664,273. Frictional vibration - dampers. GAUDIN, C.. and SECHAUD, R. F. March 11. 1949. No. 6706/49. Class 108(iii) A shock-absorber for motor vehicles comprises a brake drum and cheeks operatively engaging with the drum, characterized by at least one control lever actuated by a member dependent on the drum and acting on the cheeks so as to provide braking of the drum only during the middle portion of each half of an oscillation, one oscillation corresponding to displacement of the drum from its normal position to an upper or lower extreme position together with its return to the normal position. In the arrangement shown in Fig. 2, relative rotation in either direction between a cam disc 7, carried in a brake drum and a pair of brake shoes carried on a back plate, actuates a cam 13 between the free ends 3a, 3a of the shoes, by means of a lever 10 and an arm 12. The free end of the lever 12 carries a roller 11, which during rotation of the drum co-operates with projections 7a or 7b on the cam disc 7. The initial position of the shoes relative to the drum is adjustable by means of a link 15 which is secured to the cam 13 and which is connected by means of a flexible cable to a handle located on the dashboard. In other arrangements, Figs. 3 and 4, (not shown, the lever bears directly on the cam disc the shape of which is also modified. In another arrangement, Fig. 5, (not shown), the free ends of the shoes are provided with bosses which bear against the lever. One of the bosses may be carried by the lever and engage a recess in the free end of the corresponding shoe. In similar arrangements, Figs. 6 and 7, (not shown), the free ends of the shoes are provided with a boss and a roller respectively. The arrangement according to Fig. 7 also includes alternative means for effecting initial adjustment of the shoes. In other arrangements. Figs. 8 and 9, (not shown), the ends of both shoes are provided with rollers. A further arrangement. Fig. 10, (not shown), similar to that of Fig. 5, includes a member which co-operates with the lever to effect initial adjustment of the shoes and the cam disc is recessed to permit assembly of the drum over the shoes. In an arrangement. Fig. 11, (not shown), similar to that of Fig. 2, the lever is bent substantially at right angles and bears on a roller carried at the end of an arm pivoted above the cam disc. In a somewhat similar arrangement, Fig. 12, (not shown), the free end of the bent lever is connected through a tension spring to the free end of a pivoted arm the other end of which carries a roller which bears on the cam disc. In a further arrangement, Fig. 13, (not shown), the free ends of the shoes carry rollers which bear against a wedgeshaped member which is carried by a lever arm at right angles thereto the lever arm being connected at its other end to one end of a pivoted arm which is parallel to the lever arm and which carries at its other end a roller which bears on the cam disc. In a modification, Fig. 14, (not shown), the lever comprises two arms fulcrumed together at one end and each carrying a roller at the other end, the free ends of both levers being resiliently maintained in contact with the shoes and cam disc respectively. In further arrangements, Figs. 15 and 16, (not shown), the cam disc is omitted and a lever which actuates a cam between the free ends of the shoes, cooperates with a pin secured to the wall of the drum. In another arrangement, Fig. 17, (not shown), the lever co-operates with a pin on the outside of the drum. In the arrangement shown in Fig. 18, the drum' is mounted on ball bearings and the brake shoes are pivoted independently. Both shoes are adjustable by means of a lever 101. An actuating cam 102 is connected to an arm 104 by means of a leaf spring 103.