EP4662380A1

EP4662380A1 - Locking pin for shoring support structure

Info

Publication number: EP4662380A1
Application number: EP24703540.5A
Authority: EP
Inventors: Austin Owens; Will HELME
Original assignee: J Strut Ltd
Current assignee: J Strut Ltd
Priority date: 2023-02-07
Filing date: 2024-02-05
Publication date: 2025-12-17
Also published as: WO2024165509A1; AU2024217293A1; US20250382809A1; CN120659917A

Abstract

A locking pin (240) for an extendable structure, such as a acrow prop, having a first protrusion (244) and a second protrusion (248) extending from the shaft (242) of the pin, the first protrusion (244) extending from an intended lower surface of the shaft and having a curved inner wall facing towards the centre of the shaft and the second protrusion (248) extending from an intended upper surface of the shaft (242) and forming a box-like structure having a recess (245) for receipt of a leash (250).

Description

LOCKING PIN FOR SHORING SUPPORT STRUCTURE

Field of the Invention.

This invention relates to a locking pin for an extendable structure, particularly but not exclusively for a shoring support structure for providing a temporary support, commonly referred to as a shore, acrow propjack post or strut.

Background of the Invention.

It is often essential to be able to support various loads in the building and construction industry to prevent them collapsing while you work in and/or around them, for example during the creation of an archway, window or doorway, during removal of a wall or to temporarily support lintels or floors. Conventionally, a temporary vertical support structure, known as an acrow prop, jack post, strut or shoring post, is inserted into the gap to shore up the load, preventing its collapse while building or repair work is carried out.

An acrow prop comprises an outer and an inner tube, generally of galvanised steel, the inner tube slidable within the outer tube. Each tube has a welded base plate at one end and the outer tube has a threaded region at the other end. A threaded collar with a handle screws onto the outer tube around the central area of the prop. The inner tube has a series of spaced apart holes along its length and a pin is provided for placement within a hole. The outer tube has a longitudinal slot. Gross adjustment of the height of the prop is made by removal of the pin, extending the inner tube so that the tubes almost fill the gap, within which supporting will be performed, and then re-inserting the pin in the relevant hole. The pin then sits on the top of the collar and fine adjustment of the prop to the exact height of the gap is achieved by rotating the collar by means of the handle. This extends the inner tube, moving it up slowly until it is adjusted to the correct height. Furthermore, the extending of the prop can apply load.

Different types of acrow prop pins exist in the marketplace but generally the pins comprise a short shaft for placement through the inner tube connected to a chain and ring. This enables the pin to remain attached to the prop when not inserted in the hole. Alternative versions include a loop with a shaft extending through the centre of the loop or a shaft in the form of a clip that extends around one side of the tube. The acrow prop is provided in different sizes, with each size fitting a different range of gap heights. Different types of plates may be provided at the upper end of the inner tube, such as L-plates and U-plates. The threaded region of the outer tube can be formed onto the tube or may be a section that is friction welded to a plain tube.

Acrow props are extremely hard wearing and are used in vast quantities in the building trade, being adjustable without additional tools or equipment. However, they do suffer from two major drawbacks. Firstly, it can be difficult to install the prop single-handedly due to the need to hold the upper tube in position whilst rotating the threaded collar into position. Secondly, the props are manually installed. This means that they can be difficult and slow to install and remove from a site. This may be particularly problematic on sites where numerous adjacent props need to be installed to support a large area.

International Patent Application Publication No. WO 2021/023669 addresses these matters by the provision of a rotatable collar mounted on the threaded region, the collar provided with a driven member, such as a bevel gear, for mating with a driving member connectable to an actuator, wherein actuation of the driving member causes rotation of the driven member to effect rotation of the collar to raise or lower the inner tube of the prop. The actuator may comprise an impact driver or electric or battery-operated drill, thus enabling the props to be installed much more quickly and easily. The driven member in the form of a bevel gear may be provided on the upper surface of the collar and a locking pin that is conventionally placed through the holes of the inner tube may serve as a shaft for connection to, or support of, the driving member or pinion gear. However, conventional locking pins are not ideal for use with a driving member due to their instability and furthermore, the chain or wire leash attached to the pin can obstruct the gear. It is desirable to provide a new locking pin that addresses these issues.

It is therefore an aim of the present invention to provide an improved locking pin for an extendable structure, particularly but not exclusively a shoring support structure, which overcomes, or at least alleviates, the above problems.

Summary of the Invention.

According to the present invention there is provided a locking pin for an extendable structure comprising: an elongated shaft member, the shaft member having at least one protrusion extending from an intended upper or lower surface thereof.

Preferably, two protrusions extend from the shaft member wherein a first protrusion extends from an intended lower surface of the shaft member and a second protrusion extends from an intended upper surface of the shaft member. The shaft member and protrusions are preferably formed of a load bearing metallic material, such as forged or machined steel.

The first protrusion preferably has an inner wall facing towards the centre of the shaft and an opposing outer wall, the inner and outer walls defining opposing side walls. Preferably, the outer wall extends substantially perpendicularly to the longitudinal axis of the shaft. More preferably still, the inner facing wall is curved. Preferably, the radius of curvature corresponds substantially to a curvature of an inner tube of a shoring structure in relation to which the locking pin is to be used. It is preferable for the inner and outer facing walls of the first protrusion to extend across the whole of the underside of the shaft, i.e., at the point where it meets the shaft the protrusion has a width corresponding substantially to the diameter of the shaft, optionally with a slight draft angle of around 5 degrees to allow the feature to be forged. However, each side wall of the protrusion preferably tapers to an apex at the end of the protrusion.

The second protrusion preferably extends substantially perpendicularly from an intended upper surface of the shaft, the protrusion being spaced laterally from the first protrusion towards an outer end of the shaft. Preferably, the second protrusion forms a box-like structure having four sides extending upwardly from the shaft. Preferably, the width of each side is slightly less than the diameter of the shaft, the protrusion optionally having a slight tapering towards it free end.

The second protrusion preferably has a recess or hole through its centre for receipt of a leash. More preferably, the second protrusion can be cold formed around an end of the leash to secure the leash to the locking pin. Preferably, the leash is formed from a wire, optionally coated with a material such as PVC. Once secured within the second protrusion, the leash preferably extends upwardly from the protrusion and shaft. Preferably, the leash is also provided with a loop spaced apart from the shaft. The loop may be formed by the provision of a ferrule which is cold formed onto the junction of the loop of the leash. Any suitable material may be provided for the ferrule that may be deformed around the leash but in a preferred embodiment the ferrule is formed from aluminium. One or both ends of the elongated shaft may include a taper for mating with a central bore of a pinion gear.

A second aspect of the present invention provides an extendable structure comprising: an outer tube having a threaded region with opposing longitudinal slots therethrough; an inner tube slidable within the outer tube and having a plurality of pairs of transverse holes at spaced apart intervals; a locking pin according to the first aspect of the present invention, the pin being receivable through the slots of the outer tube and a pair of transverse holes of the inner tube; and a collar mounted on the threaded region and being rotatable to raise and lower the pin within the slots, the protrusion of the pin being received between the collar and the inner tube; wherein the collar includes a driven member for mating with a driving member connectable to an actuator, actuation of the driving member causing rotation of the driven member to effect rotation of the collar.

In a preferred embodiment of the present invention, the extendable structure comprises a shoring support structure, for example in the form of an acrow prop. However, it is to be appreciated that the mechanism may be used on any type of extendable structure requiring relative linear movement or loading effected by a driven rotating collar.

Preferably, the driven member is a gear, preferably a bevel gear, which may be provided on an upper or lower surface of the collar. Bevel gears are gears where the axes of two shafts intersect, generally being 90 degrees apart, but can be designed to work at other angles as well.

The driving member is preferably a pinion gear that meshes with the bevel gear provided on the collar. The pinion gear preferably receives an end of the locking pin.

The bevel gear may be provided on an upper or lower surface of the collar, more preferably an upper surface of the collar. An outer surface of the pinion gear is preferably provided with a recess or protrusion for mating with a corresponding protrusion or recess of an actuator. The recess and protrusion preferably key together to impart motion from the actuator to rotation of the pinion gear.

Any suitable actuator may be used but preferably a powered actuator is provided to impart motion to the collar via the driving and driven members. For example, the actuator may comprise an impact driver or electric or battery-operated drill.

Optionally, the pinion gear may include a flange for acting on the collar to prevent axial movement of the gear and shaft. Preferably, the flange comprises an annular flange.

A non-rotatable sleeve may also be included around the locking pin to reduce wear.

The gears may be provided with any suitable tooth-bearing faces. The teeth of the respective gears may be initially sized so that they only partially contact each other but become driven in further over time as gear wear occurs. The holes through the inner tube may also be shaped such as to maintain contact between the gears.

Preferably, at least one of the inner and outer tubes terminates in a base plate. However, it is to be appreciated that other types of end members may be provided at one or both ends of the tubes depending upon end use of the structure.

The present invention also provides a kit of parts for adapting an existing extendable structure, particularly but not exclusively a shoring support structure, the kit comprising a collar with a bevel gear on an upper or lower surface thereof, a locking pin according to the first aspect of the invention and a pinion gear.

Brief Description of the Drawings.

For a better understanding of the present invention and to show more clearly how it may be carried into effect reference will now be made, by way of example, to the accompanying drawings in which:

Figures 1 A, IB and 1C are respectively front and rear perspective views and a cross-sectional view of a shoring support structure fitted with a collar and bevel gear according to the prior art;

Figure 2A is an isometric view of a locking pin according to an embodiment of the present invention; Figure 2B is a side view of the locking pin of Figure 2A;

Figure 2C is an end view of the locking pin of Figure 2A;

Figure 2D is a section through line B-B of Figure 2B;

Figure 2E is a lower view of the locking pin of Figure 2 A;

Figure 2F is a sectional view through line D-D of Figure 2E;

Figure 3 A is a side view of the locking pin and leash assembly according to an embodiment of the present invention

Figure 3B is an isometric view of the locking pin assembly of Figure 3 A

Figure 3C is a sectional view through line A-A of Figure 3A;

Figure 3D is a sectional view through line B-B of Figure 3 A;

Figure 3E is a top view of the locking pin with wire of Figure 3A;

Figure 3F is a perspective view of the ferrule of the locking pin and wire of Figure 3 A;

Figure 4A is a side view of a shoring support structure provided with a locking pin and wire of Figures 2 A to 3F;

Figure 4B is a partial sectional view through line A-A of Figure 4A; and

Figure 4C is an expanded view of region B shown in Figure 4B.

Detailed Description of the Invention.

The present invention provides an improved locking pin that may be used to lock any type of extendable structure requiring relative linear movement or loading effected by a driven rotating collar.

In the illustrated examples, the extendable structure is a shoring support structure for use during building work that may be more quickly and easily installed and removed by the user than entirely manual installation of the structures. The shoring support structure may be used in the conventional manner of a standard acrow prop or may be powered by a drill or impact driver, equipment that is normally readily available where building work is being undertaken.

Referring to Figures 1 A to 1C of the accompanying drawings, one example of a shoring support structure 3 according to the prior art is illustrated. The structure has a pair of telescopically extendable cylindrical tubes of galvanised steel, comprising an inner tube 4 and an outer tube 2. The free end of the inner tube is provided with a head plate 6 and the free end of the outer tube is provided with a base plate 6. The inner tube 4 is provided with a series of spaced apart pairs of opposing transverse holes 14 and the outer tube is provided with a threaded region 22 in an upper region of the tube which includes two opposing longitudinal slots 16. Gross adjustment of the height of the support structure is achieved by sliding the inner tube out of the outer tube so that the tubes almost fill the gap, within which supporting will be performed, and then a pin 24 in the form of a small cylindrical rod is placed through the most appropriate holes 14 and slot 16 in the tubes. The pin sits on a collar 8 threaded onto the outer tube 2 and the collar may be raised and lowered by rotating it on thread 22 to cause the inner tube to rise and fall to provide fine adjustment of the support structure. Different ranges of adjustment can be achieved by fitting the pin in different holes 14 in the inner tube 4. The collar 8 is adapted to include a driven member in the form of a bevel gear 30 on its upper surface whereby the pin 24 that is placed through the holes of the inner tube serves as a shaft for connection to, or support of, a driving member or pinion gear 40 having means for engagement with an actuator (not shown). The pinion gear 40 is provided with a flange 42 to maintain close contact between the gears.

A manual actuator may be used to turn the shaft and cause rotation of the collar via the pinion and bevel gear, such as a T-handle or right-angled square drive but, more advantageously, a powered actuator is used to operate the support structure, such as a drill or impact driver. Thus, the support structure may be installed in a conventional manner or its installation may be powered by an existing power tool, enabling one person to fix the structure in position quickly and easily.

Preferably, the gears are provided with an inclined face so that pushing the shaft axially inwards brings the bevel gear 30 and pinion gear 40 into closer contact.

It is to be appreciated that the pinion 40 may be entirely removable from the support structure such that this part may be provided as a tool for use on the installation of multiple support structures. Additionally, the gears may be sized such that they are only in partial contact and can be driven in further over time. This will increase the longevity of the structure because wear will occur in areas such as the holes, gears and pins. The act of pushing the driving member inwards will tend to keep the gears in contact but the structure could be adapted further to provide means to maintain the shaft in an appropriate axial position, such as by shaping the holes of the inner tube.

The afore-mentioned arrangement is fit for purpose but the use of a standard acrow prop pin to provide a shaft for the pinion gear is not ideal, primarily because the standard pin is not secured sufficiently within the tube. The present invention provides an improved locking pin for this purpose. Figures 2A to 2F illustrate one embodiment of a locking pin 240, shown without a securing wire fitted to it. The main body of the locking pin 240 forms a shaft 242, the length a of which is around 120mm with a diameter b of around 16mm, albeit the shaft is not limited to this size. The ends of the shaft are rounded and two protrusions 244 and 248 extend approximately at right angles to the main shaft. The first protrusion 244 extends from an intended lower surface of the shaft and has an inner wall facing towards the centre of the shaft and an opposing outer wall, the inner and outer walls defining opposing side walls. The inner and outer walls extend substantially perpendicularly to the longitudinal axis z (see Fig. 2F) of the shaft 242 but the inner facing wall 246 (see Fig. 2B) is curved to substantially correspond with the curvature of an inner tube 4 and the outer facing wall is curved to substantially correspond with the curvature of an outer tube 2 of a shoring structure (see Figs. 4B and 4C). The inner and outer facing walls of the first protrusion 244 extend across the whole of the underside of the shaft, i.e., at the point where it meets the shaft the protrusion has a width corresponding substantially to the diameter of the shaft but has a slight tapering a of around 5 degrees (see Fig. 2C). However, each side wall of the protrusion (see Fig. 2B) tapers to an apex at the end of the protrusion. For example, in the illustrated embodiment the apex have a width g of 3.1mm (see Fig. 2E).

It is to be appreciated that while it is preferred for the inner facing wall of the first protrusion to be curved to substantially correspond with the curvature of an inner tube and/or the outer facing wall is curved to substantially correspond with the curvature of an outer tube, these curvatures of the inner and outer faces of the projection are not essential as long as the projection fits between the outside diameter of the inner tube and the inside of the thread of the collar (unless a counter bore is added to allow the outer face to move outwards).

The second protrusion 248 extends substantially perpendicularly from an intended upper surface of the shaft 242, the protrusion being spaced laterally from the first protrusion 244 towards an outer end of the shaft. The second protrusion forms a box-like structure having four sides extending upwardly from the shaft. The width of each side is slightly less than the diameter of the shaft and again the protrusion has a slight tapering towards its free end (for example a tapering a of around 5 degrees). Additionally, the protrusion 248 has a recess 245 through its centre (discussed in further detail in relation to Figures 3 A to 3F below). The second protrusion is slightly longer than the first protrusion, with the second protrusion having a length c of around 18mm and the first protrusion having a length d of around 14mm (see Fig. 2C). The arc 0 of the shaft is intended to fit within the paired holes of the inner tube (see 4 in Figure 1C). In this embodiment the arc 0 is around 16 mm.

Figures 2D and 2F show further details of the preferred dimensions of the locking pin according to a preferred embodiment of the present invention. These dimensions are dictated by a particular size of acrow prop in relation to which the locking pin is used. However, it is to be appreciated that these dimensions could be altered to fit acrow prop structures of different sizes. Figure 2D illustrates a cross-section through the shaft 242 of the pin. An optional draft angle a of around 5 degrees may be applied to the top and bottom of the cylindrical profile to allow the part to be created using a forging operation.

Figure 2F more clearly illustrates the outer positioning of the second protrusion 248 relative to the first protrusion. In this respect. The inner facing wall of the second protrusion commences at around a length j from the end of the shaft that contacts an actuator, j being around 90.4mm in contrast to the inner facing surface of the first protrusion 244 being at a distance h of around 84.4mm from the end of the shaft that contacts an actuator. The outer facing wall of the second protrusion is a length k of around 20.4 from a non-contact end of the shaft, with the outer facing wall of the first protrusion being at a length i of around 32.0mm from the non-contact end of the shaft 242. Each tapered contact end of the shaft is also shown as providing angle P for mating with a central bore of a pinion gear.

Figures 3 A to 3F illustrate a locking pin according to the invention provided with a safety wire or leash 250. In the illustrated embodiment a PVC coated wire is provided for the leash but other materials may be used. The second protrusion 248 is able to receive the leash 250 within the recess 245 and the leash can be secured within the protrusion by cold forming, pointing upwardly away from the shaft 242, as shown in Figures 3A and 3B. The leash is also provided with a loop 252 spaced apart from the shaft, ideally being at a distance x of at least 110mm from the top of the protrusion 248 (see Fig. 3 A). The loop is formed by the provision of a ferrule 254 which is cold formed onto the junction of the loop of the leash. Any suitable material may be provided for the ferrule that may be deformed around the leash but in a preferred embodiment the ferrule is formed from aluminium.

As shown in Figure 3 A, distance y between the apex of the first protrusion and the top of the second protrusion is about 32mm. Figure 3C shows further detail regarding the fixing of the leash to the protrusion 248 of the locking pin 240. To clamp the wire leash 250 in place a mechanical pressing operation is used to deform the protrusion 248 while in a cold condition (cold forming). The deformation could be applied to any side of the protrusion. In this embodiment it is shown to occur over length p and to a maximum depth o from the centre of recess 245. The PVC coating is stripped from the steel wire to ensure a high clamping force when recess 245 is deformed. A small gap between end of PVC coating and top of the protrusion is expected and denoted by distance q. Again, the dimensions provided for the pin and leash are illustrative and it is to be appreciated that they could be altered dependent upon the component sizes of the shoring structure support.

The leash envelops an arc 0 r (see Fig. 3E) that is greater than the arc 0 of the outer tube (2 in Figure 1C). This enables it to be secured to the outer tube preventing loss/separation.

The ferrule is crimped over the end of the wire with an offset s that ensures the end of the wire does not protrude, preventing it from fraying and being a hazard.

Figures 4 A to 4C illustrate the locking pin of Figures 2 A to 3F in use. A shoring structure similar to that shown in Figures 1 A to 1C is shown fitted with a locking pin 240 of the invention. For the sake of simplicity, identical features already discussed in relation to Figures 1 to 3F are given the same reference numerals. The structure comprises an inner tube 4, an outer tube 2 having end plates 6. The inner tube 4 is provided with a series of spaced apart pairs of opposing transverse holes 14 and the outer tube is provided with a threaded region 22 in an upper region of the tube which includes two opposing longitudinal slots 16. A collar 8 is threaded onto the outer tube 2, the collar having a bevel gear 30 on its upper surface. Gross adjustment of the height of the support structure is achieved by sliding the inner tube out of the outer tube so that the tubes almost fill the gap, within which supporting will be performed, and then a locking pin 240 according to the invention is placed through the most appropriate holes 14 and slot 16 in the tubes. As most clearly demonstrated in Figures 4B and 4C, the shaft 242 of the pin lies above the bevel gear 30 of the collar 8 and the first protrusion 244 locates in the slot of the outer tube and is wedged between the collar and inner tube 4. This prevents axial movement of the pin when it is connected to a driving member or pinion gear 40 having means for engagement with an actuator (not shown). The pin 240 sits on the collar and mates with the pinion gear which may be driven by a handle or powered actuator, the pinion gear imparting motion to the bevel gear of the collar to cause the inner tube 4 to rise and fall to provide fine adjustment of the support structure. Different ranges of adjustment can be achieved by fitting the pin in different holes 14 in the inner tube 4. The leash 250 is provided around the inner tube 4. As shown most clearly in Figure 4B, the attachment of the leash 250 at the second protrusion 248 of the locking pin laterally from the first protrusion and upwardly from the collar ensures that the leash does not get snagged by the gear teeth during installation of the prop.

Thus, the locking pin and leash according to the present invention allows for the pin to be securely held between the collar and inner tube during operation of the gears to adjust the height of the prop. This also provides for less wear and tear of the component parts. Furthermore, the cold formation of the leash extending upwardly away from the collar prevents damage to the leash and snagging of the leash that would hinder operation of the device.

It is clear that the shoring support structure and locking pin of the present invention may be provided as a completely new product or the component parts, in particular the collar with a bevel gear and pinion with locking pin, may be provided separately to allow retrospective fitting to existing acrow props to enable these devices to be powered by an impact driver or drill.

While the illustrated embodiments are in relation to a vertical shoring support structure with flat base and head plates, it is to be appreciated that the support may be used in alternative orientations with different types of fixings, such as U-shaped head plates or L-shaped head plates. The plates may also be adjustable, for example, to enable them to be fixed at an angle depending upon the structure supported. As with conventional acrow props, the structures could be provided in a range of sizes to fit different sizes of gaps. All the component parts may be provided as a kit.

Further modifications to a locking pin for a shoring support structure may be made without departing from the principles embodied in the examples described and illustrated herein.

Claims

CLAIMS:

1. A locking pin for an extendable structure comprising: an elongated shaft member, the shaft member having at least one protrusion extending from an intended upper or lower surface thereof.

2. The locking pin as claimed in claim 1, wherein two protrusions extend from the shaft member wherein a first protrusion extends from an intended lower surface of the shaft member and a second protrusion extends from an intended upper surface of the shaft member.

3. The locking pin as claimed in claim 1 or claim 2, wherein the shaft member and protrusions are formed of a load bearing metallic material, such as forged or machined steel.

4. The locking pin as claimed in claim 1, claim 2 or claim 3, wherein the first protrusion has an inner wall facing towards the centre of the shaft and an opposing outer wall, the inner and outer walls defining opposing side walls.

5. The locking pin as claimed in claim 4, wherein the outer wall extends substantially perpendicularly to the longitudinal axis of the shaft.

6. The locking pin as claimed in claim 4 or claim 5, wherein the inner facing wall is curved.

7. The locking pin as claimed in claim 6, wherein the radius of curvature corresponds substantially to a curvature of an inner tube of a shoring structure in relation to which the locking pin is to be used.

8. The locking pin as claimed in any one of claims 4 to 7, wherein the inner and outer facing walls of the first protrusion extend across the whole of the underside of the shaft, i.e., at the point where it meets the shaft the protrusion has a width corresponding substantially to the diameter of the shaft, optionally with a slight draft angle of around 5 degrees to allow the feature to be forged.

9. The locking pin as claimed in any one of claims 4 to 8, wherein each side wall of the protrusion tapers to an apex at the end of the protrusion.

10. The locking pin as claimed in any one of claims 2 to 9, wherein the second protrusion extends substantially perpendicularly from an intended upper surface of the shaft, the protrusion being spaced laterally from the first protrusion towards an outer end of the shaft.

11. The locking pin as claimed in claim 10, wherein the second protrusion forms a boxlike structure having four sides extending upwardly from the shaft.

12. The locking pin as claimed in claim 11, wherein the width of each side is slightly less than the diameter of the shaft, the protrusion optionally having a slight tapering towards it free end.

13. The locking pin as claimed in any one of claims 2 to 12, wherein the second protrusion has a recess or hole through its centre for receipt of a leash.

14. The locking pin as claimed in claim 13, wherein the second protrusion is cold formed around an end of the leash to secure the leash to the locking pin.

15. The locking pin as claimed in claim 13 or claim 14, wherein the leash is formed from a wire, optionally being provided with a coating.

16. The locking pin as claimed in claim 13, 14 or 15, wherein the leash extends upwardly from the protrusion and shaft.

17. The locking pin as claimed in any one of claims 13 to 16, wherein the leash is provided with a loop spaced apart from the shaft.

18. The locking pin as claimed in claim 17, wherein the loop is formed by the provision of a ferrule which is cold formed onto the junction of the loop of the leash.

19. The locking pin as claimed in any one of the preceding claims, wherein one or both ends of the elongated shaft includes a taper for mating with a central bore of a pinion gear.

20. An extendable structure comprising: an outer tube having a threaded region with opposing longitudinal slots therethrough; an inner tube slidable within the outer tube and having a plurality of pairs of transverse holes at spaced apart intervals; a locking pin according to any one of the preceding claims, the pin being receivable through the slots of the outer tube and a pair of transverse holes of the inner tube; and a collar mounted on the threaded region and being rotatable to raise and lower the pin within the slots, the protrusion of the pin being received between the collar and the inner tube; wherein the collar includes a driven member for mating with a driving member connectable to an actuator, actuation of the driving member causing rotation of the driven member to effect rotation of the collar.

21. The extendable structure as claimed in claim 20, wherein the driven member is a bevel gear provided on an upper or lower surface of the collar and the driving member is a pinion gear that meshes with the bevel gear provided on the collar, the pinion gear receiving an end of the locking pin.

22. The extendable structure as claimed in claim 21, wherein an outer surface of the pinion gear is provided with a recess or protrusion for mating with a corresponding protrusion or recess of an actuator.

23. A kit of parts for adapting an existing extendable structure, particularly but not exclusively a shoring support structure, the kit comprising a collar with a bevel gear on an upper or lower surface thereof, a locking pin according to any one of claims 1 to 19 and a pinion gear.