Feed dog
Service Instructions 171/173 - 00.0 - 01/2020 31
7.3 Adjusting the retention spring on the hook
Fig. 19: Adjusting the retention spring on the hook
Proper setting
While the hook is moving from right to left, the needle thread loop (1)
must slide beyond the holding point (2) between retention spring (3) and
hook (4).
While the hook is moving from left to right, the needle thread loop (1)
will be held at the holding point (2) until the descending needle has
plunged into the thread triangle to the left of the needle thread loop (1).
When needle and hook (4) move to the top dead center and the bottom
position, respectively, the needle moves past the retention spring (3) at
a distance of approx. 0.5 mm.
To adjust the retention spring on the hook:
1. Align the retention spring (3) such that it abuts flush on the hook (4).
Make sure that the pressure is greatest in front at the holding point (2).
2. Loosen the screw (5).
3. Shift the retention spring (3).
Set the distance to 0.5 mm.
4. Tighten the screw (5).
Check the amount of contact pressure the retention spring (3) exerts on
the hook (4) when the machine is fully assembled and threaded.
To check the amount of contact pressure exerted by the retention spring (3):
1. Erect the machine head.
2. Turn by hand.
(1) - Needle thread loop
(2) - Holding point
(3) - Retention spring
(4) - Hook
(5) - Screw
To Next Page
Loading...
