Needle Avoidance Movement Of The Hook (Ellipse Width) - Duerkopp Adler 550-12-23 Service Instructions Manual

2. 9

Needle Avoidance Movement of the Hook (Ellipse Width)

1)
22
With needle avoidance movement (ellipse width) is meant that
movement which the hook conducts in order to move past behind the
needle during its movement from right to left and in front of the
needle from left to right.
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, there is a clearance of 0.1 mm between the hook tip and
the needle.
With hook movement from left to right the point of the downward
moving needle should touch the back of the hook at that moment when
the hook and the needle are in the position shown in illustration 1).
Calculation of the ellipse width
E [mm]
a [mm]
b [mm]
0,1 [mm]
x [mm]
Example for a needle 933
E = 0,7 + 1,4 + 0,1 + 0,1 = 2.3 m m
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 on the hook tip
Clearance between the hook tip and needle
by 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
Nm 120