Needle Avoidance Movement - Duerkopp Adler 550-12-12 Service Instructions Manual

2.7 Needle Avoidance Movement

a) b)
With needle avoidance movement (ellipse width) is meant the
movement, which the hook conducts in oder to pass in its movement
from right to left behind the needle and from left to right in front of the
needle.
The ellipse width is dependent on the needle system and the needle
thickness.
The ellipse width is correctly set when with hook movement from right
to left (see b )there is a clearance of 0.1 mm between hook tip and
needle.
With hook movement from left to right (see a )the needle should, in
the position shown, touch the back of the hook.
Calculation of the ellipse width:
E [mm]
a [mm]
b [mm]
0,1 [mm]
x [mm]
Example for a needle 934 Sin/ Nm 110
E = 0,7 + 1,4 + 0,1 + 0,1 = 2.3 mm
a = 0,7 mm Ellipse width
b = 1,4 mm Needle thickness in the area of the furrow
1,0 mm Clearance between hok point and needle
x = 0,1 mm Quantity by greater needle thicknesses
c)
E = a + b + 0,1 + x
Ellipse width
Needle thickness in the area of the furrow
Hook thickness in the area of the thread guide
hole at the hook tip
Clearance between hook tip and needle
with movement from right to left
Quantity by greater needle thicknesses
x = 0 for needles up to Nm 100
x = 0,1 for needles up to Nm 120
x = 0,2 for needles up to Nm 130
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