Flat knitting machine having a presser foot device

A flat knitting machine with a carriage movable over the needle beds has presser foot wires with free trailing ends arranged in holders to extend in the direction of travel of the carriage in front of the withdrawal positions of the needles. For simple construction and selective utilization of the presser foot device the holders for the presser foot wires are secured on a slider which slides along the needle beds on a thread guide rail, and the slider is selectively entrained by the carriage by means of entraining pins carried displaceably on the carriage. The holders for the stroking-in wires are preferably displaceable vertically towards the needle bed combs.

BACKGROUND OF THE INVENTION 
This invention relates to a flat knitting machine comprising a carriage 
movable over the needle beds and presser foot wires with free trailing 
ends mounted in holders so as to extend in the direction of travel of the 
carriage in front of the withdrawal positions of the needles. 
If thread combinations are to be produced on flat knitting machines, where 
the take-up device, for example in the form of take-up rollers, exerts 
insufficient influence, then presser foot wires are used which hold the 
stitches down as the needles are being withdrawn. The withdrawal of the 
needles takes place during knitting i.e. during the formation of stitches 
or loops, and upon transfer of the stitches. 
In known flat knitting machines which have a pressure foot device the 
holders for the presser foot wires are mounted on the carriage and are so 
arranged that they are always located in the direction of travel of the 
carriage in front of the withdrawal position of the needles. The presser 
foot wire lies between the needle bed combs and below the needles which 
cross upon withdrawal. The trailing wire ends must in each case be free. 
This means therefore that each presser foot wire can only be set into 
place for operation in one direction of travel of the carriage. In known 
flat knitting machines, pivotable holders arranged on the carriage have 
therefore been used for example, which each have a presser foot wire 
extending to the left and to the right and which, depending upon the 
direction of travel of the carriage, are pivoted to the left or to the 
right into the position beneath the crossing needles. In another known 
pressure foot device, for each direction of travel of the carriage, there 
is provided one presser foot wire which by means of its pivotable mounting 
on the carriage can be pivoted automatically into or out of a functional 
position. 
In another known presser foot device a presser foot wire overhangs its 
holder which is fastened to the carriage and at the positions of reversal 
of movement of the carriage is displaced across by the holder in such a 
manner that it overhangs on the appropriate side and such that it is 
brought into the presser foot position with a free trailing wire end. All 
the known presser foot devices are secured to the carriage so that they 
must always be in operation. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a flat knitting machine 
of the type first referred to above which has a presser foot device which 
is simple in construction, which can be selectively brought into operation 
by the carriage as desired, and which only moves jointly with the carriage 
if its function is necessary. 
This object is achieved in accordance with the present invention in that 
the holders for the presser foot wires are secured on a slider which 
slides along the needle beds on one of the thread guide rails, and in that 
the slider can be entrained selectively by the carriage by entraining 
means, such as pins, displaceably mounted on the carriage. 
The presser foot device of the machine of the present invention, controlled 
by the machine controls, is entrained by the carriage as the occasion 
demands, or is disconnected outside the working width of the flat knitting 
machine in the zone of carriage reversal. 
Preferably, the holders for the presser foot wires are displaceable 
vertically towards the needle bed combs, so that, depending upon the 
direction of carriage travel, the presser foot wire or wires provided for 
the next carriage traverse can be brought into their operative positions. 
Certain selected pieces of knitting, for example parts of pullovers, 
consist of a border and a patterned body part. The presser foot device is 
only required for the patterned body part, and needs to be suppressed 
during the knitting of the border. In the flat knitting machine of the 
present invention the presser foot device is disconnected as the occasion 
demands outside the working width within the carriage reversal zone and 
can be called back into action as necessary. Such a selective entrainment 
of the presser foot device can also be significant during the knitting of 
a body part, since for this the presser foot device is required several 
times or not at all. Since the holders for the presser foot wires in known 
presser foot devices are secured to the carriage, in those cases a 
selective introduction of the presser foot device is not possible. 
Preferably, lifting cams for raising the entraining pins are provided on 
the frame of the machine in the regions where the carriage reverses its 
direction of movement. Also, it is advantageous if one entraining pin is 
provided for each direction of travel of the carriage. 
The entraining pins preferably comprise an entraining or pick-up finger 
which during the traverse, opens a resilient inclined flap which 
constitutes part of the lifting cam on the machine frame, so that the 
traverse of the particular entraining pin which has been switched into 
operation is not hindered. 
Furthermore, indexing cams for vertical displacement of the holders for the 
presser foot wires are preferably provided in the region of the lifting 
cams, again on the machine frame, in order to displace the wires into and 
out of their operative positions. By means of these indexing cams on the 
left-hand and right-hand sides of the machine the particular presser foot 
wires which are in operation can be taken out of operation and the presser 
foot wires for the next carriage traverse can be brought into operation. 
In a preferred embodiment of the invention three vertically displaceable 
holders equipped with presser foot wires are provided for each direction 
of travel of the carriage.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The presser foot device of a flat knitting machine shown in the drawing 
comprises a slider 2 which slides on a thread guide rail 1 extending 
parallel to the longitudinal axis of the needle beds. Holders 3 for 
presser foot wires 4 for a working from right to left, as well as holders 
5 for presser foot wires 6 for a working from left to right, are mounted 
on the slider 2 for displaceable back and forth movement vertically 
towards the needle bed combs (not shown). In the operative position shown 
in the drawing the presser foot wires 6 for the working from left to right 
are located in their operative positions, while the presser foot wires 4 
are shifted out of their operative positions. 
On the carriage (not shown) of the flat knitting machine there are provided 
displaceable entraining pins 7 and 8 which have entraining fingers 9 and 
10 which lie within corresponding recesses 11 and 12 in the slider 2. 
At the two regions where the carriage undergoes a reversal of movement 
there are provided left and right lifting cams 13 and 14 on the frame of 
the machine. These lifting cams 13 and 14 ensure that there is a 
satisfactory alternation in the entrainment of the slider 2 of the presser 
foot device. 
Additionally, left and right indexing cams 15 and 16 are provided arranged 
on the frame of the machine at the two regions where the carriage 
undergoes a reversal of movement. By means of entraining fingers 17 and 18 
arranged on the respective holders 3 and 5 these indexing cams 15 and 16 
cause the vertical shifting of the holders 3 and 5 together with their 
presser foot wires 4 and 6 respectively. 
The two entraining pins 7 and 8, which are displaceably mounted on the 
carriage (not shown), are intended selectively to entrain or pick up the 
slider 2, and thus selectively entrain the presser foot device to move it 
in the two directions of travel of the carriage. If, for example, the 
carriage moves to the right, then the left-hand entraining pin 7 is 
engaged. It displaces the slider 2 to the right. The right-hand entraining 
pin 8 also lies within its recess 12, but it is at this time not carrying 
out any function. When the presser foot device reaches the region of the 
right-hand lifting cam 14, then the right-hand entraining pin 8 is lifted 
up. It runs along over the surface of the right-hand lifting cam 14 and 
slides down again into its recess 12 when it reaches the right-hand flank 
19 of the right-hand lifting cam 14. 
At this stage the left-hand entraining pin 7 becomes uncoupled as it 
travels up a resilient sloping flap 20 at the left-hand side of the 
right-hand lifting cam 14. The right-hand entraining pin 8 then takes over 
the task of the left-hand entraining pin 7, guides the presser foot device 
along through the right-hand carriage reversal, and drives the presser 
foot device back to the left. The left-hand entraining pin 7 lies within 
its recess 11 but has no function in this part of the cycle. 
Consequently, the right-hand entraining pin 8 is not uncoupled as the 
carriage moves to the left, and its entraining finger 10 slides in a 
groove 21 formed in the right-hand lifting cam 14. The resilient flap 20 
at the left-hand side of the right-hand lifting cam 14 opens as the 
entraining finger 10 traverses the groove 21, so that the entraining pin 8 
can carry out the traverse to the left without hindrance. At the left-hand 
position of reversal of the carriage a corresponding sequence of events 
takes place. 
The indexing cams 15 and 16 which are mounted on the left-hand and 
right-hand sides of the machine have the function of switching over the 
presser foot wires at the positions of carriage reversal, for example 
switching over the operative presser foot wires 6 to an inoperative 
position and switching over the presently inoperative presser foot wires 4 
to an operative position, and vice versa. 
FIG. 2 shows the entraining finger 10 of the right-hand entraining pin 8 
extending into the groove 21 of the right-hand lifting cam 14.