High speed yarn knitting apparatus

A knitting machine is described in which the elastic thread packages (26) are mounted in a stationary position away from the knitting head (22). This results in reducing the revolving mass and the space necessary to accommodate the revolving mass. Furthermore, the commencement of wind on the package (26) can be left as a tail which is knotted to the free end of a second package thus permitting the machine to run continuously without stopping to change packages. A plurality of like knitting heads (22) is mounted in relatively close proximity in a single knitting head frame (24) in such a manner that chain stitches are fed from a power driven warp beam (12, 16, 20). Each knitting head includes yarn positioning apparatus in which yarn (12) fed to each needle (30) of the knitting head (22) is moved under tension with minimal friction to a position where the needle (30) traps the yarn (12) on its downward stroke. Embodiments of the invention are described.

The prevent invention relates to apparatus for producing tubular fabrics 
consisting of a number of separate chain stitches connected by an inlaid 
thread typically, elastic or similar yarn. In particular, the invention 
relates to a high speed yarn knitting apparatus for knitting netting for 
covering food products, and in particular meat. 
High speed yarn knitting apparatus should satisfy a number of desirable 
criteria in addition to being reliable, fast and relatively inexpensive. 
It should permit the fabric to be continuously knitted and should require 
a minimal amount of space and be relatively lightweight. The supplies of 
yarn should be readily changed or added to without interrupting the 
operation of the machine and a counterweight should not be required to 
avoid imbalance at high speed. The high speed knitting apparatus should 
have yarn positioning apparatus which uses a minimal number of moving 
parts and wear and tear of knitting elements and yarn should also be 
minimised. Higher tensions of yarn should be obtainable so that knitting 
speeds can be increased. The apparatus should also minimise the splitting 
of yarn and the dropping of stitches. 
Prior art knitting machines are of two general types. The first type 
consists of a machine which can make several rolls at a single time using 
a reciprocal movement. However, this machine is large and the reciprocal 
movement is very slow, thus limiting the amount of rolls of knitted fabric 
which can be produced in a certain time. The second type of machine uses a 
circular movement, however, this produces only a single roll at a time and 
the size of the yarn package limits the amount of continuous netting which 
can be made without stopping. The yarn package is mounted to rotate with 
the cambox which means that the speed of rotation and hence knitting is 
limited. Also, when the weft package is empty the machine must be stopped, 
reset and retensioned before it can then operate. This takes time and the 
overall speed of the machine is relatively slow. In addition, because the 
package rotates, a counterweight is required for balance, which is heavy, 
and also requires space within the machine which results in the overall 
machine taking up a relatively large area. 
Existing circular knitting machines which are also designed to make a chain 
stitch structure use one of two generally accepted methods of supplying 
yarn to the needles of the knitting head. One method uses rotating or 
reciprocating guides which wrap the yarn around the needles. The elastic 
or other weft yarn is fed from the outside and is laid between the needles 
from the outside. This requires the weft yarn package to rotate with the 
cam box. In another method, stationary guides are present and rely on 
being struck by the needles so as to deflect the needles behind the yarn. 
The yarn is then caught by the open hook of the needle as the needle 
descends. Again, the weft yarn package revolves with the cam box. 
These existing methods have a number of problems. The former method uses 
reciprocating guides requiring a machine which is relatively complicated 
and uses a considerable number of moving parts. In the second method, as 
the needles strike the guides there is considerable wear and tear on both 
the needles and the guides. This can cause splitting of the yarn and 
dropping of stitches as well as broken knitting elements. 
An object of the present invention is to provide an improved knitting 
apparatus and yarn tensioning apparatus which obviates or mitigates the 
aforesaid disadvantages. This is achieved by providing a high speed 
knitting apparatus in which the elastic thread packages are mounted in a 
stationary position away from the knitting head and the yarn is fed from 
the exterior to the inside of each knitting head. Yarn is laid down 
outside each needle as the needle rises but falls behind the needle as the 
stitch is made allowing a stationary package. This results in reducing the 
revolving mass and the space necessary to accommodate the revolving mass. 
Furthermore, since the weft package is stationary, the commencement of 
wind on the package can be left as a tail which is knotted to the free end 
of a second package thus permitting the machine to run continuously 
without stopping to change packages. 
A yarn guide is included for each needle of the knitting head so that yarn 
is moved under tension within the guide by a rotating member with minimal 
friction to a position where the needle will trap the yarn on its downward 
stroke. 
This arrangement also permits a plurality of like knitting heads to be 
mounted in relatively close proximity in a single machine frame in such a 
manner that chain stitches can be fed from a power driven warp beam. 
In a preferred arrangement, a plurality of knitting heads are mounted on a 
knitting head frame fed from a single warp and stationary creels can be 
mounted at the sides of the frame for supplying weft yarn to respective 
knitting heads. The knitting head frame can also include a fabric take-off 
roll for receiving the knitted fabric from each of the knitting heads. In 
an alternative arrangement the knitting heads may be mounted on a frame 
fed by a plurality of warps. 
Each knitting head consists of a hollow cylinder having a plurality of 
grooves called tricks, in the outer wall, in which needles are disposed. 
Fixed feeders are disposed above the cylinder to offer the warp yarns to 
the needle. Disposed between the cylinder and the fixed feeder is a 
rotating weft feeder and yarn deflector. Rotation of the feeder is 
synchronized with a cam which raises the needles so that the feeder 
deflects the warp yarn within the yarn guide and guides and lays the 
elastic weft yarn outside the needle so that as the needle rises and falls 
the rubber yarn is trapped between the chain stitches and falls behind the 
needle as a stitch is made, in a spiral fashion to provide radial and 
circumferential elasticity or rigidity in the knitted fabric. 
The fixed feeders are mounted radially in the supported feeder head support 
tube through which passes a tube mounted in bearings and carrying the weft 
feeder and deflector so that these can be rotated by a synchronised drive 
while feeding the inlay weft thread. The fixed feeders are wire staples 
which are shaped so that pre-tensioning of the yarn before it reaches the 
guide ensures that the yarn lies in front of and to one side of the open 
hook of the needle, and limits yarn movement when contacted with the 
placer. The staple has a curved portion for defining the path of the yarn 
as it is moved. The placer is a planar element which has a curved portion 
which pushes the yarn along the internal rim of the feeder from a first 
position to a second position where the yarn is trapped. 
Accordingly, in one aspect of the present invention there is provided a 
knitting head for use with a knitting machine said knitting head 
comprising: 
a fixed hollow cylinder having a cylinder wall with a plurality of 
circumferentially spaced grooves disposed in said wall, each groove having 
a needle with a hook at its upper end disposed therein, 
said hollow cylinder being disposed in a cam box having rotary cam means 
adapted to be coupled to each needle so that rotation of said rotary cam 
means causes displacement of each needle along its respective groove, 
stationary warp yarn delivery means disposed above said hollow cylinder for 
feeding a warp yarn from a remote location to each respective needle, 
rotatable weft yarn delivery means disposed between said hollow cylinder 
and said stationary warp yarn delivery means for delivering a weft yarn 
from a remote location outside the cylinder and from the inside to the 
outside of said rotatable weft delivery means so that the weft yarn is 
laid on the outside of each successively rising needle, 
the speed of rotation of said rotary cam means and said rotatable weft yarn 
delivery means being synchronised whereby in use, upon rotation of said 
rotary cam means and said rotatable weft yarn delivery means displacement 
of said needles causes chain stitches to be made which are fed inside said 
cylinder, and said rotatable weft yarn delivery means delivers said weft 
yarn outside said needle as said needles rise and the tension in said weft 
yarn pulls it over the top of the needle when it descends to be trapped in 
a subsequent stitch which falls behind the needle as the stitch is made. 
Preferably, said needle includes a pivotable latch for preventing said weft 
yarn from being hooked by said needle on a downward stroke. Conveniently, 
said grooves are disposed in an outer wall of said hollow cylinder and 
said needle hooks face outwardly. 
Preferably also, the knitting head and needle grooves are generally 
vertically disposed and the warp yarn is fed to said knitting head in a 
generally vertical direction. 
Conveniently, said rotatable weft yarn delivery means comprises a generally 
planar horizontal weft yarn rotatable feeder and deflector element, said 
rotatable feeder and deflector element being coupled to a rotatable hollow 
yarn delivery tube which is adapted to be driven by drive means, said tube 
and said rotating feeder and deflector having passage means through which 
a weft thread can be fed to be disposed outside the needles as they rise. 
Conveniently, the deflector includes an outer cam portion for deflecting 
the warp yarn outside the periphery of the hollow cylinder as said 
deflector rotates. 
Accordingly, in another aspect of the invention there is provided a 
knitting machine comprising: 
warp yarn delivery means for delivering a plurality of warp yarns to at 
least one knitting head, said knitting head being disposed in a knitting 
head frame and the knitting head receiving a plurality of warp yarns, said 
knitting head frame having a plurality of weft yarn package holders 
disposed at a remote position from said knitting head, at least one 
package holder being adapted to supply said at least one knitting head 
with weft yarn, and a fabric take-off roll disposed in said knitting head 
frame for receiving knitted fabric from said knitting machine. 
Conveniently, said knitting machine has a plurality of knitting heads and 
said warp is driven by warp drive rollers and said warp yarn is fed across 
to said knitting head frame via a warp sheet. Conveniently also, yarn 
tensioning devices are provided for controlling the tension of each yarn 
fed to respective knitting heads. 
Alternatively said knitting machine has a single head and said warp yarn is 
fed to said single head from a creel having a plurality of package 
holders. 
Accordingly, in yet another aspect of the invention there is yet provided a 
method of knitting a tubular fabric using the knitting head as defined 
above comprising the steps: feeding a plurality of warp yarn threads to a 
knitting head; feeding at least one weft yarn inside said knitting head 
from a remote location outside said knitting head; passing the weft yarn 
from the inside to the outside of said knitting head and disposing said 
weft initially around the periphery of said knitting head by a rotary 
movement outside said needles as they arise, and synchronising the 
movement of needles with respect to the rotating weft yarn delivery means 
within said knitting head to cause the weft yarn disposed around the 
periphery of said knitting head to be trapped between successive stitches 
of said warp yarn and to fall behind the needle as a stitch is made to 
create a tubular structure. 
Conveniently, said method includes the step of feeding the warp and weft 
yarns from a remote stationary location. Preferably said warp yarns are 
fed vertically downwards to vertically disposed knitting heads. 
Conveniently also, two weft package holders are provided for each knitting 
head and the package holders are adapted to be tied together to provide 
substantially continuous knitting by each knitting head to produce a 
continuous tubular fabric. 
According to yet another aspect of the present invention there is provided 
warp yarn positioning apparatus when used in a high speed knitting 
apparatus comprising a knitting head having a plurality of needles, each 
of said needles being movable in a needle trick, said warp yarn 
positioning apparatus comprising a plurality of warp yarn guides each 
guide defining an aperture for receiving a respective warp yarn passing 
therethrough and for containing and controlling movement of each of said 
warp yarns, each warp yarn guide being mounted above a respective needle, 
at least one yarn deflecting means being adapted to rotate around said 
knitting head for engaging said warp yarn and for deflecting said yarns 
across said apertures from a first position to a second position such 
that, in said second position, each of said yarns is trapped by its 
respective needle as it descends. 
Preferably, said guide is a hardened wire staple. 
Conveniently, each of said guides are mounted in a common place on a 
shallow, cylindrical stationary dial, said dial being disposed above said 
knitting head. 
Preferably also, said yarn deflecting means is a planar placing element, 
said planar placing element being movable around said knitting head and 
passing above each of said guides. Alternatively, the placing element can 
pass beneath the shaped aperture. 
Conveniently, a plurality of placing elements are mounted on an elongate 
member connected to a cam box, said placing elements being associated with 
a cam of said cam box and said cam box being rotatable around said 
stationary dial.

Reference is first made to FIG. 1 of the drawings which depicts a high 
speed knitting machine generally indicated by reference numeral 10 in 
which warp yarn 12 is fed from a warp drum 14 driven by warp drive rollers 
16 across a generally horizontally warp sheet 20. Tensioned warp yarns are 
downwardly of each of a plurality of knitting head 22 disposed at the top 
of a knitting head frame 24. This involves guiding the yarn around the 
needles to appropriate positions which facilitate knitting by yarn 
positioning apparatus as will be later described in detail. At the side of 
the knitting head frame 24 is disposed a plurality of weft yarn package 
holders 26 and the weft yarn 27 is also fed inside respective knitting 
heads on the frame. The tubular fabric is knitted, as will be later 
described in detail and the tubular fabric is supplied to fabric take-off 
rolls 28 for storing the knitted tubular fabric. 
It will be appreciated that there is a plurality of separate knitting heads 
disposed in relatively close proximity on a single knitting head frame and 
the weft yarn package holders 26 are disposed at the side of the frame and 
one pair of weft package holders can be used to supply a single knitting 
head. Alternatively, a single package holder can be used to supply a 
single knitting head. 
It will be understood that an advantage of this arrangement is that the 
tail of one package can be tied onto the free end of the next creel to 
provide substantially continuous knitting of the tubular fabric and also 
that the knitting heads are limited to a relatively small area minimising 
the volume and weight requirements. 
Reference is now made to FIGS. 2 and 3 of the drawings which show a 
knitting head 22 incorporating warp yarn positioning apparatus in 
accordance with an embodiment of the present invention. The knitting head 
22 comprises a cylinder 34 mounted inside a rotatable cylindrical cam box 
36. Spaced around the periphery of cylinder 34 are a plurality of needle 
tricks 38. A needle 40 is mounted in each needle trick 38 and each needle 
40 is movable up and down the needle trick 38 by a mechanism, not shown in 
the interest of clarity, to facilitate the knitting process. Rotatable 
weft yarn delivery means are disposed between the hollow cylinder 34 and 
the stationary warp yarn delivery means 20 for delivering a weft yarn 27 
from a remote location outside the cylinder 34 from the inside to the 
outside of the rotatable weft yarn delivery means so that the weft yarn 27 
is laid down outside each successively rising needle 40. An example of a 
suitable weft yarn delivery means is shown in FIG. 8. 
Mounted above the cylinder 34 is a shallow cylindrical dial 42. The dial 42 
has disposed around the circumference of its outer wall a number of yarn 
guides 44 in the form of hardened wire stapled which are easy to produce 
and to locate on the dial 42. Each yarn guide 44 is disposed above a 
needle trick 38 and defines with the dial wall, an aperture 45 for 
receiving the yarn so that movement of the warp yarn 12 is guided within 
the aperture 45 around the needle 40 as will be described. 
Mounted on the rotatable cam box 36 is an upstanding elongate member 46. 
The member 46 lies adjacent to the cylinder 34 and dial 42. Mounted on top 
of member 46 is a planar placing element or deflector 48 which has a 
curved edge portion 49 for engaging the yarn 12 as seen in FIG. 3. 
The placing element 48 is rotatable around the dial 42 with the cam box 36 
as it rotates around the cylinder 34. The placing element thus passes 
above each guide 44 and causes movement of the position of the yarn 12 
within the aperture 45 within the wire guide 44 as will be described. 
Reference is now made to FIG. 4 of the drawings which is an enlarged view 
of part of the knitting head 32 showing one needle trick 38 and wire yarn 
guide 44. The yarn guide 44 is adjustable and is held in place by fixing 
screw 55. The guide has a first straight wire portion 51, a curved portion 
53 which returns to the dial wall. Yarn 12 is shown tensioned and held to 
one side of the guide 44 where it is retained at a first corner 50 of the 
guide 44 between the straight portion 51 and curved portion 53. The curved 
edge portion 49 of the placing element 48 lies intermediate portions 57 
and 59 and is proportioned to move the yarn from the corner 50 around 
portion 53 of the guide 44 so that the yarn can be trapped by a needle 40 
as will be later described. 
In operation, as the cam box rotates in the direction A as shown, the 
placing elements 48 passes above the yarn guide 44 and the portions 57 
engages the yarn 12 which is pushed around the internal rim of curved 
portion 53 of the yarn guide 44 to a second corner 52, defined by the 
portion 53 and dial wall. The yarn is secured on the hook 56 of needle 40 
as best seen in FIGS. 5a and 5b before the trailing end 54 of the placing 
element passes over the guide 44. The yarn 12 is trapped in the hook 56 
until the trailing end 54 of the placing element 48 has passed over the 
guide 44. 
Reference is now made to FIGS. 5a, 5b of the drawings which are 
diagrammatic side and front elevational views of the placing element 
engaging the yarn during operation of the apparatus. FIGS. 5a and 5b show 
that before placing element 48 passes over guide 44 the tensioned yarn 12 
is positioned and retained in the first corner 50 of guide 44. 
The yarn 12 passes down one side of the needle 40 in the raised position. 
As the placing element 48 rotates, the yarn, shown in broken outline, is 
pushed around the guide 44 to the second corner 52 best seen in FIG. 5b 
where it now lies across the raised needle 40. As described above, the 
yarn 12 will stay in this position until the placing element 48 is no 
longer above the guide 44. Before the placing element 48 has passed over 
guide 44 the needle 40 descends, the hook 56 traps the yarn 12 and pulls 
the yarn down into the previous chain stitch of chain stitches 58. When 
the placing element is no longer above the guide 44 the yarn will return 
to rest in first corner 50 of the guide 44 ready to receive the next pass 
of the placing element. This procedure is repeated for each needle around 
the periphery of the dial as the placing element 48 rotates with the cam 
box 32. 
Reference is now made to FIG. 7 of the drawings which depicts a knitting 
head in accordance with an alternative embodiment of the present 
invention, which is mounted on a knitting frame in the same manner as the 
knitting heads 22 as shown in FIG. 1. Each knitting head 32 consists of a 
vertically disposed hollow cylinder 60 which in turn is mounted in a cam 
box 62. The cylinder 60 is fixed and on its exterior periphery a plurality 
of vertical grooves 64 are disposed spaced equidistantly around the 
circumference of the cylinder 60. As will be later described in detail, 
the grooves, or "tricks", as they are known in the art and each contain a 
single needle 66 for performing the knitting operation. Disposed above the 
cylinder 60 are the warp and weft yarn feeding means. The warp yarn 
feeding means is provided via a plurality of radially disposed feeding 
elements 68 of which two are shown in detail. Each warp feeding element 
consists of a generally horizontal bar having an aperture 69 therein 
through which the warp yarn passes to be gathered by the needle 66 as will 
be described. The warp yarn feeding elements 68 are stationary and are 
secured to the knitting frame. 
As best seen in FIGS. 7 and 8 the weft yarn feeding means consists of two 
parts, the first part is a generally vertically disposed tube 70 which is 
mounted on bearings 72 within a tube support 74. The tube 70 is rotatable 
by a timing pulley 76 coupled to a timing drive belt 78 and coupled to the 
bottom of the tube 70 is a generally planar weft yarn feeder and warp yarn 
deflector generally indicated by reference numeral 80. The deflector has a 
channel 82 therein which communicates with the interior 71 of the tube 70 
through which the weft yarn 27 can be fed to the tail 84 of the feeder and 
thence to the knitting head. It will be appreciated that the deflector 80 
has an arcuate portion 86, parts of which extends beyond the outer radius 
of the cylinder 60, and this is for deflecting the warp yarn sideways 
beyond the periphery of the cylinder 60 during the knitting process to lay 
down the weft yarn 27 in a spiral fashion as will be described. It will be 
appreciated that the timing belt and timing pulley cause the tubular 
portion 70 and deflector 82 to rotate simultaneously and this rotation is 
synchronised with the rotation of the cam box which causes the needles to 
be displaced vertically upwards and downwards within the respective 
grooves as will be described. 
Reference is now made to FIGS. 9a through g of the drawings which depicts 
the operation of a single needle to knit part of a tubular fabric. It will 
be appreciated that the other needles in the knitting head operate in an 
identical manner. FIG. 9a depicts a warp yarn 12 fed through the aperture 
69 of the stationary warp feeder element 68 to the needle 66 and then to 
the fabric 88 consisting of a chain stitch. In this figure the needle is 
shown totally within the groove 64. It will be seen that the needle 
carries a pivotable latch 90 for preventing inadvertent hooking of the 
elastic weft yarn as will be described. 
Reference is now made to FIG. 9b which shows the needle 66 rising after the 
passage of the deflecting element 82 which causes the warp yarn 12 to be 
deflected outwards away from the needle 66 and simultaneously the weft 
yarn is laid on the open side or outside of the needle hook 67. After the 
passage of the deflecting element 82 the needle 66 rises further leaving 
the weft yarn 27 on the open latch 90 and permitting the warp yarn 12 to 
return to its original position. 
As the needle continues to rise as best seen in FIG. 9d the latch 90 slips 
from beneath the thread 27 and pivots upwardly to its unrestrained 
position but is prevented from closing the needle hook 69 by a latch stop 
92 disposed on the element 68. It will also be seen in FIG. 9e that the 
latch 90 has returned to a downwardly oriented position. The warp thread 
27 remains outside the needle 66 and lies under the open latch 90. As the 
needle descends as shown in FIG. 9f the latch is closed by the old stitch 
and the weft yarn 27 thus preventing the weft yarn 27 from being snagged 
in the hook 67. 
When the needle has been retracted into the groove 64 the tension in the 
weft yarn 27 pulls it over the top of the needle 67 so that it falls 
behind the needle towards the centre of the cylinder, and on the next 
ascent of the needle for the next stitch, the weft yarn is trapped between 
successive stitches. When this is repeated for each needle in the knitting 
head a tubular fabric results which consists of a plurality of vertically 
disposed chain stitches coupled by a spirally wound weft yarn which is 
made of an elastic fabric. Depending on the number of cams fitted in the 
cam box the needle will continue to knit plain chain stitches until the 
next circuit of the feeder. 
As the tubular fabric is knitted it is fed out as aforedescribed to the 
fabric take-off roll 28. 
Reference is now made to FIG. 6 of the drawings which depicts part of a net 
fabric knitted with the knitting head shown in FIGS. 7, 8, 9a-9g. It will 
be seen that the yarns 12 cross the elasticated weft yarn 27 which is 
spirally wound obliquely. If an end of warp yarn thread is pulled the 
thread unravels clear of the fabric. 
Several modifications can be made to the first embodiment hereinbefore 
described without departing from the scope of the invention. The wire 
guide and curved surface of placing element could be of any suitable shape 
as long as their engagement causes the yarn to be placed across the needle 
in such a position that it is trapped in the hook on the descent. The 
placing elements could also pass beneath the shaped aperture to move the 
yarn. Any suitable number of placing elements could be mounted around the 
cam box, one element per cam, as required to increase the number of 
stitches between inlays. Any number of needle tricks can be mounted around 
the cylinder with each needle trick having a corresponding yarn guide 
disposed above the trick on the dial. The yarn guide needs only to define 
an approximately horizontal shaped aperture to control the movement of the 
yarn. It will be understood that the yarn positioning apparatus may be 
used with a single head circular knitting machine fed from a creel as well 
as with a multiple head circular knitting machine fed from a beam. 
This involves guiding the yarn around the needles to appropriate positions 
which facilitate knitting by yarn positioning apparatus as will be later 
described in detail. 
It will be appreciated that modifications may also be made to the second 
embodiment hereinbefore described without departing from the scope of the 
invention. For example, it will be understood that the number of needles 
and the type of stitching may be varied as required to knit different 
tubular fabrics. In addition, it will be appreciated that the weft or warp 
threads could be doubled to provide a heavier stitch and the rotation rate 
of the deflector and rotary cam box drive can be varied although it has to 
be synchronized to permit a satisfactory knitting operation. It will also 
be appreciated that other means may be used to prevent the hook 67 from 
snagging on the yarn during the downward stroke although the present 
arrangement is straightforward and elegant in its simplicity. It will also 
be appreciated that the warp and weft yarns may be made of elastic or 
non-elastic materials although the warp yarn is generally non-elastic and 
the weft yarn is elastic. Also, two or more packages may be used to supply 
a single knitting head and this number can be varied. It will be 
appreciated that the knitting heads could be disposed in a non-vertical 
orientation, for example, horizontally and, if so the warp yarns also fed 
to the knitting heads horizontally. 
As with the first embodiment it will be understood that a single knitting 
head could be used which is fed from a creel containing two or more 
packages instead of a beam or frame. 
Advantages of the invention are that high speed knitting of a tubular 
fabric can be achieved in a simple and efficient manner. The knitting can 
be made continuous by simply tying the end of one package to the beginning 
of another package and this avoids the necessity for stopping and 
reloading the machine every time the package runs empty with the results 
that retensioning or resetting is also avoided. A plurality of knitting 
heads can be disposed in a single frame in proximity to each other to 
minimise the space requirements and to facilitate inspection of the 
machine and also production of the tubular fabric. 
The yarn positioning apparatus is relatively inexpensive and uses a minimal 
number of moving parts. The yarn is positioned across the needle as it is 
tensioned minimising wear and tear of the knitting elements and yarn. 
Splitting of the yarn and the dropping of stitches is minimised. High yarn 
tensions are possible and hence the apparatus can be used with high speed 
knitting machines.