Slack adjuster for a drum brake of a vehicle air braking system

A slack adjuster for a drum brake of a vehicle air braking system, the slack adjuster comprising:

• a gear set including (i) a worm wheel having an outer circumferential surface and gear teeth disposed on the outer circumferential surface, and (ii) a worm shaft having a longitudinal central axis and gear teeth that is meshed with the gear teeth on the worm wheel, wherein the worm shaft is rotated in one direction about its longitudinal central axis when the drum brake is applied and adjustment is required and in an opposite direction about its longitudinal central axis when the drum brake is released;
• and
• an anti-reversing member having an inner circumferential surface and gear teeth disposed on the inner circumferential surface, wherein the gear teeth on the inner circumferential surface of the anti-reversing member is configured to mesh with the gear teeth on the outer circumferential surface of the worm wheel to prevent rotation of the worm wheel only when the drum brake is released.

A slack adjuster for a drum brake of a vehicle air braking system, the slack adjuster comprising:

• a gear set including a worm wheel and a worm shaft having a longitudinal central axis and operatively engaged with the worm wheel, wherein the worm shaft is rotated in one direction about its longitudinal central axis when the drum brake is applied and adjustment is required and in an opposite direction about its longitudinal central axis when the drum brake is released;
• and
• means for enabling the worm wheel to rotate when the drum brake is applied and for acting directly on the worm wheel to prevent rotation of the worm wheel when the drum brake is released.

A method of operating a drum brake of a vehicle air braking system having a slack adjuster, the method comprising:

• positioning an anti-reversing member relative to a worm wheel having a longitudinal central axis such that the anti-reversing member directly acts on the worm wheel to resist rotation of the worm wheel about the longitudinal central axis when a clutch pinion of a clutch assembly returns to home position in response to the drum brake being released.