When shaft 21 rotates continuously about fixed axis A-A, worm wheels 1 and 2 rotate intermittently and alternately, one revolution at a time, about fixed axes B and C. Bevel gear 24 is keyed to shaft 21 and meshes with two bevel phinions 4 and 4' which rotate freely on shaft 23 about fixed axis D-D. Clutc member 3 slides alonhg a feather on shaft 23 and can be engaged to either pinion 4 or 4' (it is shown in the neutral position). When clutch member 3 is in engagement with pinion 4 (with a step on latch 5 engaging collar 25 on shifter slide 18 to lock clutch member 3 in its left-hand engaged position), rotation is transmitted through a free-wheeling friction clutch (consisting of inner member 7, keyed to shaft 23, and an outer member integral with gear 8), gear 9 an worm 10 to worm wheel 1. Worm wheel 2 has a dwell during this engagement because the right-hand free wheeling clutch disengages for this direction of rotation of shaft 23 so that outer member, gear 12, runs freely over inner member 11. As worm wheel 1 rotates clockwise, pin a runs against swinging arm 15, which turns freely on worm wheel shaft 22, causing the arm to contact the roller on shifter lever 16 and push the lever to the right, compressing spring 17. As shifter lever 16 continues to travel to the right its cam surface lifts latch 5, releasing spring 17 and shifter slide 18 which forces clutch member 3 to the right, into engagement with bevel pinion 4'. At this, latch 19 locks clutch member 3 in its right-hand position. Then worm wheel 1 stops, and worm wheel 2 is driven counterclockwise through inner clutch member 11, gears 12 and 13, and worm 14. Worm wheel 1 dwells, and wheel 2 rotates, until pin b turns swinging arm 20 so that it engages the second roller of shifter lever 16, first compressing spring 6 and then lifting latch 19 so that clutch member 3 is shifted into engagement again with gear 4.
$2940$CxG,ML$