JUKI lbh-1790 series Engineer's Manual page 49

1. Removing the timing belt
1) Loosen two coupling setscrews 1. (LOCKTITE is applied to setscrews 1.)
2) Loosen four main motor installing screws 2 and remove main motor 3. (When main motor 3
interferes with the presser lifter motor and it is difficult to remove it, loosen four setscrews in the
presser lifter motor and slightly move the presser lifting motor to the side.)
3) Remove left side cover B 8, adjust the idler and loosen timing belt 4. (For the adjusting procedure
of the idler, refer to "5.- (4) Adjusting the timing belt of main shaft and hook driving shaft (idler)".
2. Assembling the timing belt
1) Be caraful of the position of idler section 5 and put sprocket 7 of main shaft 6 so that timing belt
4 is set to the proper position.
2) Assemble main motor 3 to the machine head and fix two setscrews 1 of coupling.
(Be sure to assemble it so that screw No. 1 is set to the flat section of main shaft.)
Apply LOCKTITE 242 to the screws after removing oil from them.)
3) Adjust the idler and fix timing belt 4 with the proper belt tension.
Refer to "5.- (4) Adjusting the timing belt of main shaft and hook driving shaft (idler)"
(Caution) When assembling timing belt 4, be sure to turn the sewing machine several times by
hand and check that timing belt 4 is not put on one side.
Procedures of disassembling/assembling
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