Side - lever Underpick
Mechanism
Construction
A side-lever underpick mechanism is shown in Figure 3.18. A circular disc A is fixed
to the bottom shaft B. The disc contains slots. A bowl C is fixed in one of the slots. A
side lever D, which is below the disc, carries a picking shoe E at the centre and is
connected to a bracket F and spring G at the back end. The bracket acts as a fulcrum
for the side lever. A guide H is used to guide the side lever during its motion. The
lower front end of side lever touches an elbow J, which carries the picking stick K. A
picker L is loosely mounted on the picking stick. The elbow is connected to a coiled
spring M, which is in a housing bracket. The elbow is connected at the bottom to a
rocking shaft N. A buffer is fixed to the side frame of the loom and a check strap is
fixed in the slot of a bracket provided below the shuttle box. The picker is kept in
contact with the tip of the shuttle O, when it is in the shuttle box.
 |
A - Circular disc
B - Bottom shaft
C - Bowl
D - Side lever
E - Picking shoe
F - Bracket
G - Spring
H - Guide
J - Elbow
K - Picking stick
L - Picker
M - Spring
N - Rocking shaft
O - Shuttle |
Figure 3.18 Side lever
underpick mechanism
A similar arrangement is provided on the other side of the loom. But the position of
the bowl on the circular disc is shifted by 180 degrees. So, for the first 180 degrees of
the rotation of the bottom shaft, the shuttle is delivered from one side and for the next
180 degrees, it is delivered from the other side. Thus one revolution of the bottom
shaft introduces two picks.
Working
When the bottom shaft rotates in the direction shown in the figure, the bowl also rotates
with the circular disc. As the bowl comes against the shoe, it strikes the shoe and thus
lowers the forward end of the side lever. This in turn hits the elbow down and the picking
stick moves towards the centre of the loom. The picker, loosely mounted on the stick,
moves and pushes the shuttle into the shed. At the end of the motion, the stick and the
side lever are returned to their original positions by their springs respectively.
A similar arrangement of parts is provided on the opposite side of the loom to enable
the return of the shuttle for the next pick. When the picking parts on one side of the
loom are in action, those on the other side are out of action. The check strap is used
to reduce the speed of the shuttle and prevent it from rebounding. The guide-bracket
guides the lever while it is moving. There is also a buffer to absorb the shock created
during the motion of the picking stick.
Settings
The picking action starts at 180° with the picking bowl coming in contact with the
shoe.
When the loom is activated manually, the stroke of the picker is set to a value that
depends upon the loom width. The relationship between the stroke of the picker and
the loom width is given below.
Reed space,
cm
40 44
48 52
56 60 64
Stroke of picker,
cm
27 28
28 29
30 31 31
The return spring of the picking stick should be so adjusted as to bring the stick back
to its original position after the picking is over. | 