Upper Shaft And Tension Pulley Mechanism - Brother HE-800A Service Manual

3. ASSEMBLY

3-15. Upper shaft and tension pulley mechanism

4236Q
4238Q
1. Install the two retaining rings (1) to the upper shaft (2).
2. Press-fit the ball bearing (3) as far as the retaining rings (1). (Upper shaft assembly (4))
3. Place the timing pulley U assembly (5), timing belt (6), bobbin winder pulley (7) and set screw collar assembly
(8) onto the upper shaft assembly (4).
4. While pushing the timing pulley U assembly (5) against the retaining rings (1), secure it by tightening the two set
screws (9).
5. While pushing the bobbin winder pulley (7) against the timing pulley U assembly (5), secure it by tightening the
two set screws (10).
6. Install the thread take-up crank (11) to the upper shaft assembly (4) with the screw (12) and the set screw (13).
7. Secure the set screw collar assembly (8) to the upper shaft assembly (4) using the thread take-up crank (11)
and the two set screws (14) so that there is no play.
8. Provisionally install the tension pulley assembly (15) with the two bolts (15) and plain washers (17).
9. After installing the needle bar in "3-18. Needle bar and thread take-up mechanism (2)", set the phase between
the upper shaft and the lower shaft so that the mating mark A on the lower shaft timing pulley (18) is facing
straight down when the upper shaft assembly (4) is at the needle up stop position.
10.While pushing the tension pulley assembly (15) with a force of 100 N, secure it by tightening the two bolts (16).
11.Install the synchronizer assembly (19) to the arm with the two screws (20).
12.Install the pulley assembly (21) with the two set screws (22) so that the screw flat should align with the set
screw which comes first when the lower shaft is rotated in the rotation direction, and so that the clearance
between it and the synchronizer assembly (19) is 0.5 mm.
64
Upper shaft pulley
mating mark
HE-800A
Screw stop side
4237Q
4239Q