Tilt assembly for a chair

A tilt assembly for a chair comprising:

• a tilt housing;
• a back support pivotally attached to the tilt housing about a first horizontal axis, said back support moveable between at least a first position and a second position wherein the second position is at a greater rearward tilt angle than the first position;
• a power pack moveably mounted to said tilt housing, said power pack adjustably moveable relative to said tilt housing, said power pack comprising a spring having a portion biasing said back support at a first location when said back support is in said first position and at a second location when said back support is in said second position, said second location being a greater distance from said first horizontal axis than said first location, wherein said power pack and an entirety of said spring are translatably moveable relative to said tilt housing between at least a first and second position.

A method for adjusting the biasing force supporting a chair body support member, said method comprising:

• providing a tilt assembly comprising a tilt housing, a body support member pivotally attached to the tilt housing about a first horizontal axis, said body support member moveable between at least a first position and a second position, and a power pack comprising a housing moveably mounted to said tilt housing and a spring mounted to said power pack housing, said spring biasing said body support member at a first location spaced from said first horizontal axis when said body support member is in said first position, and thereby applying a moment to said body support member about said first horizontal axis;
• and
• moving said power pack relative to said tilt housing and thereby moving said first location relative to said first horizontal axis, wherein said moment applied by said spring to said body support member is adjusted.