Parts kit including a nut configured to be manually moved or driven along a longitudinally extending male thread

Abstract

1. A kit of parts comprising: an outer strut and an inner strut having an external thread that are rotationally locked and longitudinally extendable relative to one another; a nut configured to be driven along the external thread to selectively secure the inner strut relative to the outer strut in a drive mode; and a drive device comprising a drive housing containing a drive motor and a connector configured to connect the drive housing with the nut, thereby connecting the drive motor with a transmission, wherein the nut comprises a housing, a rotatable member rotatably disposed within the housing and having an internal thread configured to form a mating engagement with the external thread; and a transmission disposed within the housing and having an input shaft connectable to the drive device, the transmission being further configured to selectively rotate the rotatable member relative to the housing in a drive mode and form a coupling between the housing and the rotatable member in a manual mode, the nut being further configured to manually move relative to the external thread, the coupling causing the rotatable member and the housing to rotate in unison relative to the external thread, thereby causing the nut to move longitudinally along the external thread.

Description

[Technical field]

[0001] The present invention relates to a kit of parts, in particular a kit of parts for forming a strut, comprising a nut adapted to be manually moved or driven along a longitudinally extending male thread. [Background technology]

[0002] Nuts configured to be manually moved or driven along a longitudinally extending male thread are particularly advantageous in combination with struts used by safety and rescue workers. In the following description, the use of such nuts is also described in greater detail in connection with such struts. However, those skilled in the art will recognize that such nuts may have many other applications, particularly in industry, such as hydraulic cylinders that include a locking nut for mechanical fixation of the cylinder.

[0003] The struts comprise elongated members extending axially to define a spacer. Often, the struts are comprised of an outer strut and an inner strut that are longitudinally extensible relative to one another to allow a safety or rescue worker to set the strut to a desired length. In many applications, it is desirable that the length of the strut can be adjusted during use, for example to follow intentional or unintended load movements, and may be related to either the extension or contraction of the inner strut relative to the outer strut.

[0004] Struts are used in many applications, especially for shoring applications. In this respect, shoring is defined as providing temporary support to unstable loads, for example to make a dangerous situation safe and to provide safety and rescue personnel, such as firefighters, with the safest possible working environment available at the time. The applications of such shoring can be very diverse, such as providing support against the collapse of structures such as buildings, trench shoring to prevent landslides around trenches, stabilizing vehicles, especially after a crash, etc.

[0005] SafetyThe working conditions of rescuers need to continue to be improved, especially from the point of view of safety, but also from the point of view of user comfort and occupational health.Safety risks when dealing with unstable loads are particularly related to changing conditions, such as the initial placement of a strut supporting a still unstable load and the final removal of that strut.However, conditions can also change during use, e.g. the load moves, which may be unexpected in situations where the load is unstable.

[0006] Prior art struts often include a nut that can be manually moved along a male thread that extends longitudinally on the inner column of the expandable strut. When the nut is moved along its thread and brought into abutment against the outer column, the nut secures the inner column against contraction onto the outer column. For this reason, such nuts are also referred to as locking nuts. However, manually moving the nut requires the rescuer to manually drive the nut at an arm's length away from the nut and physically close to the strut, which is often very dangerous due to the unstable loading situation and initial unsecured condition. Given the extreme danger that may be involved in manually screwing the nut, rescuers sometimes attempt to utilize "tools" such as trying to push the nut with a rod or moving a strap wrapped around the nut to try to screw the nut in.

[0007] Ideally, the safety and rescue team would like to have the opportunity to remotely manipulate the nut along the male thread of the inner column of the expandable strut, so that the nut can be controlled from a safe distance. However, such remote control of the nut is preferably provided without sacrificing the possibility to easily move the same nut manually. After all, some unstable situations cannot be stabilized without the safety and rescue team first physically positioning the strut, due to the safety and rescue team's physical presence in a high-risk area near or below the unstable load, for example when placing a strut to provide support against structural collapse of a building. In such situations, manual manipulation of the nut may be preferred, as it is the fastest way to move the nut along the thread and obtain a safe situation as soon as possible.

[0008] The US patent application US2018 / 0313436A1 is regarded as the closest prior art and discloses a strut extension mechanism. In relation to this document, at least the characterizing features of claim 1 are novel.

[0009] German patent application DE102015121378A1 and international patent applications WO2021 / 023669A1 and WO2007 / 113891A2 are acknowledged as further prior art. Summary of the Invention [Problem to be solved by the invention]

[0010] It is an object of the present invention to provide a nut which is improved over the prior art and in which at least one of the above mentioned problems is avoided or mitigated. [Means for solving the problem]

[0011] This object is achieved according to the present invention by a kit of parts according to claim 1, which kit of parts comprises: an outer post and an inner post which are rotationally locked and longitudinally extendable relative to one another, the inner post having a longitudinally extending male thread; a nut configured to form a mating engagement with the male threads of the inner post and to be driven along the male threads to selectively secure the inner post relative to the outer post in a driven mode; a drive device comprising a drive housing accommodating a drive motor and a connector configured to connect the drive housing with a nut and thereby connect the drive motor with a transmission; The nut is -Housing; a rotatable member rotatably disposed within the housing and including internal threads configured to form a mating engagement with the external threads of the internal post; - a transmission comprising an input shaft arranged in a housing and connectable to a drive device, the transmission optionally comprising: a transmission configured to rotate the rotatable member relative to the housing in a drive mode, the transmission configured to be driven by the drive device to rotate the rotatable member relative to the male threads and move a nut longitudinally along the male threads, the nut being further configured to be manually moved along the longitudinally extending male threads in a manual mode, the transmission further configured to selectively form a coupling between the housing and the rotatable member in the manual mode, such that the nut is manually rotated relative to the male threads and the coupling causes the rotatable member and housing to rotate in unison relative to the male threads, thereby moving the nut longitudinally along the male threads.

[0012] The nut of the kit of parts according to the invention therefore allows the rescuer to screw it in both drive mode and manual mode, in which the rescuer can be remote at a safe distance, and in the optional manual mode, as mentioned above, the rescuer can also fasten the nut as quickly as possible in certain circumstances.

[0013] Additionally, the actuated modes enable a variety of additional applications, such as (auto) follow modes for extending the struts or retracting the struts. In cases where a load is moving away from the struts, it may be desirable to automatically extend the struts ("auto follow extend"), particularly to prevent the struts from accidentally leaving contact. In other situations, for example for the controlled lowering of an unstable load, it may be desirable for the struts to be able to automatically retract ("auto follow retract") to maintain contact while lowering the load. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] Preferred embodiments are the subject of the dependent claims.

[0015] The various aspects and features described and illustrated in the specification may, to the extent possible, be applied individually. These individual aspects, particularly those aspects and features described in the accompanying dependent claims, may be inventions relating to problems different from those of the prior art.

[0016] In the following description, preferred embodiments of the invention are further explained with reference to the drawings. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is a perspective view of a practical application of a strut including a nut according to the invention. [Diagram 2] FIG. 2 is a perspective view of the strut of FIG. [Diagram 3] FIG. 3 is a cross-sectional perspective view of the strut of FIGS. [Figure 4] FIG. 4 is a perspective view of a nut of the strut shown in FIGS. 2 and 3. FIG. [Diagram 5] FIG. 5 is a cross-sectional view of the nut of FIG. [Figure 6] FIG. 6 is a perspective view of the sensing device of the strut shown in FIGS. 2 and 3. FIG. [Figure 7] FIG. 7 is a cross-sectional view of the sensing device of FIG. [Figure 8] FIG. 8 is a cross-sectional view of the strut shown in FIGS. 1 and 2 with the nut of FIGS. 4 and 5 positioned adjacent to the sensing device of FIGS. 6 and 7. [Figure 9] FIG. 9 shows a detail of FIG. 8 in various states of use. [Figure 10] FIG. 10 shows a detail of FIG. 8 in various states of use. [Figure 11] FIG. 11 is a schematic diagram of a strut and its actuation and control. [Figure 12] FIG. 12 is a perspective view of the drive unit shown in FIG. [Figure 13] FIG. 13 is a perspective view of the drive unit shown in FIG. [Figure 14]FIG. 14 is a cross-sectional view of the driver placed in contact with the nut. [Figure 15] FIG. 15 is a cross-sectional view of a driver and a sensing device disposed in contact with a nut. [Figure 16] FIG. 16 is a perspective view of a drive device disposed in contact with the nut and the sensing device. [Figure 17] FIG. 17 shows two different usage states of the sensing device corresponding to FIGS. 9 and 10, respectively. [Figure 18] FIG. 18 shows two different usage states of the sensing device corresponding to FIGS. 9 and 10, respectively.

[0018] One of the many potential applications of the struts 1 is shown in the shoring situation in FIG. 1, where a collision has occurred and a tank truck 62 has stopped on top of a passenger vehicle 3. In order to safely approach the passenger vehicle 3 to provide first aid to the passengers inside the vehicle 3, a safety rescuer 4 must first stabilize the unstable load 2 defined by the tank truck 2. In this particular situation, the safety rescuer 4 uses two struts 1, the right strut 1 being actuated by a controllable actuator 5 comprising a hydraulic pump 6 arranged to pump hydraulic fluid through a hydraulic line 7, thereby extending the right strut 1. The left strut 1 comprises a drive 8 connected via a control line 9 to a control unit 10 having a power pack 11. The functionality of this left strut 1 will be explained in more detail below.

[0019] Strut 1 is shown in Figures 1 and 2 and comprises an outer strut 12 and an inner strut 13 that are extendable relative to one another in a longitudinal direction L (shown in Figures 3 and 8) and locked relative to one another. Rotational locking may be provided by a keyway 14 and associated key 15 (Figure 2). A first end 16 of strut 1 may comprise a connector half 17 configured to mechanically interlock with a geometrically identical connector half 17 of another strut 1. Both the connector half 17 at the first end 16 and the opposite end 18 of strut 1 may define a coupler 19 that allows both ends 16, 18 to be coupled to an accessory 20, such as an end plate 21 (Figure 1).

[0020] The nut 22 is configured to be manually or driven along male threads 23 extending in a longitudinal direction L. In the case of the strut 1 shown in Figures 1 and 2, the nut 22 is configured to be manually or driven along male threads 23 extending in a longitudinal direction L to form a mating engagement with the male threads 23 of the inner strut 13 and selectively secure the inner strut 13 relative to the outer strut 12. When the nut 22 is moved into abutment with the outer strut 12 or an optional sensing device 34 connected to the outer strut 12, the inner strut 13 is secured relative to the outer strut 12, preventing the inner strut 13 from moving into, or relative to, the outer strut 12. The nut 22 is therefore a locking nut.

[0021] The nut 22, which will be described in more detail with reference to Figures 4 and 5, includes a housing 24 and a rotatable member 25 rotatably disposed within the housing 24. The rotatable member 25 includes internal threads 26 configured to form a mating engagement with the external threads 23 of the inner post 13. A transmission 27 is disposed within the housing 24 and includes an input shaft 28 connectable to a drive 43. The transmission 27 is optionally configured as follows:

[0022] In a drive mode, the transmission 27 is driven by the drive unit 43 to rotate the rotatable member 25 relative to the housing 24 (Figures 11, 14, 15, 16), thereby rotating the rotatable member 25 relative to the male thread 23 and moving the nut 22 along the male thread 23 in the longitudinal direction L; and in a manual mode, a coupling is formed between the housing 24 and the rotatable member 25, and the nut 22 is manually rotated relative to the male thread 23 (Figure 8), which coupling causes the rotatable member 25 and the housing 24 to rotate in unison relative to the male thread 23, thereby moving the nut 22 along the male thread 23 in the longitudinal direction L.

[0023] In both the drive mode and the manual mode, the rotatable member 25 rotates relative to the male thread 23, thereby displacing the housing 24 of the nut 22 longitudinally along the male thread 23. Thus, the nut 22 according to the invention allows the safety rescuer 4 to screw the nut 22 in both the drive mode and the manual mode. In the drive mode, the safety rescuer 4 may be remote at a safe distance (FIG. 1), while the optional manual mode also allows the safety rescuer 4 to fix the nut 22 very quickly in certain situations. After all, since in the manual mode a coupling is formed between the housing 24 and the rotatable member 25, when the user, i.e. the safety rescuer 4, manually rotates the nut 22 along the male thread 23, the rotatable member 25 and the housing 24 rotate in unison relative to the male thread 23. In this regard, it is mentioned that the coupling formed between the housing 24 and the rotatable member 25 in the manual mode may act as a slip coupling. Those skilled in the art will appreciate that some slip may be tolerated, so long as the level of slip is small enough to allow the housing 24 and rotatable member 25 of the nut 22 to rotate in unison manually relative to the male threads 23. Ideally, a slip-free connection would allow manual rotation of the nut 22 to be losslessly translated into longitudinal displacement of the nut 22 along the male threads 23. The grease fitting 33 allows for the placement of grease within the housing 24 for lubrication of the rotatable member 25 relative to the housing 24.

[0024] In the drive mode, the housing 24 is rotationally locked relative to the male threads 23. This is preferably caused automatically by the driver 43 being placed onto the nut 22, as will be described in more detail below with reference to FIG.

[0025] The transmission 27 may be irreversible in a manual mode in which the nut 22 is manually rotated relative to the male thread 23, thereby forming a coupling between the housing 24 and the rotatable member 25. For example, the transmission 27 may comprise a self-braking gear, or more preferably, a self-locking gear. A self-locking gear is a gear in which driving the input drives the output, but driving the output does not drive the input. Thus, a transmission comprised of a self-locking gear is an irreversible transmission. A self-braking gear is interpreted as a self-locking gear that may have some slip, but the level of slip is small enough to allow the housing 24 of the nut 22 and the rotatable member 25 to rotate manually in unison relative to the male thread 23. Due to the irreversible behavior, i.e., self-braking or self-locking nature, of the transmission 27, no manual locking action is required to lock the rotation of the rotatable member 25 relative to the housing 24. The absence of such a locking action simplifies the design of the nut 22 and, more importantly, reduces the number of actions that the safety and rescue personnel 4 must take in high-risk situations. The irreversible transmission 27 adapts to the drive method, i.e. manual or automatically via the drive device 43, thereby improving safety and providing comfort for the user.

[0026] If the coupling between the housing 24 and the rotatable member 25 in the manual mode is provided by a gear ratio of the transmission 27 greater than 1:10, a self-braking feature may be obtained.

[0027] In the embodiment shown, the transmission 27 comprises a worm drive 29, with a worm 30 rotatably disposed within said housing 24, and a worm wheel 31 disposed on the outer circumference 32 of the rotatable member 25. The worm drive 29 is an embodiment of a self-braking gear, more preferably a self-locking gear. If the worm wheel 31 cannot drive the worm 30 at all, it is called self-locking or irreversible. Whether the worm drive 29 is self-locking depends on the lead angle, pressure angle, and coefficient of friction. However, it is conceivable that some configurations may experience minimal slippage, which does not result in complete locking. Some slippage may be acceptable, as long as the level of slippage is small enough that the housing 24 of the nut 22 and the rotatable member 25 can be manually rotated in unison with respect to the male thread 23.

[0028] The preferred embodiment shown in the figures includes a sensing device 34, which will be discussed in detail with reference to Figures 6 to 10. Such a sensing device 34 may provide many advantages when applied in conjunction with a drive device 43. For example, using the sensing device 34, the drive mode may enable various additional applications, such as an (auto) follow mode for extending the strut 1 or for retracting the strut 1. When the load 2 moves away from the strut 1, it may be desirable to automatically extend the strut ("auto follow extension"), especially so that the strut 1 remains in contact and does not move away accidentally. In other situations, for example for the controlled lowering of an unstable load 2, it may be desirable to be able to automatically retract the strut 1 ("auto follow retract") to maintain contact while the load 2 is being lowered. Despite the advantages offered by the sensing device 34, it is explicitly mentioned that such a drive device 43, which will be described later with reference to Figures 11 to 18, may also be used in the absence of such a sensing device 34.

[0029] The sensing device 34 is configured to provide at least one of a parameter indicative of a relative longitudinal displacement between the outer column 12 and the fixing nut 22 arranged on the threaded inner column 13 and a parameter indicative of a magnitude of a compressive force between the outer column 12 and the fixing nut 22 arranged on the threaded inner column 13. The contact sensor 35 is preferably constituted by a drive device 43, which will be described later, and is configured to detect the parameter of the sensing device 34. Such a contact sensor 35 may already be considered for measuring a load or a displacement in its most basic form, considering that it measures the presence or absence of a load or a contact. However, according to a preferred embodiment, the sensing device 34 not only provides a parameter indicative of a relative longitudinal displacement or a compressive force between the outer column 12 and the fixing nut 22 arranged on the threaded inner column 13, but also the sensing device 34 is further configured to provide a parameter indicative of a magnitude of such a displacement or a compressive force.

[0030] In the preferred embodiment shown in the figures, the sensing device 34 includes an inner ring 35 and an outer ring 36, one of which is connected to the outer strut 12 and the other of which defines an abutment 37 associated with the outer strut 12. In the embodiment shown, the outer ring 36 is associated with the outer strut 12 and the inner ring 35 is longitudinally movable relative to the outer ring 36 and defines an abutment 37 associated with the outer strut 12. When the nut 22 is threaded along the male threads 23 towards the sensing device 34 (FIG. 8), it comes into abutting contact with this abutment 37 (FIG. 9).

[0031] The guide 38 limits relative rotation between the inner ring 35 and the outer ring 36 and is configured to be slidable relative to each other in the longitudinal direction L over a predetermined sliding distance. The illustrated guide 38 includes a guide slot 39 disposed in the outer ring 36. A protrusion 40 disposed on the inner ring 35 extends into the guide slot 39. A pretensioner 41 is configured to move the inner ring 35 and the outer ring 36 away from each other. The pretensioner 41 may include a number of springs 42. As the nut 22 is further threaded toward the outer post 12 after initial butt contact with the abutment 37 (FIG. 9), the outer ring 36 and the inner ring 35 will move toward each other against the force of the pretensioner 41. The springs 42 are compressed and the projections 40 slide within their associated slots 39, which may provide a visual indication to the rescuer 4 that the nut 22 is securely abutting the outer post 12, and more particularly the abutment 37 associated with the outer post 12. The position of the projections 40 in the guide slots 39 thus provides a visual parameter indicative of the magnitude of the compressive load between the outer post 12 and the fixing nut 22, or the magnitude of the relative longitudinal displacement between the outer post 12 and the fixing nut 22 disposed on the threaded inner post 13.

[0032] The above-mentioned sensing device 34 may offer a number of additional advantages when applied in connection with a drive device 43. This drive device 43, and in particular the advantageous cooperation between the drive device 43 and the sensing device 34, will be explained in more detail with reference to Figures 11 to 18. However, the skilled person will understand that such a drive device 43 may also be used in the absence of a sensing device 34, for example if it is sufficient to remotely drive the nut 22, but more sophisticated options such as an (automatic) follow-up mode as explained below are not required.

[0033] The nut 22 may be part of an assembly or kit of parts that includes a drive 43. The drive 43 includes a drive housing 44 that houses a drive motor 45 and a connector 46 configured to connect the drive housing 44 with the nut 22, thereby connecting the drive motor 45 with the transmission 27, and more specifically, with the input shaft 28 of the transmission 27. The connector 46 includes a groove 65 (FIG. 13) in the drive housing 44 that may engage, i.e., slide over, a ridge 64 (FIG. 4) located on the housing 24 of the nut 22.

[0034] The drive 43 may be integrated in the housing 24 for very large (industrial) nuts. However, for the nut 22 used to fasten the strut 1, which is the subject of the illustrated embodiment, the drive 43 is an external drive that can be removably connected to the housing 24 of the nut 22. In Figs. 11 and 16, the nut 22 rests against the sensing device 34 and the drive 43 is shown with a dashed line indicating where the drive 43 is located when connected to the housing 24 of the nut 22. An external power source 11 is connectable to the drive 43 and is configured to provide power for driving the drive motor 45. A wired connection 9 of the drive 43 to the external power source 11 and preferably to the control unit 10 is shown diagrammatically in Fig. 11. Alternatively, the control unit 10 may have a wireless connection to the drive 43.

[0035] Figures 12 and 13 show the drive 43 in two perspective views. A control button 50 with a plus and minus sign may allow the rescuer 4 to manually control the drive 43 for extension and retraction, respectively. A visual indicator 51, such as a display or indicator light 52 (not shown), may indicate the state of the strut 1, in particular the state of the drive 43 and / or the sensing device 34 of said strut 1. Figure 13 shows the output shaft 53 of the drive 43 configured to engage the input shaft 28 of the transmission 27. The engaged state is shown in Figure 14.

[0036] In the driven mode, the housing 24 of the nut 22 is rotationally locked relative to the outer post 12, preventing relative rotation between the housing 24 of the nut 22 and the outer post 12 and allowing the rotatable member 25 to rotate relative to the housing 24. In a preferred embodiment, the driver 43 is configured to rotationally lock the housing 24 of the nut 22 relative to the outer post 12 when the driver 43 is connected to the housing 24 of the nut 22. In FIG. 15 , the locking pin 47 tensioned by the spring 66 engages one of the locking recesses 48 located on the outer periphery 49 of the outer ring 36 of the sensing device 34. Thus, the driver 43 may be configured to rotationally lock the housing 24 of the nut 22 relative to the outer ring 36 coupled to the outer post 12 when the driver 43 is connected to the housing 24 of the nut 22.

[0037] As mentioned above, the position of the projection 40 in the guide slot 39 may provide a visual parameter indicative of the relative longitudinal displacement or compressive force between the outer strut 12 and the fixing nut 22 placed on the threaded inner strut 13. In a preferred embodiment, the kit of parts forming the strut 1 comprises an abutment sensor 35 configured to detect whether the nut 22 placed on the male thread 23 of the inner strut 13 abuts against the abutment 37 associated with the outer strut 12. In a simple embodiment, the driver 43 may be powered with a constant current to force the nut 22 to screw in tighter as soon as the elongation of the strut 1 creates a gap 54 between the nut 22 and the abutment 37. However, in its most basic embodiment, with the abutment sensor 35, the driver 43 may only drive the nut 22 to screw in towards the abutment 37 as soon as the gap 54 occurs. In this basic embodiment of the abutment sensor 35, only contact may be detected, the absence of which indicates the presence of a gap 54.

[0038] The kit of parts may further include a controller 55 configured to control the drive 43 to selectively drive the transmission 27, thereby moving the nut 22 in the longitudinal direction L along the male threads 23. The controller 55 may be located within the control unit 10 or, alternatively, within the drive housing 44. The controller 55 may be configured to control the drive 43 in response to a signal received from the contact sensor 35.

[0039] In a preferred embodiment, the controller 55 is configured to control the drive device 43 depending on at least one of the sensor signal obtained from the abutment sensor 35 and the parameters provided by the sensing device 43. This provides highly advantageous options such as an auto-follow mode that may significantly improve the safety of the working situation for the safety rescuer 4.

[0040] In the "automatic follow-up extension" mode, the controller 55 is configured to move the nut 22 in the longitudinal direction L along the male thread 23 towards the outer strut 12 when the inner strut 13 extends relative to the outer strut 12 in order to restore the fixed connection between the inner strut 13 and the outer strut 12. Thus, when the strut 1 extends, the controller actively drives the nut 22 to close any gaps 54 as soon as possible. If the controller 55 is used in combination with the sensing device 34, the gaps 54 may even be actively prevented, so that the fixation of the strut 1 is further improved. After all, the controller 55 may already receive information from the sensing device 34 that the nut 22 is moving away from the outer strut 12 even before the nut 22 loses physical contact with the abutment 37 on the outer ring 36. After all, the pretensioner 41 will cause the abutment 37 to remain in abutment with the nut 22 as long as the protrusion 40 is free to move within the guide slot 39 of the guide 38. This magnitude can also be sensed by the contact sensor 35, as can the position of the protrusion 40 in the guide slot 39, which visually indicates the magnitude of the compressive load between the outer column 12 and the fixing nut 22, or the magnitude of the relative longitudinal displacement between the outer column 12 and the fixing nut 22 located on the threaded inner column 13.

[0041] Many alternatives for such an abutment sensor 35, capable of determining the magnitude of the compressive load between the outer strut 12 and the fixed nut 22, or the magnitude of the relative longitudinal displacement between the outer strut 12 and the fixed nut 22, can be easily designed by a person skilled in the art, but one practical embodiment is shown in Figs. 16-18. The lever 56 is pivotable about a pivot 57 and can abut against an edge 63 of the outer ring 36 of the sensing device 34. This causes the outer ring 36 to be displaced when the nut 22 abuts against the abutment 37. The edge 63 of the outer ring 36 is disposed opposite the abutment 37. When the outer ring 36 is displaced, the edge 63 moves the lever 56. A tension spring 58 is configured to pull the lever 56 towards the outer ring 36 and remain in contact with its edge 63. When the lever 56 rotates about the pivot 57, a toothed rack 59 can drive a pinion 60 which rotates a sensor 61, such as a potentiometer. In this way, the contact sensor 35 can obtain detailed information about any movement of the nut 22 relative to the outer post 12 .

[0042] In the "automatic retraction" mode, the controller 55 is configured to move the nut 22 a longitudinal distance L along the male thread 23 from the outer column 12 to ensure that the inner column 13 retracts said distance into the outer column 12 before the fixed connection between the inner column 13 and the outer column 12 is restored. As mentioned above, the controller 55 may already receive information from the sensing device 34 that the nut 22 has moved relative to the outer column 12 within the range provided by the guide 38. In the "automatic retraction", the nut 22 may be threaded away from the outer column 12 while maintaining abutting contact with the outer ring 36 of the sensing device 34.

[0043] It should be noted that the sensing device 34 may also be used to apply a generic "auto-follow" mode that is not limited to the preselection of either the "auto-follow extension" or "auto-follow contraction" modes described above, but in fact allows for a combination of these "extension" and "contraction" modes. This significantly improves the safety situation for the safety rescuer 4, since it is not always clear in which direction (related to "extension" or "contraction") the unstable load 2 will move. Such a generic "auto-follow" mode is possible if the controller 55 controls the drive 53 to release the protrusion 40 from both ends of the guide slot 39. In this case, the sensing device 34 will be able to inform the controller 55 related to either the extension or contraction of the strut 1. Ideally, the controller 55 controls the drive 43 to maintain the protrusion 40 at about half the free stroke allowed by the guide 38.

[0044] The above-described embodiments are intended to illustrate the present invention only and do not limit the scope of the present invention in any way. In particular, the preferred embodiment combines the nut 22, the sensing device 34, and the driving device 43, which can be used to drive the nut 22 in the absence of the sensing device 34. When features mentioned in the appended claims are followed by reference signs, it is to be understood that such signs are included only to enhance the clarity of the claims and do not limit the scope of the claims in any way. The scope of protection is defined solely by the following claims.

Claims

1. A parts kit comprising: an outer strut and an inner strut that are rotationally locked and longitudinally extendable relative to one another, the inner strut having a longitudinally extending external thread; a nut configured to form mating engagement with the external threads of the inner post and to be driven along the external threads to selectively secure the inner post relative to the outer post in a drive mode; a drive device comprising: a drive housing that houses a drive motor; and a connector configured to connect the drive housing with the nut, thereby connecting the drive motor with a transmission; The nut is Housing and a rotatable member rotatably disposed within the housing and including internal threads configured to form mating engagement with the external threads of the inner post; a transmission disposed within the housing and including an input shaft connectable to the drive device, the transmission selectively comprising: the transmission is configured to rotate the rotatable member relative to the housing in the drive mode, the transmission being driven by the drive device to thereby rotate the rotatable member relative to the external threads and move the nut longitudinally along the external threads; the nut is further configured to be manually moved along the longitudinally extending external threads in a manual mode; The transmission may further optionally include: a coupling formed between the housing and the rotatable member in the manual mode, the nut being manually rotated relative to the external threads, the coupling causing the rotatable member and the housing to rotate in unison relative to the external threads, thereby causing the nut to move longitudinally along the external threads.

2. 2. The kit of claim 1, wherein in said drive mode said housing is rotationally locked relative to said external threads.

3. 3. A kit of parts according to claim 1 or 2, wherein the transmission is irreversible.

4. 3. A kit of parts according to claim 1 or 2, wherein the transmission comprises self-braking gears, more preferably self-locking gears.

5. 3. The kit of claim 1 or 2, wherein the coupling between the housing and the rotatable member in the manual mode is provided by a gear ratio of the transmission greater than 1:

10.

6. A worm is rotatably disposed within the housing, 3. The kit of claim 1 or 2, wherein a worm wheel is disposed on the outer periphery of the rotatable member.

7. 3. The kit of parts of claim 1 or 2, wherein the driver is an external driver removably connectable to the housing of the nut.

8. 3. The kit of parts of claim 1 or 2, wherein in the drive mode, the housing of the nut is rotationally locked relative to the outer post to prevent relative rotation between the housing of the nut and the outer post, allowing the rotatable member to rotate relative to the housing.

9. 3. The kit of parts of claim 1 or 2, wherein the driver is configured to rotationally lock the housing of the nut relative to the outer post when the driver is connected to the housing of the nut.

10. The kit of parts according to claim 1 or 2, further comprising an abutment sensor that detects whether the nut disposed on the external thread of the inner post abuts against an abutment associated with the outer post.

11. a sensing device configured to provide at least one of a parameter indicative of a relative longitudinal displacement between the outer strut and the nut disposed on the inner threaded strut, and a parameter indicative of a compressive force between the outer strut and the nut disposed on the inner threaded strut; The kit of parts of claim 10 , wherein the contact sensor is configured to detect a parameter of the sensing device.

12. The sensing device an inner ring and an outer ring, one of the inner ring and the outer ring connected to the outer strut, and the other of the inner ring and the outer ring defining the abutment associated with the outer strut; a guide configured to limit relative rotation between the inner ring and the outer ring and to be slidable relative to each other in a longitudinal direction over a predetermined sliding distance; a pretensioner configured to move the inner ring and the outer ring away from each other; The kit of parts according to claim 11, comprising:

13. the outer ring is connected to the outer strut; The kit of parts of claim 12 , wherein the inner ring is longitudinally movable relative to the outer ring and defines the abutments associated with the outer posts.

14. The drive device is configured to rotationally lock the housing of the nut relative to the outer support when the drive device is connected to the housing of the nut; 14. The kit of parts of claim 13, wherein when the driver is connected to the housing of the nut, the driver is configured to rotationally lock the housing of the nut relative to the outer ring connected to the outer post.

15. 11. The kit of parts of claim 10, further comprising a controller that controls the driver to selectively drive the transmission, thereby moving the nut longitudinally along the external threads.

16. 16. The kit of parts of claim 15, wherein the controller is configured to control the drive device in response to a signal received from the contact sensor.

17. The method of claim 1, further comprising: providing a controller for controlling said drive to selectively drive said transmission and thereby move said nut longitudinally along said male thread; 12. The kit of parts of claim 11, wherein the controller is configured to control the drive device in response to at least one of a sensor signal obtained from the contact sensor and the parameter provided by the sensing device.

18. 18. The kit of parts of claim 17, wherein the controller is configured to move the nut longitudinally along the external threads toward the outer post when the inner post extends relative to the outer post to restore a secure connection between the inner post and the outer post.

19. 18. The kit of parts of claim 17, wherein the controller is configured to move the nut longitudinally from the outer post along the external threads a distance to ensure that the inner post is allowed to retract onto the outer post by said distance before the fixed connection between the inner post and the outer post is restored.

20. The kit of parts of claim 1 or 2, further comprising an external power source connectable to the drive device and configured to provide power to drive the drive motor.

21. the outer strut and the inner strut are strut members, 3. The kit of parts of claim 1 or 2, wherein the nut is a locking nut configured to selectively lock the inner strut relative to the outer strut.

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