXXIV] An aircraft movable surface control system comprises a torque shaft rotatable in either direction, and sufficiently flexible to accommodate bending of the structure from which it is supported by bearings, and a hinge, one element of which is secured to the structure, and the other element to the control surface, the hinge including a rotary speed reducing means driven from the torque shaft to cause relative rotation of the hinge elements. In Fig. 1, a prime mover 14, which may be the primary power plant of the aircraft, or a secondary power unit, or an electric, hydraulic, or pneumatic motor, is connected by shaft sections 16 and angle drive units 18, to the inputs of servo devices 22, 30, 40, 42, and 54, whose outputs are connected to the elevators 24, rudder 38, ailerons 44, 46, and wing flaps 56, respectively. The control devices 26, 32, 48, 50, and 58 of the servos are operable from the control column 28, rudder pedals 34, and flaps control 60, in conventional fashion. Each servo is such (see Groups XXIV and XXXIV) that when its control is in a neutral position, itsoutput shaft is locked against rotation. Displacement of the control in either sense from the neutral position by a mechanical demand signal causes rotation of the output shaft in a corresponding sense at a predetermined speed until the angular rotation of the output shaft recentres the control by a feedback mechanism, Fig. 4 (not shown). The power output of each servo is passed through an overload release clutch 62 (see Group XXIV) and through further shaft sections 16 and angle drive units 18 to the control surface. Each shaft section 16, Fig. 10, comprises a shaft 170 supported by bearings 176 in housings 172, 174 joined by a cover 182. the shaft has a part spherical head with splines 178 at one end, and an internally splined cylindrical coupling 180 at the other end. Each housing 174 is externally screw threaded, and each housing 176 has a part spherical boss 186 on which an internally screw threaded nut 184 is universally mounted. Successive sections 16 can be screwed together to form a flexible drive shaft, and similar provision for universal angular movement is made where a section is secured to a unit, such as units 18. The hinge mounting of an aileron is shown partly in Fig. 6, and comprises a spanwise distributed plurality of units 20, each composed of end members 216 secured to the wing, and having internal teeth 222, and a central member 218 supported from members 216 by bearings 220, being secured to the aileron and having internal teeth 224 of a pitch slightly different from teeth 222. The drive shaft 226 of the unit is interposed between two shaft sections 16, and affords eccentric journals 228, 230 on which are mounted two pinions 232 each having teeth 234 meshing with the teeth on an end member 216, and teeth 236 meshing with teeth 224. By this means a large speed reduction is effected between shaft 226 and the aileron, the gearing being irreversible.