JUKI MF-7900 Series Engineer's Manual page 123

Adjustment procedures
1. Installing the connecting rod MC40
(1) Taking care of the vertical direction of the connecting rod, fix
the top end of the rod on motor lever A using the screw of ball
joint ❶ , and fix the bottom end of the rod on pedal lever B
using the screw of ball joint ❷ . Loosen fixing screws ❸ in the
connecting rod, and adjust the length of the rod properly.
2. Adjusting the connecting rod air valve MC40
(1) Loosen setscrew ❹ in the valve holder, and adjust the position
of air valve properly. The standard position of the air valve is
obtained when the valve pin lightly comes in contact with the
head of rivet.
(2) Make the sewing machine actuate, and check the response
time of the air valve. If it is too early, separate the valve pin
from the rivet head, and adjust the response time properly.
(3) Once the air valve is properly positioned, securely tighten set-
screw ❹ in the valve holder. At this time, check the position of
thrust collar ❺ so as to eliminate a play in the spring.
Results of Improper adjustment
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