A spreader unit for a drum brake is provided with a readjustment device which ensures that the clearance remains substantially constant even in the case of wear on the brake linings. The readjustment device is arranged between actuating pistons and changes the spacing of the actuating pistons in at least one readjustment step when an actuating travel of the first and second brake shoe holders has exceeded a travel setpoint value. A thermally actuable blocking device mechanically prevents the execution of the readjustment step by the readjustment device at a temperature above a temperature setpoint value

An automatic slack adjuster includes a lever configured to be coupled to a push rod of a brake actuator, and to pivot about a rotational axis when actuated by the push rod, the rotational axis having a predetermined fixed location relative to the vehicle. A stroke indicator label is arranged on the lever and configured to designate, for the automatic slack adjuster, a predetermined zero stroke position, a working stroke range, and an overstroke range. A stroke indicator element is configured to visualize the current stroke level of the automatic slack adjuster on the indicator label by way of relative movement between the stroke indicator element and the stroke indicator label in response to pivotal movement of the lever. A mounting bracket of a mounting interface can be adjusted relative to the rotational axis for correctly installing the stroke indicator element.

An expanding device for actuating one of the brake shoes of a drum brake includes a body of revolution and transmission bodies actuated by the body of revolution via ball track ramps. A spacer body is located between two partial bodies of the body of revolution, the spacer body guided by an adjustment spring keeping the partial bodies at the respectively reached distance. The spacer body is screwed onto a pin on the first partial body. A readjustment nut ensures that, when the two partial bodies are pushed apart, the spacer body rotates on the pin and moves away from a supporting surface on a partition of the second partial body. Upon renewed actuation of the brakes, the readjustment nut is guided such that the spacer body bears against the second partial body), but takes up a different position on the pin, the position corresponding to the air clearance readjustment.

An internal expanding shoe brake includes expansion pistons for forcing opposing brake shoes apart. In each expansion piston one adjusting pin is axially movably arranged and presses against a brake shoe web by means of a pressure piece. Said pressure piece is supported on the adjusting pin by means of a ball joint so as to pivot in any direction. In order to prevent the adjusting pin from being twisted inside the expansion piston, an anti-rotation element is provided and comprises a pressure piece projection which projects over the ball joint surface of the pressure piece, said projection interlockingly engaging in a receiving opening of the adjusting pin with lateral play and forming a rotational coupling connection.

The invention relates to an actuating device for an internal shoe brake, including an automatic adjusting device with an adjusting lever which includes a guide track in the form of a guiding slot with two opposing track surfaces which cooperate with opposing sides of a housing-fixed guide element in order to convert a displacement of the adjusting lever relative to the housing-fixed guide element into pivoting movements of the adjusting lever.

The proposal is for an improved expansion device for a drum brake having an integrated readjustment unit having a readjusting screw which can be locked therein by a spring-loaded latching unit which, for a reliable readjustment function with a reduced level of force, provides for the latching unit to allow a defined idle rotation of the readjusting screw, which is defined structurally by a first stop acting in a first direction of revolution and a second stop acting in the opposite direction of revolution.

An actuating device for an internal expanding brake has a restoring device for manual adjusting and restoring of an adjusting pin relative to an expanding piston. The restoring device includes an actuating pin which is mounted rotatably in a housing and is configured for transmitting a torque which is applied manually to the actuating pin, and a restoring gear mechanism which has a first gearwheel which is coupled to the actuating pin and a second gearwheel which is coupled to an adjusting nut. The first gearwheel of the restoring gear mechanism which is coupled to the actuating pin can be displaced in the axial direction of the actuating pin and can be brought into and out of torque-proof engagement with the actuating pin by means of a coupling device in a manner which is dependent on the transmitted torque.

An automatic slack adjuster includes a lever configured to be coupled to a push rod of a brake actuator, and to pivot about a rotational axis when actuated by the push rod, the rotational axis having a predetermined fixed location relative to the vehicle. A stroke indicator label is arranged on the lever and configured to designate, for the automatic slack adjuster, a predetermined zero stroke position, a working stroke range, and an overstroke range. A stroke indicator element is configured to visualize the current stroke level of the automatic slack adjuster on the indicator label by way of relative movement between the stroke indicator element and the stroke indicator label in response to pivotal movement of the lever. A mounting bracket of a mounting interface can be adjusted relative to the rotational axis for correctly installing the stroke indicator element.

An improved electromechanically drivable spreader unit having an integrated adjustment apparatus for a drum brake, in which the linear motion of brake shoe holders is produced by two ball-ramp devices, wherein a first ball-ramp device includes a first actuation piston arranged for rotation about the axis and a second ball-ramp device includes a second actuation piston arranged for rotation about the axis, and wherein an adjustment apparatus for compensating an actuation travel that increases as a result of wear on the friction linings is arranged in an axially centered position within the housing and substantially between the actuation pistons.

An improved electromechanically drivable spreader unit having an integrated adjustment apparatus for a drum brake, in which the linear motion of brake shoe holders is produced by two ball-ramp devices, wherein a first ball-ramp device includes a first actuation piston arranged for rotation about the axis and a second ball-ramp device includes a second actuation piston arranged for rotation about the axis, and wherein an adjustment apparatus for compensating an actuation travel that increases as a result of wear on the friction linings is arranged in an axially centered position within the housing and substantially between the actuation pistons.