Abstract: An overlock sewing machine having a dial and a conversion means for converting the rotary motion of the dial into a linear motion which are associated with a cutter blade holder such that the adjustment of the distance between a stationary claw and a movable claw adjusts the looping width in correspondence with the linear movement of the cutter blade holder perpendicular to the direction of feed of the cloth caused by rotation of the dial. The movable claw, carried by a movable member, can move between an operative position in which the movable claw is positioned next to the side of the stationary claw and an inoperative position spaced away from the side of the stationary claw. The position at which the cutter blade holder is supported on the machine body is offset from the position at which the upper and lower cutting blades make contact.

Abstract: The tip end of the upper looper of an edge stitching sewing machine is adapted to have a different profile by engagement with a pawled looper arm provided on the upper looper itself or on a mounting post of the upper looper. When the pawled looper arm is engaged with the upper looper, the sewing machine performs one-needle two-thread edge stitching, while it performs its original one-needle three-thread edge stitching when the pawled looper arm is detached from the upper looper in a disengaged position.

Abstract: A transmission mechanism in a driving means for the needle of sewing machines. A needle holder having a needle secured thereto and fitted on a needle guide rod so that it is vertically oscillated thereon is joined to an oscillatory arm oscillatable along the needle guide rod by slidably fitting a front end portion of the latter in a passage provided in an end portion of a horizontal shaft which is fitted in the needle holder so as to be rotated therein to some extent. The passage in the end portion of the horizontal shaft is made at right angles thereto. The horizntal shaft has a vertical passage the diameter of which is large enough to prevent the needle guide rod passed therethrough from being slided on the inner surface thereof. The needle holder has a sufficiently large slide surface with respect to the needle guide rod.

Abstract: A knife operating device for sewing machines includes a needle stub pivotally mounted to the front part of a rocking arm. The rocking arm intersects with a needle stub guiding bar and is pivotally mounted and its rear end. A knife holder is, also, connected to the rocking arm and is guided so as to be movable with the needle stub.

Abstract: A cloth feeding device for a sewing machine and a method of adjusting the differential ratio of feeding cloth, in any desired wide range, particularly, in an overlock sewing machine. There is disclosed herein a mechanism wherein a cloth feeding arm is engaged with a vertically feeding cam fixed to a main shaft and is further connected with an eccentric horizontally feeding cam. The feeding cam comprises a flanged cam member frictionally fixed to the main shaft and an internal surface cam externally fitting it through a link mechanism. The link mechanism comprises a horizontally feeding rocker arm and a horizontally feeding rod so that the horizontal feed of the cloth feeding arm may be simply and freely adjusted by varying the phase of the eccentric double cam with an operating piece which can be operated from outside the sewing machine frame.

Abstract: The upper looper of a sewing machine is held and guided in its intermediate part by a looper guide movable therewith in the lengthwise direction. The guide rotates around a shaft upon which a rotary carriage is journalled, and is movable in a direction intersecting with the looper guiding direction, with respect to the carriage. The looper is carried on its other end by a reciprocally rotatable rocking arm. The other end of the rocking arm is connected to a driving rod which is driven by a driving shaft.