Bearing pad and bridge construction

Claim 2

A BEARING PAD FOR SUPPORTING THE WEIGHT OF A LOAD BEARING MEMBER UPON A SUPORT STRUCTURE AND FOR COMPENSATING FOR AND ACCOMMODATING MOVEMENT OF A LOAD BEARING MEMBER RELATIVE TO A SUPPORT STRUCTURE AND BEING ADAPTED TO CONFRONT AND BEAR AGAINST A SLIDE PLATE SURFACE, SAID BEARING PAD COMPRISING A MAIN BODY PORTION, AN INTERMEDIATE LAYER AND A POLYTETRAFLUOROETHYLENE LAYER, SAID MAIN BODY PORTION COMPRISING AN ELASTOMERIC MATERIAL HAVING A DUROMETER OF FROM ABOUT 40 TO ABOUT 65 AND BEING ADAPTED TO BE SUPPORTED BETWEEN A SAID LOAD BEARING MEMBER AND A SAID SUPORT STRUCTURE, SAID MAIN BODY PORTION HAVING AN UPPER AND A LOWER SURFACE AND AT LEAST ONE EXPANSIVE SHIM PLATE LYING BETWEEN SAID UPPER AND LOWER SURFACES AND IMMEDIATELY UNDERLYING SAID INTERMEDIATE LAYER, SAID INTERMEDIATE LAYER COMPRISING A NON-METALLIC COMPRESSIBLE MATERIAL WHICH IS SUBSTANTIALLY LESS COMPRESSIBLE THAN SAID ELASTOMERIC MATERIAL AND WHICH HAS A GREATER TENSION LIMITING STRENGTH UNDER COMPRESSIVE LOADING THAN DOES THE UPPER PORTION OF SAID ELASTOMERIC MATERIAL, THEREBY TO RESTRICT TENSIONING OF THE POLYTETRAFLUOROETHYLENE WHEN THE BEARING PAD IS COMPRESSIVELY LOADED, SAID INTERMEDIATE LAYER BEING BONDED TO THE UPPER SURFACE OF SAID MAIN BODY PORTION IN CLOSE PROXIMITY TO THE UPPERMOST EXPANSIVE SHIM PLATE, SAID LAYER OF POLYTETRAFLUOROETHYLENE BEING BONDED TO THE UPPER SURFACE OF AID INTERMDEIATE LAYER AND PROVIDING AN UPPER SLIDE SURFACE ADAPTED SLIDABLY TO ENGAGE A CONFRONTING SLIDE PLATE SURFACE FOR SLIDABLY ACCOMMODIATING MOVEMENT OF A SIDE LOAD BEING MEMBER RELATIVE TO A SAID SUPORT STRUCTURE.

Claim 3

A bearing pad in accordance with claim 1 in which said intermediate layer is one of a relatively hard elastomer having a durometer of from about 80 to about 100, leather, rubber bonded asbestos sheet material and a non-rigid flexible epoxy material.

Claim 4

A bearing pad in accordance with claim 1 in which said intermediate layer is a relatively hard elastomer having a durometer of from about 80 to about 100 durometer.

Claim 5

A bearing pad in accordance with claim 3 in which the durometer of said intermediate layer is from about 85 to 95 durometer.

Claim 6

A bearing pad in accordance with claim 1 in which said main body portion is at least 1 inch thick, said shim plate is from about 3/32 to about 1/4 inch thick, said intermediate layer is from about 1/16 to about 1/4 inch thick and said polytetrafluoroethylene is a Teflon sheet which is at least about 1/16 inch thick.

Claim 7

A bearing pad in accordance with claim 5 in which said intermediate layer is an elastomer having a durometer of from about 85 to about 95, and in which said intermediate layer is spaced from a shim plate by a distance of no more than a distance of up to about fifty percent of the thickness of the intermediate layer.

Claim 8

A bearing pad in accordance with claim 6 in which said elastomeric material has a durometer of from about 45 to about 55.

Claim 9

A bridge construction comprising a fixed bridge support member and a load carrying bridge member mounted for movement relative to said fixed member, a bearing pad assembly positioned between said members to compensate for and to accommodate relative movement therebetween, said bearing pad assembly comprising a bearing pad secured to one of said members and a slide plate secured to the other of said members and confronting said bearing pad, said bearing pad comprising a main body portion, an intermediate layer and a polytetrafluoroethylene layer, said main body portion comprising an elastomeric material having a durometer of from about 40 to about 65 durometer, said main body portion having an upper and a lower surface and at least one expansive shim plate lying between said upper and lower surfaces and immediately underlying said intermediate layer, said intermediate layer being bonded to said main body portion and comprising a non-metallic compressible material which is substantially less compressible than said elastomeric material and which has a greater tension limiting strength under compressive loading than does the upper portion of said elastomeric material, thereby to restrict tensioning of the polytetrafluoroethylene when the bearing pad is compressively loaded and to provide for uniform load distribution under loading by the load carrying bridge member, an upper layer of polytetrafluoroethylene bonded to the upper surface of said intermediate layer and providing an upper slide surface adapted to slidably confront and engage said slide plate for compensating for and accommodating movement of said load carrying bridge member relative to said bridge support member.

Claim 10

A bridge construction comprising a fixed bridge support member and a load carrying bridge member mounted for movement relative to said fixed member, a bearing pad assembly positioned between said members to compensate for and to accommodate relative movement therebetween, said bearing pad assembly comprising a bearing pad secured to one of said members and a slide plate secured to the other of said members and confronting said bearing pad, said bearing pad comprising a main body portion, an intermediate layer and a polytetrafluoroethylene layer, said main body portion comprising an elastomeric material having a durometer of from about 40 to about 65 durometer, said main body portion having an upper and a lower surface and at least one expansive shim plate lying between said upper and lower surfaces and immediately underlying said intermediate layer, said intermediate layer being bonded to said main body portion and comprising a non-metallic compressible material which is substantially less compressible than said elastomeric material and which has a greater tension limiting strength under compressive loading than does the upper portion of said elastomeric material, thereby to restrict tensioning of the polytetrafluoroethylene when the bearing pad is compressively loaded and to provide for uniform load distribution under loading by the load carrying bridge member, an upper layer of polytetrafluoroethylene bonded to the upper surface of said intermediate layer and providing an upper slide surface adapted to slidably confront and engage said slide plate for compensating for and accommodating movement of said load carrying bridge member relative to said bridge support member.

Claim 11

A bridGe construction in accordance with claim 8 in which said intermediate layer is one of a relatively hard elastomer having a durometer of from about 80 to about 100, leather, rubber bonded asbestos sheet material and a non-rigid flexible epoxy material.

Claim 12

A bridge construction in accordance with claim 8 in which said intermediate layer is of a relatively hard elastomer having a durometer of from about 80 to 100.

Claim 13

A bridge construction in accordance with claim 8 in which said slide plate is highly polished stainless steel and is secured to said load carrying member.

Claim 14

A bridge construction in accordance with claim 11 in which said slide plate is bonded to an intermediate elastomeric cushioning layer which in turn is secured to said load carrying member.

Claim 15

A bridge construction in accordance with claim 12 in which said intermediate cushioning layer is bonded to a mounting plate which is secured to said load carrying member.

Claim 16

A bridge construction in accordance with claim 10 in which said main body portion is at least one inch thick, said shim plate is from about 3/32 to about 1/4 inch thick, said intermediate layer is from about 1/16 to about 1/4 inch thick and said polytetrafluoroethylene is a Teflon sheet which is at least about 1/16 inch thick.

Claim 17

A bridge construction in accordance with claim 14 in which said intermediate layer is an elastomer having a durometer of from about 85 to about 95, and in which said intermediate layer is spaced from a shim plate by a distance of no more than a distance of up to about fifty percent of the thickness of the intermediate layer.

Claim 18

A bridge construction in accordance with claim 15 in which said elastomeric material has a durometer of from about 45 to about 55.

Claim 19

A bridge construction in accordance with claim 15 in which said bearing pad is secured to said fixed bridge support and said slide plate is secured to said load carrying bridge member.

Claim 20

A bridge construction in accordance with claim 17 in which said slide plate is highly polished stainless steel and is bonded to an intermediate cushioning layer which in turn is secured to said load carrying member.