THE CENTRE SHED JACQUARD MECHANISM
The centre shed jacquard
As the title suggests, the centre shed jacquard machine is built to produce a warp shed on the closed & centre shedding principle. It consequently merits all the advantage which characterizes this principle of shedding, but it also inherits all its defects.
A centre shed jacquard is very suitable for use in weaving figured gauzes where one or two dopes are placed in front of the harness mounting.
The chief details of mechanism in the centre shed jacquard are supplied in fig: 1; which is a line diagram, showing one row of upright and needles, together with a vertical section through the griffe blades and upper and lower reciprocating boards. A indicates the top and usual griffe bars’ the resting or suspension hook board free to rise or fall. The griffe A is connected to the spindle C at the position D and the board B is similarly connected to the second spindle E at the position F. The uprights are shown at G and the cross wires or needles at H. The usual card cylinder, needle board and spring box are also indicated.
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The diagram is painted and the cards cut in the usual way. There are two jacquard cross heads K and L and two head levers and reciprocating rods and a double throw eccentric as in double lift machines, but the eccentric is set screwed fast to the crank shaft, so that as the cross head K rises and falls, the cross head L falls and rises once for each pick of weft or revolution of the crank shaft.
Action of the mechanism
The crank shaft of the loom revolves as usual once, for every shot of weft. The cross head K raises with the spindle C and griffe A with all the hooks G that have been left over the griffe knives, according to pattern, to from the top warp shed. Simultaneously the cross head L with spindle E descends together with the bottom board B supporting all the hooks G that have been left clear of the top knives in griffe A ,according to pattern , to from the bottom shed. Then the weft is inserted and the griffe A descends whilst B ascends until the uprights G meet in the centre, irrespective of the position which they are to occupy on the next and succeeding picks of weft. The operation is similarly repeated for each shot of weft.
NOTE: In the given diagram the shed is fully opened.
