Automatic adjuster for a vehicle brake actuator

An automatic adjuster for a vehicle brake actuator comprising a tappet for engagement, in use, with a brake shoe, an adjuster member including a non-reversible threaded connection with a means separate from the tappet, such that rotation of the adjuster member in one direction causes axial movement of the tappet, resilient means acting to separate the tappet and the adjuster member, a clutch ring urged towards a normally non-rotatable clutch surface and operable to control rotation of the adjuster member by means of a reversible thread connection formed between the clutch ring and co-operating means, said reversible thread connection having a predetermined clearance, the arrangement being such that as the tappet moves in a shoe-applying direction, the predetermined clearance in the reversible thread is taken up and a force then generated at the reversible thread causes the clutch ring to be held against rotation by the clutch surface so that reversible threads of said reversible thread connection co-operate to cause rotation of the adjuster member in a direction to move the tappet outwardly thereof;

• and an intermediate member engaged with the adjuster member, the resilient means acting between the tappet and said intermediate member to transmit force thereby to the adjuster member;
• the non-reversible threaded connection being disposed between the adjuster member and the means separate from the tappet;
• the adjuster being arranged so that the clutch ring is permitted a degree of self-centering relative to the adjuster member and clutch surface;
• said intermediate member having a reversible thread formed thereon engaged by a corresponding thread of the clutch ring which surrounds it forming said reversible thread connection, said intermediate member being coupled to the adjuster member by a connecting device which permits radial movement of said intermediate member relative to the adjuster member, thereby facilitating said self-centering of the clutch ring.

An automatic adjuster for a vehicle brake actuator comprising a tappet for engagement, in use, with a brake shoe, an adjuster member including a non-reversible threaded connection with means separate from the tappet, such that rotation of the adjuster member in one direction causes axial movement of the tappet, resilient means acting to separate the tappet and adjuster member, a clutch ring urged towards a normally non-rotatable clutch surface and operable to control rotation of said adjuster member by means of a reversible thread connection formed between the clutch ring and co-operating means, the arrangement being such that as the tappet moves in a shoe-applying direction, a predetermined clearance in the reversible thread is taken up and a force then generated at the reversible thread causes the clutch ring to be held against rotation by the clutch surface, whereby the reversible threads of said reversible thread connection co-operate to cause rotation of the adjuster member in a direction such as to move the tappet outwardly thereof;

• and an intermediate member having a reversible thread formed thereon engaged by the corresponding thread of the clutch ring which surrounds it, said intermediate member being coupled to the adjuster member by a connecting device which permits radial movement of the intermediate member relative to the adjuster member, thereby to provide self-centering of the clutch ring;
• said intermediate member being in the form of a sleeve surrounding a shaft which forms a splined connection with the sleeve and adjuster member such as to permit relative radial movement between the sleeve and adjuster member in order to permit said self-centering of the clutch ring.

An automatic adjuster for a vehicle brake actuator comprising a tappet for engagement, in use, with a brake shoe, an adjuster member including a non-reversible threaded connection with a means separate from the tappet, such that rotation of the adjuster member in one direction causes axial movement of the tappet, resilient means acting to separate the tappet and the adjuster member, a clutch ring urged towards a normally non-rotatable clutch surface and operable to control rotation of the adjuster member by means of a reversible thread connection formed between the clutch ring and co-operating means, said reversible thread connection having a predetermined clearance, the arrangement being such that as the tappet moves in a shoe-applying direction, the predetermined clearance in the reversible thread is taken up and a force then generated at the reversible thread causes the clutch ring to be held against rotation by the clutch surface so that reversible threads of said reversible thread connection co-operate to cause rotation of the adjuster member in a direction to move the tappet outwardly thereof;

• and an intermediate member engaged with the adjuster member, the resilient means acting between the tappet and said intermediate member to transmit force thereby to the adjuster member;
• the non-reversible threaded connection being disposed between the adjuster member and the means separate from the tappet and said means separate from the tappet being rotationally and axially fixed with respect to the housing;
• the adjuster being arranged so that the clutch ring is permitted a degree of self-centering relative to the adjuster member and clutch surface;
• said intermediate member having a reversible thread formed thereon engaged by a corresponding thread of the clutch ring which surrounds it forming said reversible thread connection, said intermediate member being in the form of a sleeve surrounding a shaft, said shaft having a splined connection with said sleeve and adjuster member for coupling said intermediate member to the adjuster member and permitting radial movement of said intermediate member relative to the adjuster member, thereby facilitating said self-centering of the clutch ring.