A LOCKING PIN SYSTEM

FIELD OF THE INVENTION

The invention relates to a locking pin system. In particular, although not exclusively, the invention relates to a locking pin system for shackles and the like in earthworking equipment.

BACKGROUND TO THE INVENTION Releasably engageable locking pins are employed in a variety of engineering applications and in relation to earthworking equipment. Such locking pins may be utilized in rigid interconnection of boom elements of dragline excavators, pivotal connection of a boom to a chassis or frame, shackle pins for chains and wire ropes, dragline rigging systems and the like including spreader bars, equalizers and other dragline jewellery components.

In nearly all engineering applications and, in particular, in the field of earthworking equipment, it is necessary to secure a locking pin with a positive lock mechanism so that it does not become detached during operation. At the same time, there is a requirement that such locking pins be quickly and easily disconnected when required for maintenance and repair purposes. Typically, a releasable locking pin comprises a pin which engages in aligned apertures in spaced cheeks or lugs associated with a coupling member such as a shackle, and an enlarged head on one end of the pin engages on an outer surface of one of the cheeks or lugs. The free end of the pin often extends outwardly from an outer surface of the

opposite cheek or lug and a lock mechanism may be secured to the free end of the pin to prevent its withdrawal from the spaced cheeks or lugs of the coupling member.

An example locking pin is described in the Applicant's Australian Patent Application 2005229718 entitled "Improvements in locking pins". The locking pin of this prior art document has a shaft with an integral head portion and coupling spigot at respective opposite ends of the shaft, which, together with a socketed retaining member, retain the shaft of the locking pin in the shackle. Other example prior art lock mechanisms for locking pins are discussed in United States Patents 5,865,557, 5,433,547, 4,476,673, 4,914,903, 4,221 ,252, 4,145,874, 3,811 ,270, Re. 34046, and Australian Patent No. 727916.

A shackle pin may, for example, be locked in place by a lock mechanism in the form of a keeper pin or locking pin. The locking pin extends at least partially through an eye of one of the lugs of the shackle to engage a transverse notch cut into the part of the shaft of the shackle pin received in the eye. The locking pin positively locks the shackle pin in place. The locking pin will itself also have a shaft, a head, and a lock mechanism. A shackle employing a locking pin will generally have aligned opposite recesses in one of the lugs, in which the head portion and lock mechanism of the locking pin, respectively, are located.

During normal operating conditions, a shackle pin in the earthworking environment is frequently loaded with shock loads. Where a locking pin is employed as the lock mechanism for the shackle pin, shock

energy from the shock loads is transferred to the locking pin. The transferred shock energy abruptly displaces the locking pin in the shackle (referred to as "jumping" in the art). This shock energy is transferred from the shaft of the locking pin through to its head and lock mechanism. This can cause a bending moment on the locking pin when the locking pin jumps, which can lead to bending of the locking pin. An obvious disadvantage of bending the locking pin is that it becomes difficult to remove from the shackle during maintenance and the locking pin may have to be discarded. A further disadvantage of the prior art locking pins used in shackles is that movement of the head and retaining member of the locking pin in the recesses of the shackle allows for ingress of fine particles of earth ("fines") into the working mechanisms of the shackle and the locking pin. The fines tend to pack around the shaft of the locking pin and becomes so tightly packed between the locking pin and the shackle that the locking pin becomes difficult to dislodge (hereinafter referred to as "seizing"). A seized locking pin has to be dislodged by methods which are necessarily more forceful than had the locking pin not seized, which is a workplace health and safety hazard. Accordingly, it is an aim of the present invention to overcome or ameliorate one or more of the disadvantages associated with prior art locking pin systems and otherwise provide consumers with a greater choice of locking pin systems.

DISCLOSURE OF THE INVENTION According to the invention there is provided a locking pin system for

a coupling member, the locking pin system including:- a pin comprising a shaft which has at least one end captively beatable in a locating aperture of the coupling member, and at least one barrier beatable adjacent the locating aperture to close off the locating aperture, which barrier includes a lock formation operable to engage a locating formation associated with said coupling member to releasably lock the barrier in position, thereby preventing the shaft from being ejected through the locating aperture.

Advantageously, the barrier is isolated from transverse displacement of the shaft.

Preferably, the locking pin system includes a sleeve having the locating formation in a wall thereof, the sleeve being beatable in a recess in the coupling member, which recess is open to the locating aperture, and the barrier being beatable in a bore of the sleeve.

Alternatively, the locating formation is integrally formed with the coupling member. More specifically, the locating formation may be formed in a wall defining the recess.

Preferably, the locating formation is a shoulder projection.

Preferably, the lock formation includes a resiliently displaceable barb, which barb engages the shoulder projection to prevent displacement of the barrier away from the locating aperture. Preferably, the lock formation includes an actuating tab connected to the barb, which actuating tab is operable to, when actuated, resiliently displace the barb to a position to release the barb from locking engagement with the shoulder projection.

Preferably, the barrier comprises the lock formation and a body of resiliency deformable material.

Preferably, at least part of the lock formation is embedded in the body. Preferably, the coupling member is a shackle and the shaft of the locking pin system locks a shackle pin of the shackle in place. Preferably, the locking pin system comprises: the shaft having its ends capitvely locatable in opposite aligned locating apertures in a lug of the shackle, two barriers, each locatable adjacent a different one of the locating apertures; and two sleeves, each locatable in a recess in the lug, which recesses are each open to a different one of the locating apertures.

In another form, the invention resides in a shackle including: two lugs, one of the lugs having opposite aligned locating apertures; a shackle pin extending between eyes of the respective lugs; a locking pin system to lock the shackle pin in place, the locking pin system including:- a pin comprising a shaft which has at least one end captively locatable in one of the locating apertures of the lug, and a barrier locatable adjacent the locating aperture to close off the locating aperture, which barrier includes a lock formation operable to engage a locating formation associated with said coupling member to releasably lock the barrier in position, thereby preventing the shaft from being ejected through the locating

aperture.

BRIEF DESCRIPTION OF THE DRAWINGS To assist in understanding the invention and to enable a person skilled in the art to put the invention into practical effect, preferred embodiments of the invention will be described by way of example only with reference to the accompanying drawings, wherein:

FIG 1 shows a partially sectioned perspective view of a shackle including a locking pin system in accordance with the invention; FIG 2 shows a sectional view of a sleeve of the locking pin system of

FIG 2, fixed in a recess in one of the lugs of the shackle;

FIG 3 shows a perspective view of a barrier in accordance with the invention, used in the locking pin system of FIG 1 ;

FIG 4 shows a sectional view of the barrier of FIG 3; and FIG 5 shows a sectional view of a retaining assembly in accordance with the first aspect of the invention, in use with the shackle of FIG 1.

DETAILED DESCRIPTION OF THE DRAWINGS

In FIG 1 , a sectional view of the locking pin system 10 is shown comprising a pin in the form of a shaft 12, and retaining assemblies 14 at opposite ends of the shaft 12. The locking pin system 10 is shown, in use, with a coupling member in the form of a shackle 20. The shackle 20 has two spaced lugs 21. The shackle 20 has a shackle pin 18 which has a free end captively held in an eye of one of the shackle's lugs 21. The shackle pin 18 is locked in the shackle 20 by the locking pin system 10. The lug 21

has aligned opposite recesses 26 in which the retaining assemblies 14 are fixed.

In FIG 2, one of the ends of the shaft 12 is shown captively held in a locating aperture 16 of the lug 21. The shaft 12 extends at least partially through the eye of the lug 21 to engage a transverse notch 52 cut into the shackle pin 18. The shackle pin 18 is locked in the lug 21 by the positive location of the shaft 12 in the notch 52. The shaft 12 is generally "D" shaped in cross section and has small chamfers at its ends for ease of insertion through the locating aperture 16. The flat face of the shaft 12 mates with a flat face of the lug 21 to prevent rotation of the shaft 12 in the lug 21. Although a shaft 12 with a "D" shaped cross section is shown in the drawings, the Applicant envisages that a cylindrical shaft may similarly be used. In such an embodiment the lug 21 will also not have a flat face that mates with the shaft and the shaft will be rotatable in the lug. The locating aperture 16 is open to the recess 26 and is centrally located in the floor 32 of the recess 26.

A sleeve 22 is stitch welded into the recess 26 by weld beads 23. The sleeve 22 has a locating formation in the form of an internal shoulder projection 28. An inner end of the sleeve 22 abuts the floor 32 of the recess 26. The sleeve 22 has three longitudinally extending ribs 25 equi- spaced on the outside of the sleeve 22. The ribs 25 contact a wall 27 defining the recess 26, to seat the sleeve 22 in the recess 26. In use, the ribs 25 are ground down sufficiently to nestingly fit and centralize the sleeve 22 in the recess 26. The weld beads 23 adjoin outer ends of the ribs 25. The sleeve 22 has an outwardly divergent ramp face 30 at an

entrance thereof. The bore of the sleeve 22 is larger than that of the locating aperture 16 and when fixed in the recess 26, it is generally concentric with the locating aperture 16 and thus also with the shaft 12. Although the locating formation is described as a shoulder projection 28 in the sleeve 22, the Applicant envisages that the locating formation may similarly be a shoulder projection or the like machined or otherwise formed in the wall 27 of the recess 26, which would obviate the need for a separate sleeve 22.

FIG 3 shows a perspective view of a barrier 24 of the retaining assembly 14 and FIG 4 a sectional view of the barrier 24. The barrier 24 comprises a body 34 and a lock formation in the form of two plates 36 cast into the body 34. The body 34 is of resiliently deformable polyurethane material and the plates 36 cast therein is of metal.

The body 34 is plug-like, having a chamfered inner end 40 and a recessed outer end 42. A central dimple 51 is defined at the inner end 40 of the body 34. A cavity 43 is defined in the body 34, which cavity 43 is open to the recessed outer end 42. The body 34 has an annular sidewall 44 which is dimensioned to snugly fit in the bore of the sleeve 22 to close off the bore of the sleeve 22. Although not shown in the drawings, the Applicant envisages that the body 34 may have one or more circumferential ribs which seats in the bore of the sleeve 22 in an interference fit to sealingly close off the bore.

The plates 36 are embedded diametrically opposite each other in the body 34. The plates 36 each have a barb formation 46, an actuating tab 48, hook projections 49 and a nose section 50. Two holes 47 are defined

in each of the plates 36 to aid in anchoring the plates 36 in the body 34.

The nose sections 50 of the plates 36 are proximate each other and the plates 36 are resiliently displaceable about their nose sections 50 by pinching the actuating tabs 48 towards each other. The barb formations 46 project radially outwardly from holes in the sidewall 44. The barb formations 46 are retractable by pinching the actuating tabs 48 toward each other. The barb formations 46 are configured to engage the shoulder projection 28 of the sleeve 22 to releasably fix the barrier 24 in the sleeve 22. Pinching the tabs 48 toward each other resiliently deforms the body 34. More specifically, regions of the sidewall 44 around the barbs 46 resiliently collapse toward each other. The cavity 43 provides space for the sidewall 44 to be collapse into when pinching the actuating tabs 48 toward each other. The body 34 has a tendency to lengthen as the tabs 48 are pinched, but the lengthening is reduced by the dimple 51 which provides space into which the deformed material of the body 34 can be displaced without lengthening the body 34.

The Applicant envisages that the cavity 43 may optionally be filled with a soft resilient rubber or the like, which is softer than the polyurethane material of the body 34. Such a filling will prevent build up of fines in the cavity 43 while still allowing the sidewall 44 to be displaced into the cavity 43.

The actuating tabs 48 project outwardly into the recess at the outer end 42 of the body 34. The actuating tabs 48 are readily accessible by compressing tools such as pliers or the like to pinch the actuating tabs 48 toward each other. The resilient deformability of the body 34 forces the

plates 36 to return to their normal position, the position shown in the drawings, after the actuating tabs 48 are released from pinching.

The hook projections 49 provide for hooking of the barrier 24 by means of a loop of wire or other extraction tool to apply a pulling force on the barrier to dislodge the barrier 24 from the sleeve (when the barb formations 46 are retracted).

In FIG 5, the retaining assembly 14 is shown as comprising the sleeve 22 and the barrier 24.

The barrier 24 closes off the locating aperture 16, thereby retaining the shaft 12 in the lug 21.

In use, the retaining assemblies 14 at each end of the shaft 12 prevent the shaft 12 from being ejected from its position in the lug 21 of the shackle 20. During normal operating conditions, the shackle pin 18 of the shackle 20 is loaded with shock loads. This is especially common in the earthworking environment. The shock loads make the shaft 12 "jump" in its passage as the shock energy is transferred from the shackle pin 18 to the shaft 12. By having the barrier 24 isolated from the shaft 12, transfer of force onto the barrier 24 is limited to that which is transferred to the barrier 24 by axial displacement of the shaft 12. The shaft 12 abuts the inner end 40 of the resilient body 34, which absorbs most of the impact when the shaft 12 "jumps", in use.

Impact from the shaft 12 does not eject the barrier 24 from the sleeve 22 as the barb formations 46 engage the shoulder projection 28, preventing it from being ejected. The body 34 of the barrier 24 absorbs much of the shock energy of such axial movement of the shaft 12. Further,

the plates 36 are arranged so that any impact from the inner end 40 of the body 34 splays the plates 36 open even further, augmenting engagement between the barb formations 46 and the shoulder projection 28. Impact from the inner end 40 of the body 34 is transmitted through the plates 36 from the nose sections 50 to the barbs 46. As such, little load is taken by the body 34 as the transfer of force from the impact is from the plates 36 to the shoulder projection 28.

For maintenance purposes, it is necessary to periodically remove the shaft 12 from its position in the shackle 20. This is done by using pliers or the like to remove one or both of the barriers 24 and then pushing the shaft 12 out of the shackle 20 via the locating aperture 16 and through the bore of the sleeve 22. The pliers are used to pinch the tabs 48 to be displaced towards each other, which brings the barb formations 46 out of engagement with the shoulder projection 28 of the sleeve 22. The barrier 24 can then be safely removed by pulling it out of the sleeve 22.

When installing a shaft 12, the barrier 24 is merely inserted nose end 40 first into the sleeve 22. As it is inserted, the barb formations 46 ride up on the ramp face 30 at the entrance of the sleeve 22, compressing the plates 36. The barrier 24 is inserted further until the barb formations 46 ride over the shoulder projection 28, upon which the plates 36 snap open to bring the barb formations 46 into engagement with the shoulder projection 28.

The body 34 of the barrier 24 seals the bore of the sleeve 22, thereby preventing the ingress of fines into the notch 52 and from packing around the shaft 12. The locking pin system 10 is thus less prone to

seizing up than some prior art locking pin systems. Because the retaining assembly 14 is isolated from all but the axial movement of the shaft 12, the seal between the barrier 34 and the sleeve 22 is not broken during normal operating conditions of the shackle 20. A further benefit of isolating the displacement of the shaft 12 from the barriers 24 is that the shaft 12 is less prone to bending. Yet another benefit of the locking pin system 10 is that the shaft 12 can be replaced without having to replace the barriers 24, making the locking pin system 10 inexpensive to operate and maintain.

Throughout the specification the aim has been to describe the invention without limiting the invention to any one embodiment or specific collection of features. Persons skilled in the relevant art may realize variations from the specific embodiments that will nonetheless fall within the scope of the invention.

It will be appreciated that various other changes and modifications may be made to the embodiment described without departing from the spirit and scope of the invention. For example, although the description of the drawings refers to a locking pin system 10 including a shaft 12 and two separate barriers 24, one of the barriers 24 may be integrally formed with the shaft 12 at one end of the shaft 12. This will allow for the shaft 12 to be simultaneously removed from the shackle 20 as the barrier 24 integrally formed therewith is pulled from the sleeve 22.

Further, although the description of the drawings has referred to a locking pin system 10 used as a locking pin, the locking pin system 10 may similarly be used as a shackle pin or the like in other coupling systems.