Speed and direction changing gears

An obvious model for display demonstration purposes, but a real world application could possibly be incorporated in a sewing operation with the small gear connected to a shaft with cams on the shafts to control the pressure foot and needle, the small gear might be used to advance the material while reversing the advance to allow for a backstitch every few cycles. Gears such as these might also have been found in antique ag equipment such as planting or the sack sewing operation of a peanut thrasher , even some old hay balers had a similar arrangement incorporated in the wire tying procedure

Speed and direction changing gears - GIF