Abstract: A chair has a seat (4) and a backrest (5) which are independently pivotable within limits at extremities. The seat is biassed upwardly at the front and the backrest is biassed forwardly. The seat and the backrest have a common pivot joint (8), under the center of gravity of the occupant. There are no occupant-operated controls as the chair responds automatically to the posture of the occupant, providing full support at all relative positions of the seat and the backrest in a balanced manner for occupants of a wide range of weights.

Abstract: A chair has a seat and a backrest which are independently pivotable within limits at extremities. The seat is biased upwardly at the front and the backrest is biased forwardly. The seat and the backrest have a common pivot joint, under the center of gravity of the occupant. There are no occupant-operated controls as the chair responds automatically to the posture of the occupant, providing full support at all relative positions of the seat and the backrest in a balanced manner for occupants of a wide range of weights.

Abstract: An actuator for a chair mechanism lock moves locking members such as clutch leaves between an open position at which they are free to move relative to each other and a closed position at which they are pressed together. The actuator has a first arm which is connected on one side to the mechanism housing, and on the other side to a second arm. The second arm is in turn connected to the head of a bolt which engages the clutch leaves. The first arm incorporates a handle. In a relaxed position the actuator does not exert any pressure on the clutch leaves. To close the lock, the handle is pulled upwardly to bring the first and second arms over center at which they exert pressure on the clutch leaves.

Abstract: A chair tilting mechanism (1) is disclosed which has a fixed support (2), a seat support (3) and a backrest support (4). The seat support (3) is pivotally connected to the fixed support (2) by a pivot pin (5). The backrest support (4) is pivotally connected to the seat support (3) by a pivot pin (6). There is additionally provided a link (7) connected by pivot pins (8,9) to the backrest support (4) and the seat support (2). Because of the link (7), rotation of either the backrest or seat support causes the other of the backrest or seat support to tilt in a pre-determined synchronised manner. The manner in which synchronised tilting occurs is set by the interconnection of the various parts. The invention also provides a means (41) for pre-setting the interconnection.

Abstract: An adjustment mechanism (1) is disclosed which has a locking assembly (2) and an actuator (3). The locking assembly (2) is self-contained because it is biased by a spring (12) which acts between a housing (11) for the assembly and clutch leaves (5(a), 5(b)). The actuator (3) has a cam rod (15) which does not take any part in the clamping action on the leaves (5(a), 5(b)). There is a large mechanical advantage in the actuator (3) because the cam surface (17) is formed from a cut-out in the rod (15). A single actuator (45) may be used for two or more locking assemblies. Depending on configuration of the cam surfaces (48, 49), exclusive operation of one locking assembly may be achieved.