TOP FEED MEANS FOR SEWING MACHINES
United States Patent 3583344
Top feed device for sewing machines having a top feed transport rocking means in the form of a double lever connected with one each connecting bar with a forward feed and a raising drive means and a spring loaded material presser foot operatively connected with the top feed rocking lever, characterized in that one arm (35) of the top feed lever (32) is coupled with two generally parallel disposed link bars (33, 36) of essentially equal length, one of which (33) is pivoted on the housing (1) of the machine while the other (36) is in operative connection with the feeding drive by way of a crank arm (37) extending essentially parallel to the arm (35).
US Patent References:
Locomotive stoker
Zeier - July 1942 - 2241129
Feeding mechanism for sewing machines
Clayton - May 1949 - 2470759
Locomotive stoker
Zeier - July 1942 - 2241129
Feeding mechanism for sewing machines
Clayton - May 1949 - 2470759
Inventors:
Meier, Gunter (Weingarten, DT)
Wenz, Herbert (Kaiserslautern, DT)
Windschugl, Wilhelm (Kaiserslautern, DT)
Wenz, Herbert (Kaiserslautern, DT)
Windschugl, Wilhelm (Kaiserslautern, DT)
Application Number:
05/051592
Publication Date:
06/08/1971
Filing Date:
07/01/1970
View Patent Images:
Export Citation:
Assignee:
G.M. Pfaff AG (Konigstrasse, Kaisesslautern Pfalz, DT)
Primary Class:
International Classes:
D05B27/04; D05B27/00; D05B27/04
Field of Search:
112/212,207
Primary Examiner:
Scanlan Jr., Richard J.
Claims:
We claim
1. In a sewing machine having a housing presenting a head and having a drive shaft, top feed means comprising a rocking shaft extending through said housing to said head, a crank arm connected to said rocking shaft in said machine head, an eccentric bar connected at one end to said drive shaft and a rocking yoke supported in said housing connected to the other end of said eccentric bar, a spring-biased presser foot bar, a top feed foot, a double-armed top feed lever, supporting with one arm at its lower end said top feed foot, means operative for guiding the movements of said top feed lever and linking said top feed lever to said presser foot bar comprising, a pair of parallel link members, one extending between and connecting said top feed lever and said housing and defining a pivot joint with said top feed lever, and the other extending between and connecting the upper end of said top feed lever and said crank arm, and an articulated toggle joint including a pivot pin connecting two link bars, one connected intermediate said pivot joint and said rocking yoke by way of a link member and the other extending intermediate and connecting the upper end of said presser bar and said pivot pin.
2. Top feed means in accordance with claim 1, where said two link bars defining said articulated toggle joint extend generally vertically.
3. Top feed means in accordance with claim 2, where said presser foot is connected to said presser bar by rotation preventing means including a sliding guide device in the form of a slot and a screw.
1. In a sewing machine having a housing presenting a head and having a drive shaft, top feed means comprising a rocking shaft extending through said housing to said head, a crank arm connected to said rocking shaft in said machine head, an eccentric bar connected at one end to said drive shaft and a rocking yoke supported in said housing connected to the other end of said eccentric bar, a spring-biased presser foot bar, a top feed foot, a double-armed top feed lever, supporting with one arm at its lower end said top feed foot, means operative for guiding the movements of said top feed lever and linking said top feed lever to said presser foot bar comprising, a pair of parallel link members, one extending between and connecting said top feed lever and said housing and defining a pivot joint with said top feed lever, and the other extending between and connecting the upper end of said top feed lever and said crank arm, and an articulated toggle joint including a pivot pin connecting two link bars, one connected intermediate said pivot joint and said rocking yoke by way of a link member and the other extending intermediate and connecting the upper end of said presser bar and said pivot pin.
2. Top feed means in accordance with claim 1, where said two link bars defining said articulated toggle joint extend generally vertically.
3. Top feed means in accordance with claim 2, where said presser foot is connected to said presser bar by rotation preventing means including a sliding guide device in the form of a slot and a screw.
Description:
BACKGROUND OF THE INVENTION
The present invention concerns material feed means for sewing machines. More in particular, the invention relates to a top feed mechanism for sewing machines having a feed arm formed as a double lever which is linked to an advancing and to a lifting drive, and with a spring-loaded material presser foot which is connected with the top feed arm.
If it is necessary to equip industrial sewing machines with a top feed mechanism, the accommodating of the transmission gear and the journaling of the top feed arm present no special problem, because with an industrially used machine little discomfort results if one part of the bearing or of the transmission elements is located outside the actual machine housing.
In contrast to this, problems arise with the accommodation of the top feed mechanism in household machines, because in order to retain the appealing shape of the housing of the sewing machine it is necessary to accommodate all driving elements for the top feed, especially those members of the top feed that have to be mounted in the machine head, within a space of narrow confines. The design of these elements and their mutual position coordination must be such that only the top feed member which extends toward the stitch-forming location projects from the housing. In addition only as few parts as possible of the machine that move during operation should be in the range of vision of the seamstress.
It is therefore an object of the invention to provide a relatively simple arrangement of the top feed means and as to space the advantageous journaling of the top feed rocking arm in the machine head.
SUMMARY OF THE INVENTION
In accordance with the invention the objects are achieved in that one of the arms of the top feed rocker is coupled to two parallel guide links of essentially equal length, one of which is pivotally supported on the housing of the machine, while the other is operatively connected to the feed drive by a crank arm that extends essentially parallel to the one arm.
An advantageous and space-saving arrangement for coupling the top feed means with the lifting drive and with the material presser bar and its lifting mechanism is obtained in that the top feed rocking arm is connected with the material presser bar by way of a substantially vertically disposed articulated joint whose joint pin is engaged by a link arm which is connected with the lifting or raising drive.
In order to avoid raising of the material presser foot as the material is advanced by the top feed foot, the presser foot is connected with the material presser bar by way of a slide feed guide of limited movement that is protected against rotation. By these means the seamstress is not irritated by vibrating of the presser foot, and it rests during advancing of the material merely under the pressure of the material pressing spring.
An embodiment of the invention which is described hereinafter is illustrated in the drawing in which,
FIG. 1 is a partial view of the sewing machine with the top feed device, partly in section, in which the components located in front of the top transport arm are omitted;
FIG. 2 is a section taken through the head of the machine with the stitch forming tools in operative position, and
FIG. 3 is a section similar to FIG. 2 with the top feed and the presser foot devices in raised position, where the components located below the stitch plate have been omitted.
As shown in FIG. 2 the needle bar 2 with the needle 3 is mounted in housing 1. It is driven in a known manner, not illustrated, by the arm shaft 4.
An eccentric 5 is secured to the arm shaft 4 which is encompassed by an eccentric bar 6 that is linked to an arm 7 of a U-shaped rocking yoke 8. The rocking yoke 8 is journaled on an axle 9 that is fixed to the housing and it has a second arm 11 that is connected with a connecting link 10. The link 10 engages a pin 12 of a toggle joint which is a part of a toggle joint connection that comprises the toggle joint pin 12 and two link bars 13 and 14. The link bar 13 is joined to a clamping member 15 that is secured to a presser bar 16 that is guided in the housing 1 of the machine.
The lower part of the presser bar 16 is provided with a bore 17 in which a shaft 18 of a support 19 is slidingly mounted. A screw 21 fastened in the shaft 18 and extending through slots 20 in the presser bar 16 provides for limited vertical sliding movement of the support 19 in the bore 17. A spring 22 disposed in the bore 17 is biased at one end against shaft 18. The material presser foot 24 is mounted on the support 19 by means of a screw 23.
A further spring 26 having greater effective strength than spring 22 is provided in a bore 25 in the upper part of the presser foot bar 16 and rests at one end against a pin 27. The pin 27 engages a see-saw or rocker 28 that is journaled on the housing, and which in turn rests against an eccentrically formed head 29 of an abutment screw 30 that is threadedly secured in the housing 1. In this manner the material presser bar 16 is pressed downwardly until the presser foot 24 rests on the material being sewn.
The link bar 14 engages one end of a joint stud 31 that is secured in a double armed top feed rocking lever 32. The other end of the joint stud 31 is in engagement with a link 33 which is supported by a bolt 34 secured in housing 1. The arm 35 of the top feed rocking lever 32 is connected by way of a link 36 with a crank arm 37, which is secured to a rocking shaft 38 journaled in housing 1. The crank arm 37 extends essentially along a projection of the connecting line between the axes of the bolt 34 and the rocking shaft 38.
The other arm 40 of the top feed rocking lever 32 which projects downwardly through a slot 39 in housing 1 has a wedge-shaped free end 41 that is slidably received in a corresponding wedge-shaped recess 42 in the top feed foot 43 in order to retain the same in its position. The top feed foot 43 has a toothed member 44 which together with a sole 45 that is pivotally connected to the presser foot 24 engages the material being sewn from the top. For this purpose the sole 45 is provided with a slot 46 through which the toothed member 44 can reach.
A further recess 47 is provided above the toothed member 44 in which the end 41 of the top feed rocking lever 32 is slidably received. For this purpose the top feed foot 43 is provided with upwardly extending arms 48 which slidingly engage the arm 40 of the rocking lever 32 on both sides and which are provided with guide slots 49 into which extends a stud 50 that is secured in the top feed rocking lever 32 below the joint stud 31.
A spring 51 hooked at one of its ends to the top feed foot 43 and at its other end to the top feed rocking lever 32 pulls the top feed foot 43 upwardly in order to insure of engagement between the recess 42, respectively 47 and the end 41.
The lower feed dog 54 which is mounted on a carrier 55 cooperates with the top feed foot 43 and the presser foot 24 through slots 52 in the stitch plate 53.
The carrier 55 is connected at one end with the arm 56 of a rocking arm 57. Its other end is provided with a guide slot 58 in which a sliding stud 60 is guided which is carried by crank arm 59. The crank arm 59 is secured to a shaft 61 to which rocking movements are imparted by a lifting eccentric, in a manner not illustrated, as the machine is driven.
The rocking arm 57 journaled on an axle 62 in housing 1 has a further arm 63 that is connected by way of a link bar 64 with a crank arm 65 mounted on rocking shaft 38.
A belt chain 66 driven by arm shaft 4 (FIG. 1) drives the lower shaft 67 to which the looper of the machine which is not shown is connected. In addition shaft 67 drives an intermediate shaft 70 to which an eccentric 71 (FIG. 2) is secured by way of gears 68 and 69. The eccentric 71 is encompassed by the ring of an eccentric bar 72 that carries a bolt 73. Two link bars 74 and 75 are journaled on bolt 73, one of which bars 74 is pivotally connected by means of a stud 76 with a third arm 77 of the rocking lever 57. The other link bar 75 is pivotally connected by way of a stud 78 with an angular lever 80 that is journaled on a stationary pivot pin 79.
A rod 81 is in engagement with one free arm of the angular lever 80 (see also FIG. 1), which rod is linked to a further angular lever 82. The free end of angular lever 82 extends into a groove of a turning handle 83 mounted in housing 1, which limits its movability and which extends partly through a slot 84 in housing 1 for setting by the operator.
The spring 85 whose one end is hooked onto housing 1 and whose other end is hooked onto angular lever 80 pulls the lever mechanism described into the end position defined by the groove of the turning handle 83.
A clamp 86 is mounted on the presser bar 16 which has a rearwardly extending arm 87. Below this arm 87 a cam member 88 is located which is mounted on a stud 89 that extends through housing 1 and supports a hand lever 90 at its outer end.
The mechanism operates as follows:
As the machine is driven the arm shaft 4 drives intermediate shaft 70 by way of belt chain 66, shaft 67 and gears 68 and 69. As a result the eccentric 71 mounted on shaft 70 rocks bolt 73 about stud 78 by way of eccentric bar 72. The link bar 75 executes a true rotary movement about stud 78. On the other hand, depending on the position of stud 78 which is adjustable by means of turning grip 83 by way of double lever 82, bar 81 and angular lever 80, effects besides this rotary movement, a more or less large relative movement about pivot axis 62. This relative movement is transmitted to feed dog 54 by way of rocking arm 57.
The lifting eccentric which is not illustrated simultaneously causes a raising and lowering movement of the feed dog 54, this by means of swinging or rocking of shaft 61 whose crank arm 59 guides these rocking movements by way of sliding pin or stud 60 onto support 55.
Simultaneously with driving the feed dog 54 the rocking lever 57 imparts to rocking shaft 38 rocking movements by way of its arm 63, link rod or bar 64 and crank arm 65 which are transmitted to top feed lever 32 by way of crank arm 37 and link bar 36.
The top feed rocking lever 32 is thereby rocked about the pivot pin 31 so that the top feed foot 43 carries out the advancing movements. In view of the connection of the lower feed dog 54 as well as also the upper feed foot 43 with the rocking arm 57 their feeding paths are of equal length owing to suitable transmission relationships.
The lifting movement of the top feed foot 43 is effected by the eccentric 5 by way of the eccentric bar 6 onto rocking yoke 8. Due to its rocking the lever 10 that engages the toggle lever pin 12 alternately folds and stretches the two links 13 and 14.
Owing to the pressure of spring 26 the material presser bar 16 is pushed downwardly and presses with the upper end of the slot 20 onto the screw 21 and thus the presser foot 43 with its sole 45 onto the material being sewn.
If the two link bars 13 and 14 unbuckle the clamp member 15 secured to the material feed bar 16 constitutes a fixed point for the connection of the toggle lever whereby the joint pin 31 is raised together with the top feed bar 32 and the top feed foot 43. The top feed bar 32 thereby executes essentially a parallel displacement with respect to a straight line through the pivot points of the two links 33 and 36. Simultaneously with the raising of the top feed foot 43 from the material, a horizontal movement takes place in the manner described above by the rocking shaft 38.
The top feed foot 43 in its foremost position is lowered upon the material being sewn in that the link 10 effects a stretching movement of the toggle lever connection. Thus the top feed foot 43 supports itself by way of the material upon the stitch blade 53 or the lower feed dog 54 after a certain amount of stretching of the two link bars 13 and 14, so that now the pivot pin 31 constitutes the fixed point for the toggle joint connection.
The further stretching of the two bars 13 and 14 results in raising of the clamping member 15 against the pressure of spring 26 whose force is transferred by way of the link bars 13 and 14 and the top feed bar 32 onto the top feed foot 43. The clamping element 15 carries along the material presser bar 16 upwardly to a corresponding extent. Due to the slot 20 in the presser bar 16 the sole 45 of the material presser foot 24 remains under the influence of the spring 22 with light pressure on the material.
Simultaneously a displacement of the material takes place as a result of the rocking of the top feed lever 32 about the joint pin 31.
The raising of the presser foot 24 and of the top feed foot 43 for inserting or removing the material being sewn is effected by turning the manual lever 90. In this connection the cam member 88 presses the clamp 86 together with the presser foot bar 16 upwardly by way of arm 87. The clamping member 15 takes along the bars 13 and 14, the joint pin 31 and thereby the top feed foot 43 to which is connected the top feed bar 32, while this in turn performs a parallel displacement about the pivot points of the links 33 and 36. In this connection merely the material presser foot 24 lowers itself somewhat until engagement takes place of the screw 21 at the lower limit of the slot 20.
To disconnect the top feed foot 43 it is raised and swung rearwardly while the material presser device is manually raised against the effect of spring 51 from the end 41 of the top feed bar 32. At the same time the guide slots 49 are displaced with respect to the pin 50 and the end 41 resiliently engages the recess 47.
Having now described the invention with reference to the embodiment illustrated in the drawing, what we desire to protect by letters patent is set forth in the appended claims.
The present invention concerns material feed means for sewing machines. More in particular, the invention relates to a top feed mechanism for sewing machines having a feed arm formed as a double lever which is linked to an advancing and to a lifting drive, and with a spring-loaded material presser foot which is connected with the top feed arm.
If it is necessary to equip industrial sewing machines with a top feed mechanism, the accommodating of the transmission gear and the journaling of the top feed arm present no special problem, because with an industrially used machine little discomfort results if one part of the bearing or of the transmission elements is located outside the actual machine housing.
In contrast to this, problems arise with the accommodation of the top feed mechanism in household machines, because in order to retain the appealing shape of the housing of the sewing machine it is necessary to accommodate all driving elements for the top feed, especially those members of the top feed that have to be mounted in the machine head, within a space of narrow confines. The design of these elements and their mutual position coordination must be such that only the top feed member which extends toward the stitch-forming location projects from the housing. In addition only as few parts as possible of the machine that move during operation should be in the range of vision of the seamstress.
It is therefore an object of the invention to provide a relatively simple arrangement of the top feed means and as to space the advantageous journaling of the top feed rocking arm in the machine head.
SUMMARY OF THE INVENTION
In accordance with the invention the objects are achieved in that one of the arms of the top feed rocker is coupled to two parallel guide links of essentially equal length, one of which is pivotally supported on the housing of the machine, while the other is operatively connected to the feed drive by a crank arm that extends essentially parallel to the one arm.
An advantageous and space-saving arrangement for coupling the top feed means with the lifting drive and with the material presser bar and its lifting mechanism is obtained in that the top feed rocking arm is connected with the material presser bar by way of a substantially vertically disposed articulated joint whose joint pin is engaged by a link arm which is connected with the lifting or raising drive.
In order to avoid raising of the material presser foot as the material is advanced by the top feed foot, the presser foot is connected with the material presser bar by way of a slide feed guide of limited movement that is protected against rotation. By these means the seamstress is not irritated by vibrating of the presser foot, and it rests during advancing of the material merely under the pressure of the material pressing spring.
An embodiment of the invention which is described hereinafter is illustrated in the drawing in which,
FIG. 1 is a partial view of the sewing machine with the top feed device, partly in section, in which the components located in front of the top transport arm are omitted;
FIG. 2 is a section taken through the head of the machine with the stitch forming tools in operative position, and
FIG. 3 is a section similar to FIG. 2 with the top feed and the presser foot devices in raised position, where the components located below the stitch plate have been omitted.
As shown in FIG. 2 the needle bar 2 with the needle 3 is mounted in housing 1. It is driven in a known manner, not illustrated, by the arm shaft 4.
An eccentric 5 is secured to the arm shaft 4 which is encompassed by an eccentric bar 6 that is linked to an arm 7 of a U-shaped rocking yoke 8. The rocking yoke 8 is journaled on an axle 9 that is fixed to the housing and it has a second arm 11 that is connected with a connecting link 10. The link 10 engages a pin 12 of a toggle joint which is a part of a toggle joint connection that comprises the toggle joint pin 12 and two link bars 13 and 14. The link bar 13 is joined to a clamping member 15 that is secured to a presser bar 16 that is guided in the housing 1 of the machine.
The lower part of the presser bar 16 is provided with a bore 17 in which a shaft 18 of a support 19 is slidingly mounted. A screw 21 fastened in the shaft 18 and extending through slots 20 in the presser bar 16 provides for limited vertical sliding movement of the support 19 in the bore 17. A spring 22 disposed in the bore 17 is biased at one end against shaft 18. The material presser foot 24 is mounted on the support 19 by means of a screw 23.
A further spring 26 having greater effective strength than spring 22 is provided in a bore 25 in the upper part of the presser foot bar 16 and rests at one end against a pin 27. The pin 27 engages a see-saw or rocker 28 that is journaled on the housing, and which in turn rests against an eccentrically formed head 29 of an abutment screw 30 that is threadedly secured in the housing 1. In this manner the material presser bar 16 is pressed downwardly until the presser foot 24 rests on the material being sewn.
The link bar 14 engages one end of a joint stud 31 that is secured in a double armed top feed rocking lever 32. The other end of the joint stud 31 is in engagement with a link 33 which is supported by a bolt 34 secured in housing 1. The arm 35 of the top feed rocking lever 32 is connected by way of a link 36 with a crank arm 37, which is secured to a rocking shaft 38 journaled in housing 1. The crank arm 37 extends essentially along a projection of the connecting line between the axes of the bolt 34 and the rocking shaft 38.
The other arm 40 of the top feed rocking lever 32 which projects downwardly through a slot 39 in housing 1 has a wedge-shaped free end 41 that is slidably received in a corresponding wedge-shaped recess 42 in the top feed foot 43 in order to retain the same in its position. The top feed foot 43 has a toothed member 44 which together with a sole 45 that is pivotally connected to the presser foot 24 engages the material being sewn from the top. For this purpose the sole 45 is provided with a slot 46 through which the toothed member 44 can reach.
A further recess 47 is provided above the toothed member 44 in which the end 41 of the top feed rocking lever 32 is slidably received. For this purpose the top feed foot 43 is provided with upwardly extending arms 48 which slidingly engage the arm 40 of the rocking lever 32 on both sides and which are provided with guide slots 49 into which extends a stud 50 that is secured in the top feed rocking lever 32 below the joint stud 31.
A spring 51 hooked at one of its ends to the top feed foot 43 and at its other end to the top feed rocking lever 32 pulls the top feed foot 43 upwardly in order to insure of engagement between the recess 42, respectively 47 and the end 41.
The lower feed dog 54 which is mounted on a carrier 55 cooperates with the top feed foot 43 and the presser foot 24 through slots 52 in the stitch plate 53.
The carrier 55 is connected at one end with the arm 56 of a rocking arm 57. Its other end is provided with a guide slot 58 in which a sliding stud 60 is guided which is carried by crank arm 59. The crank arm 59 is secured to a shaft 61 to which rocking movements are imparted by a lifting eccentric, in a manner not illustrated, as the machine is driven.
The rocking arm 57 journaled on an axle 62 in housing 1 has a further arm 63 that is connected by way of a link bar 64 with a crank arm 65 mounted on rocking shaft 38.
A belt chain 66 driven by arm shaft 4 (FIG. 1) drives the lower shaft 67 to which the looper of the machine which is not shown is connected. In addition shaft 67 drives an intermediate shaft 70 to which an eccentric 71 (FIG. 2) is secured by way of gears 68 and 69. The eccentric 71 is encompassed by the ring of an eccentric bar 72 that carries a bolt 73. Two link bars 74 and 75 are journaled on bolt 73, one of which bars 74 is pivotally connected by means of a stud 76 with a third arm 77 of the rocking lever 57. The other link bar 75 is pivotally connected by way of a stud 78 with an angular lever 80 that is journaled on a stationary pivot pin 79.
A rod 81 is in engagement with one free arm of the angular lever 80 (see also FIG. 1), which rod is linked to a further angular lever 82. The free end of angular lever 82 extends into a groove of a turning handle 83 mounted in housing 1, which limits its movability and which extends partly through a slot 84 in housing 1 for setting by the operator.
The spring 85 whose one end is hooked onto housing 1 and whose other end is hooked onto angular lever 80 pulls the lever mechanism described into the end position defined by the groove of the turning handle 83.
A clamp 86 is mounted on the presser bar 16 which has a rearwardly extending arm 87. Below this arm 87 a cam member 88 is located which is mounted on a stud 89 that extends through housing 1 and supports a hand lever 90 at its outer end.
The mechanism operates as follows:
As the machine is driven the arm shaft 4 drives intermediate shaft 70 by way of belt chain 66, shaft 67 and gears 68 and 69. As a result the eccentric 71 mounted on shaft 70 rocks bolt 73 about stud 78 by way of eccentric bar 72. The link bar 75 executes a true rotary movement about stud 78. On the other hand, depending on the position of stud 78 which is adjustable by means of turning grip 83 by way of double lever 82, bar 81 and angular lever 80, effects besides this rotary movement, a more or less large relative movement about pivot axis 62. This relative movement is transmitted to feed dog 54 by way of rocking arm 57.
The lifting eccentric which is not illustrated simultaneously causes a raising and lowering movement of the feed dog 54, this by means of swinging or rocking of shaft 61 whose crank arm 59 guides these rocking movements by way of sliding pin or stud 60 onto support 55.
Simultaneously with driving the feed dog 54 the rocking lever 57 imparts to rocking shaft 38 rocking movements by way of its arm 63, link rod or bar 64 and crank arm 65 which are transmitted to top feed lever 32 by way of crank arm 37 and link bar 36.
The top feed rocking lever 32 is thereby rocked about the pivot pin 31 so that the top feed foot 43 carries out the advancing movements. In view of the connection of the lower feed dog 54 as well as also the upper feed foot 43 with the rocking arm 57 their feeding paths are of equal length owing to suitable transmission relationships.
The lifting movement of the top feed foot 43 is effected by the eccentric 5 by way of the eccentric bar 6 onto rocking yoke 8. Due to its rocking the lever 10 that engages the toggle lever pin 12 alternately folds and stretches the two links 13 and 14.
Owing to the pressure of spring 26 the material presser bar 16 is pushed downwardly and presses with the upper end of the slot 20 onto the screw 21 and thus the presser foot 43 with its sole 45 onto the material being sewn.
If the two link bars 13 and 14 unbuckle the clamp member 15 secured to the material feed bar 16 constitutes a fixed point for the connection of the toggle lever whereby the joint pin 31 is raised together with the top feed bar 32 and the top feed foot 43. The top feed bar 32 thereby executes essentially a parallel displacement with respect to a straight line through the pivot points of the two links 33 and 36. Simultaneously with the raising of the top feed foot 43 from the material, a horizontal movement takes place in the manner described above by the rocking shaft 38.
The top feed foot 43 in its foremost position is lowered upon the material being sewn in that the link 10 effects a stretching movement of the toggle lever connection. Thus the top feed foot 43 supports itself by way of the material upon the stitch blade 53 or the lower feed dog 54 after a certain amount of stretching of the two link bars 13 and 14, so that now the pivot pin 31 constitutes the fixed point for the toggle joint connection.
The further stretching of the two bars 13 and 14 results in raising of the clamping member 15 against the pressure of spring 26 whose force is transferred by way of the link bars 13 and 14 and the top feed bar 32 onto the top feed foot 43. The clamping element 15 carries along the material presser bar 16 upwardly to a corresponding extent. Due to the slot 20 in the presser bar 16 the sole 45 of the material presser foot 24 remains under the influence of the spring 22 with light pressure on the material.
Simultaneously a displacement of the material takes place as a result of the rocking of the top feed lever 32 about the joint pin 31.
The raising of the presser foot 24 and of the top feed foot 43 for inserting or removing the material being sewn is effected by turning the manual lever 90. In this connection the cam member 88 presses the clamp 86 together with the presser foot bar 16 upwardly by way of arm 87. The clamping member 15 takes along the bars 13 and 14, the joint pin 31 and thereby the top feed foot 43 to which is connected the top feed bar 32, while this in turn performs a parallel displacement about the pivot points of the links 33 and 36. In this connection merely the material presser foot 24 lowers itself somewhat until engagement takes place of the screw 21 at the lower limit of the slot 20.
To disconnect the top feed foot 43 it is raised and swung rearwardly while the material presser device is manually raised against the effect of spring 51 from the end 41 of the top feed bar 32. At the same time the guide slots 49 are displaced with respect to the pin 50 and the end 41 resiliently engages the recess 47.
Having now described the invention with reference to the embodiment illustrated in the drawing, what we desire to protect by letters patent is set forth in the appended claims.