Safety fastener

Abstract

The present invention relates to safety fasteners and / or safety systems. More particularly, but not exclusively, the present invention relates to safety fasteners that indicate when a fastener has been damaged and / or safety systems that indicate when a safety critical component has been damaged. The fastener comprises a load support that encloses an internal volume filled with fluid and also comprises a fluid sensor configured to detect the presence of fluid in the internal volume. The fluid sensor is configured such that a "fluid present" state is activated when fluid is detected. When the fastener fails, fluid escapes from the internal volume causing the fluid sensor to leave the "fluid present" state, indicating that a failure has occurred.

Description

[Technical field]

[0001] The present invention relates to safety fasteners and / or safety systems. More particularly, but not exclusively, the present invention relates to safety fasteners that indicate when a fastener has been damaged and / or safety systems that indicate when a safety critical component has been damaged. [Background technology]

[0002] Fasteners such as bolts and pins are used in many safety critical situations. For example, large machines such as grinders or chippers used to process wood in forestry applications contain numerous pins that hold various parts of the machine together. These pins experience significant, sometimes unpredictable, loads during use. Due to fatigue and / or manufacturing defects, the pins can fail during use, causing significant and expensive damage to the machine, especially which may require long time to fix in the field. Failures may also create safety hazards. Machine operators may inspect critical pins before using the machine, but such inspections may be time consuming. Also, pins with internal damage, such as cracks that have not yet migrated to the pin's surface, may not be identified, resulting in pin failure during use of the machine. Some pins may be difficult to access for inspection in the field, and / or defects may be obscured by other machine parts with which the pin interacts. In addition to visual inspection, pins may be inspected using various non-destructive testing techniques, for example, using electromagnetic sensors and testing techniques, or using ultrasonic testing. However, such testing may be time consuming and expensive. Additionally, non-destructive testing can be difficult in the field where environmental conditions can be harsh and machines can be dirty, wet, or contaminated by the materials being processed.

[0003] Those skilled in the art will appreciate that there are many other examples of fasteners used where failure of the fastener could create a safety hazard and / or cause cost or damage to the machine or structure containing the fastener, such as pins and / or bolts used in large engineering structures such as bridges and buildings, pins and / or bolts used in amusement park rides such as roller coasters and Ferris wheels, and pins and / or bolts used in automotive, space, and aviation applications.

[0004] An example of a bolt is shown in US 4447388. The bolt contains an internal chamber filled with a radioactive gas. A sensor is placed in close proximity to the bolt to detect the escape of gas from the bolt, indicating that the bolt has cracked. Summary of the Invention [Problem to be solved by the invention]

[0005] The present invention seeks to alleviate the above problems. Alternatively or additionally, the present invention seeks to provide improved fasteners and methods of testing fasteners to detect damage prior to fastener failure. [Means for solving the problem]

[0006] According to a first aspect, the present invention provides a fastener comprising a load support enclosing an internal volume filled with fluid and comprising a fluid sensor configured to detect the presence of fluid in the internal volume, the fluid sensor being configured such that a "fluid present" state is activated when the fluid sensor detects the fluid.

[0007] If the fastener breaks, such as if the load support cracks, fluid contained within the internal volume of the load support can escape through the crack, causing the fluid sensor to leave the fluid present state. This state change can be detected in a variety of ways, as described below, all of which indicate that the load support of the fastener has been damaged and the fastener needs repair or replacement.

[0008] Proactively checking for fluid presence provides the added benefit that if the fluid sensor fails, fluid presence will not be detected. Thus, detecting fluid presence provides certainty that both the load support is crack-free and that the fluid sensor is working. If the alert were only triggered if fluid was not detected, then if the fluid sensor were damaged, fluid could escape through the crack and crack damage could then be detected.

[0009] The fluid presence status may include a fluid sensor actively transmitting a fluid presence signal. The fluid presence signal may be detected by an external control unit and may indicate the fluid presence status of the fluid sensor. The external control unit may be a smart device such as a smartphone or tablet. The external control unit may form part of a controller for a machine in which the fastener is used. For example, if the fastener is used in a wood chipping or grinding machine, the external control unit may be located in the chipping or grinding machine.

[0010] The fluid presence state may comprise the fluid sensor in a passive state such that the fluid presence state is detected when the fluid sensor is interrogated by an external control unit. Such a configuration may reduce or eliminate the power requirements to operate the fluid sensor.

[0011] Whether the fastener actively or passively indicates fluid presence, the fastener can be checked for damage continuously or at a much higher frequency than conventional checking techniques. Unlike conventional checking techniques, the fastener can also be checked when the machine in which the fastener is installed is being operated. Thus, a fastener failure is much more likely to be detected in advance than a fastener breakage. Preventive maintenance may then be performed, avoiding possible damage and / or danger caused by a fastener failure. Fasteners are often used in multiple arrays. As such, a fastener may be damaged without necessarily causing equipment failure. However, if enough fasteners in an array are damaged, equipment failure may occur. The present invention allows for timely detection of a broken fastener to allow replacement of the broken fastener before equipment failure.

[0012] The fluid sensor may be hardwired to an external control unit. The fluid sensor can be hardwired to an external power source. The fluid sensor can be wirelessly connected to an external control unit, for example, using Bluetooth or other suitable short-range communication devices and protocols. The fluid sensor may be wirelessly connected to an external power source, for example, using conductive power transfer devices and protocols. The fastener may include an internal power source connected to the fluid sensor, for example, a battery.

[0013] The fastener may be a pin. The fastener may be a bolt. Those skilled in the art will appreciate that the present invention may be applied to many different fasteners, provided that they include load bearing fasteners. The present invention is particularly applicable to any safety critical fastener to prevent damage to machinery, structures, or assets, or to users operating or located near the machinery or structure. For example, the fastener may be a pin used in a wood processing machine, such as a grinder or chipper. The fastener may be a pin or bolt used in an amusement park ride, such as a roller coaster or Ferris wheel. The fastener may be a pin or bolt used in aerospace, automotive, or aviation applications. For example, the fastener may be a pin or bolt used in a vehicle chassis construction.

[0014] The fluid may be held under greater than atmospheric pressure within the interior volume of the load support, which may increase the rate at which the fluid escapes cracks in the load support, and therefore increase the rate at which cracks are detected and a crack warning signal is triggered.

[0015] The fluid may be a liquid. The liquid may be brightly colored to aid in visual detection of cracks in the fastener if the liquid passes through a crack in the fastener's load support. The liquid may be selected such that the liquid fluoresces under ultraviolet light to aid in visual detection of cracks in the fastener's load support. The liquid may be selected to foam, bubble, or solidify if it escapes through a crack in the load support and becomes exposed to air.

[0016] The fluid sensor may be a level sensor, for example a level sensor arranged to detect the presence of liquid above a threshold level within the internal volume of the load support, for example if the liquid level within the internal volume of the load support falls below the threshold level due to leakage through a crack, the fluid sensor may fail to detect fluid presence.

[0017] The fluid may be a gas, which can escape through cracks in the load support more quickly than a liquid, thereby allowing cracks in the load support to be detected more quickly.

[0018] The fluid sensor may be a pressure sensor, for example a pressure sensor arranged to detect pressure above a threshold level within the internal volume of the load support, for example if the pressure within the internal volume of the load support falls below the threshold level due to leakage through a crack, the fluid sensor may fail to detect the presence of fluid.

[0019] The fluid may be an inert liquid or gas. The fluid may be selected so that there is little or no impact on the environment if the fluid escapes from the load support. For example, the fluid may be water, or carbon dioxide gas. The fluid may be selected so that there is no damage caused by the fluid to the equipment surrounding the fastener if the fluid escapes from the load support.

[0020] The fastener may include a first portion and a second portion. The first portion may be mechanically joined to the second portion, for example, via a threaded connection between the first portion and the second portion. The first portion may be threaded into the second portion, or vice versa. The first portion and the second portion may comprise a load support. One or both of the first portion and the second portion may define an interior volume of the load support element. For example, the second portion may comprise an interior chamber, and the first portion may cap the interior chamber when mechanically joined to the second portion. One of the first portion and the second portion may comprise a fluid sensor.

[0021] The fastener may include a plurality of internal volumes and at least one corresponding fluid sensor configured to detect the presence of fluid within the internal volumes, the at least one fluid sensor further configured to activate a "fluid present" state upon detecting fluid.

[0022] The internal volume may be located coaxially with the central longitudinal axis of the fastener. Alternatively or additionally, there may be multiple internal volumes located toward the fastener's outer periphery. The internal volumes may be arranged to indicate when the fastener's outer periphery has worn to a set point. Such an arrangement prevents an excessively worn fastener from being used that would pose a risk of the fastener failing. Such an arrangement may be beneficial in high wear fasteners such as fifth wheel pins. The multiple internal volumes may be in fluid communication, for example, via a fluid reservoir, or may include separate internal volumes that are not connected to each other. If the multiple internal volumes are in fluid communication, a single fluid sensor may be provided. If the multiple internal volumes are not in fluid communication, a fluid sensor may be provided for each internal volume.

[0023] The fastener may include a light unit, e.g., an LED. The light unit may be activated when the fastener is in a fluid-present state, allowing easy visual confirmation that the fastener is not cracked. The light unit may be activated when the fastener is not in a fluid-present state, e.g., to flash or emit a different color of light than when the fastener is in a fluid-present state. The fastener may also include a sound unit, e.g., an audible alarm. When the fastener is in a fluid-present state, the sound unit is activated, e.g., to emit a regular beep, allowing easy audible confirmation that the fastener is not cracked. The sound unit may be activated when the fastener is not in a fluid-present state, e.g., to emit an audible alarm signal to alert the user to damage to the fastener.

[0024] According to a second aspect, the present invention provides a method for detecting cracks in a load support of a fastener according to the first aspect of the invention, the method comprising the step of observing the fastener and, upon observation, activating an alarm signal if the fastener is not in the presence of fluid. The alarm signal may trigger a visible or audible alarm. For example, the alarm signal may activate a light associated with the fastener so that a user will know that the fastener requires attention. Alternatively or additionally, an audible signal such as a buzzer may be activated to inform a user that the fastener requires attention. The alarm signal may result in a notification being sent to a control unit, for example a control unit forming part of the machine including the fastener, or a remote control unit associated with the machine, or a smart device such as a smartphone or tablet. Alternatively or additionally, the alarm signal may cause a shutdown of the machine including the fastener, automatically preventing further damage from occurring. The alarm signal may need to be cleared before the machine can be operated again, for example by physically inspecting the fastener or replacing the fastener. Such an arrangement may prevent the machine from being damaged by a user ignoring the alarm signal.

[0025] The fastener may include an interior volume and a detection bar located within the interior volume. The interior volume may correspond to the fluid filled interior volume or may be a separate interior volume. As the fastener deforms, the detection bar may contact a surface defining the interior volume. Such contact may be detected and prompt a deformation alert or notification to be triggered.

[0026] According to a third aspect there is provided a fastener comprising a load support comprising an internal volume defined by an inner surface of the load support and a detection bar located within the internal volume, wherein in a normal condition the detection bar is not in contact with the inner surface of the load support and in a deformed condition the detection bar is in contact with the inner surface of the load support.

[0027] Deformed conditions include when the load support is subjected to excessive loads, causing the load support to bend, twist, or lose its shape. When the load support is deformed beyond a certain point, the fastener may no longer be suitable for use, for example due to an increased risk of failure.

[0028] The fastener may be configured to trigger an alarm or notification when the detection bar contacts the inner surface of the load support. For example, the inner surface of the load support and the detection bar may comprise a conductive material. When the detection bar contacts the inner surface of the load support, a circuit may be completed, which triggers, for example, a visible or audible alarm or notification, which is sent, for example, to a smart device. The fastener may include a light emitting device or a sound generating device. The fastener may include a communication unit, for example, a wireless communication unit. Alternatively, the communication unit may be a wired communication unit. The fastener may include a power source, for example, a battery.

[0029] The detection bar may include detection contacts that extend away from the longitudinal axis of the detection bar. Such a configuration may allow for adjustment of the fastener configuration to a particular interval indicative of a particular deformation of the fastener. The detection bar may include multiple detection contacts spaced apart along the detection bar. Such a configuration may allow different levels of deformation to be detected. For example, a centrally located detection contact may contact an inner surface of the load support when the fastener is at an allowable deformation level. A second detection contact may be spaced apart from the centrally located detector contact and may be positioned to contact an inner surface of the load support when the fastener exceeds an allowable deformation level. One skilled in the art will appreciate that multiple detection contacts may be spaced apart from one another to provide additional accuracy in the indication of the deformation of the fastener.

[0030] According to a fourth aspect, the present invention may provide a component comprising a body enclosing an internal volume filled with a fluid and also comprising a fluid sensor configured to detect the presence of fluid within the internal volume, the fluid sensor being further configured such that a "fluid present" state is activated upon detection of fluid.

[0031] The component may be any component for which it is desirable to detect damage to the component, for example the component may be a wheel hub of an aircraft, train, or automobile.

[0032] According to a fifth aspect of the present invention there is provided a fastener comprising a load support comprising a first internal volume filled with a fluid and a fluid sensor configured to detect the presence of fluid in the first internal volume, wherein a "fluid present" state is activated when the fluid sensor detects the fluid, the fastener further comprising a second internal volume, the internal volume being defined by an inner surface of the load support, and a detection bar arranged such that in a normal state the detection bar does not contact the inner surface of the load support and in a deformed state the detection bar contacts the inner surface of the load support.

[0033] Such an arrangement provides a fastener that is able to exhibit damage such as cracks or excessive wear, as well as deformation of the fastener.A fifth aspect of the invention may comprise any of the features of the first, second, third or fourth aspects of the invention.

[0034] According to a sixth aspect, a load support is provided, the load support enclosing a gas-filled internal volume and a sensor configured to detect the presence of gas in the internal volume, the sensor configured such that a gas presence condition is activated when the sensor detects gas. Such an arrangement may be used to detect cracks in a fastener used while submerged in liquid. For example, if the fastener is underwater and a crack develops in the load support, the internal volume is compromised. This causes gas to escape the internal volume and be replaced by water, which will be detected by the sensor. As in the previous embodiment of the invention, this may trigger an alarm or notification that a crack has been detected and the fastener is replaced or repaired.

[0035] Of course, it will be understood that features described in relation to one aspect of the invention may be incorporated in other aspects of the invention, for example a first aspect of the invention may incorporate any of the features described with reference to other aspects of the invention, and vice versa. [Brief description of the drawings]

[0036] Embodiments of the invention will now be described, by way of example only, with reference to the accompanying schematic drawings, in which: FIG. [Figure 1] FIG. 1 is a side view of a shear bolt according to a first embodiment of the present invention. [Diagram 2] 2 shows a cross-sectional view of the shear bolt of FIG. 1. [Diagram 3] FIG. 2 shows a side view of a threaded bolt according to a second embodiment of the invention. [Figure 4] 4 shows a cross-sectional view of the threaded bolt of FIG. 3. [Diagram 5] FIG. 4 shows a side view of a threaded bolt according to a third embodiment of the invention. [Figure 6] 6 shows a cross-sectional view of the threaded bolt of FIG. [Figure 7] 4 shows a safety system according to a fourth embodiment of the present invention. [Figure 8]13 shows a cross-sectional view of a deflector bar with multiple contact points and a fastener with multiple internal volumes according to a fifth embodiment of the present invention. [Figure 9] FIG. 9 illustrates a cross-sectional view of a fastener similar to that shown in FIG. 8 without multiple internal volumes. [Figure 10] 13 shows a cross-sectional view of a fastener with multiple internal volumes according to a sixth embodiment of the present invention. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0037] 1 and 2 show a shear bolt 10. The shear bolt 10 comprises a load-bearing body 16 that includes an internal volume 12. The internal volume 12 is defined by the inner surface of the load support 16 with a sensor element 14 arranged to seal the internal volume 12 so that it is fluid-tight. In this embodiment, the sensor element 14 is a pressure sensor that is threaded and screwed into place. In other embodiments, alternative fastening methods may be used, such as an interference fit. The internal volume 12 is filled with a fluid, in this case carbon dioxide gas under pressure, and the sensor element 14 is arranged to detect an increased pressure compared to atmospheric pressure. When an increased pressure is detected, the sensor is in a "fluid present" state. If the load support 16 cracks and the internal volume 12 defined by the inner surface of the load support 16 is no longer fluid-tight, fluid will escape from the internal volume 12 and the sensor element 14 will no longer detect an increased pressure relative to atmospheric pressure and will exit the fluid present state. The sensor element 14 includes a power source and a light source unit 18. When in a fluid-present condition, the light unit 18 is positioned to be activated to emit light. Thus, the sensor element 14 provides positive confirmation that the sensor is in a fluid-present condition. This indicates that the sensor is working and that the shear bolt 10 is not cracked. When the light unit 18 is not illuminated, it is evident that either the shear bolt 10 is cracked or the sensor element 14 or light unit 18 is not functioning. In either case, the shear bolt 10 requires closer inspection and possible replacement.

[0038] 3 and 4 show a bolt 30 having a load support 36, an internal volume 32 filled with fluid, and a sensor element 34. This configuration applies to a different type of fastener, but is similar to that described with reference to FIGS. 1 and 2. The sensor element 34 includes a communication unit 38 arranged to transmit a "fluid present" signal when the sensor element 34 is in a fluid present state and a "fluid absent" signal when the sensor element is not in a fluid present state. In this embodiment, the signal is actively sent at regular intervals. The signal is wirelessly transmitted via any suitable wireless communication protocol, as will be appreciated by those skilled in the art. The signal may be received by a smart device, for example a control panel or a phone or tablet device. Such a configuration allows for remote monitoring of the integrity of the fastener when it is difficult to visually observe the fastener. In an alternative configuration, the communication unit 38 can be configured in a passive state such that the state of the sensor element is detected by interrogation of the communication unit 38 by a suitable wireless communication device. A passive configuration may require less power storage in the fastener than an active configuration, which may be particularly advantageous when the fastener is not connected to a mains power supply that may comprise, for example, a battery.

[0039] 5 and 6 show a bolt 50. The bolt 50 comprises a load support 58 with an interior volume 52 defined by the inner surface of the load support 58. A sensor element 54 is provided, which includes an elongated rod 60 extending along the interior volume 52. When the bolt 50 is in a normal, undeformed state, the elongated rod does not contact the inner surface of the load support 58. However, the spacing between the elongated rod 60 and the inner surface of the load support 58 is small, such that deformation of the load support 58 causes contact between the elongated rod 60 and the inner surface of the load support 58. The inner surface of the load support 58 and the elongated rod 60 are both made of a conductive material, and the sensor element is arranged to pass a current through the elongated rod 60 to detect contact between the elongated rod 60 and the inner surface of the load support 58. In this configuration, when no contact is made between the elongated rod 60 and the inner surface of the load support 54, the sensor element 54 is in a "normal" state. This normal condition may result in the activation of a signal, such as a normal notice or the activation of a light as previously described. As in the above embodiment, such an arrangement indicates that the sensor element 54 is activated and the bolt 50 is undeformed. An insulating washer 56 is provided on the end of the elongated rod 60 to ensure that vibration of the bolt 50 does not cause the elongated rod 60 to contact the interior surface of the load support 58, causing a false indication of damage to the bolt 50.

[0040] Figure 7 shows a safety system including a fastener 70, which can be described with reference to any of Figures 1 to 6. The fastener 70 comprises a sensor element equipped with a wireless communication unit arranged to send an indication of the state of the fastener 70 to a receiving unit 72. The receiving unit 72 may be a control screen forming part of the machine or structure of which the fastener 70 is a part. Alternatively, the receiving unit 72 may be a smart device, for example a phone or tablet. In another embodiment, the communication unit of the fastener 70 may be hardwired to the receiving unit 72.

[0041] FIG. 8 shows the fastener 80 extending between a first attachment point 82 and a second attachment point 84 of a common body. The fastener 80 is threaded (not shown) to allow engagement with complementary threads at the first attachment point 82 and the second attachment point 84. Those skilled in the art will appreciate that in alternative embodiments, the fastener may be secured by other fastening mechanisms. An elongated rod 86 extends through a cavity 88 along a central longitudinal axis of the load support 81 of the fastener 80 and forms part of a sensor assembly 90, with a detection unit 92 located at one end of the fastener 80. The elongated rod 86 is isolated from the body of the fastener 80 by an insulated washer 94, which also acts to dampen any vibrations experienced by the fastener 80 that may cause erroneous readings. The insulated washer 94 is also configured to isolate the elongated rod 84 from deformation of the load support 81 of the fastener. The elongated rod 86 further has a first contact portion 96 and a second contact portion 98. The first contact portion 96 is located approximately in the middle of the length of the fastener 80 and the second contact portion 98 is located closer to the end of the fastener 80. When the fastener 80 deforms due to a load on the load support 81, the first contact portion 96 will contact the body of the fastener. As the fastener 80 deforms further, the second contact portion 98 will contact the fastener body. The first contact portion 96 and the second contact portion 98 are electrically insulated from each other. By passing a current along the elongated rod to each of the first contact portion 96 and the second contact portion 98, it can be detected when the first contact portion 96 and / or the second contact portion 98 contact the fastener body. This may then provide an alarm or warning as previously described, indicating deformation of the fastener and allowing for closer inspection or replacement. By including multiple contact points, the level of deformation may be indicated. For example, the first contact portion 96 is configured to indicate an acceptable level of deformation, while the second contact portion 9 is configured to indicate that deformation has exceeded a maximum limit and that replacement of the fastener 80 is necessary.The fastener 80 also comprises a first internal volume 100 and a second internal volume 102 extending along the length of the fastener 80 towards the periphery of the fastener 80, the first internal volume 100 and the second internal volume 102 being in fluid communication with each other via a fluid reservoir 104. A fluid sensor 106 is associated with the fluid reservoir 104 and configured to detect a "fluid present" state and a "fluid absent" state. When in the "fluid present" state, the fluid sensor 106 is configured to indicate this by activating a light and / or transmitting a "fluid present" state to a remote device, e.g., a smartphone or computer. This provides confidence that fluid is present within the internal volumes 100 and 102 and the sensor 106 is operational. If the fastener 80 is damaged, for example due to a crack, fluid will flow out of the internal volumes 100 and 102 and the sensor will move to a "fluid absent" state. The fluid sensor 106 then no longer activates the light and / or stops communicating the "fluid present" status to the remote device, and the lack of positive confirmation of fluid indicates that the fastener may be damaged and requires inspection. If the fluid sensor 106 fails, there may also be no positive confirmation of fluid presence, which may lead to inspection of the fastener and a malfunctioning sensor may be detected. As will be appreciated by those skilled in the art, the fluid may be a liquid or a gas. Preferably, the fluid is present in the internal volumes 100 and 102 at a pressure higher than the ambient pressure. Thus, if the fastener cracks or wears such that the internal volumes 100, 102 are compromised, the fluid will escape under pressure, thus triggering the "no fluid present" status. By positioning the first internal volume 100 and the second internal volume 102 towards the periphery of the fastener 80, excessive wear of the fastener 80 may be detected.

[0042] Figure 9 shows a fastener 980 extending between a first attachment point 982 and a second attachment point 984 on a common body. The fastener 980 also extends through a bore 985 in a separate body 987 to secure the two bodies together. The internal configuration of fastener 980 is consistent with that of fastener 80 described with reference to Figure 8, except that there is only a flexure bar rather than a fluid-filled internal volume.

[0043] FIG. 10 shows a cross-sectional view of a fastener 120 according to the present invention. The fastener 120 is a fifth wheel pin commonly used in the transportation industry. The fastener 120 comprises a body 122 with a first internal volume 124 and a second internal volume 126. The fastener 120 has a longitudinal axis XX, and the first internal volume 124 and the second internal volume 126 extend in the direction of the longitudinal axis XX towards the periphery of the main body 122. The first internal volume 124 and the second internal volume 126 are in fluid communication with a shared fluid reservoir 128, fluid-filling the internal volumes and the fluid reservoir, and the fluid sensor 130 is positioned to plug the fluid reservoir 128. The fluid is present at a pressure higher than the ambient pressure, so that if the internal volume is compromised, the fluid escapes. In such a configuration, the fluid sensor 130 is a pressure sensor. The fluid sensor 130 is further configured to detect the presence of fluid in the fluid reservoir 128. When fluid is detected, the fluid sensor 130 enters a "fluid present" state and a fluid present signal is transmitted to an external monitoring device. When no fluid is detected or the fluid sensor 130 fails, the fluid present signal stops transmitting, thereby notifying the user that there is a potential problem with the fastener 120. The first and second internal volumes 124, 126 are located toward the periphery of the body 122 at locations selected to indicate specific wear of the fastener 120. The internal volumes are small bores within the body 122 and have little or no effect on the overall strength of the fastener 120. When the body 122 wears to a set point, one or more of the internal volumes will be compromised and any fluid present will be able to release pressure. This will move the fluid sensor 130 to a "no fluid present" state, which state is transmitted to the user as described above. Thus, excessive wear of the fastener 120 is indicated without the need to constantly inspect the fastener 120 during use.

[0044] While the present invention has been described and illustrated with reference to specific embodiments, those skilled in the art will recognize that the present invention lends itself to many different variations not specifically illustrated herein. Merely by way of example, certain possible variations are described herein.

[0045] Similar arrangements to those shown with respect to the fasteners of Figures 1 through 6 may be applied to any load-bearing component. For example, similar configurations may be applied to the wheel hubs of an automotive vehicle, or any other vehicle or transportation machine. Alternatively, similar arrangements may be applied to load-bearing structures such as bridges or building components.

[0046] Where reference is made in the foregoing description to numbers or elements having known, obvious or foreseeable equivalents, such equivalents are incorporated herein as if individually set forth. Reference should be made to the claims to determine the true scope of the invention, which should be construed to encompass such equivalents. The reader will also understand that any numbers or features of the invention described as preferred, advantageous, convenient, etc. are arbitrary and do not limit the scope of the independent claims. It will be further understood that any such numbers or features, while beneficial in some embodiments of the invention, may not be desirable and therefore may not be present in other embodiments.

Claims

1. 1. A fastener comprising a load support, the load support enclosing a fluid-filled internal volume, the load support comprising a fluid sensor configured to detect the presence of fluid in the internal volume, the fluid sensor configured such that a "fluid present" state is activated when the fluid sensor detects the fluid.

2. The fastener of claim 1 , wherein the fluid sensor is hardwired to an external control unit.

3. The fastener of claim 1 or 2, wherein the fluid sensor is hardwired to an external power source.

4. The fastener of claim 1 , wherein the fluid sensor is wirelessly connected to an external control unit.

5. The fastener of claim 1 or 4, wherein the fluid sensor is wirelessly connected to an external power source.

6. The fastener of claim 1 , wherein the fastener comprises an internal power source connected to the fluid sensor.

7. The fastener of claim 1 or 2, wherein the fastener is a pin.

8. The fastener of claim 1 or 2, wherein the fastener is a bolt.

9. 3. The fastener of claim 1 or 2, wherein the fluid is held under greater than atmospheric pressure within an interior volume of the load support.

10. The fastener of claim 1 or 2, wherein the fluid is a liquid.

11. The fastener of claim 1 or 2, wherein the fluid is a gas.

12. 3. The fastener of claim 1 or 2, comprising a first portion and a second portion.

13. The fastener of claim 12 , wherein the first portion is mechanically joined to the second portion.

14. The fastener of claim 12 , wherein the first portion and the second portion comprise the load support.

15. The fastener of claim 14 , wherein one or both of the first and second portions define an interior volume of the load support.

16. The fastener of claim 15 , wherein one of the first portion and the second portion comprises the fluid sensor.

17. 3. The fastener of claim 1 or 2, comprising a plurality of internal volumes and at least one corresponding fluid sensor configured to detect a presence of fluid in the internal volumes, the at least one fluid sensor configured such that a "fluid present" state is activated when the at least one fluid sensor detects the fluid.

18. 3. The fastener of claim 1 or 2, wherein the interior volume is coaxial with a central longitudinal axis of the fastener.

19. 20. The fastener of claim 17, wherein the plurality of internal volumes are located toward a periphery of the fastener.

20. 20. The fastener of claim 17, wherein the plurality of internal volumes are in fluid communication.

21. 20. The fastener of claim 17, wherein the plurality of interior volumes are separate interior volumes that do not communicate with one another.

22. 3. The fastener of claim 1 or 2, comprising an interior volume and a detection bar located within the interior volume, the detection bar configured such that upon deformation of the fastener, the detection bar contacts a surface defining the interior volume, the contact prompting a deformation warning or notification to be triggered.

23. 10. A method for detecting cracks in a load support of a fastener as recited in claim 1, comprising the steps of observing the fastener and issuing an alarm signal if the fastener is not in a fluid present condition upon observing the fastener.

24. 24. The method of claim 23, wherein the alarm signal produces a visual or audible alarm.

25. 24. The method of claim 23, wherein the alarm signal causes a control unit or a smart device to send a notification.

26. 24. The method of claim 23, wherein the alarm signal causes a shutdown of a machine containing the fastener.

27. 1. A fastener comprising a load support having an interior volume defined by an inner surface of the load support, and a detection bar such that in a normal state, the detection bar does not contact the inner surface of the load support, and in a deformed state, the detection bar contacts the inner surface of the load support.

28. 28. The fastener of claim 27, wherein the detection bar includes detection contacts that extend away from a longitudinal axis of the detection bar.

29. 30. The fastener of claim 27 or 28, wherein the detection bar comprises a plurality of detection contacts spaced along the detection bar.

30. 30. The fastener of claim 29, wherein the detection bar comprises a centrally located first detection contact and a second detection contact spaced apart from the centrally located first detection contact.

31. 1. A fastener comprising a load support, the load support including a first internal volume filled with a fluid and a fluid sensor configured to detect the presence of fluid in the first internal volume, the fluid sensor configured to activate a "fluid present" state when detecting the fluid, the fastener further including a second internal volume, the internal volume being defined by an inner surface of the load support, a detection bar located within the second internal volume, and in a normal state, the detection bar does not contact the inner surface of the load support, and in a deformed state, the detection bar is positioned to contact the inner surface of the load support.

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