Abstract: A seat suspension system for supporting a seat support member on a base member includes support arms which cooperate with a spring suspension so as to suspend loads imposed on the seat. The support arms are connected to one of the seat support member and base member by a support mechanism. A cam element acts upon at least one of the seat support member and the base member and presents a cam surface offering a resistance to the motion of the accompanying cam follower which varies depending upon the height of the seat support member. The system preferably includes a height adjust mechanism for adjusting the unloaded distance between the seat support member and the base member. The height adjust mechanism may be either a ratchet mechanism which is operated by lifting the seat support member, or a spring assisted mechanism which is operable independently of the main suspension springs and which automatically biases an unloaded seat support member upwardly.

Abstract: A sprung seat suspension comprising a base frame; a seat carrier frame including height sensor assembly; linkage mounted on the base frame and operative to adjustably, vertically support the seat carrier frame with respect to the base frame and including an actuator which strokes the sensor assembly along a path during vertical movement of the seat carrier frame. A mover is mounted on the base frame and for adjustably vertically displacing the seat carrier frame from the base frame. An extension is connected to the height sensor assembly and the mover for selectively extending the mover. A retractor is connected to the height sensor assembly and the mover for selectively retracting the mover. The sensor assembly comprises a plurality of sensors positioned along the stroke path of the actuator which may be selectively independently activated to selectively activate the extension and retraction as the actuator strokes the sensor assembly.

Abstract: 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.