WO2024011013A1

WO2024011013A1 - Wear pad assembly

Info

Publication number: WO2024011013A1
Application number: PCT/US2023/068695
Authority: WO
Inventors: Richard D. N. SURTEES; Robin J. HOLDEN
Original assignee: Caterpillar Inc
Current assignee: Caterpillar Inc
Priority date: 2022-07-08
Filing date: 2023-06-20
Publication date: 2024-01-11
Anticipated expiration: 2025-01-08
Also published as: GB2620454B; GB2620454A; GB202210097D0

Abstract

The present disclosure is directed towards a wear pad assembly (20) for an extendable boom having a first boom section (21) and a second boom section. The wear pad assembly (20) comprises an anchor (30) for mounting to the first boom section (21). The anchor (30) comprises a pin (31) extending between a first end (32) and a second end (33) along a longitudinal axis (34). The anchor (30) further comprises a wear pad (40) having a thickness (41) extending between a coupling surface (42) and an opposing sliding surface (43), the coupling surface (42) comprising a recess (44) for engagement with the pin (31) of the anchor (30). The recess (44) is configured to provide a clearance fit with the pin (31).

Description

WEAR PAD ASSEMBLY

Technical Field

This disclosure is directed towards a wear pad assembly for an extendable boom, and a machine or telehandler comprising such a wear pad.

Background

Machines such as telehandlers (also known as telescopic handlers or roto telehandlers) typically comprise a lifting arm. These lifting arms are used to lift, carry and place materials around construction sites, agricultural sites and the like. The lifting arm typically comprises an extendable boom or telescopic cylinder to which a work tool, such as a fork or bucket, can be attached. The extendable boom comprises a main boom section attached to the main body of the telehandler via a hinge, and a telescopic boom section mounted in the main boom section. The telescopic boom section is slidable along the main boom section between retracted and extended orientations. The telehandler may have further telescopic boom sections mounted within the telescopic boom section.

One or more sacrificial and replaceable wear pads are typically located between two sliding telescopic sections, to prevent wear of the telescopic sections, to reduce friction, and to take up gaps between the telescopic sections. Due to variation in fabrication tolerances, shims are commonly used to achieve desired wear pad running clearances between sliding telescopic sections. Shims may also be used to maintain desired running clearances during the lifetime of a wear pad, thereby prolonging the lifetime of the wear pad. JP-Y2-H0649581 discloses a wear pad assembly that uses shims to adjust a gap between the telescopic sections.

There is an ongoing need to improve the structure of wear pad assemblies for telescopic sections, to increase the ease with which the wear pad assembly can be adjusted. A particular need is to reduce servicing costs, which can be relatively high due to the cost of the skilled labour required in the servicing of telehandlers. Furthermore, many telehandlers are rented to operators and thus reduced service or down time would be particularly beneficial.

Summary

The present disclosure provides a wear pad assembly for an extendable boom having a first boom section and a second boom section, the wear pad assembly comprising: an anchor for mounting to the first boom section, the anchor comprising a pin extending between a first end and a second end along a longitudinal axis; and a wear pad having a thickness extending between a coupling surface and an opposing sliding surface, the coupling surface comprising a recess for engagement with the pin of the anchor; wherein the recess is configured to provide a clearance fit with the pin.

Optionally, the recess engages with the pin such that the wear plate engages with the anchor but is detached from it.

Optionally, the recess is sized and/or shaped to provide the clearance fit with the pin.

Optionally, the pin and the recess are circular.

Optionally, an outer surface of the pin is smooth.

Optionally, a perimeter of the sliding surface of the wear pad comprises a chamfer.

Optionally, the anchor further comprises a connecting portion extending outwardly from the first end of the pin in a plane perpendicular to the longitudinal axis. Optionally, the connecting portion comprises at least one connecting aperture.

Optionally, the wear pad assembly further comprises one or more shims for positioning between the base plate and the wear pad, each shim comprising a shim aperture for engagement with the pin of the anchor.

Optionally, the shim aperture is configured to provide a clearance fit with the pin of the anchor. Optionally, the shim aperture is sized and/or shaped to provide a clearance fit with the pin of the anchor.

Optionally, the shim aperture is circular. The present disclosure further provides an extendable boom having a first boom section and a second boom section, the extendable boom comprising the aforementioned wear pad assembly.

Optionally, the wear pad assembly is mounted to the first boom section and the second boom section is configured to slide relative to the first boom section along the sliding surface of the wear pad.

Optionally, the wear pad is positioned on a first side of the first boom section, the wear pad being located between the first boom section and the second boom section, and the anchor is mounted to a second opposing side of the first boom section, the pin extending through a first boom aperture in the first boom section and into the wear pad recess.

Optionally, the wear pad is constrained in a direction perpendicular to a plane of the first boom section by the first and second boom sections.

The present disclosure further provides a telehandler comprising the aforementioned extendable boom.

Brief Description of the Drawings

Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 shows a schematic side elevation of a telehandler comprising a wear pad assembly in accordance with the present disclosure;

Figure 2 shows an exploded perspective view of a wear pad assembly in accordance with the present disclosure;

Figure 3 shows a perspective cross-sectional view of the wear pad assembly of Figure 2, mounted to a first boom section; and

Figure 4 shows a side cross-sectional view of the wear pad assembly of Figures 2 and 3, mounted to a first boom section and facing a second boom section. Detailed Description

Figure 1 illustrates a telehandler 10 comprising the wear pad assembly 20 of the present disclosure (not visible in Figure 1). The telehandler 10, also known as a telescopic handler, may be any type of telehandler, such as a roto or rotating telehandler. The telehandler 10 may comprise a chassis or main body 11 and a boom 12 mounted thereto at a boom hinge 13. The boom 12 may comprise a main boom section 14 and a telescopic boom section 15 mounted to the main boom section 14. The telescopic boom section 15 may be retractably mounted inside the main boom section 14 such that the telescopic boom section 15 is slidable relative to the main boom section 14 along a sliding direction 80. Although not shown in Figure 1, a further telescopic boom section may be retractably mounted inside the telescopic boom section 15 such that the further telescopic boom section is slidable relative to the telescopic boom section 15 along the sliding direction 80. A work tool 16, in this case a fork, may be attached to the telescopic section 15 for performing work.

At least one wear pad assembly 20 may be located between the main boom section 14 and the telescopic boom section 15, such that the boom sections 14,15 may slide relative to one another along a wear pad 40 of the wear pad assembly 20. The at least one wear pad assembly 20 may prevent wear of the boom sections 14,15 from the sliding motion, reduce friction, and increase stability of the boom 12 by taking up gaps between the boom sections 14,15. Typically a plurality of wear pad assemblies 20 may be provided between the boom sections 14,15. For example, for typical square boom sections 14,15, one or more wear pad assembly(ies) 20 may be provided on each of two opposing sides, or even on all four sides, of the main boom section 14 or the telescopic boom section 15. Furthermore, wear pad assemblies 20 may be provided at both upper and lower ends of the boom sections 14,15. The following description in relation to a single wear pad assembly 20 may equally apply to some or all of the other wear pad assemblies 20. The wear pad assembly 20 may be mounted to the main boom section 14 such that the telescopic boom section 15 slides along it, or the wear pad assembly 20 may be mounted to the telescopic boom section 15 such that the main boom section 14 slides along it. The boom section 14, 15 to which the wear pad assembly 20 is mounted will be referred to herein as the first boom section 21 and the boom section 14, 15 that slides along the wear pad assembly 20 will be referred to herein as the second boom section 22. There may be no contact between the boom sections 14, 15 during extension and retraction other than via the wear pad assembly(ies) 20.

As shown in Figures 2 to 4, the wear pad assembly 20 generally comprises an anchor 30 and a wear pad 40. The wear pad assembly 20 may further comprise one or more shims 50.

The anchor 30 may comprise a pin 31 extending between a first end 32 and a second end 33 along a longitudinal axis 34. The pin 31 may have a circular transverse cross-section (that is, perpendicular to the longitudinal axis 34), as shown in the specific embodiment of Figures 2 to 4. Alternatively, the pin 31 may have a cross-section that is square, triangular, another polygonal shape, or an irregular shape. An outer surface 39 of the pin 31 may be smooth. In particular, the outer surface 39 of the pin 31 may be threadless. The pin 31 may be hollow or solid.

The first end 32 of the pin 31 may be provided with a connecting portion 35. The connecting portion 35 may comprise a planar element extending outwardly from the first end 32 of the pin 31 in a plane perpendicular to the longitudinal axis 34. The connecting portion 35 may extend outwardly from the whole perimeter of the pin 31, as illustrated in Figure 2. Alternatively, the connecting portion 35 may extend outwardly from only a part of the perimeter of the pin 31, for example from one side of the perimeter of the pin 31 or from opposing sides of the perimeter of the pin 31. The pin 31 and the connecting portion 35 may be separate parts joined together by known means, such as via a weld 36 as shown in the specific embodiment of Figures 2 to 4. As further shown in the specific embodiment of Figures 2 to 4, the first end 32 of the pin 31 may be provided with a stepped shoulder 38 that may act as an abutment for locating the separate connecting portion 35 on the pin 31. Alternatively, the pin 31 and the connecting portion 35 may be fabricated as a unitary element.

The anchor 30 may be configured to be releasably mounted to the first boom section 21. For example, as shown in Figures 2 to 4, the connecting portion 35 may comprise at least one connecting aperture 37 for receiving a fastener 62. As shown in the specific embodiment of Figures 2 to 4, two spaced apart connecting apertures 37 may be provided. As further shown, the two connecting apertures 37 may be located towards opposing ends of the connecting portion 35.

The anchor 30 may be formed from any suitable material. In particular, the anchor 30 may be formed from any type of weldable steel.

The wear pad 40 may extend across a thickness 41 between a coupling surface 42, which may face and be coupled to the first boom section 21, and an opposing sliding surface 43, which may be configured for the second boom section 22 to slide therealong. Hence the wear pad 40 may be coupled to the first boom section 21, and the second boom section 22 may be configured to slide relative to the first boom section 21 along the sliding surface 43 of the wear pad 40, particularly in the sliding direction 80. In the present disclosure the term “coupled” means two parts contacting each other, such as one part resting on another part, and does not connote or imply any form of attachment.

The wear pad 40 may be a plate and the dimensions across the coupling and/or sliding surfaces 42,43 may be substantially greater than the thickness 41. The mounting and/or sliding surfaces 42,43 may be substantially circular and the wear pad 40 may be substantially cylindrical, although other shapes are possible. For example, the mounting and/or sliding surfaces 42,43 may be substantially square or rectangular and the wear pad 40 may be a substantially square or rectangular cuboid.

The coupling surface 42 of the wear pad 40 may be provided with a recess 44 for engaging with the pin 31 of the anchor 30. That is, the recess 44 may be shaped and sized to fit around the pin 31. As shown in the specific embodiment of Figures 2 to 4, the recess 44 may be circular (that is, it may have a circular transverse cross-section), to correspond with the circular shape of the pin 31. A circular pin 31 and recess 44 may be advantageous so that a particular rotational orientation of the wear pad 40 relative to the pin 31 is not required to achieve engagement between the recess 44 and the pin 31. Alternatively, a square or other polygonal shaped pin 31 and recess 44 may be advantageous if a particular rotational orientation of the wear pad 40 relative to the pin 31 is desired. The recess 44 may be a through recess, such that it penetrates through the thickness of the wear pad 40, as illustrated in the specific embodiment shown in Figures 2 to 4. Alternatively, the recess 44 may be a blind recess, such that it does not penetrate through the thickness of the wear pad 40.

The recess 44 may be configured to provide a clearance fit with the pin 31 of the anchor 30, such that the wear pad 40 may be assembled with the anchor 30 (and subsequently disassembled) without the need for force or the use of a tool. In particular, the recess 44 may be shaped and/or sized to provide a clearance fit with the pin 31 of the anchor 30. The term “clearance fit” is used herein to mean that the dimensions of a hole and a shaft are such that a clearance or gap exists between the hole and the shaft when they are assembled; that is to say, the hole is larger than the shaft. Thus the recess 44 may be larger than the pin 31.

One or more edges of the perimeter of the sliding surface 43 of the wear pad 40 may be provided with a chamfer 45. As illustrated in the specific embodiment of Figures 2 to 4, for a circular wear pad 40 the entire perimeter edge of the sliding surface 43 may be provided with a chamfer 45. In the case of a rectangular or other polygonal wear pad 40 (not shown), the two leading edges of the perimeter of the sliding surface 43 of the wear pad 40 (relative to sliding direction 80) may be provided with a chamfer 45. However, any number or all of the edges of the perimeter of the sliding surface 43 of the wear pad 40 may be provided with a chamfer 45. The chamfer 45 may aid in reducing friction by providing a transitional edge to the wear pad 40. The chamfer 45 may also serve as an indicator for monitoring the wear of the wear pad 40. For example, the wear pad 40 may be replaced when the sliding surface 43 of the wear pad 40 has worn away such that the chamfer 45 is no longer visible.

The wear pad 40 may comprise a suitable pad material for wearing away during use. The pad material may have a lower hardness than the boom sections 21,22 (14,15), such that the wear pad sacrificially wears away rather than the boom sections 21,22 (14,15). The pad material may, for example, comprise nylon.

One or more shims 50 may be provided for positioning between the anchor 30 and the wear pad 40. The one or more shims 50 may be identical to each other in all aspects other than thickness. Each shim 50 may be planar, having a length and a width that are substantially greater than its thickness. The shim 50 may have a substantially circular shape, as illustrated. Alternatively, the shim 50 may have a rectangular shape, another polygonal shape, or an irregular shape. The shape and size of the shim 50 may correspond to the shape and size of the wear pad 40, although this is not required

The shim 50 may comprise a shim aperture 51 for engagement with the pin 31 of the anchor 30. That is, the shim aperture 51 may be shaped and sized to fit around the pin 31. As shown in the specific embodiment of Figures 2 to 4, the shim aperture 51 may be circular, to correspond with the circular pin 31. A circular pin 31 and shim aperture 51 may be advantageous so that a particular rotational orientation of the shim 50 relative to the pin 31 is not required to achieve engagement between the shim aperture 51 and the pin 31. Alternatively, a square or other polygonal shaped pin 31 and shim aperture 51 may be advantageous if a particular rotational orientation of the shim 50 relative to the pin 31 is desired. The configuration of the shim aperture 51 in the shim 50 may correspond to the configuration of the recess 44 in the coupling surface 42 of the wear pad 40, such that the shim aperture 51 may align with the wear pad 40 recess 44 when the wear pad 40 is stacked on top of the shim 50.

The shim aperture 51 may be configured to provide a clearance fit with the pin 31 of the anchor 30, such that the shim 50 may be assembled with the anchor 30 (and subsequently disassembled) without the need for force or the use of a tool. In particular, the shim aperture 51 may be shaped and/or sized to provide a clearance fit with the pin 31 of the anchor 30. Thus the shim aperture 51 may be larger than the pin 31.

The one or more shims 50 may be of equal thickness to each other. Alternatively, shims 50 of differing thickness may be provided.

The one or more shims 50 may be made from any suitable material. For example, the one or more shims 50 may be made from ‘shim steel’, which is a cold-rolled carbon steel tempered to a specified hardness range.

A first boom aperture 60 may be provided in the first boom section 21, for receiving the pin 31 of the anchor 30. The first boom aperture 60 may be shaped and sized to fit around the pin 31. As shown in the specific embodiment of Figures 2 to 4, the first boom aperture 60 may be circular, to correspond with the circular shape of the pin 31. The first boom aperture 60 may be configured to provide a clearance fit with the pin 31 of the anchor 30, such that the pin 31 of the anchor 30 may be passed through the first boom aperture 60 (and removed therefrom) without the need for force or the use of a tool. Thus the first boom aperture 60 may be larger than the pin 31. At least one second boom aperture 61 may further be provided in the first boom section 21 corresponding to the at least one connecting aperture 37 of the connecting portion 35 of the anchor 30. The at least one second boom aperture 61 may be threaded.

To assemble the wear pad assembly 20, a technician may measure the wear pad 40 against the gap 23 between the first and second boom sections 21,22. If the wear pad 40 does not substantially fill the gap 23, one or more shims 50 may be stacked below the wear pad 40 to form a wear pad 40 / shim 50 stack 70. It is to be understood that the wear pad 40 / shim 50 stack 70 may comprise the wear pad 40 on its own (with no shims 50) or the wear pad 40 with one or more shims 50 stacked below it. The optimal thickness of the wear pad 40 / shim 50 stack 70 may be such that, when wear pad 40 / shim 50 stack 70 contacts the first boom section 21, a running clearance 53 is present between the sliding surface 43 of the wear pad 40 and the second boom section 22. The running clearance 53 may be set to avoid binding of the first and second boom sections 21,22 due to variation in the first and second boom sections 21,22 along the path of travel (that is, in the sliding direction 80). For example, if a running surface of the first or second boom section 21,22 has a flatness of 2mm, the running clearance 53 may be set to 3mm.

When the desired thickness is achieved, the wear pad 40 / shim 50 stack 70 may be slid along a first side 25 of the first boom section 21, between the first and second boom sections 21,22. The technician may adjust the position of the wear pad 40 / shim 50 stack 70 along the first side 25 of the first boom section 21 to visually align the first boom aperture 60 with the recess 44 in the wear pad 40 and with the shim aperture(s) 51 if shim(s) 50 are present. When the first boom aperture 60, the wear pad 40 recess 44, and any shim apertures 51 are aligned, the second end 33 of the pin 31 of the anchor 30 may be inserted into the first boom aperture 60 from a second side 24 of the first boom section 21 (the second side 24 of the first boom section 21 opposing the first side 25 of the boom section 21) until the connecting portion 35 of the anchor 30 contacts the first boom section 21, causing the pin 31 to extend into any shim apertures 51 and then the wear pad 40 recess 44. A circular pin 31, wear pad 40 recess 44, and shim aperture 51 (if present) may be advantageous so that a particular rotational orientation of the wear pad 40 and shim(s) 50 (if present) relative to the pin 31 is not required. Alternatively, a square or other polygonal shaped pin 31, wear pad 40 recess 44, and shim aperture 51 (if present) may be advantageous if a particular rotational orientation of the wear pad 40 and shim(s) 50 (if present) relative to the pin 31 is desired.

The at least one connecting aperture 37 of the connecting portion 35 of the anchor 30 may be aligned with the at least one second boom aperture 61. The anchor 30 may then be secured to the first boom section 21 by inserting a releasable fastener 62 through the at least one connecting aperture 37 of the connecting portion 35 of the anchor 30 and into the aligned at least one second boom aperture 61. Any suitable releasable fastener may be used. As shown in the specific embodiment of Figures 2 to 4, the fastener 62 may, for example, be a threaded bolt (which may be installed using a washer 63 in the usual manner). This may provide a hard joint that may be resistant to loosening.

Thus the anchor 30 is mounted to the second side 24 of the first boom section 21 and the wear pad 40 and any shims 50 are located on the first side 25 of the first boom section 21. The wear pad 40 and any shims 50 are located between the first boom section 21 and the second boom section 22.

In the assembled wear pad assembly 20 the wear pad 40 and any shims 50 (if present) are not secured or attached to each other. The wear pad 40 and any shims 50 (if present) contact and engage with each other but remain detached. Similarly, the lowermost element of the wear pad 40 / shim 50 stack 70 contacts the first boom section 21. The wear pad 40 and any shims 50 (if present) are not secured or attached to the anchor 30 or to the first boom section 21.

Although the wear pad 40 and any shims 50 (if present) are not attached to each other or to the anchor 30, the wear pad 40 and any shims 50 (if present) are constrained in use in a Z-direction perpendicular to a plane of the first boom section 21 (as indicated in Figure 4) by and between the first and second boom sections 21,22. That is to say, the wear pad 40 and any shims 50 (if present) are held captive in the Z-direction by and between the first and second boom sections 21,22. The pin 31 of the anchor 30 and corresponding wear pad 40 recess 44 and shim aperture(s) 51 (as well as the releasable fasteners 62) constrain the wear pad assembly 20 in X- and Y-directions in the plane of the first boom section 21 (as indicated in Figure 4).

A strengthening plate (not shown) may be provided on the second side 24 of the first boom section 21 to strengthen the first boom section 21 in the region of the boom apertures 60,61, the strengthening plate being provided with corresponding apertures. The strengthening plate may be non-releasably attached to the second side 24 of the first boom section 21, for example by welding.

In use, the thickness 41 of the wear pad 40 reduces due to the sliding contact of the second boom section 22 upon it. The wear pad assembly 20 may periodically be checked to monitor the wear of the wear pad 40. In the present disclosure the term “wear” refers to a reduction in thickness from an original, predetermined and pre-installation thickness 41 due to sacrificial removal of the wear pad 40 material resulting from the sliding contact of the second boom section 22 upon the wear pad 40.

If the clearance between the sliding surface 43 of the installed wear pad 40 and the second boom section 22 increases beyond a predetermined size, the wear pad assembly 20 may be adjusted by adding one or more shims 50 to increase the thickness of the wear pad 40 / shim 50 stack 70. First, the wear pad assembly 20 may be disassembled by removing the fasteners 62, retracting the anchor 30 out of the first boom section 21, and then sliding the wear pad 40 / shim 50 stack 70 out from between the first and second boom sections 21,22. One or more additional shim(s) 50 may be added to the wear pad 40 / shim 50 stack 70 to achieve the optimal thickness. The adjusted wear pad 40 / shim 50 stack 70 may then be reinserted between the first and second boom sections 21,22, the anchor 30 reinserted through the first boom aperture 60 into the shim aperture(s) 51 and the wear pad 40 recess 44, and the connecting portion 35 of the anchor 30 secured by the fastener(s) 62. When the wear pad 40 reaches the end of its usable life, it can be replaced by a new wear pad 40 having the pre-installation thickness.

Industrial Applicability

By virtue of being able to adjust the thickness of the wear pad assembly 20 using one or more shims 50, the wear pad assembly 20 can be tailored to the required thickness to achieve an optimal running clearance 53 between the first and second boom sections 21,22 for a particular telehandler. Furthermore, as the thickness 41 of the wear pad 40 reduces during the life of the wear pad 40, the thickness of the wear pad assembly 20 can be maintained by adding one or more shims 50, thereby prolonging the lifetime of the wear pad assembly 20 and thus reducing cost and waste.

Providing a clearance fit between the wear pad 40 and the anchor 30, and between any shim(s) 50 and the anchor 30 reduces the complexity of assembling and disassembling the wear pad assembly 20. This is turn may reduce servicing time and thus servicing costs.

Locating the fastener(s) 62 outside of the load path may result in a hard joint that is resistant loosening. Again, this may reduce servicing requirements and thus costs.

Claims

1. A wear pad assembly (20) for an extendable boom (12) having a first boom section (21) and a second boom section (22), the wear pad assembly (20) comprising: an anchor (30) for mounting to the first boom section (21), the anchor (30) comprising a pin (31) extending between a first end (32) and a second end (33) along a longitudinal axis (34); and a wear pad (40) having a thickness (41) extending between a coupling surface (42) and an opposing sliding surface (43), the coupling surface (42) comprising a recess (44) for engagement with the pin (31) of the anchor

(30); wherein the recess (44) is configured to provide a clearance fit with the pin

(31).

2. A wear pad assembly (20) according to claim 1, wherein the recess (44) is sized and/or shaped to provide the clearance fit with the pin (31).

3. A wear pad assembly (20) according to claim 1 or claim 2, wherein the pin (31) and the recess (44) are circular.

4. A wear pad assembly (20) according to any one of the preceding claims, wherein an outer surface (39) of the pin (31) is smooth.

5. A wear pad assembly (20) according to any one of the preceding claims, wherein a perimeter of the sliding surface of the wear pad (40) comprises a chamfer (45).

6. A wear pad assembly (20) according to any one of the preceding claims, wherein the anchor (30) further comprises a connecting portion (35) extending outwardly from the first end of the pin (31) in a plane perpendicular to the longitudinal axis (34).

7. A wear pad assembly (20) according to claim 6, wherein the connecting portion (35) comprises at least one connecting aperture (37).

8. A wear pad assembly (20) according to any one of the preceding claims, further comprising one or more shims (50) for positioning between the base plate and the wear pad (40), each shim (50) comprising a shim aperture (51) for engagement with the pin (31) of the anchor (30).

9. A wear pad assembly (20) according to claim 8, wherein the shim aperture (51) is configured to provide a clearance fit with the pin (31) of the anchor (30).

10. A wear pad assembly (20) according to claim 8 or claim 9, wherein the shim aperture (51) is sized and/or shaped to provide a clearance fit with the pin (31) of the anchor (30).

11. A wear pad assembly (20) according to any one of claims 8 to 10, wherein the shim aperture (51) is circular.

12. An extendable boom (12) having a first boom section (21) and a second boom section (22), the extendable boom (12) comprising a wear pad assembly (20) according to any one of the preceding claims.

13. An extendable boom (12) according to claim 12, wherein the wear pad assembly (20) is mounted to the first boom section (21) and the second boom section (22) is configured to slide relative to the first boom section (21) along the sliding surface of the wear pad (40).

14. An extendable boom (12) according to claim 12 or claim

13, wherein: the wear pad (40) is positioned on a first side (25) of the first boom section (21), the wear pad (40) being located between the first boom section (21) and the second boom section (22); and the anchor (30) is mounted to a second opposing side (24) of the first boom section (21), the pin (31) extending through a first boom aperture (60) in the first boom section (21) and into the wear pad (40) recess (44). 15. An extendable boom (12) according to any one of claims

12 to 14, wherein the wear pad (40) is constrained in a direction perpendicular to a plane of the first boom section (21) by the first boom section (21) and the second boom section (22). 16. A telehandler (10) comprising an extendable boom (12) according to any one of claims 12 to 15.