US2958103A

US2958103A - Schrotz

Info

Publication number: US2958103A
Authority: US
Original assignee: SKF Kugellagerfabriken GmbH
Current assignee: SKF GmbH
Priority date: 1958-06-12
Filing date: 1959-04-13
Publication date: 1960-11-01
Anticipated expiration: 1977-11-01
Also published as: CH366223A; NL100806C; FR1226211A; DE1087944B; GB855531A

Description

NE 2 Sheets-Sheet 1 K TZ CHANISM FOR TOP ROLLS CARRYING A DRAFTING ASSEMBLY OF A SPINNING MA Filed April 13. 1959 SCHRO Nov. 1, 1960 LOCK ME INVENrOP Nov. 1, 1960 LOCK MECHANI A DRAFTING Filed April 15. 1959 SM F ASSE

TOP ROLLS LY OF A SP SCHROTZ INN CARR NG ARM 0F MACHINE 2 Sheets-Sheet 2 mmswrox Kw 5M5,

United States Patent LOCK MECHANISM FOR TGP ROLLS CARRYING ARM OF A DRAFTING ASSEMBLY OF A SPIN- NING MACHINE Kiirt Schrotz, Michelberg, Germany, assignor to SKF Kugellagert'abriken G.m.b.H., Schweiufnrt, Germany Filed Apr. 13, 1959, Ser. No. 805,810

Claims priority, application Germany June 12, 1958 9 Claims. (Cl. 19-135) The present invention relates to drafting assemblies of spinning machines.

Such drafting assemblies include top rolls carrying arms which are conventionally movable between lower operating and upper inoperative positions.

More particularly, the present invention relates to a lock structure which will lock such a top rolls carrying arm both in its lower operating position as well as in its upper inoperative position.

'Oneof the objects of the present invention is to provide a lock structure of the above type which renders it unnecessary to depress the top rolls carrying arm when it is desired to release the latter for movement to its upper inoperative position. Although locks are known which can be released upon depression of the top rolls carrying arm slightly so that the operator while depressing the arm with one hand can release the lock with the other hand, these types of lock mechanisms are not suitable in constructions where a relatively large load is applied to the top rolls carrying arm since with such a large load it is not possible for the operator to depress the arm further in order to release a conventional lock of this type.

Another object of the present invention is to provide a lock structure which is made up of a relatively small number of parts which occupy a relatively small space so that the space required for a series of drafting assemblies according to the invention is not undesirably increased in order to accommodate the lock structure.

A further object of the present invention is to provide a lock structure of the above type which does not extend below the top rolls carrying arm so that when the latter is in its upper inoperative position free access may be had to all of the parts of the drafting structure in order to service these parts.

An additional object of the present invention is to provide a lock structure of the above type which will not only hold the top rolls carrying arm in its lower operative and its upper inoperative positions, but which will also determine the upper inoperative position of the top rolls carrying arm.

It is also an object of the present invention to provide a lock structure of the above type made up of simple rugged elements which cooperate with each other in such a way that the forces are evenly distributed through the parts of the mechanism so that there will be no localized wearing away of any one part of the mechanism during use of the structure of the invention.

With the above objects in view the present invention includes in a drafting assembly of a spinning machine a support and a top rolls carrying arm turnably connected to the support for movement between a lower operating and an upper inoperative position. In accordance with the present invention a toggle linkage means is connected to the support and to the arm and moves between one end position slightly beyond a dead center position of the toggle linkage means through the dead center position to an opposite end position where the parts of the toggle linkage means are substantially at the end of their possi- "ice ble movement with respect to each other, this toggle linkage means locking the top rolls carrying arm in its lower operating position when the toggle linkage means is in the said one end position thereof and locking the top rolls carrying arm in its upper inoperative position when the toggle linkage means is in the said opposite end position thereof.

The novel features which are considered as characteristic for the invention are set forth in particular in the appended claims. The invention itself, however, both as to its construction and its method of operation, together with additional objects and advantages thereof, will be best understood from the following description of specific embodiments when read in connection with the accompanying drawings, in which:

Fig. 1 is a diagrammatic side elevational view of a drafting assembly which includes the structure of the invention;

Fig. 2 is a sectional elevational view on an enlarged scale, as compared to Fig. 1, of that portion of the drafting assembly of Fig. 1 to which the lock structure of the invention is connected;

Fig. 3 is an end view of the structure of Fig. 2 as seen in the direction of the arrows III of Fig. 2, part of the structure being broken away in Fig. 3 so as to clearly illustrate the elements of the lock structure of the invention;

Fig. 4 shows the position which the parts of Fig. 2 take when the top rolls carrying arm is in an upper inoperative position, this arm being shown in its lower operating position in Fig. 2; and

Fig. 5 illustrates the position of the parts of Figs. 2 and 4 at a point intermediate the positions thereof illustrated in Figs. 2 and 4.

Referring now to the drawings, it will be seen that the structure illustrated therein includes a top rolls carrying arm 1 which is of U-shaped cross section and which has a top wall formed with a longitudinally extending slot 1' which terminates short of the ends of the arm 1. This slot 1 enables in a known way a plurality of support units for the saddle arms 2 to be located between the side walls of the arm 1 for adjustable longitudinal movement therealong so that the positions of the saddle arms 2 along the arm 1 can be adjusted in a known way. These saddle arms 2, which are conventional, carry in a known way the saddles 3, respectively, which in turn are connected in a known Way with the shafts of the several pairs of top rolls 4 whicch cooperate with the bottom rolls 5 shown in Fig. 1 also in a conventional manner. An unillustrated loading means cooperates in a known way with the top rolls 4 to urge the latter downwardly toward the bottom rolls 5. The top rolls carrying arm 1 is turnable upwardly from the lower operating position thereof illustrated in Fig. 1 to an upper inoperative position. Thus, a stationary support in the form of bracket 6 carries a forward pivot pin 7 on which the top rolls carrying arm 1 is turnable. The support 6 includes a pair of parallel plates interconnected by a plurality of spacer pins one of which simultaneously forms the pivot pin 7, and these parallel plates 6 are of a springy material and are formed with aligned openings through which the stationary support bar 9 extends, each of the plates 6 being formed with a slit extending from the opening which receives the bar 9 to the outer edge of the plate 6. These plates 6 are also formed with aligned openings which receive a nut to which a bolt 8 is threaded, the head of the bolt engaging a bottom edge of each plate 6 at the rear of the latter so that when the bolt 8 is tightened the slit of each plate 6 will tend to close and thus the plate 6 will tightly grip the stationary bar 9. A cover 6 made of sheet metal or plastic, for example, encloses the support 6, this cover 6' being formed with openings through which the support bar 9 passes and the cover 6' covering the opposite sides 3 as well as the rear of the support 6. It will be noted that the cover 6' is open at its bottom so as to render the bolt 8 accessible for tightening or loosening.

At its rear end which is adjacent to the support 6, the arm 1 carries a pivot pin 10 which also has a portion acting as a stop, as will be apparent from the description below. This pivot pin 10 pivotally carries a lever 11 which forms part of a toggle linkage means. The lever 11 is made up of a pair of identical lever portions located in side by side relation and spaced slightly from each other, these portions of the lever 11 being turnable on the pin 10 or being fixed to the latter and the pin 10 in this case is turnably carried by the arm 1 in the side walls thereof, as is particularly apparent from Fig. 3. A second lever 12 of the toggle linkage means extends into the space between the pair of lever portions which form the lever 11, and this lever 12 is pivotally carried by a pivot pin 13 which is directly carried by the support 6. Thus, the

levers

11 and 12 have overlapping portions, and these overlapping portions of these levers are formed with cutouts which also overlap each other. Thus, the pair of lever portions which form the lever 11 are formed with substantially triangular cutouts 11 which are aligned with each other, while the lever 12 is formed with an elongated cutout 12 extending along an arc of a circle whose center is in the axis of the pivot pin 13. An operating pin 14 which is parallel to the

pins

10 and 13 extends through the cutouts 11' and 12' and is carried at its ends by the side walls of an operating lever 15 which is pivotally carried by end portions of the pin 13 which project through and beyond the plates 6 as well as the side walls of the cover 6. As is apparent from Fig. 1 the operating lever 15 extends over and longitudinally along the arm 1 in the position of the part shown in Fig. 1, and as a result of its length the lever 15 can be easily operated to place the arm 1 in its lower operating or upper inoperative position even when the loading pressures for the top rolls are relatively high.

Referring now to Fig. 2, when the center of the operating pin 14 is located in the straight line which connects the centers of the

pins

10 and 13, the toggle linkage means is in its dead center position. In the position of the parts shown in Fig. 2, the center of the pin 14 is slightly to the left of the straight line connecting the centers of the

pins

10 and 13, so that in this position of the parts, which is the lower operating position of the arm 1, the operating pin 14 is slightly beyond the dead center position of the toggle linkage means. In the position of the parts shown in Fig. 2, if the arm 1 is raised so as to turn in a clockwise direction around the pivot pin 7, the lever 11 will tend to push the pin 14 downwardly against the lever 12, so that the toggle linkage means blocks such movement of the arm 1, and furthermore, any tendency of the operating pin 14 to turn in a counterclockwise direction around the pin 13 during an attempt to raise the arm 1 in the position of the parts shown in Fig. 2 will only tend to press the operating lever 15 against the arm 1 in a downward direction so that the arm 1 is effectively locked in the position of the parts shown in Figs. 1 and 2. It will be noted that in the position of the parts shown in Fig. 2 the operating pin 14 is at the upper apex of the substantially triangular cutouts 11' of the portions of the lever 11.

As may be seen from Figs. 2 and 3, the lever 12 has a hook portion 12" integrally formed therewith and extending therefrom in the manner shown most clearly in Fig. 2, and a Wire spring 16 has a substantially U-shaped portion embracing the lower portion of the lever 12 as viewed in Fig. 2 the legs of this U-shaped portion of the wire spring 16 being coiled about the pin 13 on the opposite sides of the plate or lever 12 and extending to the rear edges of the pair of plates of the support 6 where the outer extremities of the spring 16 are bent so as to overlap and engage these rear edges, so that the spring 16 continuously urges the lever 12 in a clockwise direction,

as shown in Fig. 2, so as to maintain the left end of the cutout 12', as viewed in Fig. 2, in engagement with the operating pin 14. The thickness of the pair of portions of the lever 11 is chosen, in accordance with the particular requirements of the structure of the invention, and in relation to the thickness of the walls of the lever 15, in such a way that the bearing surface provided by the portions of the lever 11 for the operating pin 14 is as great as the area of contact between the pin 14 and the lever 15, so that in this way the forces which the pin 14 is required to withstand are distributed over a sufficient area of the pin 14 and furthermore localized wear of the pin 14 is avoided.

In order to unlock the arm 1 in order to raise the latter to its upper inoperative position illustrated in Fig. 4, the operator turns the operating lever 15 in the direction indicated by the arrow A in Fig. 1. During this turning of the lever 15, the operating pin turns with the lever 15 around the pin 13 in a clockwise direction, as viewed in Fig. 2, and the pin 14 simply rides along the right edge of the cutouts 11', as viewed in Fig. 2, turning the lever 11 until the pin 14 engages the base of the triangular cutouts of the portions of the lever 11. In this position the arm 1 simply rests as a result of its own Weight in its operating position with the top rolls 4 engaging the bottom rolls 5, so that if desired the arm 1 can again be locked at this time. However, if it is desired to turn the arm 1 upwardly to its inoperative position and to lock it in this latter position, the operator continues to turn the lever 15 in a direction of the arrow A of Fig. 1, so that the operating pin 14 which now engages the base of the triangular cutout of each portion of the lever 11 pulls to the right, as viewed in Figs. 2 and 5, on the lever 11 so as to act through the pin 10 on the arm 1 to turn the latter around the pin 7 in a clockwise direction, as viewed in Fig. 2. Of course, during the turning of the operating pin 14 with the lever 15 the spring 16 turns the lever 12 so as to maintain the left end of the slot 12', as viewed in Fig. 2, in engagement with the pin 14. Thus, the hook portion 12" turns upwardly at this time. As soon as the operating pin 14 acts through the lever 11 on the pin 10 to pull the arm 1 in a clockwise direction around the pin 7, the pin 10 starts to turn downwardly around the pin 7 and thus the pin 10 and the hook portion 12" approach each other and then engage each other, the intermediate portion of the pin 10 which is located between the pair of plates which form the lever 11 forming a stop portion which cooperates with the hook portion 12 of the lever 12. During the continued turning of the operating lever 15, the downwardly turning pin 10 with its intermediate stop portion engaging the hook portion 12" acts on the lever 12 through the hook portion 12" to prevent the spring 16 from causing the lever 12 to follow the pin 14, and at this time parts will have the position indicated in Fig. 5, the pin 10 continuing to ride downwardly along the tip of the hook portion 12" until this hook portion can snap over the stop portion of the pin 10. As soon as the central stop portion of the pin 10 rides over the tip of the hook portion 12", the spring 16 snaps the lever 12 around to the position shown in Fig. 4 so that the hook portion 12" is now located over the pin 10. The arm 1 is shown in its upper inoperative position in Fig. 4, and it will be noted that because the hook portion 12" is over the pin 10, any tendency of the arm 1 to turn downwardly from the position of Fig. 4 will be resisted by the hook portion 12", so that the arm 1 is reliably locked in its upper inopertive position With the structure of the invention, when this structure has the position shown in Fig. 4. It will be noted that in the position of the toggle linkage means illustrated in Fig. 4, the components of the toggle linkage means have moved with respect to each other substantially to the end of their possible movement with respect to each other on the right side of the line of centers connecting the centers of the

pins

10 and 13.

As is apparent from Fig. 4, when the operator desires to turn the arm 1 to its operating position indicated in Fig. 1, it is only necessary to turn the operating lever 15 in a direction opposite to the direction indicated by the arrow A of Fig. 1. This turning of the lever 15 will cause the pin 14 to turn the lever 12 in a counterclockwise direction, as viewed in Fig. 4, in opposition to the spring 16, so as to move the hook portion 12" away from the pin and thus the arm 1 can now move downwardly toward its operating position where the top rolls 4 engage the bottom rolls 5. As was mentioned above, the arm 1 always tends to return to its operating position due to its own weight and the weight of the parts connected thereto. Thus, as the hook portion 12" turns in a counterclockwise direction from the position shown in Fig. 4 the arm 1 due to its own weight will tend to turn around the pin 7 in a counterclockwise direction and thus as soon as the hook portion 12" has turned downwardly through a sufiicient distance the pin 10 will again ride along the tip of the hook portion 12". Of course, the counterclockwise turning of the lever will cause the operating pin 14 to move upwardly in the triangular cutouts 11' and the pin 14 will move upwardly from the position of Fig. 4 to that of Fig. 5. The downwardly turning arm 1 will act through the stop portion formed by the intermediate part of the ipn 10 on the tip of the hook portion 12" to turn the lever 12 to the position shown in Fig. 5 while the lever 11 pulls to the left, as viewed in Fig. 5, on the pin 14 so as to urgethe lever 15 toward the position thereof shown in Fig. l, and in this way the weight of the arm 1 and the parts connected thereto will automatically continue the movement of the parts beyond the position shown in Fig. 5 back toward the position indicated in Fig. 2. In this way the entire lever 11 will move to the left beyond the position shown in Fig. 5 while the pin 10 turns upwardly from the position of Fig. 5 to that of Fig. 2, and when the pin 10 moves upwardly away from the tip 12" the spring 16 will turn the lever 12 in a clockwise direction so that the left end of the slot 12 will engage the pin 14, as indicated in Fig. 2. When the arm 1 has reached its operating position the pin 14 will be located slightly to the right of the dead center of the toggle joint, as viewed in Fig 2 and the arm 15 will still be slightly above the position thereof shown in Fig. 1. The operator will then move the arm 15 down to the position shown in Fig. l and this will result in turning of the pin 14 through and beyond the dead center of the toggle joint to the position indicated in Fig. 2, thus locking the parts in the operating position as pointed out above. Upon return of the lever 15 to the position of Fig. 1 the pin 14 will have moved slightly beyond the dead center position of the toggle linkage means, as described above, sothat the arm 1 is again locked in its operating position.

Of course, only one embodiment of the invention has been described above. Variations are possible in the details of the structure. For example, the form of the individual levers of the toggle linkage means and in their connection with the top rolls carrying arm 1 and the support 6 may vary. Also, there may be variations with respect to the hook portion 12" Without detracting from the advantages of the invention. Furthermore, it is possible to adjust the position of the operating pin 14 with respect to the lever 15 so as to be able to control the extent through which the arm 1 turns from its lower operatingposition to its upper inoperative position. In the same way, the path of turning of the arm 1 can be adjusted by choosing a proper size for the cutouts 11 of the portions of the lever 11, and the size of these cutouts may be rendered adjustable by providing elements which are slidably connected to the portions of the lever 11 to be fixed to the latter in an adjusted position over lapping the cutouts 11' so as to regulate the effective size thereof. Furthermore, instead of a pair of independent plate portions forming the lever 11, this lever 11 may have the form of a single plate portion which is bifurcated at its lower end, and of course in this case the end of such a 6 lever would be displaced from the plane of the hook portion 12" so that the latter could cooperate properly with the central stop portion of the pin 10.

It will be noted that the lock structure of the invention is composed of relatively small simple elements which occupy only a small amount of space which is part of the space occupied in any event by the arm 1 and support 6, so that the amount of space required for a series of drafting assemblies is not increased by the lock structure of the invention. Furthermore, it will be seen that when the arm 1 is in its upper inoperative position indicated in Fig. 4, none of the lock structure of the invention extends to the left, as viewed in Fig. 4, beyond the arm 1, so that all of this space is freely accessible for convenient servicing of the structure. Also, none of the structure of the invention is so positioned that fibers will collect thereon, so that the structure of the invention also remains perfectly clean.

It will be understood that each of the elements described above, or two or more together, may also find a useful application in other types of drafting assemblies differing from the types described above.

While the invention has been illustrated and described as embodied in lock structures for drafting assemblies, it is not intended to be limited to the details shown, since various modifications and structural changes may be made without departing in any way from the spirit of the present invention.

Without further analysis, the foregoing Will so fully reveal the gist of the present invention that others can by applying current knowledge readily adapt it for various applications Without omitting features that, from the standpoint of prior art, fairly constitute essential characteristics of the generic or specific aspects of this invention and, therefore, such adaptations should and are intended to be comprehended within the meaning and range of equivalence of the following claims.

What is claimed as new and desired to be secured by Letters Patent is:

1. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; and toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means locking said arm in said lower operative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof, said toggle linkage means including a first lever pivotally carried by said arm, a second lever pivotally carried by said support, said first and second levers overlapping each other and being respectively formed with overlapping cutouts at their overlapping portions, and an operating pin extending through said overlapping cutouts; and an operating lever turnably carried by said support and carrying said operating pin so that the latter moves during turning of said operating lever.

2. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means -locking said arm in said lower operative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof, said toggle linkage means including a first lever pivotally carried by said arm and a second lever pivotally carried by said support and overlapping said first lever, one of said levers having a hook portion; and a stop portion with which said hook portion cooperates when said toggle linkage means is in said opposite end position thereof, said stop portion and hook portion being respectively turnable along arcs of circles whose centers are displaced from each other.

3. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means locking said arm in said lower operative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof, said toggle linkage means including a first lever pivotally carried by said arm and a second lever pivotally carried by said support and overlapping said first lever, one of said levers having a hook portion; and a stop portion with which said hook portion cooperates when said toggle linkage means is in said opposite end position thereof, said stop portion and hook portion being respectively turnable along arcs of circles whose centers are displaced from each other and said circles intersecting each other when said stop portion and hook portion are in the positions they take when said toggle linkage means is in said opposite end position thereof.

4. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means locking said arm in said lower operative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof, said toggle linkage means including a first lever pivotally carried by said arm and a second lever pivotally carried by said support and overlapping said first lever, one of said levers having a hook portion; a stop portion with which said hook portion cooperates when said toggle linkage means is in said opposite end position thereof, said stop portion and hook portion being respectively turnable along arcs of circles whose centers are displaced from each other and said circles intersecting each other when said stop portion and hook portion are in the positions they take when said toggle linkage means is in said opposite end position thereof; and an operating lever operatively connected to said toggle linkage means for operating the same, said lever moving said hook portion away from said stop portion when said operating lever is actuated to release said arm for movement from its upper inoperative position back to its lower operative position.

5. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means locking said arm in said lower 0perative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof; said toggle linkage means including a first lever pivotally carried by said arm and a second lever pivotally carried by said support and overlapping said first lever, said second lever having a hook portion; and a stop portion carried by said arm, said hook portion cooperating with said stop portion carried by said arm for maintaining the latter in its upper inoperative position when said toggle linkage means is in its opposite end position.

6. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; and toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means locking said arm in said lower operative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof, said toggle linkage means including a first lever, a pivot pin pivotally connecting said first lever to said arm and a second lever pivotally carried by said support and overlapping said first lever, said second lever having a hook portion; and a stop portion carried by said arm, said hook portion cooperating with said stop portion carried by said arm for maintaining the latter in its upper inoperative position when said toggle linkage means is in its opposite end position, said stop portion being formed by part of said pivot pin which pivotally connects said first lever to said arm.

7. In a drafting assembly of a spinning machine, in combination, a stationary support; an elongated top rolls carrying arm pivotally carried by said support for turning movement between a lower operative and upper inoperative position; and toggle linkage means connected to said support and arm and movable between one end position slightly beyond a dead center position of said toggle linkage means through said dead center position to an opposite end position where the elements of said toggle linkage means are substantially at the end of their possible movement with respect to each other, said toggle linkage means locking said arm in said lower operative position thereof when said toggle linkage means is in said one end position thereof and said toggle linkage means locking said arm in said upper inoperative position thereof when said toggle linkage means is in said opposite end position thereof, said toggle linkage means including a first lever pivotally carried by said arm, a second lever pivotally carried by said support and overlapping said first lever, said first and second levers being formed With cutouts at their overlapping portions and said cutouts also overlapping each other and said toggle linkage means including an operating pin extending through said cutouts of said first and second levers; an operating lever carried by said support and carrying said operating pin for moving the latter so as to move said toggle linkage means between said end positions thereof, the size of the cutout of said first lever determining the upper inoperative position of said arm.

8. In a drafting assembly of a spinning machine, in combination, a stationary support; a forward pivot pin carried by said support; a rearward pivot pin carried by said support rearwardly of said forward pivot pin; a top rolls carrying arm connected by said forward pivot pin to said support for turning movement with respect to the latter; a third pivot pin carried by said arm for movement therewith around said forward pivot pin; a first lever connected to said rearward pivot pin for tuming movement with respect to said support around the axis of said rearward pivot pin; a second lever connected to said third pivot pin for turning movement with respect to said arm, said first and second levers overlapping each other and being formed with cutouts at their overlapping portions and said cutouts also overlapping each other, the cutout of said first lever extending substantially along an arc of a circle whose center is in the axis of said rearward pivot pin; an operating pin parallel to the other pins and extending through said cutouts of said first and second levers; an operating lever pivotally carried by said rearward pivot pin and fixedly carrying said operating pin; and spring means cooperating with said first lever for urging the latter to turn with respect to the axis of said rearward pivot pin in a direction which maintains one end of the cutout of said first lever in engagement with said operating pin.

9. In a drafting assembly of a spinning machine, in combination, a stationary support; a forward pivot pin carried by said support; a rearward pivot pin carried by said support rearwardly of said forward pivot pin; a top rolls carrying arm connected by said forward pivot pin to said support for turning movement with respect to the latter; a third pivot pin carried by said arm for movement therewith around said forward pivot pin; a first lever connected to said rearward pivot pin for tuming movement with respect to said support around the axis of said rearward pivot pin; a second lever connected to said third pivot pin for turning movement with respect to said arm, said first and second levers overlapping each other and being formed with cutouts at their overlapping portions and said cutouts also overlapping each other, the cutout of said first lever extending substantially along an arc of a circle whose center is in the axis of said rearward pivot pin; an operating pin parallel to the other pins and extending through said cutouts of said first and second levers; an operating lever pivotally carried by said rearward pivot pin and fixedly carrying said operating pin; spring means cooperating with said first lever for urging the latter to turn with respect to the axis of said rearward pivot pin in a direction which maintains one end of the cutout of said first lever in engagement with said operating pin; and a hook portion fixed to said first lever for turning move ment therewith and extending around said third pivot pin when said arm is in an upper inoperative position, said operating lever being manually turnable to move said first lever through pressure of said operating pin thereon against the force of said spring means in a direction which turns said hook portion away from said third pivot pin to release said arm for movement back to its operating position.

References Cited in the file of this patent UNITED STATES PATENTS