GB818821A - Improvements in or relating to mechanisms for producing rotational movement of a mass about an axis with a periodic reversal of the direction of rotation - Google Patents

Abstract

818,821. Reverse gearing; friction clutches. GENERAL ELECTRIC CO. Ltd., and BRIDEN, H. Sept. 26, 1957 [Sept. 27, 1956], No. 29605/56. Class 80 (2). A mass is oscillated back-and-forth in an arc of a circle with the movement of an arm driven through reverse gearing by a continuouslyrotating motor, the gearing containing a double clutch which is first engaged to swing the arm in one direction and is automatically disengaged when the end of the arcuate path is neared, a spring then being put under strain to absorb the kinetic energy of the mass and reverse its direction of travel, automatic re-engagement of the clutch swinging the arm back in the opposite direction. At the other end of the arcuate path, the process is repeated, and continues as long as the motor operates. In the form shown, the mass is a radar reflector mounted at the end of an arm 2. An electric motor drives through gears 7 to rotate two gears 5, 6 continuously in opposite directions. A gear 10, fast on an axially slidable shaft 11, lies between the gears 5, 6 and carries on its opposite faces friction linings 14 engageable with the continuouslydriven gears. The gear 10 meshes a toothed segment 24 fast with the arm 2. The shaft 11 carries a piston 20 in a cylinder 21, to which. oil under pressure is supplied through a control valve 23 to raise or lower the piston and hence engage the friction linings on the gear 10 either with the gear 6 or with the gear 5. A torsionbar spring 27 has its upper end fast with the arm 2, and its lower end secured by a tubular case 28 to an arm 29 which engages at the ends of the oscillating movement of the arm 2 &c. with stops 32, 33 fast on a frame member. Pins 30, 31 pass through the two stops 32, 33 and engage at their inner ends with a lever 34 which rocks between two end positions and is connected by links 36 to the control valve 23. As the arm 2 swings in one direction or the other, the arm 29 traverses with it and approaches one or other of the stops 32, 33. When the radar reflector approaches the end of its travel, the arm 29 first engages one or other of the pins 30, 31, and rocks the lever 34 so that the links 36 move the control valve 23. The piston 20 and shaft 11 are thereby allowed to move to a, posi. tion where the gear 10 is free of both the gears 5, 6. The arm 29 then engages either the stop 32 or the stop 33, and the spring 27 is accordingly twisted. The kinetic energy of the radar reflector and its arm 2 are absorbed by the spring 27, which starts the arm 2 &c. moving back in the opposite direction. During this process, the piston 20 and shaft 11 continue to move, and engage the friction linings 14 on the gear 10 with whichever of the gears 5, 6 was previously not engaged. Drive then takes up and the arm 2 is swung by the motor in the opposite direction.