Slay operating mechanism for a loom

[57] ABSTRACT

A slay operating mechanism for a loom comprises an operating rod adapted to be pivoted at one end to a slay; a bell crank lever, one arm of which is pivoted to the other end of the operating rod and the central portion of which is pivotally mounted on a shaft; a connecting rod pivoted at one of its ends to a second arm of the bell crank lever; an operating lever pivoted at one end to the other end of the connecting rod and at its other end to fixed structure; a beam pivoted intermediate its ends to the operating lever; two cams cooperating with the ends of the beam, each being mounted on a support shaft; a driving shaft for driving the cams; a Maltese cross for each cam and having at least four radial openings evenly distributed about the periphery thereof, each cam having at least one active face which cooperates, directly or indirectly, with one of the ends of the beam; an arm for each cam and rotatable with the driving shaft and axially movable relative thereto, each arm carrying, at its free end, a roller engageable into one of the openings and, a selection mechanism for selectively positioning the roller either in the plane of the Maltese cross or in a plane parallel to the plane of the Maltese cross; and a cam locking device for locking each cam in the selected position, the locking device being operated by the selection mechanism.

Claims, 10 Drawing Figures

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Patented Aug. 14, 1973

3,752,196

Sheets-Sheet 1

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Patented Aug. 14, 1973

3,752,196

Sheets-Sheet 2

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Patented Aug. 14, 1973

3,752,196

Sheets-Sheet 3

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Patented Aug. 14, 1973

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Sheets-Sheet 4

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SLAY OPERATING MECHANISM FOR A LOOM

The present invention relates to slay operating mechanisms for looms and, in particular, although not so restricted, to slay operating mechanisms for ribbon looms.

Known slay operating mechanisms are of complicated construction and have a relatively slow operating speed.

The present invention seeks to provide a slay operating mechanism where it is possible to control the positioning of a slay with a very high degree of accuracy and at a high speed.

According to the present invention there is provided a slay operating mechanism for a loom comprising: at least one operating rod adapted to be pivoted at one end to a slay; at least one bell crank lever, one arm of which is pivoted to the other end of the operating rod and the central portion of which is pivotally mounted on a shaft; a connecting rod pivoted at one of its ends to a second arm of the bell crank lever; an operating lever pivoted at one end to the other end of the connecting rod and at its other end to fixed structure; a beam pivoted intermediate its ends to the operating lever; two eccentric means cooperating with the ends of the beam, each being mounted on a support shaft; at least one driving shaft for acting upon at least one of the eccentric means, clutching means interposed between each eccentric means and a drive means and operable by an operating mechanism; each eccentric means comprising a cam and a Maltese cross having at least four radial openings evenly distributed about the periphery thereof, each cam having at least one active face which cooperates, directly or indirectly, with one of the ends of the beam; coupling means for each cam comprising at least one arm rotatable with the driving shaft and axially movable relative thereto, the or each arm carrying, at its free end, a roller engageable into one of said openings and a selection mechanism for selectively positioning the roller either in the plane of the Maltese cross or in a plane parallel to the plane of the Maltese cross; and cam locking means for locking each cam in the selected position, the locking means being arranged to be operated by the selection mechanism.

The selection mechanism for each cam may comprise a disc connected with the said a;m and having at least two segments of different diameters, a staged lateral ramp being provided on each face of the disc extending progressively from one end of the segment with the greater diameter towards a portion parallel with the plane of the disc, the selection means including abutment means movable into the path of at least one of the two ramps to engage the ramp to effect axial displacement of the disc and the arm, the abutment means cooperating with at least one operating member adapted to be operated by the operating mechanism.

Alternatively, the selection mechanism for each cam may comprise a disc having at least one pair of segments of smaller diameter and one pair of segments of greater diameter, a ramp on each side of the disc in an annular zone between the segments of smaller diameter and the segments of greater diameter, the segments of greater diameter being symmetrically and alternately disposed relative to the smaller diameter segments, and an abutment means arranged for movement in a plane perpendicular to that of the disc.

Preferably, each cam locking means comprises a plurality of arcuate segments provided on each Maltese cross between adjacent openings, each segment having a radius of curvature the centre of which is located at substantially the axis of the driving shaft when the plane of symmetry of said each segment passes through the said axis, and a circular locking disc the radius of which is the same as the radius of curvature of the segments and which is at least axially movable on the said driving shaft and is axially fixed on the arm to cooperate with the selection mechanism, the arrangement being such that the plane of symmetry of a segment coincides with the said axis of the driving shaft when the roller leaves or engages an opening in the Maltese cross.

The invention is illustrated, merely by way of example, in the accompanying drawings, in which:

FIG. 1 is an elevational side view of the principal parts of a loom provided with a slay operating mechanism according to the present invention;

FIG. 2 is a section, in plan, of the slay operating mechanism of FIG. 1;

FIG. 3 is a cross-section of the slay operating mechanism taken on the line III—III of FIG. 2;

FIG. 4 is a cross-section of the slay operating mechanism taken on line IV—IV of FIG. 3;

FIG. 5 is a cross-section of part of the slay operating mechanism taken on the line V—V of FIG. 4;

FIG. 6 is a plan view, partly in section, showing part of the slay operating mechanism;

FIG. 7 is a section on the line VII—VII of FIG. 6;

FIG. 8 is a plan view, partly in section, showing an alternative construction of the part of the slay operating mechanism in FIG. 6; and

FIG. 9 is a section on the line IX—IX of FIG. 8.

FIG. 10 is a perspective view of the structure of selection disc 92-93.

In the following discussion references to “front,” “rear,” “side,” “horizontal,” “vertical” etc. refer to the directions as seen in the drawings.

Referring first to FIG. 1, there is shown a side view of a loom having a slay operating mechanism according to the present invention. The loom comprises a frame 1 on which is mounted a motor 2 acting through a speed variator 3 and a belt transmission 4 to drive a flywheel 5, the rotational axis 6 of which is housed in the frame 1. A rear end 7α of a driving rod 7 is mounted eccentrically and radially adjustably on the flywheel 5. A front end 7b of the driving rod is pivoted to a square 8. The square 8 is supported by two suspension or support levers 9, 10. The lower ends of the support levers 9, 10 are pivoted to the frame 1 at articulation points 13, 14 respectively, and the upper ends of the support levers 9, 10 are pivoted to the square 8 at articulation points 11, 12 respectively. The articulation points 11, 12 and 13,14 are at the same horizontal level. The four articulation points, together with the support levers 9, 10, define a deformable parallelogram. On the front face of the square 8 a beam 15 is pivoted at 26, 27, the beam extending along the length of the front face of the loom and is pivoted on the other side face (not shown) of the loom and, if need be, also at the centre of the loom, on another square identical to the square 8. Moreover, on this other side face, and also possibly at the centre of the loom, there is provided a further driving rod and a further flywheel driven by the speed variator 3.

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The beam IS supports a slay 16 which extends along the entire width of the front face of the loom and is mounted for vertical movement in guides 15α on the beam 15. The slay 16 is provided with one or more sets 17, 18 of groups of superimposed shuttles 17, 18. For greater simplicity, a slay operating mechanism for the shuttles 17, 18 has only been represented diagrammatically at 19 in FIG. 1. A transmission 20 causes movement of the slay 16 in response to the slay operating mechanism. The slay operating mechanism will be described in greater detail hereinafter.

Two sheds 21, 22, healds 23, a stop motion device 24 and a loom beam 25 are indicated diagrammatically in FIG. 1.

The transmission 20 comprises an operating rod 30 one end of which is pivotally connected to the lower end of the slay 16 and the other end of which is pivotally connected to one arm 31α of a bell crank lever 31. The lever 31 has a shaft part 32 which extends over the entire width of the loom and has a second arm 31b. It will be appreciated that a plurality of arms, similar to the arm 21α, may be provided on the shaft part 32, these arms being distributed therealong and each being connected to the slay 16 by a respective rod similar to the rod 30. In this case, the arms 21α and the rods 30 will be parallel to one another. The second arm 31b of the bell crank lever 31 is arranged vertically and is pivoted at its free end to a connecting rod 33 which is substantially horizontal. The rod 33 extends through an opening 35 in the front face of a casing 34 of the slay operating mechanism 19 (see FIG. 2). Thus the slay operating mechanism will cause vertical reciprocating movement of the slay 16.

As seen in FIG. 1, the slay comprises two sets 17, 18 of three vertically disposed shuttles. The number of shuttles in each set is, in this embodiment, three so that the slay 16 can take up three different positions: that is to say, there are three positions of the slay 16 where there is a shuttle at the level of each of the sheds 21, 22. The slay 16 is in its centre position when the centre shuttle of each set is at the level of the sheds 21, 22.

It will be appreciated that when the rod 33 causes the bell crank lever 31 to pivot in a clockwise direction, the slay 16 is brought into its lowermost position in which the upper shuttle of each set is located at the level of the sheds, and when the bell crank lever 31 is pivoted in an anticlockwise direction, the slay is brought into its uppermost position in which the lower shuttle of each set is located at the level of the sheds 21, 22.

The invention is not limited to the sets comprising three vertically arranged shuttles, it also applies to the case where the sets comprise two vertically arranged shuttles or more than three vertically arranged shuttles.

Referring now to FIGS. 2 and 3, the rear end of the rod 33 is pivoted to the upper end of an operating lever 36, the lower end of which is pivotally mounted on a shaft 36 located in bearing 38 secured to the casing 34. For reasons of symmetry, the operating lever 36 has two lateral cheeks 36α, 36b parallel to one another and interconnected at their ends by shafts 37, 39. The lever 36 pivots about the shaft 37 after rod 33 pivots about the shaft 39. A beam 40 is pivotally mounted on a shaft 41 connected to the centre of the lever 36. The beam 40 has, on either side of the shaft 41, two arms of equal length, the total length of the beam 40 being less than the distance between the two shafts 37, 39. The beam is arranged between the two lateral cheeks 36α, 36b of the lever 36 and also comprises two cheeks 40α, 40b.

Two operating cams 42, 43 are provided and one cam cooperates with each end of the beam 40. Each cam 42, 43 is free to rotate about, but is axially fixed on, a supporting shaft 44, 45 respectively. These supporting shafts 44, 45 are parallel and vertically arranged one above the other. The ends of the shafts are mounted in suitable bearings 46, 47 respectively on the casing 34.

The cams 42, 43 may be connected directly on the ends of the beam 40. In this case, the ends of the beam are urged against an active surface on each of the cams 42, 43 by means of springs (see FIG. 6 and 7).

In the case where the slay 16 is capable of taking one of three different positions, that is to say, uppermost, centre and lowermost positions, the two cams each have an active surface consisting of two active faces 42α and 42b, 43α and 43b symmetrically disposed to each other relative to the respective supporting shaft 44, 45. The two active faces of each cam may, for example be a disc freely mounted on the axis of the respective supporting shaft, the two active faces having different radii of curvature. The centre of curvature of the two active faces coincides with the axis of the respective supporting shaft and are interconnected by flat faces. This case is illustrated on FIG. 6 and 7. Again, the ends of the beam 40 are constantly urged by springs 62 against the corresponding cams 42, 43. When the two ends of the beam 40 rest against the active faces which have the smaller radius of curvature, i.e. the active faces which are nearer the supporting shafts 44,45, the lever 36 is pivoted and, according to the arrangement shown in FIG. 1, the slay 16 occupies its uppermost position. On the other hand, when the ends of the beam 40 engage the active faces which have a greater radius of curvature, i.e., are the furthest from the supporting shafts 44,45, the lever 36 pivots about the shaft 37 so that the slay 16 is in its lowermost position. The slay 16 is in its centre position when the active face with the smaller radius of curvature of one of the cams is in contact with one of the ends of the beam 40 while the active face with the greater radius of curvature of the upper cam is in contact with the other end of the beam 40.

The active surfaces of the cams may be constituted by grooves 48, 49 of suitable section made in a lateral face of a disc-like cam. Spigots 50, 51 are engaged in the grooves 48, 49 respectively. Each of the spigots 50, 51 is mounted on the end of a connecting rod 52, 53. ' The other ends of the connecting rods are pivotally mounted on opposite ends of the beam 40. Preferably, the two cheeks 40α, 40b of the beam are connected at their ends by means of respective shafts 54, 55 on which the connecting rods 52, 53 are pivotally mounted.

The cams 42, 43 are freely mounted on their respective supporting shafts 44, 45, for example by means of suitable ball bearings 56, 57 respectively. Alternatively, they may be splined onto their respective supporting ¹ shafts which are then mounted for rotation in the bearings 46, 47.

Each of the grooves 48, 49, represented in dotted lines in FIG. 3, has four active faces arranged around . the respective supporting shaft at 90° intervals. Naturally when each cam has only two active faces, the latter are angularly spaced apart by 180°. This spacing of the active faces is employed in the case where the ac3,752,196 tive faces form the profile of the cam as well as in the case when the active faces are formed in a groove. The radial extent of the active faces on each of the cams may be relatively small. Nevertheless, the extent must be large enough to constitute a correct supporting area, either directly for the corresponding end of the beam 40 or for a respective spigot 50, 51 on the connecting rods 52, 53. The portions of the active surface between the two active faces of each cam may exhibit any profile preferably continuous and progressive, but in no event should these portions be at a distance from the respective supporting axis which is less or greater than that of the active faces.

The use of a cam having a groove therein, where the active surface of said groove is parallel with the respective supporting shaft, is particularly advantageous because it makes it possible to provide each of the cams 42, 43 with two pairs of active faces 42α, 43α and 42b, 43b respectively. The active faces 42α, 43α of the respective cams are diametrically opposed to each other and alternate with the respective active faces 42b, 43b. In this case the active faces 42α, 43α have a greater radius of curvature and so are disposed at a greater distance from the respective supporting shaft than the active faces 42b, 43b which have a smaller radius of curvature and thus are closer to the respective supporting shaft. The active surfaces 42a, 43a are convex and the acting surfaces 42b, 43b are concave.

In view of the fact that the active faces are spaced apart by 90° around each cam a quarter of a complete revolution of the cam is sufficient to change the active face cooperating with one end of the beam 40. Thus, the rate of change of position of the slay 16 is considerably increased.

The tops or recesses of the active faces 42α, 42b or 43α, 43b have, preferably, a more pronounced curvature so as to prevent an undesirable lateral shift of the respective spigot 50, 51 in a horizontal plane passing through the supporting shaft 44, 45. The shafts 54, 55 of the beam 40 are also located in this horizontal plane in each of its positions corresponding to the three positions of the slay 16. Only when one end of the beam 40, for example the end carrying the shaft 54, passes from one position to another while the other end, for example the end carrying the shaft 55, retains its initial position, does the shaft 54 depart slightly and temporarily from this horizontal plane. This departure is, however, very small and does not have any appreciable influence upon the lever 36 because the beam 40 is relatively long.

Instead of a groove in each cam, it is possible to have an internal shoulder of suitable profile on each cam behind which shoulder the spigot 50, 51 respectively is engaged. Indeed, as the shaft 41 of the lever 36 is constantly urged by the weight of the slay 16, the radially inner face of the groove does not engage the respective spigot and so does not play any essential part. Thus when a shoulder is used in place of the groove, it is unnecessary to provide a shoulder corresponding to the radially inner face of the groove.

When the four active faces form the profile of each cam it is advantageous either to guide the respective spigot 50, 51 in the horizontal plane or to make a rigid connection between the respective connecting rod 52, 53 and the corresponding end of the beam 40 and to urge the spigot 50, 51 towards the active faces by means of a spring. In the case of this rigid connection between the connecting rods 52, 53 and the beam 40, the active faces 42α, 42b and 43α, 43b will require an adequate area to take into account the angular displacement of the ends of the connecting rods 52, 53.

The two alternative constructions of the cams discussed above are shown in FIGS. 6 to 9. For each construction only one of the cams will be described but it will be appreciated that the other cam is of similar or identical construction.

As may be seen in FIGS. 6 and 7 the cam 42 is mounted by means of the bearings 56 on the supporting shaft 44 and has four active faces 42α, 42b on its profile. The active faces are equi-angularly spaced apart by 90° and are alternately disposed. The active faces 42α are disposed at a greater distance from the supporting shaft 44 than the active faces 42b. It will be observed that opposite the spigot 50 the connecting rod 52 has a guide finger 59 slidably mounted in a horizontal slide 60,61 integral with the casing 34 and forming with the spigot an articulation of the connecting rod 52. This guiding of the spigot 50 ensures that only the position of the cam 42 in relation to the spigot 50 determines the position of the beam 40. A return spring 62 is fixed between the guiding finger 59 and the shaft 44 to urge the spigot 50 towards the cam 42.

In FIGS. 8 and 9 there is shown a construction for the cam 43 which is mounted for free rotation on its supporting shaft 45 through the bearings 57. As in the previous embodiment, the cam 43 is prevented from axial movement by means of safety washers 64 embedded in the hub of a Maltese cross 66 on which the cam 43 is keyed and which will be described later. Opposite the spigot 51, the connecting rod 53 has a guiding finger 59 which is coaxial with the said spigot 51 and which is guided along a horizontal plane passing through the axis of the supporting shaft 45, through suitable slides 60, 61 integral with the casing 34. The spigot is urged to bear upon an internal shoulder 58 of the cam 43 by the weight of the slay 16, which always exerts a force upon the ends of the beam 40. This internal shoulder 58 has four active faces 43α, 43b equi-angularly spaced apart by 90° and alternately disposed relative to one another.

As will be seen from FIGS. 2, 3 and 6 to 9 each cam 42, 43 is fixed to a Maltese cross 66. Each Maltese cross 66 is free to rotate about, but is axially fixed on a respective supporting shaft 44, 45. Each Maltese cross 66 has at least four radial openings 67, 68, 69, 70 which are open laterally on the side opposite to the cam 42, 43 respectively. These radial openings 67 to 70 are equi-angularly spaced apart and, in the embodiment illustrated, are spaced apart by 90°. At least one roller 71, carried by an arm 73, is arranged on a principal drive shaft 75 through a hub 77. At least one roller 72 is carried by an arm 74 and is arranged on an auxiliary drive shaft 76 through a hub 78. The hubs 77, 78 of the arms 73, 74 respectively are axially movable on the respective shafts 75, 76 each of which is provided with coaxial grooves or splines 79 evenly distributed over the periphery along a portion of the length thereof. The hubs 77, 78 have corresponding grooves or splines 80. The shafts 75, 76 are arranged in the same horizontal planes as the supporting shafts 44, 45 respectively. The location of the rollers 71, 72 is such that for a first position of the arms 73, 74 they extend radially into openings in the Maltese crosses 66 and in a second position they abut the periphery of the Maltese crosses between

3,752, 7 adjacent openings. As illustrated in FIG. 3 each arm 73, 74 has two rollers 71, 72 respectively diametrically opposed to each other.

At the openings 67 to 70 the circumference of each Maltose cross 66 is formed by arcuate segments the 5 centre of curvature of which is located at the axis of the respective supporting shaft. Between each pair of openings there is provided a circumferential locking segment 81. Each segment 81 is arcuate, the centre of curvature of which is the principal drive shaft 75 or the 10 auxiliary drive shaft 76. When a segment 81 is engaged with a correspondingly shaped portion of the respective arm, it is symmetrically disposed about the horizontal plane passing through either of the shafts 44, 75 or the shafts 45, 76. ¹⁵

The length of the arms 73, 74 and the radial depth of the openings 67 to 70, account being taken of the distance between the shafts 75, 76 and the shafts 44, 45, are selected in such a way that the engagement of the rollers 71, 72 in an opening causes rotation of the Mai- 20 tese cross by a quarter of a revolution. It is important that the tops or recesses of the active faces 42α, 42b, 43α, 43b of each cam 42, 43 should coincide with the plane of symmetry between two adjacent openings. Thus, in FIG. 3, the active surface 42α of each cam co- ²⁵incides with the plane of symmetry between the two adjacent openings 69, 70, said plane of symmetry being that of the segment 81.

With each of the segments 81 of each Maltese cross, there is a cooperating circular locking disc 82, 83 ³⁰which is mounted on the hub 77, 78 respectively in such a way as to be axially movable relative to the shafts 75, 76 and to be axially fixed relative to the arm 73,74. Each locking disc 82,83 and the respective arm 73, 74 are arranged in relation to each other in such a ³⁵way that either can operate alternately with the corresponding Maltese cross 66. Each locking disc has a circular profile and a diameter such that it can be engaged laterally in a segment 81 of a Maltese cross 66 when the latter occupies a position in which the horizontal plane passing through the principal drive shaft or the auxiliary drive shaft constitutes the plane of symmetry of the segment. This is always the case when a roller 71, 72 has just left one of the openings 67 to 70 of each Maitese cross 66. At this moment, an active face 42α, 42b and 43α, 43b of each cam 44, 45 respectively occupies its operating position and the locking disc engages a segment 81, so that the latter is immobile during the subsequent rotation of the shaft 75, 76 respectively. ₅θ Thus, the stresses acting upon the slay 16 and consequently upon the lever 36 and the beam 40, cannot influence the rotation of the shafts 75, 76.

It is; moreover, advantageous to mount each locking disc 82, 83 on the corresponding hub 77, 78 through &amp; 55 bearing 84, 85 and to prevent any axial displacement of the locking disc in relation to its hub by means of a safety washer 86, 87 respectively.

When a locking disc 82, 83 is engaged with its respective Maltese cross 66, the roller moves along a plane ₆θ parallel to that of the Maltese cross 66 and cannot be engaged in one of the openings 67 to 70. The principal drive shaft 75 is driven by the speed variator 3. As shown in FIG. 4, the auxiliary shaft 76 is driven from the shaft 75 by means of a toothed reversing wheel 88 ₆₅which is freely mounted on an intermediate shaft 89 and engages, on the one hand, with a toothed wheel 90 keyed to the shaft 75 and, on the other hand, to a

196 toothed wheel 91 keyed to the shaft 76. Of course, the wheel 88 and the wheels 90,91 may be replaced by any other means such as a chain transmission, a notched belt transmission, etc.

Each locking disc 82, 83 has a respective selection mechanism for causing its axial displacement and simultaneous displacement of the respective arms 73, 74 along the corresponding shaft 75, 76. The selection mechanism is shown in FIG. 2, 3 and 5 and comprises for each Maltese cross 66 a selection disc 92, 93 connected for rotational and axial displacement with the corresponding arm 73, 74. Each selection disc 92, 93 comprises at least two parts or segments 94, 95 of different diameters. The segment 94 has the greater diameter and comprises, when there is only one segment of this type, on each side a staged lateral ramp starting (seen in the direction of rotation of the disc 92,93 indicated by the arrow f) progressively along a slope 98 towards a portion 99 of the ramp, this portion being parallel to the face of the disc 92, 93. The segment 95 of smaller diameter is radially retracted in relation to the ramp and serves for the passage of a selection abutment 100, 101. The abutment may be disposed in the path of the slope 98 and immobilised in that position so that, when the slope comes into contact with this abutment, the selection disc 92,93 moves to the right or to the left taking with it the respective roller 71, 72 and the locking disc 82, 83 until the portion 99 of the ramp bears against the abutment. It should be noted that the peripheral length of the portion 99 of the ramp is of little importance as it does not serve to keep the respective roller 71, 72 and the locking disc 82, 83 in a selected position. Indeed, no axial stress, with the exception of that originating from the abutment 100,101 can act on the roller 71, 72, the arm 73, 74 and the locking disc 82, 83. The angular position of the slope 98 in relation to the arm 73,74 is selected in such a way that immediately after a roller 71, 72 comes out of an opening 67 to 70 this slope 98 can cooperate with the abutment 100, 101.

As seen in FIGS. 2 to 5 and 10 each selection disc 92, 93 comprises two pairs of diametrically opposed ramps on opposite sides of the said selection disc. Each pair of ramps is separated from the other by an angular recess the bottom of which delimits the segment 95 of smaller diameter. This arrangement enables the axial displacement of the roller 71,72 and of the locking disc 82, 83 at each half revolution of the driving shaft 75, 76 respectively.

The displacement of the abutment 100, 101 is obtained with the aid of a set of levers 100, 104 pivoted, on the one hand, about a pivot 105, 106 respectively fixed to the casing 34 and, on the other hand, about a electromagnet 107,108 respectively receiving its operating impulses from a Jacquard mechanism or the like.

According to an alternative form of selection mechanism, two abutments are placed on either side of each selection disc in such a way that each is capable of being interposed in the path of one of the two ramps on the selection disc. Each abutment, for example, constituted by a roller mounted so as to move around the axis perpendicular to that of the selection disc, is mounted on the end of a rod axially movable in a plane parallel with that of the selection disc, each rod being rigidly guided in its axial displacement and carrying, between its two ends, a toothed rack engaging with a toothed transmission wheel. The toothed racks of the two rods

3,752,196 are in engagement with the toothed transmission wheel on either side of the rotational axis of the latter and in such a way that when one of the abutments is interposed in the path of one of the ramps the other abutment is removed from the path of the other ramp. The transmission wheel is controlled by the operative part of the electromagnet of a Jacquard mechanism through another toothed rack connected with the operative part of the electromagnet.