Pro-Techtor-International Services
Support tube for an office chair
 A support tube for an office chair includes an outer tube, an inner tube fitted in the outer tube, and a shaft fitting movably in the inner tube. The inner tube has a spiral continual oil groove formed in an inner surfacer for a substantial portion, and an upper and a lower annular oil limit groove respectively connected with an upper end and a lower end of the spiral continual oil groove to stop lubricating oil in the spiral oil groove from flowing out of the inner tube so as to always enable the shaft rotate and move up and down smoothly relative to the inner tube. 
Jing-Dean Enterprises Co., Ltd.
A
A47C
inventional
Yung-Hsiang
Chen