GB862641A - Improvements relating to limit stop mechanism - Google Patents

Abstract

862,641. Locking rotary elements. PERKINELMER CORPORATION. March 26, 1959 [March 31, 1958], No. 10630/59. Class 80 (4). Rotation of a shaft 11 relatively to a coaxial body 10 is positively stopped after a predetermined number of revolutions by the engagement of a pin 19, axially projecting from a flanged eccentric 14 fixed on the shaft 11, with an arm 16 of a lever 15 pivoted on the body 10, the lever 15 being moved, against a spring 21, from its normal position (Fig. 1) to the stopping position (Fig. 7) by the engagement between an arm 18 thereon and a pin 20 projecting from a disc 13 which is carried by the eccentric 14 so that it is rolled around the inside of a ring 12 in the body 10. The interengaging surfaces of the ring 12 and disc 13 may or may not be toothed, there being, for example, one tooth difference so that as the shaft 11 rotates, say, clockwise, and the eccentric 14 causes the pin 20 to oscillate substantially radially, the disc 13 is slowly rotated anticlockwise from the Fig. 1 position until the oscillating pin 20, which passes over the arm 16, is in a position to engage the upturned tip of the arm 18 and so move the arm 16 into its stopping position. The pin 20 may subsequently be moved to free the lever 15 by turning the shaft 11 anticlockwise, and the shaft may then be rotated anticlockwise for a number of turns determined by the epicyclic gear ratio between the shaft 11 and disc 13, until the pin 20 is again in position to move the lever 15 and stop the shaft. The disc 13 may be provided with a second pin which is angularly displaced from the pin 20 and also co-operates with the arm 18, the number of turns of the shaft 11 allowed between its stopping positions then being determined by the angular distance between the two pins on disc 13. In a modification, the two pins are replaced by a single bar extending chordwise. In a further modification, Fig. 9 (not shown), the ring 12 is mounted for limited rotation between stops in the body 10, whereby when the pin 20 first strikes the arm 18, the spring 21 is strong enough to prevent movement of the lever. It is stated that the ring 12 is then rotated by a small amount, such as one tooth pitch, until the pin 20 moves inwardly again. The shraft 11 may thus make further revolutions until the ring 12 reaches the limit of its permitted angular movement, whereupon the spring 21 yields and the arm 16 is moved as previously into the path of the pin 19 to stop the shaft 11. Specification 765,124 is referred to.