1. Field of Invention
The invention relates generally to brakes, and more particularly to a brake apparatus and a brake shoe retainer apparatus.
2. Description of Related Art
A “direct-acting brake” may refer to a brake having an actuator that transmits a brake actuation force directly on a brake shoe, without transmitting the brake actuation force through a brake caliper.
One known direct-acting brake includes a main frame defining a plurality of through-openings, which slidably receive respective pins connected to a brake shoe. The brake shoe is actuatable in a brake actuation direction away from the main frame, and the pins slide through the respective through-openings in response to movement of the brake shoe in the brake actuation direction, or in a direction opposite the brake actuation direction. When a brake lining on the brake shoe frictionally contacts an object to be braked, a braking force urges the brake shoe in a direction of movement of the object to be braked. The brake shoe transmits the braking force to one or more of the pins, which transmit the braking force to the main frame. However, unless the through-openings and pins are very precisely machined, the pins will not bear the braking force evenly, and the main frame and the pins may thus disadvantageously wear unevenly. Further, if the brake shoe expands or contracts due to thermal expansion or contraction of one or more of the aforementioned components, one or more of the pins may become seized in their respective through-openings, thus disadvantageously seizing the brake. Further, some known direct-acting brakes disadvantageously require significant and time-consuming disassembly and reassembly to install and remove a brake shoe.
In accordance with one illustrative embodiment, there is provided a brake apparatus including: a first brake body; a first retaining means for retaining a first brake shoe against the first brake body while permitting the first brake shoe to be actuated in a brake actuation direction, away from the first brake body, to cause an outer frictional contact surface of a first brake lining connected to the first brake shoe to contact frictionally an object to be braked; and a second retaining means for selectively retaining the first brake shoe against lateral movement in a direction of movement of the object to be braked.
The apparatus may further include a means for actuating the first brake shoe in the brake actuation direction.
The means for actuating may include a brake piston for transmitting a brake actuation force directly on the first brake shoe.
The first retaining means may include a means for resiliently urging the first brake shoe against the first brake body.
The apparatus may further include the first brake shoe.
The first retaining means may be configured to retain the first brake shoe with a lateral space between the first brake shoe and the second retaining means while permitting the first brake shoe to move towards and contact the second retaining means when the first brake shoe is urged in the direction of movement of the object to be braked.
The second retaining means may include at least one retainer body removably connectable to the first brake body.
The at least one retainer body may include a key having a connecting portion and a retaining portion, and the first brake body may define a recess for attachably receiving the connecting portion to connect the key removably to the first brake body.
Each one of the at least one retainer body may include a threaded portion and a retaining portion, and the first brake body may define at least one threaded opening for attachably receiving the threaded portion of a respective one of the at least one retainer body to connect the respective one of the at least one retainer body removably to the first brake body.
The first brake body may be configured to permit the first brake shoe to be installed in or removed from the brake apparatus generally in the direction of movement of the object to be braked when the second retaining means does not retain the first brake shoe against lateral movement in the direction of movement of the object to be braked.
The apparatus may further include a brake frame including: the first brake body; and a second brake body connectable to a second brake shoe connected to a second brake lining having an outer frictional contact surface. The brake frame may define a recess between the first and second brake bodies, and the first and second brake shoes may be positionable in the recess such that the respective outer frictional contact surfaces of the first and second brake linings are opposite each other in the recess generally perpendicular to the brake actuation direction.
The recess may be sized to receive at least a portion of a rotatable disc having first and second generally circular opposite sides, and the first and second brake shoes may be positionable in the recess such that the first and second brake linings are positionable apart from the first and second generally circular opposite sides respectively of the rotatable disc when the first brake shoe is not actuated in the brake actuation direction and such that the respective outer frictional contact surfaces of the first and second brake linings are positionable in frictional contact with the first and second generally circular opposite sides respectively of the rotatable disc when the first brake shoe is actuated in the brake actuation direction.
The frame may include a means for mounting the frame slidably in a direction generally parallel to the brake actuation direction.
In accordance with another illustrative embodiment, there is provided a brake apparatus including: a first brake body; a brake shoe retainer for retaining a first brake shoe against the first brake body while permitting the first brake shoe to be actuated in a brake actuation direction, away from the first brake body, to cause an outer frictional contact surface of a first brake lining connected to the first brake shoe to contact frictionally an object to be braked; and a lateral retainer for selectively contacting the first brake shoe to retain the first brake shoe selectively against lateral movement in a direction of movement of the object to be braked.
The apparatus may further include an actuator connectable to the first brake body for actuating the first brake shoe in the brake actuation direction.
The actuator may include a brake piston for transmitting a brake actuation force directly from the actuator to the first brake shoe.
The brake shoe retainer may be configured to urge the first brake shoe resiliently against the first brake body.
The apparatus may further include the first brake shoe.
The brake shoe retainer may be configured to retain the first brake shoe with a lateral space between the first brake shoe and the lateral retainer while permitting the first brake shoe to move towards and contact the lateral retainer when the first brake shoe is urged in the direction of movement of the object to be braked.
The lateral retainer may include at least one retainer body removably connectable to the first brake body.
The at least one retainer body may include a key having a connecting portion and a retaining portion, and the first brake body may define a recess for attachably receiving the connecting portion to connect the key removably to the first brake body.
Each one of the at least one retainer body may include a threaded portion and a retaining portion, and the first brake body may define at least one threaded opening for attachably receiving the threaded portion of a respective one of the at least one retainer body to connect the respective one of the at least one retainer body removably to the first brake body.
The first brake body may be configured to permit the first brake shoe to be installed in or removed from the brake apparatus generally in the direction of movement of the object to be braked when the lateral retainer does not retain the first brake shoe against lateral movement in the direction of movement of the object to be braked.
The apparatus may further include a brake frame including: the first brake body; and a second brake body connectable to a second brake shoe connected to a second brake lining having an outer frictional contact surface. The brake frame may define a recess between the first and second brake bodies, and the first and second brake shoes may be positionable in the recess such that the respective outer frictional contact surfaces of the first and second brake linings are opposite each other in the recess generally perpendicular to the brake actuation direction.
The recess may be sized to receive at least a portion of a rotatable disc having first and second generally circular opposite sides, and the first and second brake shoes may be positionable in the recess such that the first and second brake linings are positionable apart from the first and second generally circular opposite sides respectively of the rotatable disc when the first brake shoe is not actuated in the brake actuation direction and such that the respective outer frictional contact surfaces of the first and second brake linings are positionable in frictional contact with the first and second generally circular opposite sides respectively of the rotatable disc when the first brake shoe is actuated in the brake actuation direction.
The frame may include a slide bearing for mounting the frame slidably in a direction generally parallel to the brake actuation direction.
In accordance with another illustrative embodiment, there is provided a brake shoe retainer apparatus including: first and second brake shoe connectors connectable to respective spaced apart regions of a brake shoe; a force transfer element connectable to the first and second brake shoe connectors; a guide connectable to a brake body and configured to guide the force transfer element relative to the brake body in a brake actuation direction and in a direction opposite the brake actuation direction; and a means for urging the force transfer element in the direction opposite the brake actuation direction.
The first brake connector may include a first shaft and a first end stop on an end of the first shaft. The second brake connector may include a second shaft and a second end stop on an end of the second shaft. The first and second end stops may have respective widths. The force transfer element may have opposite inward-facing and outward-facing surfaces. The force transfer element may define first and second through-openings, extending between the inward-facing and outward-facing surfaces, for receiving the respective shafts of the first and second brake shoe connectors respectively. The first and second through-openings may have respective widths less than the widths of the first and second end stops respectively, such that the force transfer element can retain at least respective portions of the first and second end stops against the outward-facing surface to prevent the first and second end stops from passing through the first and second through-openings respectively when the first and second through-openings receive the first and second shafts respectively.
The width of the first through-opening may be greater than a width of the first shaft, and the width of the second through-opening may be greater than a width of the second shaft, such that when the first and second brake shoe connectors are connected to the brake shoe and connected to the force transfer element, the first and second brake shoe connectors are movable relative to the force transfer element to accommodate movement of the brake shoe relative to the force transfer element.
The guide may include a post having a longitudinal axis, and the force transfer element may define a third through-opening generally complementary to the post.
The first and second through-openings may be on respective opposite ends of the force transfer element, and the third through-opening may be between the first and second through-openings.
The first through-opening may extend to a first side of the force transfer element and the second through-opening may extend to a second side of the force transfer element opposite the first side of the force transfer element. The force transfer element may be rotatable about the post such that the first and second shafts are receivable in and removable from the first and second through openings respectively in response to rotation of the force transfer element about the post.
The first brake connector may further include a first inner stop positionable against the inward-facing surface of the force transfer element when the first through-opening receives the first shaft. The second brake connector may further include a second inner stop positionable against the inward-facing surface of the force transfer element when the second through-opening receives the second shaft.
The means for urging may include a resilient body positionable in contact with the force transfer element and the brake body.
The resilient body may include a coil spring positionable around a portion of the guide.
Other aspects and features of the present invention will become apparent to those ordinarily skilled in the art upon review of the following description of specific embodiments of the invention in conjunction with the accompanying figures.
In drawings of illustrative embodiments:
Referring to
The brake frame 112 defines a recess shown generally at 114 between the first brake body 106 and the second brake body 108. In the embodiment shown, the recess 114 is sized to receive a portion of a rotatable disc 116 rotatable about a rotatable shaft 118. The rotatable disc 116 has first and second opposite side surfaces 120 and 122. The opposite side surfaces 120 and 122 may be referred to as “generally circular” because the rotatable disc 116 may be either exactly circular, or approximately and sufficiently circular such that the brake system 100 functions as a disc brake to brake an object to be braked, which in the embodiment shown is the rotatable disc 116.
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The first brake assembly 102 in the embodiment shown also includes a first brake shoe 138 connected to a first brake lining 140. In the embodiment shown, the first brake shoe 138 includes a metallic plate, and the first brake lining 140 has an outer frictional contact surface 142 for frictionally contacting the first generally circular side surface 120 of the rotatable disc 116 (shown in
When the rotatable disc 116 rotates about the rotatable shaft 118, the first generally circular side surface 120 of the rotatable disc 116 (shown in
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In the embodiment shown, the first brake body 106 defines threaded openings 180, 182, 184, and 186 to receive respective portions of the threaded fasteners 170, 172, 174, and 176 respectively in a rear side shown generally at 188. The first brake body 106 also defines a through-opening 190 extending between the rear side 188 and a front side shown generally at 192, and the through-opening 190 in the embodiment shown receives the brake piston 178 to facilitate contact of the brake piston 178 against the first brake shoe 138.
The first brake body 106 also defines through-openings 196 and 198 both extending between the rear side 188 and the front side 192. The through-openings 196 and 198 in the embodiment shown receive respective portions of first and second brake shoe connectors 200 and 202 respectively, which are connectable to respective spaced apart regions of the first brake shoe 138. At respective rear ends, the first and second brake shoe connectors 200 and 202 have respective stops 204 and 206. The first brake assembly 102 includes first and second coil springs 208 and 210 positioned between the rear side 188 of the first brake body 106 and the first and second stops 204 and 206 respectively. The first and second coil springs 208 and 210 are resiliently compressed in the embodiment shown in
On the first lateral side 148 of the first brake assembly 102, the first brake body 106 defines first and second openings 214 and 216 for receiving respective fasteners 218 and 220. In the embodiment shown, the fasteners 218 and 220 are connectable to the first lateral retainer 152, and thus removably connect the first lateral retainer 152 to the first brake body 106. Corresponding through-openings and fasteners (not shown) removably connect the second lateral retainer 154 to the first brake body 106.
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When the brake piston 178 moves in the direction of the arrow 212 opposite the brake actuation direction and thus ceases transmitting a brake actuation force on the first brake shoe 138, the first and second coil springs 208 and 210 expand to urge the first and second brake shoe connectors 200 and 202, and thus the first brake shoe 138, in the direction of the arrow 212 opposite the brake actuation direction again to retain the first brake shoe 138 against the front side 192 of the first brake body 106. The first and second brake shoe connectors 200 and 202 and the first and second coil springs 208 and 210 in the embodiment shown thus function as a brake shoe retainer to retain the first brake shoe 138 against the first brake body 106 while permitting the first brake shoe 138 to be actuated in the brake actuation direction of the arrow 194, away from the first brake body 106. Further, the first and second coil springs 208 and 210 in the embodiment shown resiliently urge the first brake shoe 138 against the first brake body 106.
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Because the first and second lateral retainers 152 and 154 retain the first brake shoe 138 against lateral movement in the directions of the arrows 144 and 146, and because the first and second brake shoe connectors 200 and 202 permit lateral movement of the first brake shoe 138 for the first brake shoe 138 to contact one of the first and second lateral retainers 152 and 154, it is not necessary to machine the components of the first brake assembly 102 as precisely as may be required in other brake assemblies. In the embodiment shown, lateral contact surfaces 254 and 256 of the first and second lateral retainers respectively provide relatively large surface areas to retain the first brake shoe 138 against lateral braking forces without requiring machining of such components as precisely as may be required to provide similar surface areas for laterally retaining the first brake shoe 138 against such lateral braking forces in other brake assemblies. Further, the surface areas of the lateral contact surfaces 254 and 256 are unaffected by thermal expansion or contraction of the first brake shoe 138, and thus the first brake assembly 102 may be less likely to seize in response to thermal expansion of the first brake shoe 138 when compared to other brake assemblies.
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More generally, in the embodiment shown in
Further, because the first and second lateral retainers 152 and 154 are connectable to and removable from the first brake assembly 102, one or both or the first and second lateral retainers 152 and 154 can selectively retain the first brake shoe 138 against lateral movement in a direction of movement of an object to be braked, such as the rotatable disc 116 for example.
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Further, the outer frictional contact surfaces 142 and 310 in the embodiment shown are generally perpendicular the brake actuation direction of the arrow 194, meaning that the outer frictional contact surfaces 142 and 310 are either perpendicular the brake actuation direction of the arrow 194, or sufficiently perpendicular such that the brake system 100 functions as a brake to brake an object to be braked, which in the embodiment shown is the rotatable disc 116.
In operation, when the first brake shoe 138 is retained against the front side 192 of the first brake body 106 and not actuated in the brake actuation direction of the arrow 194, the outer frictional contact surface 142 of the first brake lining 140 is spaced apart from the first generally circular side surface 120 of the rotatable disc 116, and the outer frictional contact surface 310 of the second brake lining 308 is spaced apart from the second generally circular side surface 122 of the rotatable disc 116. The rotatable disc 116 and the rotatable shaft 118 may thus rotate without braking force from the brake system 100. However, when the brake actuator 160 actuates the first brake shoe 138 in the brake actuation direction of the arrow 194, the outer frictional contact surface 142 of the first brake lining 140 approaches and eventually frictionally contacts the first generally circular side surface 120 of the rotatable disc 116. As the brake actuator 160 continues to actuate the first brake shoe 138 in the brake actuation direction of the arrow 194, the brake system 100 slides relative to the stationary object 304 in a direction opposite the brake actuation direction of the arrow 194 until the outer surface 310 of the second brake lining 308 frictionally contacts the second generally circular side surface 122 of the rotatable disc 116. The combined frictional contact of the outer frictional contact surfaces 142 and 310 brakes, and thus retards or prevents rotation of, the rotatable disc 116 and the rotatable shaft 118. Such braking may be released by releasing brake actuation of the brake actuator 160.
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As with the first and second lateral retainers 152 and 154 (shown in
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When the rear side 372 of the brake shoe 356 is retained against a front side 391 of the brake body 352, the threaded openings 374, 376, 378, and 380 are aligned with the through-openings 364, 366, 368, and 370 respectively such that the through-openings 364, 366, 368, and 370 can receive shafts 375, 377, 379, and 381 respectively, and such that the respective threaded portions of the brake shoe connectors 382, 384, 386, and 388 may be threadedly received in the threaded openings 374, 376, 378, and 380 respectively to connect the brake shoe connectors 382, 384, 386, and 388 to the brake shoe 356.
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The first force transfer element 394 has first and second opposite ends shown generally at 404 and 406, and first and second laterally opposite sides shown generally at 408 and 410. Proximate the end 404, the force transfer element 394 defines a through-opening 412 extending to the first side 408. Also, proximate the end 406, the force transfer element 394 defines a through-opening 414 extending to the side 410. Therefore, the shafts 375 and 377 are receivable in and removable from the through openings 412 and 414 respectively in response to rotation of the first force transfer element 394 about the post 401.
The end stops 383 and 385 contact the first force transfer element 394 on an outward-facing side of the first force transfer element 394, and in the embodiment shown the brake shoe connectors 382 and 384 also include respective inner stops 415 and 417 that contact an inward-facing side of the first force transfer element 394 opposite the outward-facing side of the first force transfer element 394. The end stops 383 and 385 and the inner stops 415 and 417 may be threadedly removable and positionable, for example, on the brake shoe connectors 382 and 384 to fit tightly on the opposite outward-facing and inward-facing sides of the first force transfer element 394, thereby securing the brake shoe connectors 382 and 384 in respective positions relative to the first force transfer element 394 to maintain the brake shoe 356 and the brake lining 358 in a generally consistent orientation, which may advantageously distribute braking wear generally evenly over an outer frictional contact surface of the brake lining 358.
The shafts 375 and 377 have respective widths 416 and 418, the through-openings 364 and 366 have respective widths 420 and 422, the through-openings 412 and 414 have respective widths 424 and 426, and the end stops 383 and 385 have respective widths 428 and 430. The widths 424 and 426 are less than the widths 428 and 430, and therefore the brake shoe connectors 382 and 384 are connectable to the first force transfer element 394 because the first force transfer element 394 can retain the end stops 383 and 385 from passing through the through-openings 412 and 414 respectively when the through-openings 412 and 414 receive the shafts 375 and 377 respectively.
Therefore, when the brake shoe connectors 382 and 384 are connected to the first force transfer element 394 and connected to the brake shoe 356 as shown in
In the embodiment shown, the brake shoe connectors 382 and 384, the first force transfer element 394, and the first coil spring 398 retain the brake shoe 356 against the brake body 352 with one or both of the first and second lateral spaces between the brake shoe 356 and lateral retainers (such as the first and second lateral retainers 152 and 154 or the retainer bodies 332, 334, 336, and 338 described above, for example).
Further, in the embodiment shown, the widths 424 and 426 are greater than the widths 416 and 418 respectively, and the widths 420 and 422 are also greater than the widths 416 and 418 respectively. Therefore, when the brake shoe connectors 382 and 384 are connected to the brake shoe 356 and connected to the first force transfer element 394, the brake shoe connectors 382 and 384 are movable relative to the first force transfer element 394 to accommodate movement of the brake shoe 356 relative to the first force transfer element 394. Such movement of the brake shoe 356 relative to the first force transfer element 394 may be in a direction of movement of an object to be braked (not shown) in response to the outer frictional contact surface of the brake lining 358 frictionally contacting the object to be braked, as described above for example.
Because the first guide 390 guides first force transfer element 394 along the longitudinal axis of the post 401, and because the brake shoe connectors 382 and 384 are connectable to respective spaced apart regions of the brake shoe 356 on respective opposite sides of the first guide 390, the first force transfer element 394 may advantageously transfer a force from the first coil spring 398 generally evenly to such spaced apart regions of the brake shoe 356. Transferring such a force generally evenly to such spaced apart regions of the brake shoe 356 may tend to urge, the brake shoe 356 in an orientation generally perpendicular to the longitudinal axis of the post 401, which may advantageously prevent misalignment of the brake shoe 356. Further, because the shafts 375 and 377 are receivable in and removable from the through openings 412 and 414 respectively in response to rotation of the first force transfer element 394 about the post 401, a brake shoe retainer including the brake shoe connectors 382 and 384, the first guide 390, the first force transfer element 394, and the first coil spring 398 may advantageously permit a brake shoe to be installed or removed from a brake assembly more efficiently than in other brake assemblies.
The threaded opening 360, the through-openings 368 and 370, the brake shoe connectors 382 and 384, the first guide 390, and the first coil spring 398 are substantially the same as the threaded opening 362, the through-openings 364 and 366, the brake shoe connectors 386 and 388, the second guide 392, and the second coil spring 400 respectively.
Alternative embodiments may differ in numerous ways from those described above. For example, the coil springs described above may be replaced with other springs, or more generally with other resilient bodies. Further, where threads are shown and described above, such threads may be replaced with other fittings or attachment configurations, or with welding, adhesives, or still other alternatives. Still further, alternative embodiments may include two or more brake actuators, and combinations of one or more of the brake shoe retainers described above or other brake shoe retainers.
While specific embodiments of the invention have been described and illustrated, such embodiments should be considered illustrative of the invention only and not as limiting the invention as construed in accordance with the accompanying claims.