Abstract: A chair base includes a rigid base member having a plurality of elongate tubular leg members disposed angularly around and radiating outwardly from a central hub. Each leg member adjacent an outer free end thereof has a hub structure defining a through vertical bore for retaining the pintle of a caster. The hub structure includes coaxially aligned upper and lower sleevelike hub parts which are monolithically and integrally joined to and extruded transversely into the interior of the leg member from the respective top and bottom walls thereof. The pintle-retaining hub structure is formed by a pierce-and-extrude process whereby small pilot openings are initially formed through the respective walls, and the annular wall portion surrounding the respective pilot opening is thereafter transversely extruded to effect forming of the respective hub part. The pierce-and-extrude process for each hub part is, in a preferred process, carried out by a single forming tool.

Abstract: A synchrotilt mechanism for a chair to provide improved control over the relative but synchronized tilting of the back and seat during tilting. The chair back is supported on a rigid upright assembly including lower lever arms which project under the chair seat and are coupled at forward ends to a horizontal tilt shaft which is disposed under the front of the chair seat and is supported on a control housing fixed to the upper end of the base pedestal. A tension control mechanism is coupled between the tilt shaft and the control housing for normally urging the upright arrangement, and the chair back, into an upright position. The chair seat is movably supported on the lower lever arms by a support arrangement which permits the chair seat to pivot relative to the upright assembly about a generally transverse horizontal axis which is preferably slightly below the upper surface of the seat when the latter is in a nondeformed condition, i.e., the seat is not occupied.

Abstract: A chair base includes a rigid base member having a plurality of elongate tubular leg members disposed angularly around and radiating outwardly from a central hub. Each leg member adjacent an outer free end thereof has a hub structure defining a through vertical bore for retaining the pintle of a caster. The hub structure includes coaxially aligned upper and lower sleevelike hub parts which are monolithically and integrally joined to and extruded transversely into the interior of the leg member from the respective top and bottom walls thereof. The pintle-retaining hub structure is formed by a pierce-and-extrude process whereby small pilot openings are initially formed through the respective walls, and the annular wall portion surrounding the respective pilot opening is thereafter transversely extruded to effect forming of the respective hub part. The pierce-and-extrude process for each hub part is, in a preferred process, carried out by a single forming tool.

Abstract: A chair base includes a rigid base member having a plurality of elongate tubular leg members disposed angularly around and radiating outwardly from a central hub. Each leg member adjacent an outer free end thereof has a hub structure defining a through vertical bore for retaining the pintle of a caster. The hub structure includes coaxially aligned upper and lower sleevelike hub parts which are monolithically and integrally joined to and extruded transversely into the interior of the leg member from the respective top and bottom walls thereof. The pintle-retaining hub structure is formed by a pierce-and-extrude process whereby small pilot openings are initially formed through the respective walls, and the annular wall portion surrounding the respective pilot opening is thereafter transversely extruded to effect forming of the respective hub part. The pierce-and-extrude process for each hub part is, in a preferred process, carried out by a single forming tool.

Abstract: A synchrotilt mechanism for a chair to provide improved control over the relative but synchronized tilting of the back and seat during tilting. The chair back is supported on a rigid upright assembly including lower lever arms which project under the chair seat and are coupled at forward ends to a horizontal tilt shaft which is disposed under the front of the chair seat and is supported on a control housing fixed to the upper end of the base pedestal. A tension control mechanism is coupled between the tilt shaft and the control housing for normally urging the upright arrangement, and the chair back, into an upright position. The chair seat is movably supported on the lower lever arms by a support arrangement which permits the chair seat to pivot relative to the upright assembly about a generally transverse horizontal axis which is preferably slightly below the upper surface of the seat when the latter is in a nondeformed condition, i.e., the seat is not occupied.

Abstract: A chair base includes a rigid base member having a plurality of elongate tubular leg members disposed angularly around and radiating outwardly from a central hub. Each leg member adjacent an outer free end thereof has a hub structure defining a through vertical bore for retaining the pintle of a caster. The hub structure includes coaxially aligned upper and lower sleevelike hub parts which are monolithically and integrally joined to and extruded transversely into the interior of the leg member from the respective top and bottom walls thereof. The pintle-retaining hub structure is formed by a pierce-and-extrude process whereby small pilot openings are initially formed through the respective walls, and the annular wall portion surrounding the respective pilot opening is thereafter transversely extruded to effect forming of the respective hub part. The pierce-and-extrude process for each hub part is, in a preferred process, carried out by a single forming tool.