Slack adjuster for vehicle brakes

A slack adjuster for connecting an air actuated piston rod to rotate a cam shaft in a vehicle brake system comprising a housing, a worm gear mounted to rotate in said housing, means for connecting said worm gear to the cam shaft, said worm gear and said cam shaft rotating together about a first axis, a shaft mounted in said housing to rotate about a second axis perpendicular to said first axis, said shaft having first and second ends and defining a worm intermediate said ends engaged with said worm gear, a drive and a coupling each mounted coaxially to rotate on said shaft, ratchet means interconnecting said drive and said coupling for allowing said drive to rotate about said shaft axis relative to said coupling in only one direction, slip means interconnecting the coupling and said shaft, said slip means slipping when a predetermined rotational force is exerted between said coupling and said shaft, clevis means connecting said housing to the piston rod at a predetermined point spaced from said first axis, a link connected to said clevis means at a point spaced from the connection between said clevis means and said housing, and means interconnecting said link and said drive for rotating said drive and said coupling as the vehicle brakes are applied.