Spring shackle assembly

Abstract

An improved spring shackle assembly is utilized in an improved vehicle suspension system and includes a pair of socket assemblies which connect an end portion of a leaf spring with a mounting bracket. Each of the socket assemblies includes a rigid metal housing having an inner surface which defines a socket chamber in which a bearing liner is disposed. Each of the bearing liners encloses a spherical end portion of a ball stud. Each ball stud has a generally cylindrical shank which extends into an opening formed in an end portion of the spring. In order to tend to minimize the sideward load applied to the mounting bracket, the bearing liners have spherical surfaces which cooperate with the spherical head ends of the ball studs so that offsetting axial or sidewise forces are applied to the bearing liners by the ball studs. The socket assembly has a unitary construction to facilitate assembly and to minimize the chance for dirt and other foreign materials to enter the socket chamber. In one embodiment of the invention, the bearing lines are integrally formed of a suitable polymeric material. In another embodiment of the invention the bearing liners are formed in two sections. One of the two bearing sections carries a larger bearing load and is formed of a material having a higher modulus of elasticity than the other bearing section.

Having described specific preferred embodiments of the invention, the following is claimed: 
     
       1. A spring shackle assembly for use in connecting an end portion of a leaf spring with the frame of a vehicle, said spring shackle assembly comprising a bracket connected with the frame of the vehicle, said bracket including a pair of mounting sections spaced apart by a distance which is at least as great as the width of the end portion of the spring and having surfaces defining a pair of coaxial openings extending through the mounting sections, a pair of rigid metal housings each of which is disposed in an associated one of said openings, each of said housings having an inner surface at least partially defining a socket chamber having a closed end portion and open end portion facing toward the space between said mounting sections, a pair of bearing liners formed of polymeric material, each of said bearing liners being disposed in an associated one of said socket chambers and having a spherical inner surface at least partially defining a bearing cavity having an open end facing toward the space between said mounting sections, a pair of ball studs each of which is associated with one of said bearing liners, each of said ball studs having a head end portion with a spherically shaped outer surface disposed in sliding engagement with the spherical inner surface of the associated one of said bearing liners and having a cylindrical shank portion integrally formed with an associated head end portion and extending outwardly through a socket chamber opening into the space between said mounting sections, said shank portions being disposed in axial alignment with each other and being disposed in an opening in the end portion of the leaf spring, each of said spherical head end portions having a circular medial surface area which is coaxial with the central axis of the associated shank portion and which extends for a substantial distance on both sides of a plane through the center of the spherical head end portion to provide abutting engagement between the circular medial surface area of the head portion of the ball stud and the spherical surface of the associated one of said bearing liners in an area which forms at least part of a sphere and curves inwardly toward the central axis of the shank portion of the ball stud on opposite sides of the plane through the central axis of the head portion of the ball stud to provide for the application of at least partially axially offsetting bearing forces between the ball stud head portion and said bearing liner upon the application of a load to the vehicle spring. 
     
     
       2. A spring shackle assembly as set forth in claim 1 wherein each of said housings includes an annular inwardly projecting lip means circumscribing the open end portion of a socket chamber for retaining the associated one of said bearing liners in said socket chamber. 
     
     
       3. A spring shackle assembly as set forth in claim 1 wherein each of said housings includes surface means defining an annular groove extending around the housing, said spring shackle assembly further including a pair of retainer members mounted on an associated one of said mounting sections in engagement with the annular groove in the associated one of said housings to retain the housing against movement relative to the associated mounting section. 
     
     
       4. A spring shackle assembly as set forth in claim 3 wherein each of said retainer members includes means for deflecting the associated mounting section to apply a clamping force to the associated housing. 
     
     
       5. A spring shackle assembly as set forth in claim 1 wherein each of said bearing liners includes a first section having a first modulus of elasticity and a second section having a second modulus of elasticity which is greater than said first modulus of elasticity, said spherical inner surface of each of said bearing liners being partially disposed on the first section of the associated one of said bearing liners and being partially disposed on the second section of the associated one of said bearing liners. 
     
     
       6. A spring shackle assembly as set forth in claim 5 wherein the head end portion of each of said ball studs is effective to apply a first bearing force to said first section of the associated one of said bearing liners and is effective to apply a second bearing force which is less than said first bearing force to said second bearing section of the associated one of said bearing liners. 
     
     
       7. A spring shackle assembly for use in connecting an end portion of a leaf spring with the frame of a vehicle, said spring shackle assembly comprising a pair of mounting sections spaced apart by a distance which is at least as great as the width of the end portion of the spring, a pair of housings each of which is connected with one of said mounting sections, each of said housings having an inner surface at least partially defining a socket chamber having a closed end portion and open end portion facing toward the space between said mounting sections, a pair of bearing liner sections disposed in each of said socket chambers with a first one of each pair of bearing liner sections being disposed adjacent to the closed end portions of the associated one of said socket chambers and a second one of each pair of bearing liner sections being disposed adjacent to the open end portion of the associated one of said socket chambers, said first and second bearing liner sections of each pair of bearing liner sections having spherical inner surfaces at least partially defining a bearing cavity having an open end facing toward the space between said mounting sections, a pair of ball studs, each of said ball studs having a head end portion with a spherically shaped outer surface disposed in sliding engagement with the spherical inner surfaces of the associated pair of bearing liner sections and having a cylindrical shank portion extending into the space between said mounting sections, said shank portions being disposed in an opening in the end portion of the leaf spring, said first bearing liner sections have a first modulus of elasticity and said second bearing liner sections have a second modulus of elasticity which is greater than said first modulus of elasticity, said first bearing liner sections being compressed so that they will expand to maintain tight engagement between the head end portion of the associated one of said ball studs and said second bearing liner sections to compensate for wear between the outer surfaces of said ball stud head end portions and said bearing liner sections. 
     
     
       8. A shackle assembly as set forth in claim 7 wherein each of said spherical head end portions has a circular medial surface area which has a substantial portion disposed in abutting engagement with the spherical surface of one of said first bearing liner sections and a substantial portion disposed in abutting engagement with the spherical surfaces of one of said second bearing liner sections. 
     
     
       9. A spring shackle assembly for use in connecting an end portion of a leaf spring with the frame of a vehicle, said spring shackle assembly comprising a pair of mounting sections spaced apart by a distance which is at least as great as the width of the end portion of the spring, a pair of housings each of which is connected with one of said mounting sectons, each of said housings having an inner surface at least partially defining a socket chamber having a closed end portion and open end portion facing toward the space between said mounting sections, a pair of bearing liner sections disposed in each of said socket chambers with a first one of each pair of bearing liner sections being disposed adjacent to the closed end portions of the associated one of said socket chambers and a second one of each pair of bearing liner sections being disposed adjacent to the open end portion of the associated one of said socket chambers, said first and second bearing liner sections of each pair of bearing liner sections having spherical inner surfaces at least partially defining a bearing cavity having an open end facing toward the space between said mounting sections, a pair of ball studs, each of said ball studs having a head end portion with a spherically shaped outer surface disposed in sliding engagement with the spherical inner surfaces of the associated pair of bearing liner sections and having a cylindrical shank portion extending into the space between said mounting sections, said shank portions being disposed in an opening in the end portion of the leaf spring, said head end portion of each of said ball studs being effective to apply to the first bearing liner section of the associated pair of bearing sections a first force urging the first bearing liner section away from the space between said mounting sections and to apply to the second bearing liner section of the associated pair of bearing liner sections a second force urging the second bearing liner section toward the space between said mounting sections, said second force being greater than said first force to retard spreading apart of said mounting sections. 
     
     
       10. A shackle assembly as set forth in claim 9 wherein said second bearing liner sections have a greater modulus of elasticity than said first bearing liner sections. .Iadd. 11. A pivot means constructed to interconnect first and second members for angular displacement of one of said members relative to the other of said members about a fixed pivot axis; said pivot means comprising a pair of ball studs;   each of said ball studs having a shank portion and a head portion;   said shank portions being in axial alignment with the ends of said shank portions being in juxtaposed relationship;   a sleeve surrounding said shank portions supported by one of said members;   a pair of socket means enclosing said head portions of said pair of ball studs;   each of said socket means being secured to the other of said members. .Iaddend..Iadd. 12. A pivot means for a suspension system for a motor vehicle having a frame member, a wheel support member constructed to rotatably support a road wheel and a leaf spring interconnecting said frame member and said wheel support member,   said pivot means being connected to said leaf spring and said frame member;   a pair of spaced apart supports connected to said frame member;   said leaf spring having an eye formed at one end and said eye being disposed between said supports;   a pair of ball studs having shank portions disposed in said eye;   said ball studs having a pair of spaced apart head portions;   each of said head portions being rotatably supported in a socket means;   said socket means being secured to said spaced apart supports;   whereby said leaf spring may deflect about a pviot axis that extends through said pair of spaced apart head portions and is fixed relative to   
     
     
        said head portions and said socket means. .Iaddend..Iadd. 13.  A pivot means according to claim 12 and including: an annular thrust washer and seal surrounding said shank portions of each of said ball studs;   said thrust washers and seals having elastomeric sealing surfaces engaging said shank portions of said ball studs. .Iaddend..Iadd. 14. A pivot means according to claim 12 and including:   one of said socket means comprising a cup-shape plastic bearing supported in a socket part;   an annular retaining ring disposed in said socket part and engaging an end of said bearing;   said socket part having a peripheral lip engaging said retaining ring and exerting a preload on said bearing;   a first annular seal having a portion engaging said peripheral lip of said socket part, said retaining ring and said shank of said ball stud   
     
     
        supported in said one socket means. .Iaddend. .Iadd. 15.  A pivot means according to claim 12 and including: an annular thrust washer and seal surrounding said shank portions of each of said ball studs;   said thrust washers and seals having sealing surfaces engaging said shank portions of said ball studs. .Iaddend.