Abstract: A bobbin thread holding device for a lockstitch sewing machine adapted to temporarily form an entrapping hole under a throat plate wherein a bobbin thread is captured. A recess provided at the sidewall of the throat plate and a hook with a crooked portion at one end form the entrapping hole. A movable blade, provided underneath the throat plate, moves to cut the bobbin thread. In cooperation with the motion of the movable blade, the hook picks up the bobbin thread and, as the bobbin thread is held in the entrapping hole, the bobbin thread is crossed with a needle thread loop.

Abstract: A thread tightening device for a sewing machine of the type having a main shaft, a vertically reciprocable needle bar with a needle carrying an upper thread, a loop taker and a drive shaft for driving the loop taker and a feed dog; the thread tightening device includes a group of pattern cams operatively connected to the main shaft, pattern selecting device and an arrangement for controlling the vertical movement of the feed dog. This arrangement comprises a control cam and a rotatable shaft, the control cam being slidably axially mounted on the rotatable shaft but not turnable with respect to the shaft. The thread tightening device also includes an element arranged for vertical reciprocating movement in a timed relation with the feed dog, which element engages a lower thread during the stitching operation of the sewing machine.

Abstract: A thread tightening device for a sewing machine of the type having a main shaft, a vertically reciprocable needle bar with a needle carrying an upper thread, a loop taker and a drive shaft for driving the loop taker and a feed dog, the thread tightening device includes a group of pattern cams operatively connected to the main shaft, pattern selecting device and an arrangement for controlling the vertical movement of the feed dog. This arrangement comprises a control cam and a rotatable shaft, the control cam being slidably axially mounted on the rotatable shaft but not turnable with respect to the shaft. The thread tightening device also includes an element arranged for vertical reciprocating movement in a timed relation with the feed dog, which element engages a lower thread during the stitching operation of the sewing machine.

Abstract: This disclosure relates to means for providing adjustment of the needle to hook point relationship in a sewing machine without disturbing the proper mesh and timing of the gears used in the drive mechanism for the hook. The hook includes a shaft supported in a bushing which has a bore having an axis eccentric to the axis of the bushing body. An interposer member is operatively connected to the drive mechanism and is disposed coaxially with the hook shaft for transmitting driving motion to the hook shaft. The hook point is adjustable relative to the needle by means of rotation of the hook bushing about its axis which thereby changes the relative position of the hook and its shaft without causing any change in the relative driving relationship of the interposer and the drive mechanism thereby unaffecting the timing of the hook drive mechanism.