When handle H is turned clockwise, gear 3 is brought into engagement with gear 1 so that rotation is transmitted from gear 1 to gear 4 through gear 3. When handle H is turned counterclockwise, gear 2 is brought into engagement with gear 1 so that rotation is transmitted through gears 2 and 3. Thus, with gear 1 rotating continuously in one direction, gear 4 can be reversed.
$2937$CxG,ML$