Pneumatic needle positioner

摘要

A pneumatic needle positioner for positioning a needle of sewing and stitching machines in a predetermined position in the sewing or stitching cycle is provided by utilizing a handwheel sensing device in cooperation with a pneumatically powered positioning motor engageably disposed relative to a drive V-belt which engages the V-belt with a V-belt pulley of the pneumatic needle positioning motor at the end of the sewing cycle, by the actuation of a biasing piston having a roller to tension the V-belt toward the pulley disposed on the pneumatically powered positioning motor. Preferably the biasing piston and roller for the pneumatically powered positioning motor is disposed slightly above or below an axially adjacent position to the air motor pulley to provide a sinesoidal shaped bias against the pnematically powered positioning motor pulley to more effectively cooperate with the positioning device to achieve a more reliable and accurate positioning of the needle. The cooperation and disposition of the pneumatically powered positioning motor in cooperation with the biasing piston device and handwheel positioning device provides a simplified, yet reliable and economical needle positioning apparatus for a variety of sewing and stitching machines which may be utilized in new equipment or readily added to existing machinery to enhance the accuracy or the positioning of the sewing needle in the sewing or stitching cycle.