Abstract: A thread routing mechanism for needle-switchable type sewing machine is installed on a needle bar switching mechanism of the sewing machine, and includes a thread take-up lever, a cylindrical needle bar case and a plurality of threads. The thread take-up lever includes a sway control end and a thread take-up end having thread holes. The cylindrical needle bar case has a rotation axis and a plurality of spaced needle bar holes, and internally defines a hollow space. The needle bar holes are equally distant from the rotation axis, and each receives a needle bar therein. The needle bars respectively carry a needle having an eye formed thereon. The threads are separately routed through a thread course defined by the thread holes, the hollow space and the needle eyes, such that the length of the threads in the thread course maintains same without being affected by a needle bar switching operation.

Abstract: A sewing machine feed mechanism is mounted on a work table of a sewing machine for transporting fabrics to be sewn, and includes a feed belt defining an encircled space; two belt wheels, on which two opposite ends of the feed belt are mounted; a driving source for driving the two belt wheels and the feed belt to rotate synchronously; a plurality of pressing elements located in the encircled space with respective bottom in contact with the feed belt; and an airbag located atop the pressing elements and connected to an external control device to have adjustable internal pressure. With these arrangements, the sewing machine feed mechanism has simplified structure to allow easy mounting/dismounting and reduced manufacturing cost thereof. Further, fabrics placed between the work table and the feed belt can be evenly pressed while being transported into a stitch forming area of the sewing machine for sewing.

Abstract: A sewing machine needle bar changing device includes a needle bar case having multiple needle bar holes, each of which receives a needle bar and has at least one longitudinal slide way formed on one side thereof; a needle bar case holder located at one side of the needle bar case and having a control guide way, which is engaged with the needle bars and has a longitudinal opening; a needle bar guide member engaged with one needle bar that is moved to a sewing position to align with the longitudinal opening, and brought by a crank link of the sewing machine to move upward and downward synchronously with the engaged needle bar; and a driving mechanism for moving and then holding a selected needle bar to the sewing position. All other needle bars not in the sewing position are restricted by the control guide way from moving axially.

Abstract: A thread routing mechanism for needle-switchable type sewing machine is installed on a needle bar switching mechanism of the sewing machine, and includes a thread take-up lever, a cylindrical needle bar case and a plurality of threads. The thread take-up lever includes a sway control end and a thread take-up end having thread holes. The cylindrical needle bar case has a rotation axis and a plurality of spaced needle bar holes, and internally defines a hollow space. The needle bar holes are equally distant from the rotation axis, and each receives a needle bar therein. The needle bars respectively carry a needle having an eye formed thereon. The threads are separately routed through a thread course defined by the thread holes, the hollow space and the needle eyes, such that the length of the threads in the thread course maintains same without being affected by a needle bar switching operation.

Abstract: A sewing machine needle bar changing device includes a needle bar case having multiple needle bar holes, each of which receives a needle bar and has at least one longitudinal slide way formed on one side thereof; a needle bar case holder located at one side of the needle bar case and having a control guide way, which is engaged with the needle bars and has a longitudinal opening; a needle bar guide member engaged with one needle bar that is moved to a sewing position to align with the longitudinal opening, and brought by a crank link of the sewing machine to move upward and downward synchronously with the engaged needle bar; and a driving mechanism for moving and then holding a selected needle bar to the sewing position. All other needle bars not in the sewing position are restricted by the control guide way from moving axially.