AU2021218164A1

AU2021218164A1 - Jack stand with integrated load sensing means

Info

Publication number: AU2021218164A1
Application number: AU2021218164A
Authority: AU
Inventors: Brian Mobbs
Original assignee: Individual
Current assignee: Individual
Priority date: 2021-05-13
Filing date: 2021-08-19
Publication date: 2022-12-01

Abstract

A jack stand for a towable apparatus comprises a shank with an upper portion and a lower portion that has a ground-engaging foot. A spindle is received threadedly by the lower portion such that rotating the spindle causes relative vertical translational movement between the upper and lower portion. The jack stand comprises a handle to rotate the spindle and a thrust bearing to support the upper portion relative to the spindle. A load cell is disposed above the thrust bearing that comprises first and second annular members spaced-apart by a connection member and an elongate passage that receives the spindle. A downwards force acting on the load cell by the upper portion causes the first annular member to undergo strain and the load cell to generate a signal in response to the strain. Based on the signal, a processor calculates and displays a weight value on a display device. 1/7 26 32 10 3 0 16 .-----2 64 2 1-124 14 20 FIG. 1

Description

1/7 26

32 10 30 16

64 22.- -

1-124

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20

FIG. 1

JACK STAND WITH INTEGRATED LOAD SENSING MEANS

Field

[0001] The present invention relates to a jack stand for a towable apparatus and, more particularly, to a jack stand comprising an integrated load sensing means.

Background

[0002] A jack stand is a device that is commonly provided on a towable apparatus and used to raise and lower an end of the apparatus relative to the ground. A common example of a type of jack stand is a jockey wheel, which is a wheel-based mechanism often provided on trailers and caravans. Trailers and caravans include a drawbar that has a coupling at one end that is connected to a tow ball, or tow hitch, of a towing vehicle such as a car. The jockey wheel provides for steering and guidance and allows the drawbar to be raised and lowered relative to the ground so that its coupling can be connected to the tow ball. Serious safety issues can arise if an excessive load is exerted on the tow ball by the drawbar. Similarly, safety issues can arise if the towed apparatus is unbalanced such that an insufficient load is exerted on the tow ball.

[0003] Consequently, there are two main engineering specifications which must be taken into account when determining the safety factors and legal requirements for towing a trailer. Firstly, the maximum weight allowable as a downward force acting on the tow ball must be considered. This weight is calculated using the distance between the tow ball and the towing vehicle's rearmost wheel axle and the maximum overall weight that is lawfully permitted to be applied to the centre of the vehicle's wheel axle group to ensure safe driving. The maximum engineered weight on the centre of the wheel axle group is usually displayed on a specification plate attached to the vehicle's tow bar or specified in the vehicle's driving manual. Secondly, the maximum allowable weight at the trailer's tow ball coupling must be taken into account.

[0004] Over or under loading of a vehicle's tow ball can stop the connected trailer from tracking smoothly behind the vehicle which can result in serious accidents occurring. Typically, it is recommended that the tow ball weight in any towing vehicle/trailer combination should not exceed 10-15% of the trailer's aggregate trailer mass (ATM), and should remain below the maximum tow ball weight as allowed by the towing vehicle's tow bar specification and the trailer's maximum tow ball weight detailed in its specification.

[0005] A driver who wishes to tow a trailer must, therefore, know the laden trailer's tow ball weight at the time of hitching the trailer and/or loading the trailer. The tow ball weight may be estimated manually using a lever system and a set of bathroom scales. This method is complicated because it requires a working knowledge of geometry and levers and forces. The method is also time consuming to perform and is prone to error. Weight measuring devices are commercially available which use mechanical spring resistance tools placed under the trailer's tow coupling. These devices comprise an arrow attached to the internal spring of the device which moves under load and points to a corresponding weight value marked on a scale displayed on the outer sleeve of the device. These devices are inaccurate and suffer from spring memory deterioration over time as well as fluctuations in the spring's resistance as a result of temperature fluctuations.

[0006] It is to be understood that, if any prior art is referred to herein, such reference does not constitute an admission that the prior art forms a part of the common general knowledge in the art, in Australia or any other country.

Summary

[0007] According to the present invention, there is provided a jack stand for a towable apparatus, the jack stand comprising: a shank comprising an upper portion and a lower portion, wherein the lower portion comprises a ground-engaging foot; a spindle comprising a threaded portion received threadedly by the lower portion such that axial rotation of the spindle relative to the upper portion causes relative translational movement between the upper portion and lower portion in a vertical direction; a handle for axially rotating the spindle; a thrust bearing arranged to support the upper portion relative to the spindle and to facilitate the axial rotation of the spindle; a load cell comprising a sensor arrangement, wherein the load cell is disposed above the thrust bearing such that the sensor arrangement generates a signal in proportion to a downwards force acting on the load cell by the upper portion due to a weight of the towable apparatus; a processor configured to calculate a weight value based on the signal; and a display device connected to the processor for displaying the weight value, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

[0008] The connection member may comprise a tubular support having a diameter that is less than respective diameters of the annular members.

[0009] The first of the annular members may comprise a support arrangement vertically projecting from a perimeter region of a vertical end of the first of the annular members.

[0010] The support arrangement may comprise an annular skirt extending around the perimeter region.

[0011] The first of the annular members may be a lowermost of the annular members, and the support arrangement may downwardly project from a lowermost end of the lowermost of the annular members.

[0012] The sensor arrangement may comprise a plurality of sensors that are disposed in an annular channel provided in the first of the annular members.

[0013] The annular channel may be formed in the vertical end of the first of the annular members and may be disposed inwardly of the perimeter region.

[0014] The plurality of sensors may be sealed in the channel by a layer of silicone putty.

[0015] The plurality of sensors may be included in a Wheatstone bridge circuit of the load cell.

[0016] The jack stand may comprise a cap disposed over an uppermost end of the upper portion of the shank, wherein the cap comprises an aperture that receives the spindle and is adapted to prevent ingress of moisture and/or debris into the upper portion.

[0017] The jack stand may comprise a washer disposed between the thrust bearing and load cell to support the load cell.

[0018] The jack stand may comprise an annular support extending circumferentially around a longitudinal axis of the spindle, and the thrust bearing may be mounted on the support.

[0019] The processor may be configured such that the weight value that is calculated by the processor is the downwards force acting on the load cell.

[0020] The processor may be configured such that the weight value that is calculated by the processor is a downwards force acting on a tow ball or tow hitch of a vehicle that the towable apparatus is connectable to.

[0021] The processor may be configured to calculate the downwards force acting on the tow ball or tow hitch using a formula (JW x D1) / D2, where JW is a downwards force acting on the load cell, D1 is a distance between an axle of a wheel of the towable apparatus and the foot of the jack stand and D2 is a distance between the axle of the wheel of the towable apparatus and a position of the tow ball or tow hitch.

[0022] The processor may be configured to calculate the downwards force acting on the tow ball or tow hitch using a formula (JW x (D2-D3)) / D2, where JW is a downwards force acting on the load cell, D2 is a distance between an axle of a wheel of the towable apparatus and a position of the tow ball or tow hitch and D3 is a distance between the foot of the jack stand and the position of the tow ball or tow hitch.

[0023] The apparatus may comprise a cylindrical housing that is disposed between the upper portion of the shank and the handle, wherein the housing comprises the processor and the display device.

[0024] The jack stand may be a jockey wheel and the foot may comprise a ground-engaging wheel.

[0025] The present invention also provides a jack stand for a towable apparatus, the jack stand comprising: a shank comprising an upper portion and a lower portion, wherein the lower portion comprises a ground-engaging foot; a spindle comprising a threaded portion received threadedly by the lower portion such that axial rotation of the spindle relative to the upper portion causes relative translational movement between the upper portion and lower portion in a vertical direction; a handle for axially rotating the spindle; a thrust bearing arranged to support the upper portion relative to the spindle and to facilitate the axial rotation of the spindle; a load cell comprising a sensor arrangement, wherein the load cell is disposed above the thrust bearing such that the sensor arrangement generates a signal in proportion to a downwards force acting on the load cell by the upper portion due to a weight of the towable apparatus; and a processor connected to a wireless transmitter, the processor being configured to transmit data to a remote user device using the wireless transmitter, wherein the data corresponds to the signal or to a weight calculated by the processor based on the signal, and wherein the remote user device is configured to cause a display of the remote user device to show a weight value corresponding to the data, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

[0026] The present invention also provides a load measuring system for a jack stand, the system comprising: a load cell configured to be positioned inside a shank of the jack stand above a thrust bearing of a spindle of the jack stand, wherein the spindle extends axially through the shank, the load cell comprising a sensor arrangement configured to generate a signal in proportion to a downwards force acting on the load cell by an upper portion of the shank due to a load supported by the jack stand; a processor configured to calculate a weight value based on the signal; and a display device connected to the processor for displaying the weight value, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

[0027] The present invention also provides a load measuring system for a jack stand, the system comprising: a load cell configured to be positioned inside a shank of the jack stand above a thrust bearing of a spindle of the jack stand, wherein the spindle extends axially through the shank, the load cell comprising a sensor arrangement configured to generate a signal in proportion to a downwards force acting on the load cell by an upper portion of the shank due to a load supported by the jack stand; and a processor connected to a wireless transmitter, the processor being configured to transmit data to a remote user device using the wireless transmitter, wherein the data corresponds to the signal or to a weight calculated by the processor based on the signal, and wherein the remote user device is configured to cause a display of the remote user device to show a weight value corresponding to the data, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

[0028] The present invention also provides a chock for a jack stand, the chock comprising: a recess for receiving the jack stand; a load cell comprising a sensor arrangement, wherein the sensor arrangement generates a signal in proportion to a weight of the jack stand acting on the chock; a processor configured to calculate a weight value based on the signal; and a display device connected to the processor for displaying the weight value.

[0029] The load cell may be positioned such that an uppermost surface of the load cell is positioned at a base of the recess, and such that the jack stand bears downwardly on the uppermost surface when the jack stand is received in the recess.

[0030] The display device may be provided on a side of the chock. For example, the display device may be provided in a housing that is attached to a side of the chock such that the display device is viewable from the side.

[0031] The present invention also provides a chock for a jack stand, the chock comprising: a recess for receiving the jack stand; a load cell comprising a sensor arrangement, wherein the sensor arrangement generates a signal in proportion to a weight of the jack stand acting on the chock; and a processor connected to a wireless transmitter, the processor being configured to transmit data to a remote user device using the wireless transmitter, wherein the data corresponds to the signal or to a weight calculated by the processor based on the signal, and wherein the remote user device is configured to cause a display of the remote user device to show a weight value corresponding to the data.

Brief Description of Drawings

[0032] Embodiments of the invention will now be described by way of example only with reference to the accompanying drawings, in which: FIG. 1 is sectional side elevation view of a jack stand comprising a jockey wheel according to an example embodiment of the invention; FIG. 2 is an enlarged sectional side elevation view of an upper portion of the jockey wheel;

FIG. 3A is a sectional side elevation view of a load cell of the jockey wheel; FIG. 3B is a further sectional side elevation view of the load cell, wherein the load cell is shown being deformed; FIG. 3C is a bottom view of the load cell; FIG. 3D is a plan view of the load cell; FIG. 4 is a schematic view of a car towing a trailer that includes the jockey wheel; FIG. 5 depicts a chock for a jack stand, wherein the jack stand is a jockey wheel; FIG. 6 is sectional side elevation view of a jack stand comprising a jockey wheel according to a further example embodiment of the invention; FIG. 7A is an isometric view of an inner portion that forms part of an uppermost housing of the jockey wheel of FIG. 6; FIG. 7B is isometric view of an outer portion that forms part of the uppermost housing; and FIG. 7C is an isometric view of a cap that forms part of the uppermost housing.

Description of Embodiments

[0033] Referring to the FIGS. 1 to 4, an example embodiment of the present invention provides a jack stand 10 for a towable apparatus 12. Thejack stand 10 comprises a shank 14 comprising an upper portion 16 and a lower portion 18, wherein the lower portion 18 comprises a ground-engaging foot 20 of the jack stand 10, and a spindle 22 comprising a threaded portion 24 that is received threadedly by the lower portion 18 such that axial rotation of the spindle 22 relative to the upper portion 16 causes relative translational movement between the upper portion 16 and lower portion 18 in a vertical direction. The jack stand also comprises a handle 26 for axially rotating the spindle 22 and a thrust bearing 30 arranged to support the upper portion 16 relative to the spindle 22 and to facilitate the axial rotation of the spindle 22. The jack stand 10 also comprises a load cell 32 comprising a sensor arrangement 34, wherein the load cell 32 is disposed above the thrust bearing 30 such that the sensor arrangement 34 generates a signal in proportion to a downwards force acting on the load cell 32 by the upper portion 16 due to a weight of the towable apparatus 12. The jack stand 10 also comprises a processor 36 configured to calculate a weight value based on the signal and a display device 38 connected to the processor 36 for displaying the weight value. The load cell 32 comprises a first annular member 40 and a second annular member 42, wherein the annular members 40, 42 are joined together in a vertically spaced-apart relationship by a connection member 44. An elongate passage 46 extends coaxially through the annular members 40, 42 and through the connection member 44 that rotatably receives the spindle 22. The load cell 32 is dimensioned such that the downwards force acting on the load cell 32 causes at least the first of the annular members 40 to undergo strain, and the sensor arrangement 34 is configured to generate the signal in response to the strain.

[0034] More particularly, in the example depicted the jack stand 10 is in the form of a jockey wheel that comprises a ground-engaging wheel 20. FIGS. 3A to 3D show the load cell 32 that may be integrated into the jockey wheel 10 in isolation. The annular members 40, 42 of the load cell 32 may each be substantially cylindrical in shape. The two members 40, 42 may be held in a vertically stacked arrangement relative to one another by the connection member 44. The connection member 44 may comprise a tubular support that is also substantially cylindrical and coaxial with the annular members 40, 42. The tubular support 44 may upwardly extend from an uppermost surface of the first (lowermost) annular member 40 to a lowermost surface of the second (uppermost) annular member 42. The annular members 40, 42 and tubular support 44 may be integral one another, or may be formed separately and joined together, and made of a strong and resilient material that is substantially rigid but that elastically deforms by a small amount when the load cell 32 is supporting a substantial weight. For example, the material may be aluminium, a steel alloy or stainless steel.

[0035] The tubular support 44 may have a diameter that is less than respective diameters of the annular members 40, 42. In the example depicted, the diameter of the uppermost annular member 42 is slightly less than the diameter of the lowermost annular member 40. This advantageously allows the load cell 32 to be slotted easily into position up through the upper portion 16 of the shank 14 when the jockey wheel 10 is being assembled during manufacture.

[0036]The lowermost annular member 40 and the tubular support 44 may be mutually dimensioned such that the lowermost annular member 40 is slightly deformed by the tubular support 44 when a load bears downwardly on an upper surface of the upper annular member 42. For example, a support arrangement may project vertically downwards from a perimeter region of the lowermost vertical end of the lowermost annular member 40. The support arrangement 50 may comprise an annular skirt that extends circumferentially around the perimeter region. The skirt 50 provides a base of the load cell 32 that holds the lowermost annular member 40 elevated slightly above the surface underlying the load cell 32. When the tubular support 44 is forced in a downwards direction by the load placed on the upper annular member 42, as illustrated in FIG. 3B the skirt 50 causes the lowermost annular member 40 to flex elastically such that the cylindrical inner wall 52 of the elongate passage 46 moves in a downwards direction. It will be appreciated that the lowermost annular member 40 only flexes by a small degree in use, and the degree of flexure has been exaggerated in FIG. 3B for the sake of illustrating the mechanical operating principles of the load cell 32. The materials and structural properties of the load cell 32 enable accurate load readings to be taken for a range of loads that the load cell 32 may be commonly subjected to during normal use of the jockey wheel 10. For example, the load cell 32 may have an effective working range of 0 to 1,000 kgs and be configured such that peak accuracy is achieved when the load cell 32 is subjected to loads within the range 50 to 500 kgs. A maximum permitted load before destruction/failure of the load cell 32 may be 2,000 kgs.

[0037] The sensor arrangement 34 may be located and configured to measure the flexing of the lowermost annular member 40. In the example depicted, the sensor arrangement 34 is positioned in the upper region of an annular channel 54 formed in the lowermost surface of the lowermost annular member 40. The channel 54 may be disposed inwardly of the perimeter region that the skirt 50 extends around. The sensor arrangement 34 may comprise a Wheatstone bridge circuit that includes a plurality of sensors that are configured to measure changes in electrical resistance caused by deformation of the annular member 40. For example, as depicted by the broken lines in FIG. 3C, the Wheatstone bridge circuit may comprise four sensor arms 56 arranged at regular angular intervals around the channel 54 that measure the changes in resistance. The four sensor arms 56 may be sealed in the channel 54 by a layer of silicone putty that stops ingress of moisture and debris into the channel 54 that could interfere with the operation of Wheatstone bridge circuit.

[0038] As best shown in FIG 2, the load cell 32 may be disposed inside the upper shank portion 16 at an uppermost end of the shank portion 16 immediately below the ceiling of the shank portion 16. In this arrangement, the load placed on the jockey wheel 10 due to the weight of the towable apparatus 12 causes the ceiling of the shank portion 16 to bear downwardly on upper member 42 of the load cell 32. A washer 58 may be disposed between the thrust bearing 30 and load cell 32. The washer 58 provides a resilient platform that the load cell 32 rests on and allows the lower member 40 of the load cell 32 to deform when the load acts on the upper member 42. In other examples, the load cell 32 may be placed into the upper shank portion 16 upside down such that the ceiling of the shank portion 16 bears downwardly on lower member 40 of the load cell 32 and the upper member 40 rests on the washer 58.

[0039] The jockey wheel 10 may also comprise a cap 60 that is arranged over an uppermost end of the upper shank portion 16. The cap 60 provides a weather proof seal to prevent ingress of moisture and/or debris into the interior region of the upper shank portion 16 that could interfere with the load cell 32 and/or thrust bearing 30. The cap 60 has a centrally-disposed aperture that receives the spindle 22 such that the cap 60 fits nearly onto the shank portion 16 and is in abutting contact with the outer cylindrical surface of the spindle 22. The cap 60 may be made of UV-stabilised plastic. The upper shank portion 16 is slightly wider in diameter than the lower shank portion 18 and, therefore, receives the lower shank portion 18 such that the two portions 16, 18 are telescopically extendable and retractable.

[0040] To receive the axial load of the spindle 22, the thrust bearing 30 may rest on an annular support 62 that extends circumferentially around the longitudinal axis of the spindle 22. The annular support 62 may be fixedly connected to the spindle 22. For example, the annular support 62 may be welded to the spindle 22. The threaded portion 24 of the spindle 22 may be threadedly received into a complimentary threaded aperture provided in a collar 64 located at an upper end of the lower shank portion 18. In this configuration, the upper shank portion 16 is lifted by the spindle 22, thrust bearing 30 and load cell 32 when the spindle 22 turns within the aperture of the collar 64 when the handle 26 is rotated to raise the drawbar of the towable apparatus 12 during use. The thrust bearing 30 causes the upper shank portion 16 to be lifted without rotating when the spindle 22 turns within the aperture of the collar 64.

[0041]The jockey wheel 10 may also comprise a weatherproof housing 70 attached to a side of the shank 14. The housing 70 may comprise a circuit board that comprises the processor 36 and display device 38. The processor 36 and display device 38 may be powered by one or more batteries 72 disposed inside the housing 70. The type and number of batteries 72 will be selected such that the processor 36, display device 38 and load cell 32 operate for a significant period of time before the battery 72 needs to be replaced or recharged. The type and configuration of the foregoing electrical components will also be selected such that they operate in an energy efficient manner. Preferably, the electrical components and batteries 72 will allow for at least 12 months of use.

[0042] The processor 36 and/or the display device 38 may be configured to automatically 'sleep' to conserve energy after a prescribed period of non use. The load cell 32 may be configured such that it is constantly active and measuring load readings even when the display 38 goes to sleep. This ensures that the load cell 32 is taking load readings at all times and can, therefore, provide an accurate load signal to the processor 36 immediately when the display device 38 is switched on.

[0043] The processor 36 may be configured such that the weight value that is calculated by the processor 36 is equal to the downwards force acting on the load cell 32. In such examples, the calculated weight value is effectively the load that is being supported by the jockey wheel 10. In other examples, the processor 36 may be configured such that the weight value that is calculated by the processor 36 is a downwards force acting on a tow ball or tow hitch of a vehicle that the towable apparatus 12 is connectable to. For example, as illustrated in FIG. 4, the jockey wheel 10 may be used on a trailer 12 that is attached to a tow ball 74 of a car 76. The lower shank portion 18 of the jockey wheel 10 is shown retracted into the upper shank portion 16 in FIG. 4 such that the wheel 18 of the jockey wheel 10 is raised above the ground. In use, the processor 36 may calculate the weight acting on the tow ball 74 using the formula:

TBW = (JWx D1) /D2

[0044] In the above formula: TBW = the weight acting on the tow ball 74; JW= the downwards force acting on the jockey wheel 10, measured by the load cell 32; D1 = the distance between the axle of the wheel 78 of the trailer 12 and the axle of the wheel 18 of the jockey wheel 10; and D2 = the distance between the axle of the wheel 78 of the trailer 12 and the position of the tow ball 74. In examples where the trailer 12 has a set of wheels, the value of D2 may be the distance between a centre of the axles of the wheels and the position of the tow ball 74.

[0045] To allow this calculation to be performed, the housing 70 may be provided with a user input device that allows a user of the jockey wheel 10 to input distances D1 and D2 in advance into a storage device (not shown) that is connected to the processor 36.

[0046] In another example, the user input device may allow the user to input distance D2 into the storage device and a distance D3, wherein D3 is the distance between the axle of the wheel 18 of the jockey wheel 10 and the position of the tow ball 74. In such examples, the processor 36 may calculate the weight acting on the tow ball 74 using the formula:

TBW = (JW x (D2-D3)) / D2

[0047] In other examples, the housing 70 may comprise a wireless transmitter, such as a Bluetooth transmitter, connected to the processor 36 that is configured to transmit data corresponding to the relevant signal or weight value that is received/calculated by the processor 36 to a remote user device 80. The user device 80 may comprise a smartphone or tablet device that comprises a display. The user device 80 may be configured to show a weight value on its display that corresponds to the data received from the processor 36. For example, the processor 36 may calculate the weight acting on the jockey wheel 10 (or tow ball 74) locally and transmit data corresponding to this weight to the user device 80.

The user device 80 may then use these data to show the relevant weight on its display. In another example, the processor 36 may transmit data to the user device 80 that corresponds to the weight acting on the jockey wheel 10, and the user device 80 may, in turn, use these data to calculate and display the weight acting on the tow ball 74. In the later example, the user device 80 will include functionality that enables a user to input the distances D1 and D2 (or D2 and D3) into the user device 80 in advance so that the tow ball weight can be calculated. It will be appreciated that the weight values that are calculated by the processor 36 and displayed to the user, including tow ball weight, will be accurate when the trailer 12 is resting on a level surface. That is to say, the trailer 12 is on a level surface, and the chassis of the trailer 12 is oriented parallel with the level surface.

[0048] Whilst the jack stand 10 that is depicted in FIGS. 1 to 4 is in the form of a jockey wheel, it will be appreciated that in other examples the jack stand 10 may comprise a wheelless jack stand that comprises a foot that engages the ground, as sometimes used on large and heavy trailers and caravans.

[0049] Referring now to FIG. 5, there is shown a chock 90 for a jack stand 92 which, in the example depicted, is in the form of a jockey wheel. The chock 90 comprises a recess 94 for receiving the jockey wheel 92. A load cell (not shown) may be attached to, or embedded into, the chock 90. The load call may comprise a sensor arrangement that generates a signal in proportion to a weight of the jockey wheel 92 bearing down on the recess 94. The load cell may be positioned such that an uppermost surface of the load cell is positioned at a base of the recess 94. For example, the load cell may be positioned such that its uppermost surface upwardly protrudes by a small amount from the base. In such examples, the jockey wheel 92 bears downwardly on the uppermost surface when the jockey wheel 92 is received into the recess. The chock 90 may also be provided with a processor that is configured to calculate a weight value based on the signal generated by the sensor arrangement and a display device attached to a side of the chock (not shown) for displaying the weight value. The display device may be positioned generally at the side region of the chock 90 that is labelled 96 in FIG. 5. In other examples, the chock 90 may also comprise a wireless transmitter for transmitting the weight value to a remote user device to be shown on a display of the user device. The load cell may comprise the same load cell 32 that is used in the jockey wheel 10 depicted in FIG. 1.

[0050] Referring now to FIG. 6, there is depicted a jack stand that comprises a jockey wheel 100 according to a further example embodiment of the invention. The jockey wheel 100 is materially the same as the jockey wheel 10 depicted in FIGS. 1 to 4 except that, instead of the cap 60, the jockey wheel 100 comprises a cylindrical housing 102 that is disposed between (i) a rotational axle 104 of the handle 106 of the jockey wheel 100 and (ii) the uppermost end 108 of the upper shank portion 110 of the jockey wheel 100. The housing 102 comprises the display device 112 and the batteries 114 and processor 116 of the jockey wheel 100. The display device 112 is provided on a side of the housing 102 so that it can be easily read by the user. The lowermost end of the housing 102 may extend around the perimeter of the uppermost end 108 of the upper shank portion 110. The housing 102, therefore, provides a weather-proof seal over the uppermost end 108 and prevents ingress of moisture and/or debris into the interior region of the upper shank portion 110 that could interfere with the load cell and/or thrust bearing disposed therein.

[0051]The cylindrical housing 102 is shown in simplified form in FIG. 6. Referring to FIGS. 7A-7C, in examples the housing 102 may comprise a tubular inner portion 120. The inner portion 120 comprises a cylindrical lumen extending vertically therethrough that receives the spindle of the jockey wheel 100 and rests on top of the uppermost end 108 of the upper shank portion 110. The housing 102 may also comprise a cylindrical outer portion 122 that slides over the inner portion 120 and extends around the perimeter of the uppermost end 108 of the upper shank portion 110. The printed circuit board, display device 112, batteries 114 and processor 116 of the jockey wheel 100 may be contained within the annular space that is formed between the inner and outer portions 120, 122. The housing 102 may also comprise a cap 124 that is configured to fit over the outer portion 122. The cap 124 may comprise a central aperture that aligns with the lumen of the inner portion 120 when the cap 124 is placed onto the outer portion 122. A cylindrical skirt 126 may extend around the central aperture of the cap 124 that nests into the mouth of the lumen of the inner portion 120. Any ingress of water into the centre of the cap 124 during use, therefore, flows down the lumen of the inner portion 120.

[0052] For the purpose of this specification, the word "comprising" means "including but not limited to", and the word "comprises" has a corresponding meaning.

[0053] The above embodiments have been described by way of example only and modifications are possible within the scope of the claims that follow.

Claims

1. A jack stand for a towable apparatus, comprising: a shank comprising an upper portion and a lower portion, wherein the lower portion comprises a ground-engaging foot; a spindle comprising a threaded portion received threadedly by the lower portion such that axial rotation of the spindle relative to the upper portion causes relative translational movement between the upper portion and lower portion in a vertical direction; a handle for axially rotating the spindle; a thrust bearing arranged to support the upper portion relative to the spindle and to facilitate the axial rotation of the spindle; a load cell comprising a sensor arrangement, wherein the load cell is disposed above the thrust bearing such that the sensor arrangement generates a signal in proportion to a downwards force acting on the load cell by the upper portion due to a weight of the towable apparatus; a processor configured to calculate a weight value based on the signal; and a display device connected to the processor for displaying the weight value, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

2. The jack stand according to claim 1, wherein: the connection member comprises a tubular support having a diameter that is less than respective diameters of the annular members; and the first of the annular members comprises a support arrangement vertically projecting from a perimeter region of a vertical end of the first of the annular members.

3. The jack stand according to claim 2, wherein the support arrangement comprises an annular skirt extending around the perimeter region.

4. The jack stand according to claim 2 or 3, wherein the first of the annular members is a lowermost of the annular members, and the support arrangement downwardly projects from a lowermost end of the lowermost of the annular members.

5. The jack stand according to any one of claims 2 to 4, wherein the sensor arrangement comprises a plurality of sensors that are disposed in an annular channel provided in the first of the annular members.

6. The jack stand according to claim 5, wherein the annular channel is formed in the vertical end of the first of the annular members and is disposed inwardly of the perimeter region.

7. The jack stand according to claim 5 or 6, wherein the plurality of sensors are sealed in the channel by a layer of silicone putty.

8. The jack stand according to any one of claims 5 to 7, wherein the plurality of sensors is included in a Wheatstone bridge circuit of the load cell.

9. The jack stand according to any one of the preceding claims, wherein the jack stand comprises a cap disposed over an uppermost end of the upper portion of the shank, wherein the cap comprises an aperture that receives the spindle and is adapted to prevent ingress of moisture and/or debris into the upper portion.

10. The jack stand according to any one of the preceding claims, wherein the jack stand comprises a washer disposed between the thrust bearing and load cell to support the load cell.

11. The jack stand according to any one of the preceding claims, wherein the jack stand comprises an annular support extending circumferentially around a longitudinal axis of the spindle, and wherein the thrust bearing is mounted on the support.

12. The jack stand according to any one of the preceding claims, wherein the processor is configured such that the weight value that is calculated by the processor is the downwards force acting on the load cell.

13. The jack stand according to any one of claims 1 to 11, wherein the processor is configured such that the weight value that is calculated by the processor is a downwards force acting on a tow ball or tow hitch of a vehicle that the towable apparatus is connectable to.

14. The jack stand according to claim 13, wherein the processor is configured to calculate the weight value using a formula (JW x D1) / D2 where JW is a downwards force acting on the load cell, D1 is a distance between an axle of a wheel of the towable apparatus and the foot of the jack stand and D2 is a distance between the axle of the wheel of the towable apparatus and a position of the tow ball or tow hitch.

15. The jack stand according to claim 13, wherein the processor is configured to calculate the weight value using a formula (JW x (D2-D3)) / D2 where JW is a downwards force acting on the load cell, D2 is a distance between an axle of a wheel of the towable apparatus and a position of the tow ball or tow hitch and D3 is a distance between an axle of the foot of the jack stand and the position of the tow ball or tow hitch.

16. The jack stand according to any one of the preceding claims, wherein the apparatus comprises a housing that is disposed between the upper portion of the shank and the handle, wherein the housing comprises the processor and the display device.

17. The jack stand according to any one of the preceding claims, wherein the jack stand is a jockey wheel, and wherein the ground-engaging foot comprises a wheel.

18. A jack stand for a towable apparatus, comprising: a shank comprising an upper portion and a lower portion, wherein the lower portion comprises a ground-engaging foot; a spindle comprising a threaded portion received threadedly by the lower portion such that axial rotation of the spindle relative to the upper portion causes relative translational movement between the upper portion and lower portion in a vertical direction; a handle for axially rotating the spindle; a thrust bearing arranged to support the upper portion relative to the spindle and to facilitate the axial rotation of the spindle; a load cell comprising a sensor arrangement, wherein the load cell is disposed above the thrust bearing such that the sensor arrangement generates a signal in proportion to a downwards force acting on the load cell by the upper portion due to a weight of the towable apparatus; and a processor connected to a wireless transmitter, the processor being configured to transmit data to a remote user device using the wireless transmitter, wherein the data corresponds to the signal or to a weight calculated by the processor based on the signal, and wherein the remote user device is configured to cause a display of the remote user device to show a weight value corresponding to the data, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

19. A load measuring system for a jack stand, comprising: a load cell configured to be positioned inside a shank of the jack stand above a thrust bearing of a spindle of the jack stand, wherein the spindle extends axially through the shank, the load cell comprising a sensor arrangement configured to generate a signal in proportion to a downwards force acting on the load cell by an upper portion of the shank due to a load supported by the jack stand; a processor configured to calculate a weight value based on the signal; and a display device connected to the processor for displaying the weight value, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.

20. A load measuring system for a jack stand, comprising: a load cell configured to be positioned inside a shank of the jack stand above a thrust bearing of a spindle of the jack stand, wherein the spindle extends axially through the shank, the load cell comprising a sensor arrangement configured to generate a signal in proportion to a downwards force acting on the load cell by an upper portion of the shank due to a load supported by the jack stand; and a processor connected to a wireless transmitter, the processor being configured to transmit data to a remote user device using the wireless transmitter, wherein the data corresponds to the signal or to a weight calculated by the processor based on the signal, and wherein the remote user device is configured to cause a display of the remote user device to show a weight value corresponding to the data, wherein the load cell comprises first and second annular members joined together in a vertically spaced-apart relationship by a connection member, an elongate passage extends coaxially through the annular members and connection member that rotatably receives the spindle, the load cell is dimensioned such that the downwards force causes at least the first of the annular members to undergo strain, and the sensor arrangement is configured to generate the signal in response to the strain.