Tubular springs composed of rubber or of a plastics elastomer

1,000,372. Rubber springs. K. PLANTA. May 15, 1962 [May 19, 1961], No. 18644/62. Heading F2S. A hollow spring constituted by a body of revolutions and made of rubber or elastic synthetic plastics material and of the kind having apertured ends for the reception of fastening members and a constriction 10 in one crosssectional plane which counteracts expansion of the elastic material is characterized in that the constriction subdivides the spring into unequal part-height portions 11, 12 when the member is in the non-loaded state. The spring has a low rate until the curved faces bear against one another when the spring characteristic rises steeply. The constriction 10 has an arcuate concave outer surface 10a and a knife-edged inner surface 10b. The outer wall surfaces of the upper and lower parts 12, 11 have arcuate and concave portions 12a, 11a respectively which are of larger radius of curvature than the surface 10a and which merge into frustoconical surfaces 14a, 13a at the upper and lower ends of the spring.