Split nut mechanical height adjusting mechanism for chair

摘要

A load-released height-adjusting mechanism coacting between the relatively rotatable spindle and pedestal of a chair. The mechanism employs a split nut threadably engaged with the pedestal. A wedge is continuously spring-urged into engagement with the nut for urging the sectors thereof radially for engagement with the threaded pedestal. The wedge is loaded downwardly by the spindle when the chair seat is occupied to cause the nut sectors to lockingly and nonrotatably engage the pedestal to permit free rotation of the spindle without effecting height adjustment. The wedge is not acted on by the spindle when the latter is in a raised position due to the chair seat being unoccupied, but the frictional treaded engagement between the pedestal and nut prevents free-wheeling of the chair while permitting manual rotation of the chair seat and nut to effect height adjustment.