JUKI lbh-1790 series Engineer's Manual page 55

1. Disassembling the face plate section
1) Remove the face plate and the needle.
2) Loosen setscrews 3 and 4 in needle bar rocking frame fulcrum shaft 1 and rocking frame support
shaft 2 and remove needle bar rocking frame 5.
(Remove the needle bar and neel bar bracket together with needle bar rocking frame 5.)
3) Loosen two fixing screws 7 in the thread take-up lever attached to counter weight 6.
4) Loosen two setscrews 9 in thread take-up crank shaft 8 and two setscrews !1 in thrust collar !0 ,
and remove thread take-up crank shaft 8.
5) Remove three setscrews !3 in square block base !2 and remove thread take-up lever (total asm
!4 . ) and square block base !2 as a set.
2. Assembling the face plate section
1) Set the set of square block base !2 and thread take-up lever (total asm !4 . ) to counter weight 6.
2) Fix the flat section of needle bar crank ! 7 of thread take-up lever (total asm ! 4 . ) so that it is set to
screw No. 2 side of fixing screws 7 attached to counter weight 6. Fix screw No. 1 side as well.
(The proper needle stroke cannot be obtained if screws No. 1 and No. 2 are attached in reverse
order.)
3) Put thrust collar !0 and temporarily put thread take-up crank shaft 8 in the machine head.
4) Temporarily tighten setscrew !3 in square block base !2 , turn main shaft !5 by hand, and fix setscrew
!3 in square block base at the position where link !6 can smoothly rock without uneven torque.
(Lightly put your hand on the upper hole section of link ! 6 , turn the sewing machine and rock the link
to the right and left to check the motion.)
5) Fix thrust collar !0 so that there is no longitudinal play of the thread take-up lever support.
(There is one flat section for thrust collar setscrew on thread take-up crank shaft 8.)
6) Fix thread take-up crank shaft 8 to the machine head at the position where main shaft ! 5 is turned
several times and it is stabilized.
(Fixing of thread take-up crank shaft 8 is performed at two places and the flat section is on the front
side.)
7) Set needle bar rocking frame 5.
(Insert it while being careful of the square block and the shaft section of needle bar bracket.)
8) Fix needle bar rocking frame fulcrum shaft 1 and needle bar rocking frame support shaft 2 so that
the thrust play does not occur at needle bar rocking frame 5. (Rock needle bar rocking frame 5 to
the right and left after closing the play and check that the rocking is not heavy.)
(Caution) Be sure to perform the break-in operation for nearly one hour when performing re-
arranging the face plate section, and check there is no noise or uneven rotation.
Procedures of disassembling/assembling
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