Pirn changing and weft replenishing motion
The following parts or attachments are found essential for operating this mechanism:
· A large shuttle and pirn with a few changes in the design.
· Changes in the design of the shuttle boxes and sley.
· A rotary magazine to accommodate 24 to 30 fully wound pirns.
· A feeler mechanism on the starting handle side to detect the almost exhausted weft pirn.
· A mechanism to push the fully wound pirn from the magazine into the shuttle and at the same time eject the empty pirn.
· A self threading device in the shuttle.
· A device to cut the two ends of weft at the selvedge of the cloth at the pirn changing side. Among the two weft ends, one of which from the outgoing almost empty pirn and the other from a new fully wound in going pirn.
· A mechanism known as shuttle protector, to prevent changing mechanism from fraying to insert a new fully wound pirn in the shuttle, should the shuttle fail to be exactly in the correct position for receiving the bobbin.
Mechanism:
The change shaft which runs across the width of the breast beam is partially rotated so as to impart an upward movement to the shuttle protector lever A, which contacts the peg B and gives a forward throw to the shuttle protector C. The latch depressor D which moves along with the protector C releases its hold on the peg E with the result that the peg follows the depressor under pressure from the latch spring F and ultimately always the latch G to swing upwards into line with the bunter H which is fixed on the sley front. Under normal running conditions the spring loaded transfer latch G is held in the depressed position by means of a peg E which resists against the latch depressor D.
As the sley moves forward for beating up of weft and the shuttle having reached the battery end, the bunter H engages the notch on the latch G, forcing it backwards against the resistance of the hammer coil spring S thereby depressing the transfer hammer I fulcrummed on the stud J, together with the transfer depressor K. During the downward movement, the hammer and the depressor K imparts a sharp blow to the fully wound pirn that is immediately underneath, held by the battery. When a full pirn is forced into the shuttle, it expels the almost empty pirn out of the shuttle, making it pass through the slots provided in the bottom of the shuttle and the box and fall into a container. The new pirn which is forced into the shuttle is firmly held in the spring jaws of the shuttle.
Connected to the transfer hammer (I) is the feed pawl L, the catch of which rests in one of the teeth of the ratchet wheel M. As the hammer is depressed for the transfer of the new pirn into the shuttle, it lowers the feed pawl L so that the catch slips into the next tooth of the ratchet wheel. As soon as the transfer of the pirn has taken place, the receding sley breaks the contact between the bunter and the latch and enables the hammer to move up to its original position due to the pressure of the hammer coil spring S, and in doing it pushes the feed pawl L upwards aided by a spring underneath the pawl, and turns the ratchet wheel M one tooth bringing the next full pirn in the battery right below the hammer for the subsequent transfer.
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