SHOCK ABSORBING TOOL CONNECTION

Abstract

A tool connection (9, 47) for connecting a tool (1) to a tool support (16), the tool connection (9, 47) including at least one radial shock absorber (19, 20) for at least partially absorbing shock imparted by the tool (1) via the tool connection (9, 47). The radial shock absorber (19, 20) has shock absorbing assemblies (22, 23), each including at least two elastic layers (24) and at least one inelastic layer (25) interleaved between the elastic layers (24). The layers (24, 25) of the shock absorbing assemblies (22, 23) are radially distributed with respect to a connection axis (10, 11) passing through the tool connection (9, 47), the shock absorbing elastic layers (24) including an inner elastic layer (24) and an outer elastic layer (24) radially proximal and distal respectively to the connection axis (10, 11).

Claims

1. A tool connection for connecting a tool to a tool support, the tool connection including at least one radial shock absorber for at least partially absorbing shock imparted by the tool via the tool connection, the radial shock absorber having at least one shock absorbing assembly including: at least two elastic layers; at least one inelastic layer interleaved between said elastic layers, wherein the layers of the shock absorbing assembly are radially distributed with respect to a connection axis passing through the tool connection, the shock absorbing assembly elastic layers including an inner elastic layer and an outer elastic layer radially proximal and distal respectively to the connection axis; wherein the inelastic and elastic layers are un-bonded, permitting relative movement therebetween.

2. (canceled)

3. (canceled)

4. The tool connection as claimed in claim 1, wherein the at least one shock absorbing assembly is radially distributed between an inner inelastic layer and an outer inelastic layer, the outer inelastic layer including the inner walls of a housing at least partially encircling the connection axis.

5. (canceled)

6. (canceled)

7. The tool connection as claimed in claim 4, wherein movement of the at least one shock absorbing assembly about the connection axis is restricted by the interior surface of the housing.

8. (canceled)

9. (canceled)

10. (canceled)

11. The tool connection as claimed in claim 1, wherein the at least one shock absorbing assembly includes at least three elastic layers and at least two inelastic layers, the inelastic layers interleaved between adjacent pairs of elastic layers.

12. The tool connection as claimed in claim 1, wherein the at least one shock absorbing assembly only partially encircles the connection axis.

13. The tool connection as claimed in claim 1, wherein the shock absorber includes at least one deformation void for the elastic layers to deflect or deform into.

14. The tool connection as claimed in claim 13, wherein the deformation void is provided between inelastic layers adjacent a periphery of a said elastic layer between the inelastic layers.

15. The tool connection as claimed in claim 1, wherein the shock absorber includes at least two of said shock absorbing assemblies, each shock absorbing assembly including: at least two elastic layers; at least one inelastic layer interleaved between the two elastic layers.

16. (canceled)

17. (canceled)

18. The tool connection as claimed in claim 15, wherein the at least two shock absorbing assemblies collectively only partially encircle the connection axis.

19. The tool connection as claimed in claim 18, wherein a deformation void is formed in a gap about the connection axis between the at least two shock absorbing assemblies.

20. The tool connection as claimed in claim 1, wherein the elastic layers are substantially coterminous perpendicular to a direction of principal load.

21. The tool connection as claimed in claim 1, wherein alignment of the at least one shock absorbing assembly is maintained by at least one locator, positioned between the connection axis and the at least one shock absorbing assembly.

22. (canceled)

23. The tool connection as claimed in claim 21, wherein the locator includes a shaped locator bearing located about the connection axis, the locator bearing including an aperture for a shaft to pass therethrough which is capable of rotating about the connection axis relative to the locator bearing.

24. The tool connection as claimed in claim 21, wherein the locator is non-circular in cross-section perpendicular to the connection axis.

25. The tool connection as claimed in claim 24, wherein in cross-section perpendicular to the connection axis, the locator is shaped as one of a: polygon; truncated ellipse; regular hexagon; irregular hexagon with a long axis and a short axis intersecting at the connection axis.

26. (canceled)

27. (canceled)

28. (canceled)

29. The tool connection as claimed in claim 1, wherein relative alignment of the shock absorbing assembly layers is maintained by nesting the shock absorbing assembly layers.

30. (canceled)

31. The tool connection as claimed in claim 1, wherein location features are provided in or on the shock absorbing assembly layers to limit relative movement of adjacent layers wherein the location features are provided as mating, interlocking or meshing features on adjacent layers.

32. (canceled)

33. (canceled)

34. (canceled)

35. (canceled)

36. (canceled)

37. The tool connection as claimed in claim 1, wherein the tool is an impact hammer formed with a moveable mass in a hammer housing and a striker pin, and the tool support is an operating arm of a carrier.

38. (canceled)

39. (canceled)

40. (canceled)

41. (canceled)

42. (canceled)

43. The tool connection as claimed in claim 1, wherein a said shock absorbing assembly includes multiple inelastic layers interleaved between corresponding pairs of elastic layers.

44. A radial shock absorber for use in a tool connection, the radial shock absorber having at least one shock absorbing assembly radially distributed between two inelastic layers, the shock absorbing assembly including: at least two elastic layers; at least one inelastic layer interleaved between said elastic layers, wherein the layers of the shock absorbing assembly are radially distributed with respect to a connection axis passing through the tool connection, the shock absorbing assembly elastic layers including an inner elastic layer and an outer elastic layer radially proximal and distal respectively to the connection axis; wherein the inelastic and elastic layers are un-bonded, permitting relative movement therebetween.

45. (canceled)

46. (canceled)

47. An impact hammer including: a movable mass capable of linear reciprocating movement for impact along an impact axis, an elongated striker pin received within the hammer having a longitudinal axis substantially parallel or coaxial with said impact axis, said striker pin having two opposed ends with one end projecting from the hammer to form an operative tool head; a tool connection, hereinafter primary tool connection adapted for attaching the hammer to a distal end of an operating arm attached to the carrier; wherein the impact hammer includes at least one shock absorber at the primary tool connection, for at least partially absorbing shock imparted by the hammer via the tool connection, the radial shock absorber having at least one shock absorbing assembly including: at least two elastic layers; at least one inelastic layer interleaved between said elastic layers, wherein the layers of the shock absorbing assembly are radially distributed with respect to a connection axis passing through the tool connection, the shock absorbing assembly elastic layers including an inner elastic layer and an outer elastic layer radially proximal and distal respectively to the connection axis.

48. (canceled)

49. (canceled)

50. (canceled)

51. (canceled)

52. (canceled)

53. (canceled)

Description

BRIEF DESCRIPTION OF DRAWINGS

[0192] Further aspects and advantages of the present invention will become apparent from the following description which is given by way of example only and with reference to the accompanying drawings in which:

[0193] FIG. 1 shows a side elevation of a hammer attached to an carrier via an articulated control linkage;

[0194] FIG. 2 shows a side elevation of a preferred embodiment of the present invention of an articulated control linkage connecting a hammer to a carrier arm;

[0195] FIG. 3a) shows a plan view of the first link of the articulated control linkage;

[0196] FIG. 3b) shows a side view of the first link of the articulated control linkage;

[0197] FIG. 4a shows a partial horizontal cross-section of a secondary tool connection including a shock absorber in the first link of the articulated control linkage;

[0198] FIG. 4b) shows a partial vertical cross-section of the tool connection of FIG. 4a;

[0199] FIG. 5) shows a vertical cross-section of an alternative embodiment of a tool connection;

[0200] FIG. 6a) shows a partial plan view of the primary tool connection of the hammer to the carrier;

[0201] FIG. 6b) shows a side view of the primary tool connection of the hammer to the carrier;

[0202] FIG. 7a shows a partial horizontal cross-section of a shock absorber at the primary tool connection;

[0203] FIG. 7b) shows a partial vertical cross-section of the tool connection of FIG. 6b;

[0204] FIG. 8) shows a perspective view of a hammer incorporating the shock absorbers of FIGS. 4 and 7, the hammer making a strike on an inclined rock surface;

[0205] FIG. 9 shows a side view of the hammer of the previous figures in a levering and raking operation;

[0206] FIG. 10a shows a side view of the hammer of the previous figures making a strike on an inclined rock surface; and

[0207] FIG. 10b shows a side view of the hammer of the previous figures making a strike on a rock surface inclined in the opposite direction to that shown in FIG. 10a.

[0208] FIG. 11a shows a side view of an inelastic layer of a shock absorbing assembly;

[0209] FIG. 11b shows the inelastic layer of FIG. 11a in a bent state ready for assembly;

[0210] FIG. 11c shows another inelastic layer of a shock absorbing assembly.

[0211] FIG. 12 shows the inelastic layer of FIG. 11b.

BEST MODES FOR CARRYING OUT THE INVENTION

[0212]

TABLE-US-00001 1 Hammer 2 Carrier 3 Articulated control linkage 4 first link 5 second link 6 striker pin 7 striker pin head 8 lift drive 9 primary tool connection 10 primary connection axis 11 secondary connection axis 12 tertiary connection axis 13 quaternary connection axis 14 impact axis 15 hydraulic ram 16 carrier arm 17 first link shaft 18 work surface 19 linkage shock absorbers 20 mounting shock absorbers 21 primary pivot point shaft 22 first shock absorbing assembly 23 second shock absorbing assembly 24 elastic layers 25 inelastic layers 26 housing interior surface at secondary tool connection 27 housing interior surface at primary tool connection 28 first locator bearing 29 second locator bearing 30 first coupling 31 second coupling 32 secondary load direction at secondary axis 33 end caps 34 end cap bolts 35 hammer lugs 36 truncated oval shock absorber 37 third locator bearing 38 third coupling housing interior surface 39 principal load direction at primary pivot axis 40 hammer mounting 41 deformation space 42 principal load direction at secondary axis 43 Inelastic layer location projections 44 Inelastic layer bend 45 Inelastic layer periphery 46 secondary load direction at primary connection axis 47 secondary tool connection 48 tertiary tool connection 49 quaternary tool connection 50 housing at secondary tool connection 51 housing at primary tool connection 52 elastic layer location apertures 53 elastic layer periphery

[0213] FIGS. 1-4 and 5-10 show a first embodiment of the present invention in the form of a tool connection (9, 47) for connecting a tool in the form of impact hammer (1) with tool support in the form of an operating arm (16) of a carrier (2).

[0214] The impact hammer (1) is attached to the carrier arm (16) via mounting (40) and an articulated control linkage (3). The articulated control linkage includes first (4) and second (5) links. The articulated control linkage (3) enables the hammer (1) to be used for levering and raking. It will be understood both the hammer (1) and carrier (2) shown are used for exemplary purposes only and the invention is not limited to same.

[0215] The present invention is primarily adapted for use with impact hammers (1) such as gravity drop hammers, powered drop hammers, hydraulic hammers, pneumatic hammers, vacuum-assisted hammers and the like. Although specific implementations of such designs differ, each generally includes some form of movable mass located within the hammer housing and capable of linear reciprocating movement along an impact axis (14).

[0216] The hammer (1) includes an elongate striker pin (6) having two opposed ends and a longitudinal axis coaxial with the impact axis (14). A movable mass (not shown) within the hammer (1) is lifted by drive (8) and then dropped onto the striker pin (6). One end of the striker pin (6) projects from the hammer (1) to form an operative tool head (7) which contacts rock to be broken while the other end receives the movable mass impact. The striker pin (6) is also used during levering and/or raking operations.

[0217] The striker pin (6) is located at the lower end of the hammer (1). Such a configuration is described in greater detail in U.S. Pat. No. 7,980,240 by Robsonincorporated herein by reference.

[0218] In alternative embodiments, the movable mass and striker pin may be formed as a single element which is locked from movement during levering and raking with one end of the pin projecting from the hammer to form the tool head. It will be appreciated however that in such embodiments (not shown), a hammer tool lock (as described in U.S. Pat. No. 7,407,017 by Robsonincorporated herein by reference) is beneficial in order to fix the mass and pin relative to the hammer housing during raking and levering operations.

[0219] Thus, depending on the construction of the hammer (1), the tool may be formed as a moveable weight and locked from movement during levering and raking; or, the formed as a separate element (i.e. the striker pin (6)) distinct from the movable mass.

[0220] The hammer (1) is attached at a primary tool connection (9) at a distal end of the operating arm (16) of the carrier (2) enabling relative pivotal movement about a primary connection axis (10) orthogonal to the impact axis (14).

[0221] The articulated control linkage (3) provides a means for effecting pivotal movement of the hammer (1) about the primary axis (10) in response to movement from a drive in the form of a hydraulic ram (15) attached to the operating arm (16).

[0222] The first link (4) is pivotally attached to the hammer (1) at a first end to form a secondary tool connection (47) enabling relative rotation of the hammer (1) and first link (4) about a secondary connection axis (11) parallel to the primary axis (10). The first link (4) is also pivotally attached at a second end to the second link (5) at a tertiary tool connection (48) enabling relative rotation of the first (4) and second (5) links about a tertiary connection axis (12).

[0223] The second link (5) is pivotally attached at a first end to form a quaternary tool connection (49) enabling relative rotation about a quaternary pivot point axis (13) with respect to the carrier arm (16), the quaternary connection axis (13) being parallel to the secondary (11) and tertiary (12) axes, the second link (5) also being pivotally attached at a second end to the second end of the first link (4) at the tertiary connection axis (12) and to the drive (15), coaxial with the tertiary pivot point axis (12). The first link (4) is comprised of a pair of arms (4) passing either side of the hammer (1) as shown in FIG. 3a). Encircling the hammer (1) in this manner provides a robust configuration capable of withstanding the high loads imposed during levering and raking operations whilst also reducing the tipping moment of the carrier (2). A shaft (17) extending along the secondary connection axis (11) between the arms (4) provides further structural integrity to the control linkages. It will be appreciated that in an alternative embodiment (not shown), a pair of the drives (15), on opposed lateral sides of the arm (16), may be used to act on the individual arms (4) on opposing sides of the hammer (1).

[0224] Thus the primary tool connection axis (10) is located laterally to the impact axis (14) between the opposed distal ends of the striker pin (6) and the primary, tertiary and quaternary pivot axes (10, 12, and 13) are all located on an opposing side of the impact axis (14) to the secondary connection axis (11). The primary tool connection (9) is located in a region between the striker pin head (7) and a line subtended orthogonally from the impact axis (14) from the end of the striker pin (6) distal to the tool head (7).

[0225] This enables significantly higher levering forces/torque to be applied by the striker pin (6) by increasing the separation between the primary connection axis (10) and the secondary connection axis (11) whilst minimizing the distance from the striker pin tip (7) to the primary connection axis (10). Moreover, the geometry of the control linkage (3) enables a higher degree of levering power to be applied evenly throughout the full stroke of the drive (7) pivoting the hammer (1) about the primary axis (10).

[0226] In operation; extension or retraction of the hydraulic ram (7) acts to pivot the first and second links (4, 5) in opposing directions about the secondary connection axis (11) and quaternary connection axis (13) respectively. Both links also pivot in opposite directions about the tertiary connection axis (12). As the ram (15) extends, the first and second links (4, 5) are splayed apart at the tertiary connection axis (12) and thus the angle subtended therebetween is increased whilst the secondary connection axis (11) is pushed out away from the carrier arm (16). The force from the drive (15) acting along the first link (4) applies a torque to the hammer (1) at the secondary connection axis (11), causing the hammer (1) to pivot about the primary connection axis (10) with the tip of the striker pin (6) moving towards the carrier.

[0227] Thus, the hammer (1) may not only be operated to break rock, concrete or other material by percussion impacts of the striker pin (6) along the impact axis (14), but also to rake or lever material by a pivoting and locking action about the primary connection axis (10).

[0228] When working in breaking applications the hammer (1) is used to deliver impacts to a rock, steel or other work surface to be broken. Minimising the distance between the striker tip (7) to the primary connection axis (10) also optimises the raking ability of the hammer (1) and carrier arm (16) assembly in addition to minimising the shock loading on the carrier (2) during percussion impacts on the striker pin (6).

[0229] In ideal conditions, the striker pin (6) impacts a surface aligned perpendicular to the impact axis (14) so that all the force is transmitted to the surface (18) and any shock travels along the impact axis (14), constraining the majority of any shock within the hammer (1). However, if the surface (18) is not perpendicular to the impact axis (14), a portion of the impact force is diverted laterally and/or rotationally with respect to the impact axis (14). The carrier arm (16) is held stationary by the carrier (2) and thus the diverted impact forces try to move the hammer (1) with respect to the carrier arm (16), thereby causing significant shock and/or torsion to the hammer (1) and connections (3, 40).

[0230] Moreover, in levering and raking applications there are very high loadings on the tool connections (9, 47, 48, 49) and linkages (4, 5) of the articulated control linkage (3).

[0231] The forces involved in operating the hammer (1) are such that inclined impacts as described above or levering/raking operations can result in reactionary forces that damage the hammer (1), linkage (3), mounting (40) and/or associated tool connections to the carrier arm (16). The potentially damaging forces are typically high-magnitude, short time period forces, i.e. shocks. The shock can be sufficient to crack the steel welds in the mounting (40), linkage (3) or carrier arm (16). Shock absorbers (19, 20) are thus provided to shock isolate the carrier arm (16) from the hammer (1) and mitigate the potential for damage. There are inherent space constraints in these tool connections and thus prior art shock absorbers, (necessarily very large) would not be suitable.

[0232] FIG. 2 shows shock absorbers (19, 20) incorporated into two of the tool connections (9, 47). The tool connections (9, 47) each include a shaft (21, 17) with a longitudinal axis (10, 11) forming the corresponding connection axis (10, 11).

[0233] FIGS. 3-4 show more clearly the shock absorber (19) of the secondary tool connection (47) at the coupling (30) of the hammer (1) to the arms of the first link (4).

[0234] The shock absorber (19) includes two shock absorbing assemblies (22, 23), with each assembly including radially distributed layers (24, 25). The embodiment shown includes three elastic layers (24) with two inelastic layers (25) interleaved therebetween. Each shock absorbing assembly (22, 23) is radially distributed two corresponding inelastic layers provided in the form of steel locator bearings (28) and housing interior surfaces (26), also constructed from steel. The steel locator bearings (28) thus provide an inner inelastic layer of the shock absorber while the housing interior surfaces (26) provide the outer inelastic layer of the shock absorber (19). The housing inner surfaces (26) form part of a housing (50) at the end of the corresponding couplings (30). The housing (50) encases and encloses the shock absorber assemblies (22, 23).

[0235] The locator bearings (28) also form corresponding locators for maintaining alignment of the shock absorbing assemblies (22, 23).

[0236] The layers (24, 25, 26, 28) of the shock absorber (19) are un-bonded and radially stacked with respect to the corresponding connection axis (11), with an inner layer (28) located at a smaller radial distance to the corresponding connection axis (11) than an outer layer (26).

[0237] The shock absorbers (19) are each formed from an un-bonded stack of interleaved elastic (24) and inelastic (25) layers such that the elastic layers (24) will deform and spread along the abutting surfaces of the adjacent inelastic layers (25, 26, 28) under load. The energy of the load is absorbed, not only in deformation of the elastic layers (24) but also in the friction resulting from the relative movement between the elastic (24) and inelastic layers (25, 26, 28). Such a multi-layered un-bonded shock absorber (19) is capable of absorbing far greater loads than a unitary shock absorber of same volume, or bonded multi-layer shock absorber.

[0238] The shock absorbing assemblies (22, 23) each only extend about a portion of the connection axis (11) to ensure that there are deformation voids (41) to accommodate deformation of the elastic layers (24). Thus, the elastic layers (24) are constrained only by the adjacent inelastic layers (25, 26, 28) in directions perpendicular to the plane of the elastic layers (24).

[0239] The shock absorbing assemblies (22, 23) are positioned diametrically opposite each other about the connection axis (11) and aligned to absorb the load in the principal or primary direction. In typical applications, this principal load direction (42) is aligned along the first link arms (4), particularly during levering or raking using the hammer (1). Alignment of the shock absorbing assemblies (22, 23) is thus important to retain maximum effectiveness. The steel locator bearings (28) and coupling interior surfaces (26) are therefore shaped so as to limit movement of the shock absorbing assemblies (22, 23) about the connection axis (11) relative to the housing interior surface (26).

[0240] The embodiment of the shock absorbers (19) shown in FIGS. 1-4 has a locator bearing (28) with an irregular hexagonal shape in a cross-section perpendicular to the connection axis (11). Similarly, the housing interior surface (26) of the coupling (30) also has a hexagon shaped cross-section, though regular. The layers (24, 25) of each shock absorbing assembly (22, 23) are correspondingly shaped to match those of the locator bearing (2) and housing interior surface (26).

[0241] Thus, the shock absorbing assemblies (22, 23) are constrained in their location (relative to the first link (4) by the locator (28), and coupling interior surface (26). The shaped locator bearing (28) and housing inner surface (26) provide constrictions at each change in angle, thereby opposing any rotation of the shock absorbing assemblies (22, 23). The shock absorber (19) is thus shaped to prevent rotation and thereby maintain the orientation relative to the principal load direction (42) at the secondary connection axis (11).

[0242] In contrast, using a circular cross-section arrangement with concentric layers would likely result in the assemblies (22, 23) moving about the connection axis (11) and becoming misaligned, thus requiring some other form of locating mechanism.

[0243] It is also important to limit the relative movement of layers (24, 25) about the connection axis (11) so they do not become misaligned. Thus, the inelastic layers (25) include location features provided in the form of steel projections (43) (shown in FIG. 11a, 11b, 11c) welded to the inelastic layers (25). When the shock absorbing assemblies (22, 23) are assembled, the projections (43) are inserted inside corresponding location features (provided as apertures (52)) in the adjacent elastic layers (24). The projections (43) thus limit the relative movement of the layers (24, 25) and maintain alignment.

[0244] Similar location features may also be provided on the housing interior surfaces (26, 27) and/or the shaft (17, 21).

[0245] It is important that the elastic layers (24) interleaved between inelastic layers (25) are capable of deforming under compression and thus the projections only project from the inelastic layer (25) to extend partially through the thickness of the elastic layers (24) when assembled.

[0246] The location projections (43) may however cause damage to the elastic layers (24) if there is sufficient relative movement with adjacent inelastic layers (25) such that, for example, a projection (43) pushes against the side of a corresponding aperture.

[0247] The portions of the elastic layers (24) toward their periphery generally move a greater distance under compression than portions closer to the center and therefore have the potential to provide the greatest degree of relative movement between layers (24, 25). Thus, it is preferable to locate the location projections (43) on portions of the layers (25) that experience the least or only small degrees of relative movement with adjacent layers.

[0248] Thus, the projections (43) are located closer to the bend line (44) of the inelastic layers (25) than to the periphery (45). It should be appreciated that the coupling (30) may be provided as a separate component to the link (4), e.g. a separate joint, bearing or other mechanism.

[0249] The potential loading applied in other directions to the principal load direction (42) noted above is generally much less than the principal load but may still be significant. The shape of the locator bearing (28) and housing interior surface (26) ensures that if the locator bearing (28) experiences a load with a component in a direction perpendicular (hereinafter secondary load direction (32)) to the principal load direction (42) it will still compress the shock absorbing assemblies (22, 23) and cause relative movement of the layers (24, 25) therein. The shock absorber (19) is thus also capable of mitigating shock with a component in the secondary load direction (32).

[0250] Moreover, torsional loads about the link (4) are also mitigated by the shock absorber (19). It can thus be seen that although the shock absorber (19) does not fully encircle the connection axis (11) it is still capable of mitigating shock in any direction to varying levels.

[0251] The shaft (17) of the first link (4) passes through an aperture in the locator bearing (28) and is free to rotate within the locator bearing (28) about the secondary connection axis (11). The shock absorbing assemblies (22, 23) are axially constrained about the shaft (17) by the connecting lugs (35) of the hammer (1) and end caps (33) which are bolted to shaft (17) via bolts (34). Thus, the shock absorbing assemblies (22, 23) cannot fall out of the couplings (30, 31).

[0252] The housing interior surface (26) is formed from cast steel which typically has a rough surface unless machined smooth. This rough surface can damage the adjacent elastic layer (24). It may thus be necessary to machine the coupling interior surface (26) when replacing worn shock absorbers (19). This requirement can result in significant downtime in operation, particularly, if the machining must be completed offsite. Thus, thin, low-friction linings (not shown but being of the same shape as the interior surface (26)) of steel or any smooth material, may also be provided between the shock absorber outer elastic layer (24) and the coupling interior surfaces (26). The lining can be replaced when a shock absorbing assembly (19) is replaced, thus avoiding the need to smooth the coupling interior surfaces (26).

[0253] FIG. 5 shows the tool connection (47) with a shock absorber (36) according to another embodiment of the present invention and operates in a generally similar manner to the shock absorbers (19) of FIGS. 3-4. However, the shock absorber (36) differs in that its locator bearing (37) and coupling interior surface (38) have a cross-sectional shape of a truncated oval rather than the hexagonal version of the aforementioned shock absorber (19). The shock absorbing assembly layers (24, 25) are thus correspondingly shaped as arcuate layers to match the curvature of the locator bearing (37) and coupling interior surface (38).

[0254] FIGS. 6 and 7 shows the primary tool connection (9) of the hammer (1) to the carrier arm (16). The shock absorbers (20) (only one shown) in the primary tool connection (9) are located in housings (51) at the couplings (31) on either side of the carrier arm (16), the coupling (31) pivotally attached to a shaft (21) passing through carrier arm (16).

[0255] The shock absorbers (20) at the primary tool connection (9) as shown in FIGS. 6 and 7 are generally similar and operate equivalently to that of the shock absorbers (19) at the secondary tool connection (47) of FIGS. 3-5 but differ in that the locator bearing (29) has a regular hexagonal cross-section and the housing interior surface (27) has an irregular hexagonal cross-section. The principal load direction (39) at this primary tool connection (9) is generally aligned along the hammer mounting (40).

[0256] An example of a strike on an inclined work surface (18) is shown in FIG. 8 and shows the hammer (1) making a strike on an inclined work surface (18) orientated at 45 degrees to the impact axis (14). The striker pin (6) and hammer (1) are deflected sideways with a force vector (A) resulting in a linear component generally in the direction (A) along with a torque component (B) about an axis perpendicular to the impact axis (14). The torque component (B) results in loads on the tool connections (9, 47) in both the secondary load directions (32, 46) and principal load directions (42, 39).

[0257] The hammer (1) is constrained by the tool connection (9) to the carrier arm (16) and so the linear component (A) results in a torque component (C) about an axis generally located at the connection to the carrier arm (16) and approximately parallel to the impact axis (14). This torque component (C) has components (E) and (F) along the principal load direction (42) at linkage shock absorbers (19) and with components (D) and (G) along principal load direction (39) at shock absorbers (20).

[0258] In the example of FIG. 8 the linkage shock absorbers (19) at the secondary connection axis (11) work to mitigate the shock components (B), (E) and (F) while the hammer mounting shock absorbers (20) at the primary connection axis (10) reduce the shock components (B), (D) and (G). It will be appreciated that this is a simplistic example only as the work surface (18) in actual operation will be rarely inclined at such a constant angle. The actual force components will thus vary depending on the inclination and direction of the work surface (18), the impact force and orientation of the hammer (1). However, the shock absorbers (19, 20) as described ensure that they will absorb shock no matter what direction the impact force components take and thus reduce the shock transmitted to the carrier arm (16) and thus carrier (2).

[0259] FIG. 9 shows an example of the loads on the articulated control linkage (3) when the hammer (1) is used in raking or levering operations.

[0260] FIG. 9 shows the hammer (1) after an impact where the striker pin (6) has cracked a rock (18) with the striker pin (6) in the crack. The rock (18) can be levered apart by extending or retracting hydraulic ram (15) to respectively spread or close linkages (4, 5) to pivot the hammer (1) and striker pin (6) about the primary connection axis (10) (as indicated by arrow (AL) thus levering the rock (18) apart. The torque (AL) and opposing resistance from the rock (18) results in linear components: [0261] (H) along the first link (4), and [0262] (I) along the hammer mounting (40).

[0263] In raking operations, the carrier arm (16) or carrier (2) is manoeuvred to pull or push the striker pin (6) generally in the directions indicated by double arrow (AR). Raking thus also results in load components along (H) and (I).

[0264] In both levering and raking applications the linkage shock absorbers (19) at the secondary connection axis (19) at least partially absorb any shock or vibration component (H) while the hammer mounting shock absorbers (20) at the primary connection axis (10) least partially absorbs any shock component (I).

[0265] FIG. 10 shows two examples of the hammer (1) making strikes on rocks with inclined surfaces (18). FIG. 10a shows a rock with surface (18) inclined with respect to the impact axis (14) downwardly in a direction directly away from the carrier (2). FIG. 10b shows the converse arrangement with surface (18) inclined with respect to the impact axis (14) downwardly in a direction directly toward the carrier (2).

[0266] In the example of FIG. 10a the striker pin (6) is deflected with vector (A1) and the hammer experiences shock in directions (J1) and (K1). The linkage shock absorbers (19) at the thus absorb part of the (J1) component while the hammer mounting shock absorbers (20) absorb part of the (K1) component. The example of FIG. 10b has a principal load vector (A2) in the opposite direction to that shown in FIG. 10a and thus components (J2) and (K2) are opposite to that shown in FIG. 10a.

[0267] The shock absorbers (19, 20) as described ensure that they will absorb shock no matter what direction the impact force components (J, K) take and thus reduce the shock transmitted to the carrier (2).

[0268] FIGS. 11 and 12 show elastic and inelastic layers with mating location features (43, 52) therein.

[0269] FIG. 11a shows an enlarged view of an inelastic layer (25) before being bent ready for assembly. Location projections (43) are welded to one side of the steel inelastic layer (25) and will mate with corresponding recesses or apertures (52) in an adjacent elastic layer (24) that when assembled will be to the left (with respect to drawing) of the inelastic layer (25). FIG. 11b shows the same inelastic layer (25) when bent about bend (44) that extends parallel with the corresponding connection axis (10, 11) when assembled.

[0270] FIG. 12 shows the inelastic layer (25) and elastic layer (24), the inelastic layer (25) having the location projections (43) thereon and the elastic layer (24) having corresponding recesses (52). The recesses and (52) and projections (43) are proximal to the bend lines (44) relative to the corresponding periphery (53, 45).

[0271] The radially inner-most inelastic layer (25) of each shock absorbing assembly (22, 23) holds the inner-most elastic layer (24) in relative alignment.

[0272] The outer-most inelastic layer (25) is shown enlarged in FIG. 11c and has location projections (43) on both sides, mating with recesses in elastic layers (24) on either side.

[0273] The movement of each elastic layer (24) is thus limited by the projections (43) of an adjacent inelastic layer (25), ensuring the elastic layers maintain alignment.

[0274] Each assembly (22, 23) is thus formed from sets of connected layers (connected by projections (43)) with an: [0275] inner-most pair of an inelastic layer (25) and an elastic layer (24), and [0276] outer-most triple comprised of an inelastic layer (25) interleaved between two elastic layers (24).

[0277] It should be appreciated that alternatively the inner-most inelastic layer (25) could have projections (43) on both sides mating with recesses in elastic layers (24) on either side, thus forming the triple set.

[0278] This configuration, ensures that each set of layers, as pairs or a triple, is still free to move relative to an adjacent set(s) thus ensuring that the shock absorbers (19, 20) can accommodate loads with a component along the secondary load directions (32, 46).

[0279] The drawings of the shock absorbing assemblies (22, 23) are simplified for clarity and show only five layers in total, three elastic (24) and two inelastic (25) layers. However, more layers are typically included, with the number of elastic layers (24) equal to the number of inelastic layers (25) plus one.

[0280] It should be understood that there exist implementations of other variations and modifications of the invention and its various aspects, as may be readily apparent to those of ordinary skill in the art, and that the invention is not limited by specific embodiments described herein. Features and embodiments described above may be combined with and without each other. It is therefore contemplated to cover any and all modifications, variations, combinations or equivalents that fall within the scope of the basic underlying principals disclosed and claimed herein.