ABS Description

DESCRIPTION
The Expansion Brake Spring (ESB) is used to hold the piston in the upmost or home position. An ESB is a spring that is retained in a housing at a close tolerance. One end of the spring is in contact with the motor drive dog and the other end is in contact with the pinion drive dog. In normal braking, brake pressure is present on the top of the piston, applying a downward force. The force applies a counterclockwise torque to the motor pinion which tries to rotate the spring counterclockwise. The counterclockwise torque expands the spring outward within the housing and prevents gear rotation. When the motor is turned on and tries to drive the ball screw nut, the end of the ESB in contact with the motor drive dog rotates inward causing the spring to contract in its housing allowing the motor to rotate the modulator gear.