A parking brake for a wheel rotor having a brake pad associated therewith includes a housing defining first and second passages. First and second pistons are provided in the respective first and second passages. Spindles extend into and are connected with each piston. A clutch unit is connected to the spindles and includes a motor. The clutch unit has a first condition allowing for rotation of the spindles in response to hydraulic pressure applied to the pistons such that the pistons are axially movable within the passages and relative to the spindles into engagement with the brake pad. The clutch unit has a second condition for rotating the spindles to drive the pistons into the brake pad and apply the parking brake.

A brake system for selectively actuating at least one wheel brake includes a reservoir and a power transmission unit for selectively providing pressurized hydraulic fluid for actuating at least a selected one of the wheel brakes during a braking event. A first electronic control unit at least partially controls at least one of the power transmission unit and a selected one of the pair of rear brake motors. A second electronic control unit at least partially controls at least one of the power transmission unit and an other one of the pair of rear brake motors. The first electronic control unit controls at least one SAP valve, an isolation valve, and a dump valve for a selected two of the wheel brakes, and the second electronic control unit controls at least one SAP valve, an isolation valve, and a dump valve for an other two of the wheel brakes.

A motor gear unit for a disc brake apparatus is provided. A speed reduction mechanism is connected to a first connection portion of a motor shaft of an electric motor. A non-excited operation type brake is connected to a second connection portion of the motor shaft.

In a state where the disc brake apparatus is attached to a vehicle body, the motor shaft is disposed so as to be orientated in an upper-lower direction, and the non-excited operation type brake is disposed above the electric motor.

Disclosed is an actuator for a brake device. In accordance with an aspect of the disclosure an actuator for a brake device includes a motor; a first reduction gear unit connected to the motor; and a second reduction gear unit connected to the first reduction gear unit; wherein the first reduction gear unit is provided as a planetary gear assembly, and the second reduction gear unit is provided as a bevel gear assembly.

A motor gear unit for a disc brake apparatus includes an electric motor, a speed reduction mechanism configured to transmit rotation of the electric motor to a plurality of rotary-to-linear motion conversion mechanisms arranged in a plurality of cylinders provided in a caliper, and a housing accommodating the electric motor and the speed reduction mechanism. The speed reduction mechanism includes a plurality of final gears connected directly or via another member to the plurality of rotary-to-linear motion conversion mechanisms and a power distribution mechanism that includes one support shaft and that is configured to distribute and transmit input power to the plurality of final gears. The power distribution mechanism is supported by the housing by supporting and fixing end portions of the support shaft on axially both sides to the housing.

A planetary gear speed reducing mechanism installed in a disc brake as a brake device includes a small diameter shaft portion to which rotation from an electric motor is transmitted, and a sun gear to which rotation from the small diameter shaft portion is transmitted. The small diameter shaft portion has outer diameter that is smaller than tip diameter of the sun gear. It is therefore possible to reduce torque loss from the electric motor, for example, during operation of a parking brake, and repress a deterioration in torque transmission efficiency.

Disclosed is an actuator for a brake device. An actuator for a brake device according to embodiment of the disclosure includes a housing accommodating a motor, a power transmission unit connected to the motor, and a reduction gear unit connected to the power transmission unit; and a cover covering an open top of the housing and having a shaft support portion; wherein the reduction gear unit includes a worm wheel including a concave receiving groove on an upper surface thereof and a locking rib provided in the receiving groove, a sun gear supported rotatably on a bottom of the receiving groove and having a support rib contactable with the locking rib during rotation, and a clutch spring provided in a state of being slidably wound around an outer circumferential surface of the shaft support portion, and configured to tighten or loosen selectively an outer circumferential surface of the shaft support portion according to a rotation direction when the worm wheel and the sun gear are rotated relative to each other.

A disc brake caliper has a caliper body arranged straddling a brake disc having a rotation axis defining an axial direction and opposite friction surfaces, pads accommodated in the caliper body, a cylinder forming a cylindrical wall and a bottom wall, a piston, and a parking-braking system having a rotating member accommodated within a rotation housing formed in the bottom wall. The cylinder defines a first annular housing and a second annular housing both made in the bottom wall, and extending in a direction transverse to the axial direction and leading into the rotation housing. The second annular housing is distinct from the first annular housing and positioned in a direction opposite to an inner surface of the bottom wall. The first annular housing accommodates a first seal. The second annular housing accommodates a second seal. The first and second seals act between the rotating member and the bottom wall.

A disk brake allowing a connector terminal (255) and a joining terminal (256) to be easily positioned in a width direction thereof and a direction toward an opening portion of a housing, because the joining terminal fixed to one end of a harness includes individual protruding portions (265) and a pair of biasing portions (264). Further, due to each of the biasing portions, the connector terminal and the joining terminal can be brought into close contact with each other. Further, due to the protruding portions of the joining terminal, an end (258A) of the connector terminal and an end (268A) of a contact surface portion (263) can be brought into alignment with each other, which facilitates formation of such a welded portion (266) that extends over the respective ends, and thus achieves a secure connection between the connector terminal and the joining terminal

The present disk brake includes a braking force holding mechanism configured to restrict a rotation of a rotational shaft (a ratchet gear) to hold a braking force based on driving of a solenoid actuator. The braking force holding mechanism includes a holding member configured to move based on the driving of the solenoid actuator to restrict the rotation of the ratchet gear, and an engagement member coupled with this holding member. The engagement member is rotatably supported on a gear housing portion, and is configured to prohibit a movement of the holding member. Due to this configuration, an excitation force applied from outside to the holding member can be canceled out with the aid of the engagement member, and thus the disk brake can realize a size reduction and achieve cost saving.