Pfaff Industriemaschinen Gmbh

Albert Dusch

Karl-Heinz Walther

Erich Willenbacher

Kurt Vollmar

Karl-Heinz Walter

Lower feed dog lifting, lowering, and horizontal coupling

Thread cutting device on a sewing machine

Sewing machine with a lamp

A lockstitch sewing machine includes a rotary hook. For the rotation secure retention of the bobbin housing of the hook, two cams are arranged in the central region of the loop cast-off side, which receive a spring rod between them. A shoulder formed at the bobbin housing is associated with the cam or with the spring rod. Through the special position of the cams, the movement resistances during the guiding of the needle thread loop around the bobbin housing is reduced to a minimum.

Lockswitch sewing machine having a rotary hook

A drive device for positioning a sewing machine main shaft and driven by a positioning motor into a needle-up position when it is stopped for example, after the thread is cut comprises a removable drive lever member which has a tappet portion which engages wtih the shoulder of a cam which is mounted on the main shaft for rotation therewith. The drive lever is driven by a device such as a fluid pressure operated piston cylinder combination and when it moves the tappet engages the cam face and rotates the cam with the main shaft to a second position which is predetermined. The mechanism also includes a stop which is effected between a face of the cam and a lever member which is shifted by the drive lever to stop the backward movement of the cam with the main shaft at a precise second position.

Positioning device for sewing machine main shaft

A lockstitch sewing machine includes a rotary hook, with a bobbin housing and a cam is provided for the rotation-secure retention of the bobbin housing and it is arranged a small distance behind the stitch hole in the direction of hook rotation. A holding finger for holding the bobbin housing against rotation with the hook body projects from the bobbin housing, as well as a supporting finger arranged substantially 90.degree. before the stitch hole. A shoulder projecting from the bobbin housing is associated with the supporting finger.

Lockstitch sewing machine with a rotary hook

A thread cutting device for a lockstitch sewing machine having a rotary hook rotating in a horizontal plane, comprises a thread catcher which is pivotable in a horizontal plane and designed with a catch shoulder for needle and bobbin threads. The catcher cooperates with a stationary cutting tool as well as with a leaf spring which serves as a clamp for the end portion of the bobbin thread. The thread catcher is designed with a retaining shoulder by which the needle thread loop, upon being passed around the bobbin case, is caught and then released before being cut. The temporarily retained thread length substantially corresponds to the thread length which is pulled out sidewards while the thread catcher moves into its cutting position. Since no needle thread is thereby pulled off the thread supply by the thread catcher, only a minimum force is needed for moving the catcher.

Thread cutting device in lockstitch sewing machines

A drive mechanism for connecting a drive shaft of a sewing machine to a plurality of reciprocatable needle bars which are advantageously mounted in a single guide frame for reciprocation in the machine includes a link connection for each bar. The link connection includes an oscillatable two armed lever for each bar. It has an input arm driven by a shaft mounted in the machine for oscillation about a fixed axis and an output arm connected to a first link of a cooperative pivotally interconnected first and second link pair. An actuator shaft for each bar carries a respective actuator crank which in turn is connected through a link of relatively short length to the upper ends of the needle bars by a pivotal connection. The guide link is connected to the cooperative link pairs at their pivotal interconnection to each other and it may be moved by a setting mechanism which is either hydraulically or electrically actuated and is effective to change the reciprocation of each needle bar separately or together and without disconnecting the operating mechanism driving the needle bars.

Needle bar detachable drive and stroke adjusting mechanism

A material presser device on a sewing machine, includes a presser foot which is attached to a vertically movable presser bar and to which lift movements are imparted by a swing mechanism driven by the main shaft acting through a knee-joint transmission which, in its extended position, extends substantially in the movement direction of the presser bar. For positive connection of the presser foot with the swing mechanism, the presser bar is articulated via an intermediate pitman to one end of the connecting rod of a four-joint transmission. The other end of the four-joint transmission is connected by a connecting rod with an abutment which applies under the action of a spring, against a counter abutment secured to the housing. The connecting rod is connected to the knee joint transmission, the knee joint of which is connected to the sewing machine.

Material presser device for a sewing machine

A sewing machine comprises a rotatable main shaft which drives a needle upwardly and downwardly over a sewing station to sew through material which is moved thereover and which includes a trimming knife mounted adjacent the needle for upward and downward movement for selectively and periodically cutting the material. The trimming knife is driven by a linkage mechanism from an eccentric drive and the eccentric drive is detachably connected between the main shaft and the linkage mechanism and permits the knife to be driven with the mainshaft of the sewing machine or by an independent drive through a separate detachable drive mechanism. In one embodiment a positioning motor is connected to the drive through a hand wheel and an engageable and disengageable clutch so that it may drive a linkage mechanism including an eccentric to move the knife upwardly and downwardly for cutting the material being sewn during the operation of the sewing machine or separately when the sewing machine drive is discontinued. The drive is defined from the positioning motor to the hand wheel and through a clutch to the main shaft of the sewing machine which drives an eccentric for operating the linkage mechanism to reciprocate the knife. Another embodiment includes a separate trimming drive including two free wheel clutch arrangements permitting the knife to be driven synchronously with the sewing machine needle drive as well as its separate drive.

Detachable drive for sewing machine trimming knife

A transport device for a sewing machine having a housing, a feeder foot and a fabric presser foot, a drive mechanism for driving the feeder foot and the presser foot, a transmission operatively interconnecting the presser foot and the feeder foot to the drive mechanism for alternately reciprocating the feeder foot and the presser foot relative to each other in up and down motions directed perpendicular to a stitch plate of the sewing machine, comprises linkages which cause the feeder foot and the presser foot, during their up and down motion, to move at a speed approaching zero during a touchdown phase of the motion. The transmission includes an eccentric connected to the drive mechanism which oscillates at a selected frequency. A triangular lever is connected to the feeder foot and the presser foot. A coupling member is connected to the eccentric and to the linkages with a link of the linkages pivotally mounted to the sewing machine housing and interconnecting the coupling member with the triangular lever. The transmission also includes a steering arm mechanism for providing a variable transmission ratio between the eccentric and the coupling member. A further linkage transmission connected to the drive mechanism varies the transmission ratio of the steering mechanism, the linkage transmission operating at twice the frequency of the steering mechanism.

Growing community of inventors

Kaiserslautern, Germany

Albert Dusch