Spring mechanism for a tiltable member of a tilting chair

Claim 2

A spring mechanism for a tiltable member of a tilting chair having a base, said spring mechanism comprising a support member mountable on the base, a frame including side pieces, means connecting the frame to the support member for pivotal movement about a horizontal tranverse tilting axis, the latter said means comprising first and second torsion bars extending transversely of the side pieces of the frame, said first torsion bar extending in horizontal alignment with said transverse tilting axis, said second torsion bar being spaced rearwardly thereof, a first tubeshaped member secured to the support member, tube-shaped bearing sleeves secured to said side pieces of the frame and rotatably receiving said first tube-shaped member, a second tube-shaped member spaced rearwardly from said first tube-shaped member and secured to said side pieces of the frame, said first torsion bar extending longitudinally within said first tube-shaped member, said second torsion bar extending longitudinally and freely rotatably within the second tube-shaped member, means at one of the side pieces of the frame connecting one end of said first torsion bar non-rotatably to the first tube-shaped member, further means at said one side piece of the frame connecting one end of said second torsion bar non-rotatably to said one side piece, means at the other side piece of the frame operatively interconnecting the other of the ends of the first and second torsion bars so that as the frame is tilted both torsion bars will twist simultaneously and exert a combined resilient restraining force in opposition to the tilting movement of said frame, said means which operatively interconnects said other ends of the torsion bars comprising levers respectively fixed to said other ends of the torsion bars and extending towards one another, said levers having free ends freely overlapping one another, and contact means carried by one of said levers at said free end thereof and freely bearing against the free end of the other of said levers to provide a substantially point contact between said levers when they are moved relative to one another in one direction while permitting unhindered relative movement in the other direction, and stop means operatively cooperating between said frame and said support member for limiting the tilting movement of said frame relative to said support member in a direction opposite the normal direction of tilting of said frame.

Claim 3

A mechanisim as claimed in claim 1 wherein the support member is secured to the first tube-shaped member intermediate the opposite ends of the latter.

Claim 4

A mechanism as claimed in claim 1 comprising means connecting said contact means to said free end of said one lever for adjustment of the position of the contact means towards thE free end of the other lever.

Claim 5

A mechanism as claimed in claim 1 wherein said contact means comprises an adjusting screw threaded through the end of said one lever for contacting the end of said other lever, whereby adjustable pre-tensioning of the torsion bars may be effected by forcing the lever ends apart.

Claim 6

A mechanism as claimed in claim 1 wherein said levers are integral with their respective torsion bars and form a bent portion thereof.

Claim 7

A spring mechanism for a tiltable member of a chair having a base, said spring mechanism comprising a support member mountable on the base, a frame including side pieces, connecting means rigidly connecting the frame to the support member, a pivotal member adapted for connection with said tiltable member, means connecting the pivotal member to the frame for pivotal movement about a horizontal transverse tilting axis, the latter said means comprising first and second torsion bars extending transversely of the side pieces of the frame, said first torsion bar extending in horizontal alignment with said transverse tilting axis, said second torsion bar being spaced rearwardly thereof, a first tube-shaped member secured to the pivotal member, said connecting means including tube-shaped bearing sleeves secured to said side pieces of the frame and rotatably receiving said first-tube-shaped member, a second tube-shaped member spaced rearwardly from said first tube-shaped member and secured to said side pieces of the frame, said first torsion bar extending longitudinally within said first tube-shaped member, said second torsion bar extending longitudinally and freely rotatably within the second tube-shaped member, means at one of the side pieces of the frame connecting one end of said first torsion bar non-rotatably to the first tube-shaped member, further means at said one side piece of the frame connecting one end of said second torsion bar non-rotatably to said one side piece, means at the other side piece of the frame operatively interconnecting the other of the ends of the first and second torsion bars so that as the pivotal member is tilted both torsion bars will twist simultaneously and exert a combined resilient restraining force in opposition to the tilting movement of said pivotal member, said means which operatively interconnects said other ends of the torsion bars comprising levers respectively fixed to said other ends of the torsion bars and extending towards one another, said levers having free ends freely overlapping one another, and contact means carried by one of said levers at said free end thereof and freely bearing against the free end of the other of said levers to provide a substantially point contact between said levers when they are moved relative to one another in one direction while permitting unhindered relative movement in the other direction, and stop means operatively cooperating between said pivotal member and said support member for limiting the tilting movement of said pivotal member relative to said support member.

Claim 8

A spring mechanism for a tiltable member of a chair having a base, said spring mechanism comprising a support member mountable on the base, a frame including side pieces, connecting means rigidly connecting the frame to the support member, a pivotal member adapted for connection with said tiltable member, means connecting the pivotal member to the frame for pivotal movement about a horizontal transverse tilting axis, the latter said means comprising first and second torsion bars extending transversely of the side pieces of the frame, said first torsion bar extending in horizontal alignment with said transverse tilting axis, said second torsion bar being spaced rearwardly thereof, a first tube-shaped member secured to the pivotal member, said connecting means including tube-shaped bearing sleeves secured to said side pieces of the frame and rotatably receiving said first-tube-shaped member, a second tube-shaped member spaced rearwardly from said first tube-shaped member and secured to said side pieces of the frame, said first torsion bar extending longitudinally within said first tube-shaped member, said second torsion bar extending longitudinally and freely rotatably within the second tube-shaped member, means at one of the side pieces of the frame connecting one end of said first torsion bar non-rotatably to the first tube-shaped member, further means at said one side piece of the frame connecting one end of said second torsion bar non-rotatably to said one side piece, means at the other side piece of the frame operatively interconnecting the other of the ends of the first and second torsion bars so that as the pivotal member is tilted both torsion bars will twist simultaneously and exert a combined resilient restraining force in opposition to the tilting movement of said pivotal member, said means which operatively interconnects said other ends of the torsion bars comprising levers respectively fixed to said other ends of the torsion bars and extending towards one another, said levers having free ends freely overlapping one another, and contact means carried by one of said levers at said free end thereof and freely bearing against the free end of the other of said levers to provide a substantially point contact between said levers when they are moved relative to one another in one direction while permitting unhindered relative movement in the other direction, and stop means operatively cooperating between said pivotal member and said support member for limiting the tilting movement of said pivotal member relative to said support member.

Claim 9

A mechanism as claimed in claim 1 comprising means connecting said contact means to said free end of said one lever for adjustment of the position of the contact means towards the free end of the other lever.