The present invention relates to a switching apparatus for selectively engaging and disengaging a mechanism.
Chairs are known to have adjustment mechanisms for their various adjustable parts. For example, an angle a backrest makes with reference to a chair seat may be adjustable by an adjustment mechanism provided between the backrest and the seat. Similarly, the angle that the chair seat makes with reference to a seat support (and thus the floor) may be adjustable by an adjustment mechanism provided between the seat and the seat support. In order to control such adjustment mechanisms, a user operable switching apparatus may be provided.
A switching apparatus may employ a cam rotatable about a pivot by means of a handle. An example of such a switching apparatus is shown in U.S. Pat. No. 5,356,200 to Stumpf et al. In certain designs, the cam must bear a significant amount of force and, over time, the cam face may wear down. Excessive wear on the cam face may result in loosening of parts and early breakdown of the switching apparatus. It is thus desirable to design a mechanism with reduced mechanical wear on its key parts. U.S. Pat. No. 5,676,425 to Pernicka and U.S. Pat. No. 6,394,550 to Liu attempt to address this issue with a bearing plate against which the cam bears. However, the problem of cam wear remains.