Patent ID: 7708122
Filing Date: 2010-05-04
Classification: F16D

Abstract:
1. A method of operating a vehicle drum brake in response to actuation of the vehicle brake, said method comprising the steps of: pivoting a slack adjuster body in an apply direction about a camshaft axis, in response to actuation of the brake; moving a worm that is in the slack adjuster body in an arc about the camshaft axis in response to the pivoting of the slack adjuster body; transmitting torque from the moving worm to a worm wheel thereby to apply a first torque to the worm wheel to effect rotation of the worm wheel about the camshaft axis in an apply direction; rotating a pinion mechanism about a pinion axis in an apply direction during the initial period of pivoting of the slack adjuster body in the apply direction, in response to the pivoting of the slack adjuster body in the apply direction and during the step of moving the worm in the slack adjuster body; rotating the worm in an apply direction about a worm axis in response to rotational force of the pinion mechanism; transmitting torque from the rotating worm to the worm wheel thereby to apply a second torque to the worm wheel to effect rotation of the worm wheel about the camshaft axis at an increased speed in the apply direction; rotating a brake camshaft with the worm wheel thereby to operate the vehicle drum brake; rotating a control member with the worm during the initial period of pivoting of the slack adjuster body in the apply direction to take up initial clearance and excess clearance, the control member being rotatable about the worm axis for helping to control the rotation of the worm about the worm axis; blocking rotation of the control member after a predetermined amount of rotation; and thereafter rotating the worm further in the apply direction to take up additional excess clearance until brake resistance blocks further worm rotation.