Brake adjusters

Claim 2

A slack adjuster for a brake system comprising a first nonrotatable member, a second rotatable member and a third nonrotatable member having a common thrust axis; a non-reversible screw-thread connection between said first and second members, said second member being axially displaceable and rotatable relative to said third member and said second and third members having mating abutment surfaces for the transmission of thrust between said first and third members via said abutment surfaces, said second member and said non-reversible screw-thread connection; a fourth member coaxial with said thrust axis; a reversible screw-thread connection between said fourth member and one of said second and third members; axially cooperating friction surfaces between said fourth member and the other of said second and third members, said fourth member being freely rotatable relatively to said other member when said friction surfaces are axially parted, said fourth member having a resting position relative to said one member when said abutment surfaces are in interengagement; and spring means axially biassing said fourth member into said resting position and in a direction to urge said friction surfaces towards one another.

Claim 3

A slack adjuster according to claim 1 in which said spring means acts between said other member and said fourth member.

Claim 4

A slack adjuster according to claim 1 for a drum brake having opposed brake shoes, which slack adjuster acts as a strut between said opposed brake shoes to limit retraction of the brake shoes.

Claim 5

A slack adjuster according to claim 3 having a mechanical actuator which acts between one brake shoe and one end of said strut.

Claim 6

A slack adjuster according to claim 3 having a hydraulic actuator which is arranged to act on the brake shoes in the region of the adjuster.

Claim 7

A slack adjuster according to claim 2 in which said one member comprises said second member and said other member comprises said third member.

Claim 8

A slack adjuster according to claim 1 for a spot type disc brake having a hydraulic actuator with opposed pistons in which said first member is one of said pistons of the hydraulic actuator.

Claim 9

A slack adjuster according to claim 7 having a mechanical actuator which acts between the other of said pistons and said third member.

Claim 10

A slack adjuster for a brake system comprising a first non-rotatable member, a second rotatable member and a third non-rotatable member having a common thrust axis; a non-reversible screw-thread connection between said first and second members, said second member being axially displaceable and rotatable relative to said third member and said second and third members having mating abutment surfaces for the transmission of thrust between said first and third members via said abutment surfaces, said second member and said non-reversible screw-thread connection; a fourth member coaxial with said thrust axis and having a domed head; a reversible screw-thread connection between said fourth member and one of said second and third members; cooperating friction surfaces between said fourth member and the other of said second and third members, said fourth member being freely rotatable relatively to said other member when said friction surfaces are parted, said fourth member having a resting position relative to said one member when said abutment surfaces are in interengagement; and spring means acting between said other member and the center of said domed head on said fourth member to bias said fourth member into said resting position and in a direction to urge said friction surfaces towards one another.

Claim 11

A slack adjuster for a brake system comprising a first non-rotatable member, a second rotatable member and a third non-rotatable member having a common thrust axis; a non-reversible screw-thread connection between said first and second members, said second member being axially displaceable and rotatable relative to said third member and said second and third members having mating abutment surfaces for the transmission of thrust between said first and third members via said abutment surfaces, said second member and said non-reversible screw-thread connection; a fourth member coaxial with said thrust axis and having a domed head; a reversible screw-thread connection between said fourth member and one of said second and third members; cooperating friction surfaces between said fourth member and the other of said second and third members, said fourth member being freely rotatable relatively to said other member when said friction surfaces are parted, said fourth member having a resting position relative to said one member when said abutment surfaces are in interengagement; and spring means acting between said other member and the center of said domed head on said fourth member to bias said fourth member into said resting position and in a direction to urge said friction surfaces towards one another.

Claim 12

A slack adjuster according to claim 9 in which a cup-shaped element is fitted between said spring means and said domed head, said cup-shaped element having a flat bottom resting against the center of said domed head.

Claim 13

A slack adjuster according to claim 9 in which said spring means comprises a conical spring having a narrow end resting directly against the center of said domed head.

Claim 14

A slack adjuster according to claim 2 for a brake having a retraction spring, further comprising additional spring means acting between said second and third members in a direction to tend to part said abutment surfaces.

Claim 15

A slack adjuster for a brake system comprising a first non-rotatable member, a second rotatable member and a third non-rotatable member having a common thrust axis; a non-reversible screw-thread connection between saId first and second members, said second member being axially displaceable and rotatable relative to said third member and said second and third members having mating abutment surfaces for the transmission of thrust between said first and third members via said abutment surfaces, said second member and said non-reversible screw-thread connection; a fourth screw member coaxial with said thrust axis and having a domed head; a reversible screw-thread connection between said fourth screw member and one of said second and third members, the external thread being on said fourth screw member; cooperating friction surfaces between said fourth screw member and the other of said second and third members, said fourth screw member being freely rotatable relative to said other member when said friction surfaces are parted; and means engaging the center of said domed head with low frictional resistance to rotation of said fourth screw member to hold said fourth screw member in a resting position with respect to said one member when said abutment surfaces are in engagement with one another.

Claim 16

A slack adjuster for a brake system comprising a first non-rotatable member, a second rotatable member and a third non-rotatable member having a common thrust axis; a non-reversible screw-thread connection between saId first and second members, said second member being axially displaceable and rotatable relative to said third member and said second and third members having mating abutment surfaces for the transmission of thrust between said first and third members via said abutment surfaces, said second member and said non-reversible screw-thread connection; a fourth screw member coaxial with said thrust axis and having a domed head; a reversible screw-thread connection between said fourth screw member and one of said second and third members, the external thread being on said fourth screw member; cooperating friction surfaces between said fourth screw member and the other of said second and third members, said fourth screw member being freely rotatable relative to said other member when said friction surfaces are parted; and means engaging the center of said domed head with low frictional resistance to rotation of said fourth screw member to hold said fourth screw member in a resting position with respect to said one member when said abutment surfaces are in engagement with one another.

Claim 17

A slack adjuster according to claim 13 in which said element comprises stop means on said other member.

Claim 18

A slack adjuster according to claim 14 further comprising a biassing spring acting on said one member in a direction to urge said abutment surface thereon against said abutment surface on said other member, an axial clearance at said non-reversible screw-thread connection providing a desired brake slack.

Claim 19

A slack adjuster according to claim 13 in which said one member comprises said third member and said other member comprises said second member.