Abstract: A brake mechanism is disclosed wherein a support lever is pivoted at a pivot end to a stationary end plate and is urged by a spring, which engages the support lever at its free end, toward the end plate to effect clamping of a rotatable friction disc between a brake shoe and friction plates disposed near the pivot end of the support lever. A solenoid is mounted on the support lever and is connected to a cam pivoted to the end plate and adapted to contact the support lever near its free end to overcome the force of the spring and to release the brake when the solenoid is energized. The location of the spring and cam near the free end of the lever and the configuration of the lever provides mechanical advantages that permits the use of a smaller solenoid and spring. The arrangement of parts is such that the solenoid mechanical advantage is between approximately 24-32 to 1, depending upon the selected brake releasing clearance, while the spring mechanical advantage is approximately 81/2 to 1.

Abstract: This caliper disc brake is normally held in its engaged position by springs and is released by a solenoid which acts through a lever assembly to activate the plunger of a hydraulic master cylinder unit which directs a measured volume of hydraulic fluid into a brake cylinder during each stroke to release the brake and provide a predetermined brake clearance. Brake wear results in a gradually diminishing volume of fluid within the brake cylinder with the excess fluid displaced therefrom flowing into a reservoir of the master cylinder prior to directing the measured volume of hydraulic fluid into the brake cylinder during the next brake releasing stroke. The cross sectional area of the master cylinder plunger and the brake piston are designed to provide a substantial mechanical advantage, and the lever assembly is fulcrum to provide an additional mechanical advantage thus requiring a much smaller than average power means for releasing the brake.