Shock resistant caster having pressure plates and centering projections

A caster comprising:

• a first structure adapted to be connected to a unit to be supported and having a top wall and two spaced side walls projecting downwardly therefrom;
• a second structure connected to said side walls of said first structure for pivotal movement relative thereto about a generally horizontal first axis, and having a generally horizontally extending pressure plate portion spaced beneath said top wall of said first structure;
• a wheel connected to said second structure for rotation relative thereto about a generally horizontal second axis which is offset from said first axis in a direction acting, when a load is imposed on the wheel, to cause relative pivotal movement of said structure about said first axis with downward movement of said first structure relative to said wheel;
• a cushion formed of elastomeric material positioned beneath said top wall of said first structure and above said pressure plate portion of said second structure and adapted to be compressed and resiliently deformed upon said load induced relative pivotal movement of said structures;
• said cushion having side surfaces at opposite sides thereof which face toward said two side walls respectively of said first structure and which have projections formed of said elastomeric material extending farther toward said side walls of said first structure than do other portions of said side surfaces of the cushion so that said side surfaces engage said side walls of the first structure only locally at said projections to essentially center the block between the two side walls and in a relation maintaining said other portions of said side surfaces in spaced relation to said side walls of said first structure, said projections occupying only a minor portion of the area of each of the side surfaces of said cushion to leave the side surfaces of the cushion free for lateral expansion at other locations toward the side walls of the first structure upon vertical compression of the cushion.

A caster comprising:

• a first structure adapted to be connected to a unit to be supported and having a top wall and two spaced side walls projecting downwardly therefrom;
• a second structure having a generally horizontally extending pressure plate portion and having two side walls projecting downwardly therefrom;
• a first pin extending horizontally through registering openings in said side walls of said first and second structures and connecting said structures together for relative pivotal movement about a generally horizontal first axis;
• a wheel connected to said side walls of said second structure for rotation about a second axis offset from said first axis in a direction acting, when a load is imposed on the wheel, to cause relative pivotal movement of said structures about said first axis with downward movement of said first structure relative to the wheel;
• a cushion formed of elastomeric material positioned beneath said top wall of said first structure and above said pressure plate portion of said second structure and adapted to be pressed downwardly against said pressure plate portion of said second structure upon imposition of a load;
• a second pin extending through openings in said side walls of said first structure and extending through a passage in said cushion;
• an additional element interposed vertically between said top wall of said first structure and said cushion and having a pressure plate portion engageable with the upper side of said cushion to compress and resiliently deform the cushion between said pressure plate portions when a load is imposed on the wheel;
• said additional element having two side walls which project upwardly from opposite edges of said pressure plate portion of said additional element and at inner sides of said two side walls of said first structure and which have upper extremities bearing upwardly against said top wall of said first structure in a relation maintaining said pressure plate portion of said additional element spaced beneath said top wall of said first structure and compressing said cushion between the two pressure plates upon imposition of the load on the wheel;
• said pressure plate portion of said additional element extending at an inclination upwardly toward said top wall of the first structure.