Brother RH-9820 Service Manual page 90

6. ASSEMBLY
E
Belt tension adjustment for needle bar gear block belt
Measurement position
0927B
81
1) Place the timing belt (8) onto the needle bar
gear block (a) and the vertical shaft timing
pulley U assembly (7), and then provisionally
install tension pulley U (14) so that it is gently
pressing against the timing belt (8).
2) Pull tension pulley U (14) in the direction of the
arrow to adjust the belt tension so that it is
within the ranges given below.
・ When using a new belt: 80 - 90 N
・ When reusing an old belt: 60 - 70 N
* Be sure to use a belt tension gauge to measure
the belt tension, and measure at the position
shown in the illustration.
* The belt tension gauge should be set to
measure a unit weight of 0.04 kg/m, a belt width
of 10 mm and a span length of 219 mm.
NOTE:
If you do not have a belt tension gauge, adjust
so that
approximately 3 mm when a pressure of 5 N is
applied to the middle of the span (the
measurement position shown in the illustration).
RH-9820
the amount of deflection is