Braking systems for rail and mover systems

Abstract

The present disclosure relates to a braking system for a track and mover system. The braking system for the track portion of a linear motor system includes a housing housing a brake pad of the mover and a first brake pad disposed within the housing and having a first inclined surface. The braking system also includes a second brake pad disposed within the housing and having a second inclined surface, and a wedge disposed within the housing and having a third inclined surface. The braking system also includes an actuator that moves the wedge, wherein activating movement of the wedge causes movement of the first brake pad and movement of the second brake pad.

Description

Technical Field

[0001] TECHNICAL FIELD The present disclosure relates generally to linear drive transport systems, and more particularly, to a braking system for a mover in a linear drive transport system. Background Art

[0002] A range of linear motors are known and used throughout industry, particularly in manufacturing, filling and material handling applications. Such motors typically comprise an elongated track in which motor coils are associated with a stator core (e.g. a laminated core). The coils may have different orientations depending on the motor design. Permanent magnet movers may be placed on the track and the fields generated by selective energisation of the track coils interact with the permanent magnets of the movers to move the movers along the track in a desired direction, speed and acceleration, and to stop and start at desired positions. Highly flexible and precise control of the movement of one or more movers may be achieved by control and driver circuitry associated with the coils of the track section.

[0003] Conventionally, the tracks used in linear drive transport systems can allow for travel in any direction, such as straight sections, curved sections, horizontal sections, vertical sections, etc. For example, in conventional configurations, a mover can travel up and down a vertical section of the track. When the linear drive transport system is shut down and power is lost, the mover can quickly fall to the bottom of the vertical section of the track, potentially damaging the mover and / or the mover's corresponding load. Therefore, as discussed herein, providing a braking system for the track section of the linear drive transport system can enable the linear drive transport system to hold the mover in place and prevent the mover and / or the load from experiencing unintended movement, such as falling off the vertical section of the track.

[0004] This section is intended to introduce the reader to various aspects of the technology that may be related to various aspects of the technology described and / or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present disclosure. Therefore, it should be understood that these statements are to be understood in this light and not as admissions of prior art. Summary of the Invention

[0005] The following describes an overview of the specific embodiments disclosed herein. It should be understood that these aspects are presented merely to provide the reader with a brief overview of these specific embodiments, and that these aspects are not intended to limit the scope of the present disclosure. In fact, the present disclosure may encompass various aspects that may not be described below.

[0006] In one embodiment, a braking system for a track portion of a linear motor system includes: a housing configured to house a brake flag of a mover of the linear motor system; and a first brake pad disposed within the housing and comprising a first inclined surface, wherein the first brake pad is configured to move between a first position and a second position, wherein the first brake pad is configured to engage the brake flag of the mover of the linear motor system in the second position. The braking system also includes: a second brake pad disposed within the housing and comprising a second inclined surface, wherein the second brake pad is configured to move between a third position and a fourth position, wherein the second brake pad is configured to engage the brake flag of the mover of the linear motor system in the fourth position; and a wedge disposed within the housing and comprising a third inclined surface configured to interface with the first inclined surface of the first brake pad and a fourth inclined surface configured to interface with the second inclined surface of the second brake pad. The braking system also includes an actuator configured to move the wedge between a fifth position and a sixth position, wherein activating movement of the wedge from the fifth position to the sixth position causes the first brake pad to move from the first position to the second position and causes the second brake pad to move from the third position to the fourth position.

[0007] In another embodiment, a linear motor system includes a mover including a brake flag and a track portion. The track portion includes a plurality of coils configured to generate a controlled magnetic field, wherein the mover is configured to be displaced by the controlled magnetic field, and the brake system is configured to engage the brake flag and to limit movement of the mover along the track portion.

[0008] In yet another embodiment, a linear motor system includes a mover having a brake flag. The linear motor system also includes a track portion including a plurality of coils configured to generate a controlled magnetic field, wherein the mover is configured to be displaced by the controlled magnetic field. The linear motor system also includes a brake system configured to engage the brake flag and to limit movement of the mover along the track portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0009] These and other features, aspects, and advantages of the present disclosure will become better understood when the following detailed description is read with reference to the accompanying drawings, in which like reference numerals represent like parts throughout, and in which:

[0010] Figure 1A is a perspective view of an exemplary linear motor system showing a straight track portion and a curved track portion and several movers positioned for movement along the portions according to embodiments described herein;

[0011] Figure 1B is a top view of a similar linear motor system according to an embodiment described herein, wherein the motor coils are arranged in a manner different from Figure 1A to locate the system.

[0012] Figure 2 is a method for use according to the embodiments described herein Figure 1A and Figure 1B A cross-sectional view of an embodiment of a braking system of a linear motor system;

[0013] Figure 3 is a method for use according to the embodiments described herein Figure 1A and Figure 1B A cross-sectional view of an embodiment of a braking system of a linear motor system;

[0014] Figure 4 According to the embodiments described herein, the Figure 2 The brake system's actuator Figure 1A and Figure 1B A diagrammatic representation of a linear motor system; and

[0015] Figure 5 is a combination of multiple braking systems according to the embodiments described herein Figure 1A and Figure 1B A perspective view of the track portion of a linear motor system. DETAILED DESCRIPTION

[0016] One or more specific embodiments of the present disclosure will be described below. In order to provide a concise description of these embodiments, all features of the actual implementation may not be described in the specification. It should be understood that in the development of any such actual implementation, as in any engineering or design project, a large number of implementation-specific decisions must be made to achieve the developer's specific goals, such as compatibility with system-related constraints and business-related constraints, and these specific goals may vary from implementation to implementation. In addition, it should be understood that such development efforts may be complex and time-consuming, but for those of ordinary skill in the art who benefit from the present disclosure, such development efforts remain a routine task of design, manufacturing, and production.

[0017] When introducing elements of various embodiments of the present disclosure, the articles "a," "an," "the," and "said" are intended to mean that there are one or more elements. The terms "comprising," "including," and "having" are intended to be inclusive and mean that there may be additional elements other than the listed elements.

[0018] Turning now to the drawings, and referring first to Figure 1A, a linear motor system 10 as shown is used to move items or products around a track 12. As will be appreciated by those skilled in the art, in many applications, the linear motor system 10 can interoperate with other machines, robots, conveyors, control devices, etc. (not separately shown) in overall automation, packaging, material handling, or other applications. The linear motor system 10 may generally be referred to as a "linear motor," as discussed below, in which the moving parts are positioned, accelerated, decelerated, and generally moved under the influence of controlled magnetic and electromagnetic fields. In the illustrated embodiment, the track 12 includes a plurality of straight track sections 14 and a plurality of curved track sections 16. These sections may generally be separate and may be mounted in a variety of physical configurations, such as Figure 1A elliptical shape shown in . It should be noted that other configurations are possible, as discussed below. These configurations can form closed loops of various shapes, but can also include open-ended segments. The linear motor system 10 can also include one or more movers 18 that can be mounted to the track 12 and movable along the track 12. Again, the position, velocity, acceleration, and higher-order derivative parameters of these movers 18 are controllable by appropriately controlling the coils of the system that are energized and de-energized. In the embodiment shown, the movers 18 interact with fixed elements in and around the periphery 20 of the track portion 16, but other configurations are also contemplated. A sensor system 22 is provided to detect the position of the movers 18 around the track 12, and such a sensor system can include permanent magnets, energized coils, Hall effect sensors, or any other suitable device. Typically, one component of the sensor system 22 can be mounted on the mover 18, while another component can be mounted at a fixed position around the track 12.

[0019] Each mover 18 may include a mounting platform 24. In actual implementations, various tools, holders, support structures, loads, etc. may be mounted to the mounting platform 24. To accommodate various loads, the movers 18 themselves may be constructed differently than those shown. Figure 1A A horizontal configuration is shown in FIG, but other orientations may be provided, such as where the ovals are shown standing generally on the sides or ends, or at any angle therebetween.

[0020] The linear motor system 10 may also include circuitry for controlling the movement of the mover 18. Figure 1AIn the illustrated embodiment, the circuitry may include a drive circuit 26 that provides signals to each track segment 16, and in particular, to the individual coils of each track segment 16, to generate an electromotive force that interacts with the magnets on the track segment 16 to drive the mover 18 to a specific position, and to drive the mover 18 to a specific position at a specific speed, acceleration, etc. The drive circuit 26 may generally include an inverter circuit that utilizes power electronic switches to provide drive power to the individual coils of each segment in a controlled manner. In some embodiments, the drive circuit 26 may be included in each individual track segment 16, and signals are provided to the drive circuit 26 by a power and control circuit 28. The power and control circuit 28 (and the drive circuit 26) may receive feedback from the mover 18 and / or from the sensor system 22 to detect the position, speed, acceleration, etc. of each mover 18. In some embodiments, the movers 18 may also be recognized by the power and control circuit 28 as separate axes that are independently controlled, but their positions, speeds, and accelerations are adjusted to avoid collisions, etc. Depending on the specific task to be performed, the specific motion profile achieved by the power and control circuitry 28 can generally be implemented when designing and commissioning the linear motor system 10. Finally, various remote control and / or monitoring circuitry 30 can be provided and linked to the linear motor system 10 via one or more networks 32. Such remote circuitry 30 can generally allow the linear motor system 10 to be coordinated with the operation of other automation components, machine systems, manufacturing and material handling machines, and the like.

[0021] Figure 1B An alternative configuration similar to the linear motor system 10 is shown. However, in this configuration, rather than positioning the motor coils around the periphery of the system 10, the coils are positioned around the top of the system 10 in a generally planar arrangement. The magnet assembly of each mover 18 faces these coils and is separated from them by a small air gap. As above, the straight track sections and curved track sections are assembled to form an elliptical shape, but other shapes and layouts are possible. As shown in Figure 1A In the case of the system shown in , the curved track portion can be adapted to a modified spline geometry, as described in more detail below.

[0022] Taking the above into consideration, Figure 2 A cross-sectional view of a brake system 60 for use with the linear motor system 10 is shown in accordance with an embodiment of the present disclosure. The brake system 60 may be incorporated into any number of track sections, e.g. Figure 1A and Figure 1B, 16. In some embodiments, each track section can include any number of brake systems 60 spaced apart along the corresponding track section. The brake system 60 can engage one or more movers 18 and restrain the movers 18 along the track. The brake system 60 can include a housing 62 that forms a portion of the track section. The housing 62 can have a U-shaped cross-section and can be formed from a metal material (e.g., aluminum, steel, titanium, etc.). The brake system 60 can include an actuator 64, such as a hydraulic cylinder, a pneumatic cylinder, an electric solenoid, a linear actuator, a servo mechanism, etc. The actuator 64 can be a component operable to move the brake system 60 between an engaged position and a disengaged position. For example, the actuator 64 can move one or more brake pads 68 into engagement with a brake flag 76 of the mover 18, and when in the engaged position, the one or more brake pads 68 can restrain the mover 18 (e.g., via the brake flag 76). In some embodiments, the actuator 64 can be coupled to the housing 62 and can be located on a bottom surface of the housing 62. In certain embodiments, the actuator 64 can include a port 64A disposed on an outer surface of the actuator 64 that can be coupled to a control circuit, such as a pneumatic circuit, a hydraulic circuit, an electrical circuit, or the like.

[0023] The actuator 64 may also include a rod 64B disposed at least partially through a hole in the housing 62. The actuator 64 may actuate the rod 64B between a first position (e.g., a lower position) and a second position (e.g., an upper position). For example, the rod 64B may move substantially vertically between the first position and the second position. In some embodiments, the actuator 64 may include a spring to bias the rod 64B toward the second position. Thus, the brake system 60 may be biased toward the engaged position so that the brake pads 68 may engage the brake flag 76 in the event that the linear motor system 10 loses power. The rod 64B may be coupled to an activation wedge 66 that may move with the rod 64B. For example, the rod 64B may be coupled to the activation wedge 66 such that when the rod 64B moves from the first position to the second position, the rod 64B may engage and abut the activation wedge 66, and the rod 64B may push the activation wedge 66 upward toward the brake flag 76 within the housing 62.

[0024] The activation wedge 66 can be disposed within the interior of the housing 62. The activation wedge 66 can move between a first position (e.g., a lower position) and a second position (e.g., an upper position), and can engage and move one or more brake pads 68. For example, the activation wedge 66 can include an inclined surface 66A that can engage a corresponding inclined surface 68A of the one or more brake pads 68. As the activation wedge 66 moves from the first position to the second position, the inclined surface 66A can engage and move along the inclined surface 68A of the one or more brake pads 68, applying a force to move the one or more brake pads 68 laterally inward within the housing 62 toward the brake flag 76. For example, the flat surface 68B of the one or more brake pads 68 can engage the brake flag 76, such that friction between the brake pad 68 and the brake flag 76 holds the mover 18 in position along the track. The brake pad 68 can be disposed within the interior of the housing 62. In some embodiments, one or more brake pads 68 may be formed of a material having a high coefficient of friction with the brake flag 76, such as a rubber material, a cork material, etc. Additionally or alternatively, the flat surface 68B may include a coating, such as a high friction coating, to help engage the brake flag 76 and hold the mover 18 in place. The brake system 60 may also include any number of bearings, such as needle bearings 70, between the inclined surface 66A of the activation wedge and the inclined surface 68A of the brake pad 68. For example, the needle bearing 70 may be at least partially disposed in the activation wedge 66 and may be coupled to the activation wedge 66. The needle bearing 70 may allow the inclined surface 66A of the activation wedge 66 to slide along the inclined surface 68A of the brake pad 68. Additionally or alternatively, the spring of the actuator 64 may bias the activation wedge 66 toward the first position via coupling with the rod 64B.

[0025] Taking the above into consideration, Figure 3 A cross-sectional view of another embodiment of a brake system 60 according to an embodiment of the present disclosure is shown. For clarity, some components of the brake system 60 may not be shown. Figure 3. The brake pad 68 can be coupled to the housing 62 via one or more guide pins 72. The guide pins 72 can guide the brake pad 68 laterally inward toward the center of the housing 62. For example, the guide pins 72 can at least partially pass through the housing 62 and / or through the brake pad 68 inside the housing 62. The brake pad 68 can move along the guide pins 72 when moving between the engaged position and the disengaged position (shown). Additionally or alternatively, the brake system 60 can include any number of springs, such as a return spring 74, to bias the brake pad 68 toward the disengaged position. For example, the return spring 74 can laterally bias the brake pad 68 away from the center of the housing 62 and away from engagement with the brake flag 76. Alternatively, the return spring 74 can bias the brake pad 68 toward the engaged position. A first end of the return spring 74 can be coupled to the housing 62, and a second end of the return spring 74 can be coupled to the corresponding brake pad 68. The return spring 74 can be disposed inside the housing 62.

[0026] Figure 4 is a diagrammatic representation of the linear motor system 10 showing one track portion 36 and one mover 18 positioned along the track portion 36 . Figure 2 The track portion 36 shown in FIG can be a straight track portion or a curved track portion, which differ in physical construction and have certain practical characteristics due to the curved nature of the curved portion, as discussed below. However, in general, each mover 18 can include a magnet array 38 on which a plurality of magnets 40 can be mounted. These magnets 40 can be permanent magnets and are mounted so that a small air gap is provided between the magnets 40 and the coils of the track portion 36. As shown in FIG Figure 2As shown, the mover 18 may also include a sensor component 42, such as a permanent magnet. However, it should be noted that the specific sensor component 42 included in the mover 18 may depend on the nature of the sensing strategy, the sensing resolution, the location of the sensor 42 on the mover 18 (and cooperating components on the track portion), etc. A platform 44 is provided on the mover 18 for use with installation tools, etc. as discussed above. Finally, bearings 46 and related components (e.g., rollers) are mounted to the mechanical structure of the mover 18 and can be used to interact with one or more guide rails of the track 48. These bearings 46 and the guide rails of the track 48 can allow the mover 18 to remain firmly attached to the track portion 36 while allowing the mover 18 to move relatively freely along the track portion 36 and support the mechanical loads and forces encountered during movement. The mover 18 may also include a brake flag 76. In some embodiments, the brake flag 76 can be a thin sheet and can be formed from a metal material. For example, the brake flag 76 can include a first surface and a second surface facing in opposite directions. When the brake pads 68 are moved to the engaged position, each surface of the brake flags 76 can face and engage a corresponding brake pad 68 of the brake system 60. When the brake flags 76 are engaged by the brake pads 68, movement of the mover 18 along the track portion 36 can be restricted.

[0027] Track segment 36 may include one or more brake systems 60 to hold mover 18 in position. In some embodiments, brake system 60 may include a sensor for sensing the position of actuator 64. For example, sensor 78 may determine whether brake system 60 is engaged or disengaged with brake flag 76 based on the position of actuator 64. In some embodiments, sensor 78 may generate and transmit a signal to circuitry of linear motor system 10, such as power and control circuitry 28 and / or remote control and / or monitoring circuitry 30, to indicate the status of brake system 60 (e.g., engaged, disengaged). Additionally or alternatively, sensor 78 may sense the position of brake flag 76 and generate and transmit another signal to circuitry of linear motor system 10. For example, sensor 78 may generate a signal indicating that brake flag 76 is positioned proximate to brake system 60. Thus, power and control circuitry 28 and / or remote control and / or monitoring circuitry 30 may receive the signal and generate and transmit a signal to operate brake system 60. For example, the power and control circuitry 28 and / or the remote control and / or monitoring circuitry 30 may transmit a signal to the braking system 60 and may instruct the braking system 60 to move the brake pads 68 into a position that engages the brake flags 76 .

[0028] The track segment 36 may also include a series of parallel coils 50 associated with a stator or armature 52. In the presently contemplated embodiment, these coils 50 may be mounted in slots in the stator 52, and the stator 52 itself may be made of a magnetic material formed into a stack of laminates and configured to allow for mounting within the track segment 36 housing. The specific configuration of the coil 50 and stator 52 components, their magnetic structure, mounting structure, etc., are generally beyond the scope of this disclosure. Drive circuitry 54 may be included in each track segment 36, as discussed above, to allow for the application of controlled power signals to the coils 50 to drive the mover 18 and properly position it around the track segment 36. Additionally or alternatively, a sensor array 58 may be provided in each track segment 36 to allow for interaction with the sensor components 42 of the mover 18. The sensor array 58 may provide feedback that may indicate the position of the mover 18 and may be used to derive velocity, acceleration, jerk, and other motion parameters. In the illustrated embodiment, a plurality of track sections 36 may be mounted end-to-end and interconnected with each other and / or with the power and control circuitry 28 to receive signals for powering the coils 50 .

[0029] As will be appreciated by those skilled in the art, the track portion 36 and the magnet array 38 of the mover 18 may generally form a system that may be considered a linear motor system 10. That is, an electromotive force is generated by the controlled fields of the coils 50, and the interaction between these fields and the magnetic field of the magnet array 38 is used to drive the mover 18 to a desired position at a desired speed, etc. As described above, these coils 50 and the linear motor itself may be designed according to various construction strategies, such as a construction strategy having the coils 50 arranged around the periphery of the track portion 36, a construction strategy in which the coils 50 are generally planar (at the top or bottom position of the portion 36), etc. Although a "linear" motor system 10 may be used in the present disclosure, it should be understood that curved portions of various configurations are intended to be included within the scope of the present disclosure.

[0030] To operate the brake system 60, the circuitry of the linear motor system 10 can instruct one or more brake systems 60 to engage the brake flag 76 of the corresponding mover 18. For example, the power and control circuitry 28 and / or the remote control and / or monitoring circuitry 30 can generate and transmit instructions to the drive circuitry 54 to stop operation of the linear motor system 10 (e.g., to stop the mover 18). Additionally or alternatively, the control circuitry 28, 30 can generate and transmit instructions to the one or more brake systems 60 to actuate the actuator 64 and move the brake pad 68 from the disengaged position to a position engaged with the brake flag 76 of the mover 18.

[0031] Taking the above into consideration, Figure 5A track portion 36 is shown incorporating multiple brake systems, such as brake systems 60A and 60B, according to an embodiment of the present disclosure. Braking systems 60A and 60B can be spaced apart along track portion 36 to ensure that brake flags 76 can be engaged by one of brake systems 60A and 60B at any location along track portion 36. For example, brake systems 60A and 60B can be installed and / or incorporated into track portion 36 at a distance 80 spaced apart along track portion 36. Distance 80 can be selected based on the size of brake flags 76 so that brake pads of brake systems 60A and 60B can engage at least a portion of brake flags 76. For example, distance 80 can be up to 90 percent of the size of brake flags 76 (e.g., up to 50 percent, up to 60 percent, up to 75 percent, etc.). In certain embodiments, track portion 36 can include a cutout 82 to receive one of brake systems 60.

[0032] The present disclosure includes a braking system in a track section of a linear drive transport system. The braking system limits movement of a mover along the track section. Limiting the movement of the mover prevents unintended movement of the mover, such as on a vertical track section. Technical benefits of the disclosed technology include preventing damage caused by unintended movement of the mover of the linear drive transport system.

[0033] Although only certain features of the present disclosure are illustrated and described herein, many modifications and changes will occur to those skilled in the art. Therefore, it should be understood that the appended claims are intended to cover all such modifications and changes that fall within the true spirit of the present disclosure. The technology proposed and claimed herein is referenced and applied to specific examples of material objects and actual properties, which significantly improves the art and is therefore not abstract, intangible or purely theoretical. In addition, if any claim attached to this specification contains one or more elements designated as "means for [performing] [function] ... " or "step for [performing] [function] ... ", it is intended that such elements will be interpreted according to 35 U.S.C.112 (f). However, for any claim containing elements specified in any other way, it is intended that such elements will not be interpreted according to 35 U.S.C.112 (f).

Claims

1. A braking system for a track portion of a linear motor system, the braking system comprising: a housing configured to accommodate a brake flag of a mover of the linear motor system; a first brake pad disposed within the housing and comprising a first inclined surface and a first vertical surface opposite the first inclined surface, wherein the first brake pad is configured to move between a first position and a second position, wherein the first brake pad is configured such that the first vertical surface engages a brake flag of a mover of the linear motor system in the second position; a second brake pad disposed within the housing and comprising a second inclined surface and a second vertical surface opposite the second inclined surface, wherein the second brake pad is configured to move between a third position and a fourth position, wherein the second brake pad is configured such that the second vertical surface engages a brake flag of a mover of the linear motor system in the fourth position; a wedge disposed within the housing and comprising a third inclined surface configured to interface with the first inclined surface of the first brake pad and a fourth inclined surface configured to interface with the second inclined surface of the second brake pad; and an actuator including a rod disposed at least partially through the aperture in the housing and coupled to the wedge, and configured to move the wedge between a fifth position and a sixth position via the rod, wherein movement of the wedge from the fifth position to the sixth position causes the first brake pad to move from the first position to the second position and causes the second brake pad to move from the third position to the fourth position; The actuator further includes a spring biasing the rod toward a position corresponding to the sixth position such that the first brake pad and the second brake pad engage the brake flag when power to the linear motor system is lost.

2. The braking system according to claim 1, wherein: The housing comprises a metal material.

3. The braking system according to claim 1, wherein: The first brake pad and the second brake pad include rubber material, cork material or a combination thereof.

4. The braking system according to claim 1, wherein: Each of the first vertical surface and the second vertical surface includes a coating.

5. The brake system of claim 1 , comprising a plurality of bearings disposed between the wedges, wherein: Each bearing of the plurality of bearings is configured to engage the first brake pad or the second brake pad.

6. The braking system according to claim 5, wherein: Each bearing of the plurality of bearings comprises a needle roller bearing.

7. The braking system according to claim 5, wherein: A first bearing of the plurality of bearings is disposed between the first inclined surface of the first brake pad and the third inclined surface of the wedge, and wherein a second bearing is disposed between the second inclined surface of the second brake pad and the fourth inclined surface of the wedge.

8. The brake system of claim 1 , comprising a sensor configured to detect the position of the brake flag, wherein The sensor is configured to generate a signal indicative of a position of the brake flag.

9. The braking system according to claim 1, wherein: The actuator is one of a pneumatic cylinder, a hydraulic cylinder, a solenoid, a linear actuator, or any combination thereof.

10. A track portion of a linear motor system, comprising: a plurality of coils capable of being energized to generate a controlled magnetic field; as well as A braking system according to any one of claims 1 to 9.

11. A method for the braking system according to claim 1, comprising: causing movement of the wedge between the fifth position and the sixth position by operating a rod of the actuator; as well as The first brake pad is moved between the first position and the second position, and the second brake pad is moved between the third position and the fourth position.

12. The method according to claim 11, comprising: biasing the first brake pad toward the first position; as well as The second brake pad is biased toward the third position.

13. The method of claim 11, comprising detecting the position of the brake flag via a sensor.

14. The method of claim 13, comprising generating a signal indicative of the position of the brake flag.

Images