A device for adjusting clearance of a drum brake has an extendable strut assembly having a toothed ring and arranged between first and second shoes cooperating with a braking surface of a drum and moved by an actuating device from a resting position, in which they are distanced from the braking surface, to a braking position, in which they abut against the braking surface. The device has a first lever assembly, a second lever assembly having a coupling portion, and a connecting member having a connecting seat. The coupling portion is coupled to the connecting seat with a predetermined functional clearance. When the first and second shoes move from the resting position, the coupling portion slides in the connecting seat with an idle stroke equal to the predetermined functional clearance without transmitting motion to the connecting member and the first lever assembly. The second lever assembly transmits motion to the connecting member after the coupling portion has covered the idle stroke.

A parking brake apparatus may include: a driving part; a driving gear rotatably connected to the driving part; a gear shaft engaged with the driving gear so as to be rotated by the driving gear; a pair of pistons disposed on both sides of the gear shaft and connected to brake shoes, respectively; a pair of nuts disposed in the respective pistons, and screwed to the gear shaft; an elastic member installed between the piston and the nut so as to pressure the nut toward the brake shoe; a holder installed in the piston so as to support the elastic member; and a constraint ring installed in the piston so as to constrain the holder.

The present disclosure relates to an electromechanical actuation unit for a motor vehicle brake comprising: at least one electromechanical actuation device for actuating at least one brake shoe of the motor vehicle brake. The electromechanical actuation device has at least drive element and at least one drive spindle, wherein the at least one drive element drives the at least one drive spindle. The electromechanical actuation device has at least one elastic element, the at least one elastic element being elastically deformable for a parking brake function.

A device for adjusting clearance of a drum brake has an extendable strut assembly having a toothed ring and arranged between first and second shoes cooperating with a braking surface of a drum and moved by an actuating device from a resting position, in which they are distanced from the braking surface, to a braking position, in which they abut against the braking surface. The device has a first lever assembly, a second lever assembly having a coupling portion, and a connecting member having a connecting seat. The coupling portion is coupled to the connecting seat with a predetermined functional clearance. When the first and second shoes move from the resting position, the coupling portion slides in the connecting seat with an idle stroke equal to the predetermined functional clearance without transmitting motion to the connecting member and the first lever assembly. The second lever assembly transmits motion to the connecting member after the coupling portion has covered the idle stroke.

A parking brake apparatus including a bolt screw rotated by a driving force transmitted from an actuator, one or more pistons disposed at one side or both sides of the bolt screw, one or more screw nuts accommodated in the piston, screwed to an end of the bolt screw, and moved along with the rotation of the bolt screw, one or more elastic members disposed around the screw nut within the piston, and elastically deformed, in response to a displacement of the screw nut while the screw nut is moved by a set distance, to press the piston toward a shoe, and a load transfer unit disposed in the piston, and configured to transmit, to the piston, a displacement of the screw nut when the screw nut moves more than the set distance, thereby pressing the piston toward the shoe.

A parking brake apparatus may include: a driving part; a driving gear rotatably connected to the driving part; a gear shaft engaged with the driving gear so as to be rotated by the driving gear; a pair of pistons disposed on both sides of the gear shaft and connected to brake shoes, respectively; a pair of nuts disposed in the respective pistons, and screwed to the gear shaft; an elastic member installed between the piston and the nut so as to pressure the nut toward the brake shoe; a holder installed in the piston so as to support the elastic member; and a constraint ring installed in the piston so as to constrain the holder.

A vehicle brake slack adjuster includes a housing coupled to a brake actuator and supporting a driving worm wheel engaging the brake cam shaft and a driving worm screw meshed with the driving worm wheel and transferring a brake actuating force, imparted by the brake actuator to the housing, to the driving worm wheel and cam shaft. The adjuster further includes a wear adjustment mechanism including a reference arm fixed against movement and including a control ring gear, a pinion gear meshed with the control ring gear and configured for rotation about an axis, a clutch ring disposed about the axis and configured for rotation with the pinion gear, a control worm screw disposed about the axis, a wrap spring engaging surfaces of the clutch ring and control worm screw and a control worm wheel meshed with the control worm screw and configured for rotation with the driving worm screw.

A vehicle brake slack adjuster includes a housing coupled to a brake actuator and supporting a driving worm wheel engaging the brake cam shaft and a driving worm screw meshed with the driving worm wheel and transferring a brake actuating force, imparted by the brake actuator to the housing, to the driving worm wheel and cam shaft. The adjuster further includes a wear adjustment mechanism including a reference arm fixed against movement and including a control ring gear, a pinion gear meshed with the control ring gear and configured for rotation about an axis, a clutch ring disposed about the axis and configured for rotation with the pinion gear, a control worm screw disposed about the axis, a wrap spring engaging surfaces of the clutch ring and control worm screw and a control worm wheel meshed with the control worm screw and configured for rotation with the driving worm screw.

A parking brake apparatus including a bolt screw rotated by a driving force transmitted from an actuator, one or more pistons disposed at one side or both sides of the bolt screw, one or more screw nuts accommodated in the piston, screwed to an end of the bolt screw, and moved along with the rotation of the bolt screw, one or more elastic members disposed around the screw nut within the piston, and elastically deformed, in response to a displacement of the screw nut while the screw nut is moved by a set distance, to press the piston toward a shoe, and a load transfer unit disposed in the piston, and configured to transmit, to the piston, a displacement of the screw nut when the screw nut moves more than the set distance, thereby pressing the piston toward the shoe.

An apparatus for a brake drum of a vehicle having a drum brake assembly with first and second brake shoes includes a motor with a pinion gear. A ball screw assembly has a nut for receiving torque from the pinion gear and a spindle threaded with the nut. The nut is aligned with the first brake shoe and the spindle is aligned with the second brake shoe. The motor is actuatable for rotating the nut to move the nut and the spindle away from one another for moving the brake shoes to apply braking force to the brake drum during a braking event. A bi-stable locking mechanism selectively locks the motor to prevent torque transfer from a back-driving ball screw assembly to the motor.