Abstract: A backrest includes a back member having an upper and lower region and a frame member. A sacral support member has at least one end connected to one of the frame member and the back member and an opposite free end. The sacral support member supports the back member at the lower region thereof. A fulcrum member is moveably disposed between a portion of the sacral support member and one of the frame member and the back member. The fulcrum member is moveable toward and away from the free end of the sacral support member. A method for adjusting a backrest includes engaging a lower region of a back member with a sacral support member having a free end and a cantilevered length, engaging the sacral support member with a fulcrum member, and moving the fulcrum member toward and away from the free end of the sacral support member so as to thereby shorten and length the cantilevered length of the sacral support member.

Abstract: A tiltable chair including a housing, a back support pivotally attached to the housing about a first horizontal axis and a seat support pivotally attached to the back support about a second horizontal axis and moveably supported by a curved track formed on the housing. A leaf spring includes a first end supported by the housing and a second end biasing the back support and seat support in an upward direction. Preferably, a fulcrum member, which includes a support surface having a curvilinear contour, is moveably supported in the housing and engages a bottom surface of the spring intermediate the first and second ends of the spring. Preferably, a linkage mechanism including a first and second link is adapted to adjust the position of the fulcrum. In another preferred embodiment, a gear housing is removably disposed in said housing and coupled to the fulcrum. In one preferred embodiment, rearward and forward tilt limiters are provided.

Abstract: A tilt assembly comprising a tilt housing, a body support member pivotally attached to said tilt housing about a first horizontal axis and a spring mounted to said tilt housing at a second horizontal axis. The body support member is moveable between a first and second position. The second horizontal axis is adjustably moveable relative to the first horizontal axis. The spring biases said body support member at a first location when the body support member is in the first position and at a second location when the body support member is in the second position, with the second location being a greater distance from the first horizontal axis than the first location. A method for supporting a chair body support member is also provided.

Abstract: A tilt assembly comprising a tilt housing, a body support member pivotally attached to said tilt housing about a first horizontal axis and a spring mounted to said tilt housing at a second horizontal axis. The body support member is moveable between a first and second position. The second horizontal axis is adjustably moveable relative to the first horizontal axis. The spring biases said body support member at a first location when the body support member is in the first position and at a second location when the body support member is in the second position, with the second location being a greater distance from the first horizontal axis than the first location. A method for supporting a chair body support member is also provided.