Brush assembly

Abstract

A brush assembly for transmitting power to a rotating component is provided, the assembly comprising: one or more conductive brushes; a housing configured to receive the one or more brushes and hold the one or more brushes aligned with an opposing surface; and one or more brush brackets, wherein each bracket is configured to receive and clamp onto a corresponding brush so that the brush can be removed from the bracket by releasing the clamp from each of the one or more brushes to its corresponding bracket.

Description

Technical Field

[0001] The present disclosure generally relates to a brush assembly (which may otherwise be referred to as a brush block assembly). In various embodiments, the brush assembly can be used to conduct power from a stationary or non-rotating power system to a rotating system, such as a propeller. The technology described herein may be particularly useful when used in conjunction with an aircraft propeller anti-icing system. Various embodiments may relate to an aircraft propeller de-icing system that includes a brush assembly. However, the application is not limited to this function and is also applicable to gas turbine engine health monitoring systems, or any other system that requires power to be transferred from a stationary system to a rotating system. For example, the technology described herein can be applied to any application involving a brush assembly that transfers power between a rotating system and a stationary system. Background Art

[0002] The transmission of power between a non-rotating power system and a rotating system is usually performed by a brush assembly, which includes brushes forming part of the non-rotating system, and the brushes are configured to ride on slip rings located on the rotating system. Thus, the brushes form a plurality of sliding contacts with the slip rings. Power can be conducted from the brushes of the fixed brush assembly to the rotating slip rings of the slip ring assembly through the plurality of sliding contacts.

[0003] Due to the continuous sliding contact with the rotating slip ring, the brushes wear during use. Therefore, they need to be replaced periodically. In conventional systems, replacing the brushes may require complete disassembly of the brush block and subsequent reassembly, including power-off operation.

[0004] There is a need for improved brush assemblies such that the brushes experience less wear during use and also such that the brushes can be more easily disposed of by a user, for example in a safe and efficient manner. Summary of the invention

[0005] In one aspect, there is provided a brush assembly for transmitting power to a rotating component, the assembly comprising:

[0006] one or more conductive brushes;

[0007] a housing configured to receive the one or more brushes and to hold the one or more brushes in alignment with the opposing surface;

[0008] One or more brush holders, each brush holder being configured to receive and clamp to a respective brush such that the brush can be removed from the holder by releasing the clamp from each of the one or more brushes to its respective holder.

[0009] The brush assembly may also include one or more resilient members (eg, springs such as coil springs) configured to bias the respective brackets toward the opposing surface.

[0010] Each resilient member is biased between the housing and a corresponding bracket.

[0011] The brushes may be replaceable and / or removable from the bracket, for example without any disassembly or damage to the rest of the assembly.

[0012] Each brush holder may be configured to slide within the housing.

[0013] Each brush holder may be configured to prevent contact between the housing and a corresponding brush.

[0014] The brush and / or the bracket may comprise one or more retaining devices configured to hold the brush in position relative to the bracket.

[0015] One of the bracket and the brush may include one or more protrusions, and the other of the bracket and the brush may include one or more recesses, wherein the protrusions and recesses are paired with each other so that when the bracket is clamped onto the brush, each protrusion cooperates with the corresponding recess to substantially prevent each brush from moving relative to the corresponding bracket.

[0016] The recess may be located on the brush and machined into a side of the brush.

[0017] The protrusion may be located on the bracket and formed in an arm of the bracket that clamps to the side of the brush.

[0018] Each of the one or more brushes may include an upper surface and a lower surface for making electrical contact with an opposing conductor. A recess or protrusion may be located at a distance between the upper contact surface and the lower contact surface along the length of the brush or bracket. One of the upper contact surface or the lower contact surface can be used as a first contact surface, then the brush is inverted after a period of operation, and the other of the upper contact surface or the lower contact surface is used as a different second contact surface. Positioning the recess or protrusion along the length of the brush or bracket can be facilitated by providing a distinct step for flipping the brush in use, as the upper contact surface or the lower contact surface will wear into (or approach) the recess or protrusion during use.

[0019] The brush assembly may further include a locking member configured to prevent movement of the bracket.

[0020] The locking member is movable between a first position in which the locking member prevents the bracket from moving in a direction toward or away from the opposing surface and a second position in which the locking member does not prevent the bracket from moving toward or away from the opposing surface.

[0021] The brush assembly may further comprise an indication device configured to indicate a maximum travel of the carriage in order to indicate a maximum wear of the brushes.

[0022] The brush assembly may further comprise one or more seals between the carrier and the housing, wherein the one or more seals are configured to prevent particles from entering an interior of the housing in use. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Various embodiments will now be described, by way of example only, and with reference to the accompanying drawings, in which:

[0024] Figure 1A , 1B and 1C show a brush assembly (which may be referred to as a brush block assembly) including one or more conductive brushes;

[0025] Figure 2 A set of conventional brushes 12 are schematically shown isolated and removed from their respective slip rings;

[0026] Figure 3 An embodiment of the present disclosure is shown in which a portion of the brush assembly is modified to improve the brush's ability to avoid wear, wherein Figure 3 Indicates passing through Figure 3A A cross section "A" of a brush assembly is shown;

[0027] Figure 4A , 4B 4C show the various parts of the brush assembly respectively;

[0028] Figure 5 Is through Figure 3A A cross section "B" of a brush assembly is shown;

[0029] Figure 6 The brush assembly is shown immediately prior to operation;

[0030] Figure 7 shows a brush assembly after a period of operation, wherein the contact surfaces of the brushes have worn;

[0031] Fig. 8A A brush assembly with a displaced locking member is shown, and Figure 8B A brush assembly is shown with the retaining arm moved to allow removal of the brushes;

[0032] Fig. 9 An embodiment of a brush is shown isolated and prior to use;

[0033] Fig. 10A and 10B Shown with the brush removed and reversed to utilize both its upper and lower contact surfaces. DETAILED DESCRIPTION

[0034] Figure 1A , 1B 1C shows a brush assembly 10 (which may be referred to as a brush block assembly), wherein one or more conductive brushes 12 are provided, which may be mounted within the assembly 10 and may each be configured to contact a conductive slip ring 20 located on an annular member 22 of a relatively rotating system. In various embodiments, one or more brushes 12 may be located on a rotating system, and one or more slip rings 20 and annular member 22 may be located on a fixed system. For the sake of brevity, the alternative will not be described in more detail, except to state that the features described below may all be applied to this alternative. The brush 12 may be made of carbon. The following may cover any alternative material.

[0035] The brush assembly 10 may also include a mounting device 14 for mounting the assembly 10 to a fixed, non-rotating system, which may be any suitable mounting device known in the art. The mounting device 14 may be mounted using fasteners extending through corresponding apertures 17 on the mounting device, although any suitable connection may be used. For example, the mounting device 14 may form an integral part of a larger assembly or device of a fixed system.

[0036] The assembly 10 also includes one or more electrical connectors 16 (see Figure 3 ), the electrical connector being configured to transmit power from a power source of a stationary power system to the brushes 12. The assembly 10 may also include additional mounting means configured to hold and guide the brushes 12 in place within the assembly 10. Any suitable mounting means or components for electrically connecting the brushes to a power system may be used.

[0037] The brushes 12 may be spring loaded in that the assembly 10 includes one or more resilient members 40 for urging each of the one or more brushes 12 toward the slip ring 20. The brushes 12 are shown as having a substantially rectangular cross-section with (optional) chamfered edges, but any other cross-sectional shape, such as circular, may be used. When assembled, the brushes 12 will mate with the Figure 1A and 1B The slide ring 20 is shown properly aligned and will remain so during use.

[0038] The slip ring 20 may form part of a propeller assembly including the annular member 22, which itself may be attached to an aircraft engine or aircraft. In various embodiments, the power conducted through the brushes 12 and the slip ring 20 may be used in an anti-icing system for the propeller assembly, such as a power source for such a system. As described above, the brush assembly 10 and the slip ring 20 may be interchangeable, such that the brush assembly 10 may be located on a rotating system and the slip ring 20 may be located on a stationary system.

[0039] Figure 1C The alignment of the brushes 12 with the slip rings 20 is shown. In this embodiment, it can be seen that the first row of brushes 12A is aligned with and configured to contact the first slip ring 20A, while the second row of brushes 12B is aligned with and configured to contact the second slip ring 20A, and the third row of brushes 12C is aligned with and configured to contact the third slip ring 20A. Any number of rows can be provided, and any number of brushes 12 can be provided within each row. In any of these configurations, one slip ring 20 is typically provided for each row of brushes 12.

[0040] The anti-icing system may be used to prevent ice from accumulating on aircraft propeller blades. The slip ring 20 may be electrically connected to a resistive heating element in the form of a flexible strip disposed along a portion of the leading edge of the propeller blade, such as near the hub of the propeller blade. Applying an electrical current to the resistive heating element (via the electrical connector 16, brushes 12, and slip ring 20) weakens the binding force between the ice and the blade surface, which may cause the ice to be displaced due to centrifugal forces generated during propeller rotation.

[0041] The power supply may be located on a non-rotating portion of the aircraft. The power supply may be configured to provide current to brushes 12, which, as described above, are in electrical contact with conductive slip rings 20 mounted to the rotating system. The slip rings may be located at the rear of the propeller assembly or on the shaft of the propeller. The power supply may be configured to provide at least 0.5, 1, or 2 kV per propeller blade to provide the de-icing function described herein.

[0042] Due to the nature of aircraft maintenance, the technology disclosed herein is particularly applicable to brush assemblies used in conjunction with propeller systems, particularly propeller de-icing systems. However, it will be appreciated that the advantages of the brush assemblies disclosed herein relate to periodic replacement of brushes, and this can be applied to any type of system. In other words, the broadest aspects of the present disclosure are not limited to aircraft or aircraft maintenance.

[0043] Figure 2 A set of conventional brushes 12 are shown schematically, isolated and removed from their respective slip rings to illustrate the wear that may occur during operation of a conventional arrangement.

[0044] The brushes 12 are held in a housing, generally indicated at 18, which includes an aperture 30 through which each brush 12 extends. In use, the contact surface 13 of each brush 12 slides along an opposing slip ring 20 which rotates in a direction of rotation as indicated by arrow 1. As mentioned above, the brushes 12 are typically spring loaded in an axial direction, as indicated by arrow 2.

[0045] Due to the continuous movement of the brush 12 in use and the rotational direction of the slip ring 20, the rear surface 11 of the brush 12 continuously rubs against the opposing surface 32 of the housing 18. Figure 2 As shown, this causes the rear surface 11 of each brush 12 to wear and creates undercuts in each brush 12 .

[0046] Figure 3 An embodiment of the present disclosure is shown in which a portion of the brush assembly 10 is modified to improve the brushes' ability to avoid wear (thereby extending useful life) and also provide a mechanism for simply replacing the brushes without substantially affecting the remainder of the assembly. Figure 3 Indicates passing through Figure 3A A cross-section "A" of the brush assembly 10 is shown.

[0047] The brush assembly 10 includes a housing 18 and one or more brushes 12 as described above. The brushes 12 may each be spring loaded using one or more resilient members 40 (e.g., springs), wherein each brush 12 may be associated with a corresponding resilient member 40. Each resilient member 40 may be configured to bias the corresponding brush 12 toward a relatively rotating member (e.g., slip ring 20).

[0048] One or more conductors 26 (eg, wires) may be provided, each connected to the electrical connector 16 , which may be used to provide an electrical connection between the electrical connector 16 and the brush 12 .

[0049] According to the present disclosure, each of the one or more brushes 12 is held within a bracket 50 that is configured to hold and clamp to the respective brush 12. The bracket 50 also provides electrical continuity with the brush 12. Each bracket 50 may be biased by a respective resilient member 40 such that the resilient member 40 pushes the bracket 50, and thereby the brush 12, in a direction toward the relatively rotating member (e.g., the slip ring 20).

[0050] Each of the one or more brushes 12 can be removed from its corresponding bracket 50 separately from the rest of the brush assembly 10 and / or the brushes 12. This means that one or more brushes 12 can be removed from the assembly 10 without substantially affecting the rest of the assembly 10, such as by disassembling other parts of the assembly 10. In addition, one or more brushes 12 can be removed without disturbing the electrical connections of the assembly 10.

[0051] The brush assembly 10 may also include one or more seals between the carrier 50 and the housing 18 , or the carrier 50 may be substantially sealed relative to the housing 18 to prevent particles from entering the interior of the housing 18 during use.

[0052] Reference now Figure 4A Each of the one or more brackets 50 may have a base 56 and one or more arms 58, 59 extending from the base 56. The base 56 and the arms 58, 59 may form a box shape that is configured to receive the brush 12. Each brush 12 may be mounted in the arm 58, 59 of the corresponding bracket 50, and may be provided with a lower surface 15 ( Figure 3 ) rests on the base 56 with a small gap between the base 56. The arms 58, 59 of the bracket 50 can be located between the housing 18 and the corresponding brush 12 to prevent the brush 12 from contacting the housing 18. This reduces the wear of the brush 12.

[0053] Alternative configurations are possible in which the retaining element is implemented on arm 58 (rather than arm 59) or on both arms 58 and 59. For simplicity, only the configuration with the clip mounted on arm 59 is shown. However, those skilled in the art may envision other configurations described and other variations suitable for a particular application.

[0054] The brushes 12 can be clamped into the brackets 50 in that the arms 58, 59 of each bracket 50 can be clamped onto the corresponding brush 12. Additionally or alternatively, the brushes 12 can be retained within the brackets 50 by a suitable engineering fit, such as an interference fit, a friction fit, a force fit, a drive fit, or a press fit. In various embodiments, the brushes 12 can be retained within the brackets 50 by a shrink fit. In each of these cases, as described above, the brushes 12 should be removable separately from the rest of the assembly 10.

[0055] like Figure 4B As shown, the brush 12 is shown isolated so that the brush 12 can be held in place. The brush 12 may include one or more recesses 60 (e.g., Figure 3), each recess is configured to cooperate with a corresponding protrusion 52 (e.g., its arm 59, which may be a displaceable tine) located on the bracket 50. The recess 60 may be machined directly into the brush material or provided by a metal insert integrated into the brush during manufacturing. When the protrusion 52 cooperates with the corresponding recess 60, movement of the brush 12 relative to the bracket 50 may be substantially prevented.

[0056] In various embodiments, the protrusion 52 and the recess 60 may be located on another component, for example, the brush 12 may include the protrusion and the bracket 50 may include the recess.

[0057] Typically, the brush 12 and / or the bracket 50 may include one or more retaining devices configured to hold the brush 12 in position relative to the bracket 50. In the illustrated embodiment, the retaining devices correspond to cooperating protrusions 52 and recesses 60, but other types of retaining devices (e.g., as described above, suitable engineering fits or other types of cooperating elements) may be envisioned by those skilled in the art.

[0058] The protrusions 52 may be located on the arms or tines 59 of the bracket 50, and the recesses 60 may be located on the sides of the brush 12 so that they do not form part of its contact surface 13. The arms 59 may be displaced or deformed to allow the brush 12 to be inserted into the bracket 50. The protrusions 52 may then be aligned with their recesses 60, and the arms 59 may then be displaced or made stationary so that the protrusions 59 mate with the corresponding recesses 60. Each of the one or more brackets 50 is then clamped onto the corresponding brush 12.

[0059] Figure 4C The brush 12 is shown mated with a corresponding bracket 50 so that the protrusion 52 mates with the corresponding recess 60 so that the brush 12 is fixed in position relative to the bracket 50. This can also be seen in FIG. Figure 5 Seen in Figure 5 To pass through Figure 3A A cross section "B" of the brush assembly 10 is shown.

[0060] Bracket 50 may be made of a conductive material such as metal so that conductor 26 may be mounted directly to bracket 50 and provide electrical connection to brushes 12 via bracket 50. An alternative may be for the bracket to include features (or electrical connections) that enable current to be transferred to the brushes.

[0061] Return to reference Figure 3, the bracket 50 may include one or more flanges 54 configured to abut a portion of the housing 18 and / or (as shown in the illustrated embodiment) a locking member 70 (e.g., a pin or screw or any other suitable locking device). The purpose of this is to prevent the bracket 50 from contacting the opposing slip ring 20 and prevent the arms or tines 59 from moving outwardly when the brushes 12 wear during use. As discussed in more detail below, this prevents the brushes 12 from being removed from the bracket 50.

[0062] If a locking member 70 is provided, it may be removed from the housing 18 to allow insertion or other manipulation of the bracket 50. When in the locked position, as shown in FIG. Figure 3 As shown, the locking member 70 can be substantially fixed to prevent it from moving in a direction toward the relatively rotating member (e.g., the slip ring 20). In this way, the bracket 50 can be prevented from contacting the relatively rotating member because the bracket cannot move past the locking member 70 due to contact between the locking member 70 and one or more flanges 54 of the bracket 50.

[0063] It should be noted that the locking member 70 can be used to detect contact with the flange 54 of the bracket 50, for example to indicate when the brush 12 is completely worn. This contact can be achieved by closing the circuit between the connector 16 (e.g., via the conductor 26) and the locking member 70. Figure 1A As shown, the locking member 70 is accessible from the exterior of the mounting device 14, which may assist in this functionality. In this way, the locking member 70 may serve as an indicator device configured to indicate maximum travel of the carriage, and thus maximum wear of the brushes.

[0064] Figure 6 The brush assembly 10 is shown immediately prior to operation, wherein the brush 12 abuts the opposing slip ring 20 to transfer current from the electrical connector 16 to the slip ring 20 via the conductor 26 and the bracket 50. As shown in FIG4 , the resilient member 40 is biased between the bracket 50 and the housing 18 and is in a highly compressed state. It should be understood that the upper contact surface or face 13 of the brush 12 contacts the opposing surface 23 of the slip ring 20, causing the contact surface 13 of the brush 12 to wear during use.

[0065] Figure 7 FIG. 1 shows the brush assembly 10 after a period of operation, from which it can be seen that the contact surface 13 of the brush 12 has worn. As a result, the elastic member 40 has worn away. Figure 6The state shown is decompressed to a relatively less compressed state. This causes the bracket 50 to shift further toward the slip ring 20. In this way, the opposing surface 23 of the slip ring 20 almost contacts the upper rim 54 of the bracket 50. However, as described above, a portion of the housing 18 or (in the embodiment shown) a locking member 70 can be configured to prevent the bracket 50 from moving further toward the slip ring 20 and prevent subsequent contact therebetween. A portion of the housing 18 or the locking member 70 can be configured so that regardless of the wear on the brush 12, the bracket 50 will always be spaced apart from the slip ring 20. This prevents undesired contact between the bracket 50 (which may be non-wearable) and the slip ring 20.

[0066] Figure 7 The brushes 12 shown are worn to the point where they should be replaced.

[0067] Figure 7 and Fig. 8A -B shows one example of how the brush 12 may be removed from the bracket 50 without substantially affecting the rest of the device 10 , such as without disassembling other parts of the device 10 or disturbing the electrical connections of the assembly 10 .

[0068] exist Figure 7 In the embodiment shown in FIG. 1 (assuming that the slip ring 20 is not present), the locking member 70 prevents the bracket 50 from moving further in a direction away from the housing 18 (as indicated by arrow 500). This means that the brush 12 cannot be removed from the bracket 50 because the protrusion 52 remains in the recess 60 and prevents the brush 12 from moving in this direction, as shown in FIG. Figure 5 shown.

[0069] To allow further movement of the bracket 50, the locking member 70 may be displaced, such as Fig. 8A As shown, this allows the bracket 50 to move further away from the housing 18 (in the direction of arrow 500). Figure 8B As shown, in this position, the bracket 50 (eg, the arms or tines 59 thereof) may be deformed such that the protrusions 52 fall out of the recesses 60, which allows the brushes 12 to move out of the bracket 50 (as shown by arrow 500) so that they may be removed therefrom.

[0070] The locking member 70 may be moved back to its original position to prevent the bracket 50 from moving toward the housing 18 , which may aid in removing the brush 12 because it prevents the bracket 50 from moving back into the housing 18 .

[0071] The bracket 50 (e.g., its arms or tines 59) can be displaced or deformed, for example, due to the inherent properties of the material from which it is formed. For example, the bracket 50 (e.g., its arms or tines 59) can be made of elastic and / or elastically deformable materials. In other embodiments, a suitable hinge can be used, which is configured to allow the aforementioned movement of the arm 58 (including the protrusion 52).

[0072] Fig. 9 An embodiment of the brush 12 is shown in isolation and before use. The brush 12 is shown as having a length L from its upper contact surface (mentioned above) 13 to the lower surface 15. The recess 60 can be located approximately halfway between the upper contact surface 13 and the lower contact surface 15, and approximately halfway along the length L of the brush 12. Since the brush 12 is symmetrical on both sides of the recess 60, instead of replacing the brush 12, it can be placed in a usable state very quickly by turning the brush 12 over so that the lower surface 15 becomes the contact surface and the upper surface 13 becomes the surface facing the base 56 of the bracket 50.

[0073] This is Fig. 10A and 10B 50, wherein it can be seen that the brush 12 can be removed from the bracket 50 (arrow 500) when in its initial orientation, wherein the upper surface 13 forms the contact surface of the brush 12 in use. The brush 12 can then be inverted so that the previous contact surface 13 now becomes the lower surface of the brush 12 configured to face the base 56 of the bracket 50, and the previous lower surface 15 becomes the upper surface configured to contact the slip ring 20. The brush 12 can then be inserted back into the bracket 50 (arrow 500). Fig. 10B and arrow 502), where because the distance between the recess 60 and the new upper surface 15 is greater, the brush 12 will have additional life before needing replacement.

[0074] In general, the present disclosure provides replaceable brushes in a brush assembly, wherein a sliding bracket can be configured to clamp onto a brush of the brush assembly. The bracket can be electrically connected to the power system via an electrical connector. One or more recesses on the brush can be machined into the brush material (e.g., carbon) or provided by a metal insert that has been integrated into the brush during manufacturing. Several methods of providing a bracket that clamps onto the brush can be envisioned, some of which are described above. However, any suitable clamping method can be used.

[0075] Another technical effect of the disclosed technology is that due to the protection provided by the bracket, the Figure 2In order to avoid the lateral wear described above, the bracket can be located between the brush (which may be abradable) and the housing. Therefore, instead of the brush contacting the housing when moving in use, the bracket contacts the housing instead. Since the bracket can be made of a material that is not easy to wear, it is not easy to wear.

[0076] As about Figure 9-10B As described, the brush design may include a symmetrical shape or extra length below the recess (e.g., in a direction away from the initial contact surface) so that the brush can be inverted and used for a period of time after the initial wear of the initial or primary contact surface. These embodiments provide the potential for continued operation in the event that severe wear of the brush has been detected, during which a new (e.g., full-length) brush can be obtained and used to replace the worn brush. This may be useful if there are no new brushes on site or if it is desired to continue operating the rotating component for a short period of time. Being able to quickly reverse or invert the brushes in order to continue operation without disassembling the entire brush assembly can be considered an important effect of these embodiments. In the illustrated embodiment, each of the one or more brushes is a roughly rectangular block or cylinder, wherein the recess may be approximately halfway along its length, wherein each brush is substantially symmetrical on either side of the recess. Although shown as halfway along its length in the illustrated embodiment, this is not required, and the recess (or protrusion, if they are interchanged) may be located at any suitable point along the length of the block.

[0077] As described above, a locking member is disclosed that is configured to prevent the carriage from moving into or out of a position from which the brushes can be removed. This can help a user replace the brushes because during this operation the carriage can be prevented from moving back into the housing. Additionally, the locking member can be configured to prevent the carriage from contacting any rotating parts, such as the slip rings described above. This can be done by limiting the movement of the carriage so that there is always a gap between the carriage and the rotating parts.

[0078] By preventing the bracket from moving out of the housing to the extent that the arms of the bracket can be opened to allow the brush to be removed, the locking member can substantially prevent the brush from being released. In other words, the locking member can prevent the bracket from moving to a position where it can be deformed and released from the brush.

[0079] While the present disclosure has been described with reference to various embodiments, it will be understood by those skilled in the art that various changes in form and details may be made without departing from the scope of the present invention as set forth in the following claims.

Claims

1. A brush assembly for transmitting power to a rotating component, the assembly comprising: one or more conductive brushes; a housing configured to receive the one or more brushes and to hold the one or more brushes in alignment with the opposing surface; one or more brush holders, each brush holder being configured to receive and clamp to a respective brush such that the brush can be removed from the holder by releasing the clamp from each of the one or more brushes to its respective holder, Each brush holder is configured to slide within the housing and includes a base and one or more arms extending from the base, and the one or more arms are located between the housing and the corresponding brush to prevent contact between the brush and the housing when sliding. 2 . The brush assembly of claim 1 , further comprising one or more resilient members configured to bias the corresponding bracket toward the opposing surface.

3. The brush assembly of claim 2, wherein each resilient member is biased between the housing and a corresponding bracket.

4. The brush assembly of any one of claims 1-3, wherein the brushes are replaceable.

5. The brush assembly of any one of claims 1-3, wherein the brush and / or the carrier comprises one or more retaining devices configured to hold the brush in position relative to the carrier.

6. The brush assembly of any one of claims 1-3, wherein one of the bracket and the brush comprises one or more protrusions and the other of the bracket and the brush comprises one or more recesses, wherein the protrusions and recesses mate with each other such that when the bracket is clamped onto the brush, each protrusion cooperates with a corresponding recess to substantially prevent each brush from moving relative to the corresponding bracket.

7. The brush assembly of claim 6 wherein the recess is located on the brush and is machined into a side of the brush.

8. The brush assembly of claim 6, wherein the protrusion is located on the bracket and is formed in an arm of the bracket that clamps to the side of the brush.

9. The brush assembly of claim 6, wherein each of the one or more brushes includes an upper contact surface and a lower contact surface for making electrical contact with an opposing conductor, wherein a recess is located a distance between the upper contact surface and the lower contact surface along the length of the brush so that one of the upper contact surface or the lower contact surface can be used as a first contact surface, and then after a period of operation the brush is inverted and the other of the upper contact surface or the lower contact surface is used as a different second contact surface.

10. The brush assembly of any one of claims 1-3 and 7-9, further comprising a locking member configured to prevent movement of the bracket.

11. The brush assembly of claim 10, wherein the locking member is movable between a first position in which the locking member prevents the bracket from moving in a direction toward or away from the opposing surface and a second position in which the locking member does not prevent the bracket from moving toward or away from the opposing surface.

12. The brush assembly of any one of claims 1-3, 7-9 and 11, further comprising an indication device configured to indicate a maximum travel of the bracket so as to indicate a maximum wear of the brush.

13. The brush assembly of any one of claims 1-3, 7-9 and 11, further comprising one or more seals between the bracket and the housing, wherein the one or more seals are configured to prevent particles from entering the interior of the housing during use.

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