Patent GB-233765-A (GB)
Title: Improvements relating to the mounting of levers and the like upon their fulcrum-pins
IPC: B62M25/04
Filed: 1924-02-12
Abstract: 233,765. Doherty, J., and Doherty, J. Feb. 12, 1924. Control mechanism.-Relates to Bowden control and like lever mechanism of the type in which clutch or friction means are interposed between the lever and its fulcrum in order to prevent undue freedom or to render the lever selfretaining in any position, and comprises an arrangement wherein the hub or fulcrum end of the lever embodies a clutch box or chamber having a closed crown or top whereby the fulcrum post and clutch parts are wholly enclosed and concealed. Preferably the clutch parts are held in engagement by a spring exerting an upward thrust upon the lever and the clutch elements are of such a character that the effective surface of the element pertaining to the lever engages underneath the complementary surface on the fulcrum post. The co-engaging parts may be projecting segments formed in the lever hub and on the fulcrum post with flat or conoidal surfaces brought into engagement in the manner of a bayonet joint. Alternatively, a split-ring may be arranged around the fulcrum post and secured in the lever hub after assembly by set screws, or a complete ring may be placed upon the fulcrum post before this is secured to its base. In the first form, shown in Figs. 2 and 3 applied to a magneto or carburettor control for attachment to the handlebar of a motor-cycle &c., the fulcrum post b is formed with a pair of inverted conoidal lugs d separated by cylindrical gaps e, the opening in the lever hub a being formed with complementary conoidal lugs g separated by gaps, allowing the lever to be placed upon the fulcrum post as shown in Fig. 3, and to be retained thereon when rotated to bring the lugs g into engagement with the lugs d as shown in Fig. 2, the hub being formed with a closed top a<1> whereby the parts are enclosed and concealed. A spring f, seated in the fulcrum post as shown or arranged between the lever and base, presses the parts into engagement. To prevent unintentional disconnection in use, rotation of the lever is limited by screwing a stud j thereinto to co-operate with a shoulder j<1> on the base b<1>, or by means incorporated in the controlled mechanism. A number of levers may be arranged on the same fulcrum post, Fig. 8, the uppermost lever being secured in the manner already indicated. The lower lever k<1> may be seated on a conical bearing m and pressed thereon by the reaction of the spring n bearing against a loose cross-bar o extending through a transverse clearance p in the fulcrum post. In the form shown in Fig. 13, the fulcrum post b forms the frustum of an inverted cone and the co-operating clutch part comprises a divided ring g<1>, g<2> placed round the fulcrum and secured by set screws h to the lever boss a after this has been placed in position over the assembled clutch parts. Alternatively, a complete clutch ring may be passed on to the fulcrum post before this is secured to the base part by riveting or screwing and keying, the lever boss being subsequently secured to the ring by set screws as in the previous form.