Chair Assembly with a Seat-Adjusting Device

A chair assembly comprising:

• a supporting frame having
• two mounting bars and each mounting bar having a front end and a rear end;
• and
• a pivot shaft mounted rotatably on the front ends of the mounting bars and having two ends;
• a backrest frame mounted securely on the mounting bars of the base frame;
• a seat frame mounted pivotally on the base frame and having
• a seat bar;
• two front connecting members mounted securely and respectively on the ends of the pivot shaft and mounted pivotally on the seat bar;
• and
• two rear connecting members mounted pivotally and respectively on the mounting bars of the base frame and mounted pivotally on the seat bar;
• a seat-adjusting device mounted between the base frame and the seat frame, selectively rotating the pivot shaft to move the seat bar backward or forward relative to the base frame and having
• a hinge mounted pivotally on one of the mounting bars of the base frame;
• an adjusting bolt mounted rotatably on the hinge and having
• a connecting end mounted rotatably on the hinge;
• and
• an adjusting end defined opposite to the connecting end;
• a nut screwed movably around the adjusting bolt;
• a transmission linkage mounted pivotally on the nut and mounted pivotally on the other mounting bar that is opposite to the hinge;
• and
• a driven linkage having two ends, one end connected pivotally to the transmission linkage and the other end connected pivotally to the pivot shaft.