Abstract: A thread monitoring device for monitoring the thread supply in a sewing machine, having a rotary hook, comprises, a hook body with a thread bobbin having thread thereon which is connected to a rotatable shaft for rotation thereby. The hook includes a stationary bobbin case which is enclosed by a hook body which has a hub portion connected to the shaft. A light source is disposed on one side of the hook and a light receiver is disposed on the opposite side. Light is transmitted by the light source through a path intercepting the thread on the bobbin so that, when the thread on the bobbin is paid out during the stitching operation, beyond a predetermined amount, the light will be transmitted to a reflective wall portion of the hook body and deflected by the wall portion to the light receiver. The light receiver is connected in a control circuit to operate a control for operating the sewing machine or for actuating an indicator to show that the thread has been used up to the predetermined amount.

Abstract: A sewing machine includes a baseplate with a pedestal thereon having an upstanding column on the pedestal supporting an upper arm carrying the drive for a reciprocating sewing needle. A fabric-supporting arm extends outwardly from the pedestal and overlies one side of the baseplate below the upper arm and carries the thread-engagement mechanism, for example. The baseplate advantageously carries a bearing bushing for pivotally supporting an add-on table so that a pivot belt of the table may be pivoted about a vertical axis which is in substantial alignment with the rear wall of the supporting arm. The add-on table includes a first portion which extends at right angles to a second portion thereof and when the first portion is pivoted alongside the front end of the fabric-supporting arm, the second portion will be disposed along a side face of the supporting arm.

Abstract: A sewing machine has a housing with a needle supported therein for reciprocation upon rotation of a main shaft to move the needle into and out of engagement with a workpiece which is fed by a feed mechanism which is driven from the main shaft. The feed means is such that the material is moved in a plurality of steps while the needle is out of engagement with the workpiece. The feed includes a workpiece support arm which has one end which is pivoted on a slide drive for effecting back and forward movement of the workpiece support arm which includes a feed dog engagement part which engages the workpiece to advance it. An eccentric portion driven from the main shaft provides for the upward and downward movement of the support arm.

Abstract: The sewing machine includes respective setting members for adjusting the overstitch width and the stitch length, with the setting members being adjusted by an actuating mechanism responsive to control signals of a program control system, the control signals corresponding to the stitches to be made. The power for driving the actuating mechanism is derived from the continuously operating main shaft of the sewing machine, through a clutch or clutches whose moment to be transmitted is controllable, such as electromagnetic clutches. In one embodiment of the invention, a single electromagnetic clutch is provided for each setting member and includes a first clutch disk connected to the respective setting member to rotate therewith and a second clutch disk secured to a shaft continuously rotated by the main shaft of the machine. A spiral spring is provided to act to rotate the respective setting member in a direction opposite to the direction of rotation thereof by the associated clutch.