JUKI lbh-1790 series Engineer's Manual page 53

Adjustment Procedures
1. Lightly loosen idler fixing screw 1 and idler fulcrum hinge screw
2, and tighten idler fixing screw 1 in the state that idler 4 is
placed to timing belt 5 by pressing with tension spring 3.
Then fix idler fulcrum hinge screw 2.
(When idler 4 is placed by pressing with tension spring 3,
100 to 120N is obtained. The tension of timing belt can be
stabilized by lightly pressing and slowly setting free timing belt
5 in the state that idler fixing screw 1 in idler 4 and idler
fulcrum hinge screw 2 are lightly loosened.
(Caution) When the screws are excessively loosened, tilt of
idler 4 occurs and the assembling may be
performed in the improper state. Or, when turning
the main shaft several times by hand, timing belt
5 may be put on one side. So, be very careful.
Results of Improper Adjustment
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