ADJUSTMENT MECHANISM WITH TORQUE LIMITING AND ANTI-LOOSENINGFEATURES

摘要

An adjustable chair seat with a locking mechanism that is torque limiting and resistant to loosening. The chair includes a seat pan, a seat plate, a rotatable fastener and two rings. The seat pan and seat plate have openings for receiving the fastener. The fastener includes a cup handle and a threaded insert. The threaded insert is engaged with the seat pan through an opening in the seat pan while the seat plate is sandwiched between the seat pan and the fastener. When being rotated, the cup handle slips relative to t he threaded insert after a predetermined resistance is reached so as to cease the application of torque to the threaded insert. One of the rings is keyed to rotate with the fastener and the other ring is keyed to remain non-rotatable . The first ring includes an array of cantilevered teeth where each tooth has a first surface disposed at a smaller angle from a horizontal reference plane and a second surface which is disposed at a greater angle from the horizontal reference plane. This arrangement results in the requirement of a lesser torque to tighten the fastener than to loosen the fastener.