Automatic drum brake adjustment - has screwed element in one brake piston rotated via friction springs by relative motion of pistons

摘要

The arrangement provides automatic adjustment of a drum brake. It comprises actuating means which respond to the relative motion of the brake pistons so as to cause rotation of a screw element relative to one piston thereby adjusting this piston in axial direction. The actuating means are arranged between the screw and the other piston and comprise springs which are capable of frictionally gripping grooves on the screw when they are subjected to torsion. Tosion of the springs is caused by axial piston movement due to each spring having a radially projecting end engaging an inclined groove in a bush secured to the other piston. The grooves are inclined in opposite directions so that one spring is operative during application of the brake, when the pistons move apart, and the other spring during release of the brake causing opposite rotations of the screw by different amounts.