Drum brake
AssigneeRobert Bosch GmbH
InventorsDirk Hofmann, Willi Nagel, Oliver Kriese
Life of this patent
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Abstract
The invention relates to a drum brake having an electromechanical actuating device. The invention proposes to convert a rotating drive movement of the actuating device by use of a gearwheel and two toothed racks. The toothed racks mesh with the gearwheel on opposite sides thereof and are driven in opposite directions by the gearwheel into translational movements for pressing attached brake shoes against a brake drum. The toothed racks are configured in such a way that the two toothed racks have a common line of action, with resulting symmetrical actuating forces. According to one embodiment of the invention, the lines of action of the toothed racks run tangentially with respect to the gearwheel.
Claims20
A drum brake comprising:
- an electromechanical actuating device;
- two brake shoes;
- a brake drum, the two brake shoes being pressed against the brake drum by the actuating device for actuation of the drum brake;
- a holder plate on which the two brake shoes are guided displaceably, radially to the brake drum, the holder plate having bearing blocks which are disposed on opposing ends of each of the two brake shoes and which guide the brake shoes radially displaceably relative to the holder plate and to the brake drum;
- the actuating device having a rotationally drivable gear wheel defining an axis of rotation, the location of which is fixed with respect to the holder plate;
- the actuating device further having two toothed racks which mesh with the gear wheel on diametrically opposite sides thereof, wherein each of the two toothed racks is operatively coupled to a respective one of the two brake shoes such that rotation of the gear wheel causes the two brake shoes to be pressed against the brake drum;
- and
- the actuating device further having two actuating levers operatively coupling each of the two toothed racks to a respective one of the two brake shoes, the two actuating levers being disposed separately from and radially inside the two brake shoes respectively, and being supported pivotably on the holder plate at a first end of each of the two actuating levers, and the two actuating levers being pivotably connected with the toothed racks at a second end of each of the two actuating levers, wherein a pivoting motion of the two actuating levers translates to a linear displacement of the two brake shoes.
A drum brake comprising:
- two brake shoes;
- a brake drum, the two brake shoes being pressed against the brake drum by an actuating device;
- a holder plate on which the two brake shoes are guided displaceably, radially relative to the holder plate and to the brake drum;
- the actuating device including a rotationally drivable gear wheel having an axis of rotation the location of which is fixed with respect to the holder plate, and a first and a second toothed rack each of which mesh with the gear wheel and which are each coupled to a respective one of two actuating levers, the two actuating levers being respectively disposed separately from and radially inside the two brake shoes and being supported pivotably on the holder plate at a first end of each of the two actuating levers, the two actuating levers being pivotably respectively coupled to each of the first and second toothed racks at a second end of each of the two actuating levers, wherein a pivoting motion of the two actuating levers translates to a linear displacement of the two brake shoes to cause the brake shoes to be pressed against the brake drum;
- a motor operatively coupled to the gear wheel to drive the gear wheel about the axis of rotation;
- and
- a locking device operatively coupled to the motor to prevent the motor from driving the gear wheel in at least one direction.
Dependencies are inferred from the claim text.