Knitting technology, Third Edition

23.5
Single needle bar structures
In the following description, for purposes of simplicity it is assumed that only one
needle bar is being employed. Essentially, the principles remain the same for double
needle bar machines which are described later in the book (Chapter 29).
When the needle bar is observed in plan view from above, it can be seen that the
guides of a guide bar are required to execute a compound movement composed of
two separately derived motions (Figures 23.1 and 23.3):
A 
swinging motion
(A-A) and a 
shogging movement
(B-B) act at right-angles 
to each other in order for their threads to form overlap and underlap paths that
combine as one thread path around the needles.
The swinging motion is in an arc from the front of the machine to the hook side
and a later return swing. It occurs between adjacent needles and is a fixed, collec-
tive, and automatic action for all the guide bars as they pivot on a common rocker-
shaft. It is derived, in a similar manner to the needle and other element bar motions,
from the main cam-shaft and is adapted via levers, pivots and linkages. The two
swinging movements produce the two side limbs when combined with the overlap
Fig. 23.3
Guide bar swinging and shogging mechanism [Reprinted by permission of 
Knitting
Times
, official publication of the NSKA in the USA].

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Basic warp knitting principles
289
shog. When the overlap is omitted, the guides swing idly between adjacent needles
and achieve no useful purpose.
On some machines, such as mechanical jacquard raschels and some multi guide
bar and double needle bar machines, it is more convenient to swing the needle bar
and trick-plate between the guide bars after they have shogged for the overlap and
underlap. This considerably reduces the complexity of movement of the heavy guide
bar assembly to only that necessary for shogging and thus increases the speed and
efficiency of the machine.
The sideways shogging movement that occurs parallel to the needle bar produces
the underlaps and overlaps. The occurrence, timing, direction and extent of each
shog is separately controlled for each guide bar by its pattern chain links or pattern
wheel attached to a horizontal pattern shaft driven from the main cam-shaft but set
at right angles to it at one end of the machine. The guide bars are shogged inde-
pendently sideways, parallel to each other, along linear bearings that support them
in the swinging frame assembly, which is keyed to the guide bar rocker-shaft.
A shogging movement can occur when the guides have swung clear of the needle
heads on the back or front of the machine. On the hook side it will produce an
overlap and on the side remote from the hooks it will produce an underlap. The
timing of the shog during the 360 degrees of the main cam-shaft revolution will thus
determine whether an overlap or underlap is produced.