GB1092652A - Improved shaft driving mechanism - Google Patents

Abstract

1,092,652. Mechanical switches. FULLER ELECTRIC Ltd. March 24, 1965 [March 23, 1964], No. 12178/64. Heading H2B. [Also in Division F2] A tap selector for a transformer comprises two selector arms on two shafts 20, 21 each co-operating with a fixed circle of contacts so that whilst one arm remains on one contact the other arm moves to the next adjacent contact. The mechanism for driving the two shafts 20, 21 from a shaft 1 comprises an arm 5 keyed to shaft 1 and carrying two pinions 6, 7 engaging a fixed gear 4, the shafts 8, 9 of pinions 6, 7 carrying arms 10, 11 having rollers 12, 13 in slots 16, 17 in arms 18, 19 keyed to shafts 20, 21 respectively. The pitch circle diameter of gear 4 is five times that of pinions 6, 7 so that as shaft 1 is rotated the axes of rollers 12, 13 trace out a five-looped hypotrochoidal path 23, Fig. 1, not shown, having its centre on the axis of shaft 1. At each loop of path 23 the angular velocity of each roller about the axis of shaft 1 is virtually zero whilst the other roller is traversing part of the path between two loops and so rotating one shaft 20 or 21 whilst the other is virtually stationary. The rollers 12, 13 may be a loose fit in slots 16, 17 to prevent slight oscillation of the shafts at each loop. By changing the ratio of the pitch circles the numbers of loops in the path can be altered but there must be more than three. For even number of loops the rollers are not diametrically opposed. In Fig. 3 (not shown) the pinions 6, 7 engaged an externally toothed, fixed gear and the path may have 1-3 loops. The number of loops in the paths may be altered by providing a step-up or step-down gear between shafts 8, 9 and arms 10, 11. In Figs. 4, 5 (not shown) a square plate is eccentrically mounted on shaft 1 and has rollers at each corner running in a fixed hypotrochoidal aperture, the two rollers 12, 13 are mounted at diagonally opposite corners of the plate to drive shafts 20, 21 as before.