High load bearing for bridges and similar structures

Claim 1

In a high load bearing comprising upper and lower plates which do not substantially increase their lateral dimensions under load, a load bearing elastomer pad on the upper surface of said lower plate and the lower surface of said upper plate being on the upper surface of said bearing pad, said elastomer pad having a groove extending around its periphery and a cooperating bearing member constructed and arranged to substantially prevent shearing movement between said plates and thereby substantially prevent shearing of said elastomer pad but permitting rotational movement between said plates, the improvement comprising means mechanically abutting said load bearing elastomer pad to at least limit lateral expansion of the upper and lower surfaces of said elastomer pad under load without preventing bulging of said periphery, said mechanically abutting means comprising means projecting from said plates adjacent the periphery of said load bearing elastomer pad, and in which a lateral clearance is provided between said surface of said load bearing elastomer pad and said projecting means when said bearing is not under load, whereby said load bearing elastomer pad is permitted limited lateral expansion before abutting said projecting means.