Patent GB-731078-A (GB)
Title: Actuating mechanism
IPC: G05D3/12
Filed: 1952-09-02
Abstract: 731,078. Controlling clutches; friction couplings. GARRETT CORPORATION. Sept. 2, 1952 [Sept. 21, 1951], No. 22051/52. Class 80 (2). [Also in Group XXXVII] A shaft 18 carrying a crank arm 19 for the actuation of a clutch is moved angularly by means of a reversible electric motor 15 through a train of reduction gears 55-61, a crown wheel 63 and a slipping friction coupling 43. A disc 83 on the shaft 18 coacts with locking pawls to position the arm 19 in its two extreme positions and in an intermediate position. Cam surfaces 126, 133 on the input member 65 of the slipping coupling actuate the pawls which in turn actuate micro-switches 85 ... 88 to control the motor 15. It is stated that the mechanism is particularly applicable to the control of a clutch between a gas turbine and a propeller. From one extreme position of the arm 19 corresponding to a disengaged position of the clutch the arm would rotate through an intermediate position in which the clutch is engaged to the other extreme position. Between the intermediate and final positions oil would be supplied to cool and lubricate the clutch whilst slipping. As soon as slipping ceased the op rator would actuate the mechanism to return the arm 19 to its intermediate position leaving the clutch fully engaged and the oil supply cut off. Movement of the arm 19 to its initial extreme position would disengage the drive. The plates of the slipping coupling 43 are loaded by a plurality of " Belleville " springs 75. A member 80 threaded into the coupling housing 65 allows adjustment of the spring loading. A member 76 urged by a spring 77 against the plates centres the springs 75. The actuator is shown diagrammatically in Fig. 12 held in its extreme counter-clockwise position by a dog 111 engaging a notch 115 in the locking disc 83. The motor 15, having field windings 170, 175 for opposite directions of rotation and a brake coil 184, is energized from a battery 160 when push buttons 163 ... 166 are actuated. If the button 165 is pushed the motor will be energized and the coupling 43 will slip until a shoulder 136 at the end of a notch 134 in the cam 133 engages a part 107a of the dog 111 which is thereby pivoted out of the notch. 115, against a spring 140, and the disc 83 together with the shaft 18 moves angularly. A dog 112 is urged into a notch 116 in the disc 83 when the intermediate position of the shaft 18 is reached and the shaft is held stationary. The motor, however, continues to rotate the housing 65 and a shoulder 138 at the end of a notch 137 in the cam 133, engages a part 108a of the dog 112 which is thereby pivoted out of the notch 116 and the shaft 18 continues to move until its extreme clockwise position is reached. At this position a dog 110 engages a notch 114 in the disc 83 which is thereby locked. The pivotal engaging movement of the dog 110 is arranged to operate a micro switch À85 to break the motor circuit. Had the button 165 been pressed the shaft 18 would have remained in its intermediate position since the pivotal movement of the dog 112 would have actuated a micro-switch 88 to break the motor circuit. To actuate the shaft 18 from its extreme clockwise position (Fig. 14, not shown) the buttons 164 or 166 are pressed depending on whether it is desired to halt the shaft at its intermediate or extreme counterclockwise position. The dog 110 will be moved out of the notch 114 by the engagement of a part 105a with a shoulder 131 at the end of a notch 130 in the cam 126. The remainder of the counter-clockwise movement is similar to that described above for clockwise movement. Abutments 120, 121, Fig. 12, on the disc 83 coact with a web 122, Fig. 1, on the gear housing to positively limit the movement of the shaft 18.