Zigzag Mechanism; Needle Bar Rocking Mechanism - Brother RH-981A Service Manual

1. MECHANICAL DESCRIPTIONS

1-4. Zigzag mechanism

1. When the pulley (1) is turned in the direction of the arrow, its motion is transmitted to the upper shaft (2) that
rotates the zigzag cam (3), and the zigzag fork (4) rocks.
2. The zigzag rock shaft (7) is rocked by the zigzag fork (4), via the zigzag connecting rod (5), and the zigzag crank
(6).
3. The rocking motion of the zigzag rock shaft (7) is transmitted to the zigzag lever (8), the needle bar lever feed link
(9), and the needle bar block clamp (10), those move the needle bar block (11) up and down.
4. The needle bar (12) is fitted on the needle bar block (11), and the needle bar guide (14) is fitted in the notch of the
needle bar block (11). When the needle bar block (11) moves up and down, the needle bar (12) oscillates.

1-5. Needle bar rocking mechanism

1. When pulse motor R (1) operates, the motion is transmitted to the driving needle pulley assembly (2), timing belt
D (3), and the looper pulley assembly (4), which then moves the driving looper shaft assembly (5).
2. The looper base (6) is rotated by the looper pulley assembly (4).
3. When the vertical shaft T pulley U assembly (7), which is attached to the driving looper shaft assembly (5), rotates,
the motion is transmitted to timing belt U (8), and the needle bar block assembly (9) that rotates the needle bar (10).
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RH-981A
3683Q
3684Q