| 摘要 |
An adjustment mechanism is provided for manually positioning and releasably locking a chair backrest in a desired vertical position relative to the chair seat. The mechanism comprises a guide rigidly secured to an upright backrest support frame of a chair and a channel rigidly secured to the backrest. The channel is mounted for vertical sliding movement on the guide. The channel comprises a slot having a plurality of vertically arranged notches along one vertical edge of the slot, an inclined surface sloping downwardly from the lowest notch at the bottom end of the slot, and a cam surface, partially straight and partially curved, extending upwardly along the other vertical edge of the slot from the lower end of the inclined surface to the highest notch. A latch bar is pivotally mounted on a pivot pin on the guide and has a latch pin extending into the slot. A two-legged torsion spring mounted on the guide between the guide and channel biases the latch bar in a latched position wherein the latch pin releasably engages a notch to maintain the backrest at a selected height. Manually raising the backrest slightly above its highest latched position (lowest notch) engages the inclined surface with the latch pin to pivot the latch bar overcenter to spring-biased unlatched position. Then, manually lowering the backrest to its lowest position (highest notch) while the latch pin engages the curved portion of the cam surface pivots the latch bar from overcenter unlatched position back to a latched position wherein the latch pin engages the highest notch to maintain the backrest in its lowest position. From there, the backrest can be lifted one notch at a time to raised positions. |
| 申请人 |
MILSCO MANUFACTURING CO., MILWAUKEE, WIS., US |
发明人 |
DONOVAN, KYLE PATRICK, BROWN DEER, WIS., US |
