GB2476915A

GB2476915A - Coupler for an excavator arm

Info

Publication number: GB2476915A
Application number: GB1107715A
Authority: GB
Inventors: Gary Miller; Howard Reay; Paul Grant
Original assignee: Miller UK Ltd
Current assignee: Miller UK Ltd
Priority date: 2007-06-13
Filing date: 2007-06-13
Publication date: 2011-07-13
Anticipated expiration: 2027-06-13
Also published as: IE86190B1; GB2450202A; GB0711428D0; GB2450127B; GB0808113D0; IE20080437A1; GB2476915B; GB201107715D0; GB2450203B; GB2450202B; GB2450127A; IE20080438A1; GB0808114D0; GB2450203A

Abstract

A coupler 10 having a frame comprising a rear jaw (22, fig 1) and a forward jaw 24 for receiving accessory pins 52 and 54 respectively. The coupler includes a mechanical actuator 32 and a first latch 26 to close the rear jaw 22, rotatable relative to the frame and pivotally connected to the actuator. A second latch 34 for closing the forward jaw 24 mechanically linked to a third element 36 which is pivotally connected to the frame. Actuation of the mechanical actuator 32 rotates the first latch 26 around the pin 54 and causes the third element 36 to rotate about its pivot moving the second latch 34 into its closed position. The second latch is visible from the excavators cab when in its closed position. The mechanical actuator is a hydraulic ram and is mounted on the frame about and between the two jaws.

Description

COUPLER

The present invention relates to a coupler for attaching an accessory, such as an excavator bucket, to an excavator arm of an excavator and in particular to a coupler comprising two jaws and two latches for selectively securing, and releasing, two attachment pins of an accessory in, or from, the jaws of the coupler.

Many couplers have been developed in the art. Some are fully automatic, i.e. fully operable from within the cab of the excavator for both coupling and decoupling an accessory to or from the coupler and some are part automatic / part manual, requiring many or most operations for coupling and decoupling of an accessory to or from the coupler to be carried out from within the cab, but with one or more operations needing to be done instead at the coupler itself. For examples, a fully automatic coupler is disclosed in GB2330570, whereas a part automatic and part manual coupler is disclosed in GB23 59062. In GB2359062 the manual step is the insertion, or removal, of a safety pin into, or from, behind a pivoting latching hook of the coupler by hand.

Due to safety concerns, however, there is a constant drive to provide fully automatic couplers so that the user can remain in the safe environment of the cab of the excavator.

After all, accessories and couplers can be extremely large and heavy, and therefore dangerous when being manipulated by an excavator. Further, there is a drive towards making the safety features, i.e. the features for preventing accidental decoupling of the accessory from the coupler in the event of a failure of a component of the coupler or the accessory, visible from within the cab. By being visible from the cab it is possible to assess their status from the cab, i.e. to carry out a remote visual check as to whether or not the safety features have adopted their correct safety position for ensuring a securement between the coupler and the accessory.

Couplers generally have a first (or top) half that is for attaching the coupler to the excavator arm of the excavator. That is usually by way of two pairs of holes through which two attachment pins of the excavator arm pass. Then, on the second (or bottom) half of the coupler, two jaws are usually provided for engagement with a second pair of attachment pins, this time on the accessory. I,

One of the jaws usually faces downwards, i.e. away from the first half of the coupler, and that jaw is usually referred to as the rear jaw -it is normally located the furthest away from the cab, and excavator arms usually extend from a rear of the excavator. The other jaw usually faces away from that rear jaw, and is usually rotated approximately 900 relative to the rear jaw. Further, being usually nearer to the cab, it is usually referred to as the front jaw.

In each of the above prior art documents a pivoting latching hook is provided for the rear jaw for locking an attachment pin within that jaw, and to couple the accessory to the coupler, a first attachment pin is first engaged by the front jaw, and the coupler is then rotated to permit the second attachment pin to engage into the rear jaw. Then the pivoting latching hook is driven rearwardly, by a hydraulic piston, to lock the rear attachment pin within the rear jaw, thereby also locking the front attachment pin in the frontjaw.

Although this securement of the accessory to the coupler is perfectly satisfactory, users of automatic or semi-automatic couplers are wanting mechanisms incorporated into these couplers to provide a guarantee that accessories cannot accidentally be decoupled from the couplers, even if the pivoting latching hook is retracted either deliberately or accidentally, but while still allowing fully automatic decoupling of the accessory from the coupler in the event that such a decoupling is desired. The present invention, therefore, seeks to provide redundant safety elements, controllable from within the cab, that will allow improved security in the securement of the accessory to the coupler, while still allowing intentional decoupling operations to be carried out.

According to the present invention there is provided a coupler for coupling an accessory to an excavator arm of an excavator, the coupler comprising a first portion for attaching the coupler to an excavator arm of an excavator and the coupler having a second portion adapted to receive an accessory with two attachment pins, wherein: the second portion has two jaws, one for receiving a first attachment pin of an accessory and the other for receiving a second attachment pin of the accessory; a first latch is associated with the first jaw for securing the first attachment pin within the first jaw when the first latch is in a latching position; a second latch is associated with the second jaw for securing the second attachment pin within the second jaw when the second latch is in a latching position; the second latch is linked or connected to a third latch that extends between the first and second latches, the third latch, when in a latching position, being adapted to resist movement of the first latch from a latching position into a non-latching position; and when the third latch is in a non-latching position, the first latch is not resisted from moving between a latching position and a non-latching position by the third latch.

Preferably the latching position of the third latch is its default position, i.e. the position it assumes during nornial use of the coupler (i.e. non-inverted and with an attachment attached thereto).

Preferably the third latch is moveable from a latching position into a non-latching position by means of gravity by at least partially inverting the coupler. Alternatively, or additionally, a mechanical actuator may be provided for moving the third latch.

A biasing member may be provided to bias the third latch towards a latching position.

Preferably the third latch, in a latching position bears against the first latch.

One or more of the latches may comprise a solid bar andlor a hook.

One or more of the latches may comprise a pair of solid bars and/or hooks.

One or more of the latches may comprise a bifurcated bar or hook.

Preferably the first latch is moveable from a latching position into a non-latching position by a mechanical actuator, such as a hydraulic ram.

Preferably the second latch is moveable from a latching position for the second jaw into a non-latching position for the second jaw by means of gravity by at least partially inverting the coupler. Alternatively, or additionally, a mechanical actuator may be provided for moving the second latch.

A biasing member may be provided to bias the second latch towards a latching position.

The same biasing member andlor mechanical actuator may control the movements of both the second latch and the third latch since those latches are linked or connected together.

Preferably the second latch is pivotally linked to the third latch. They may, however, be an integrally formed member.

Preferably the second jaw has a recessed groove in its lower half.

Preferably the coupler can accommodate a range of pin spacings between the two attachment pins of the accessory by making the rear jaw significantly wider in side view than the front jaw (or wider than the diameter of a typical rear attachment pin for that size of coupler). In this manner, accessories from different manufacturers, with different pin spacings, can be attached to the coupler without modification of either the coupler or the accessory.

For adjusting the first latch, the mechanical actuator is preferably a hydraulic ram. It might, however, be a pneumatic ram or a screwthread drive mechanism.

Preferably the mechanical actuator is mounted within the confines of the coupler, generally between and slightly above the two jaws.

Preferably the first latch is a pivoting latching hook, or a pair of pivoting latching hooks.

I

Preferably the first latch pivots to move through an arc between a latching position and a non-latching position. In other embodiments it might be a plate that slides such that it moves linearly between a latching position and a non latching position.

Each jaw may be bifurcated. It is preferred, however, that the first jaw is a pair of jaws formed in the two sidewalls of the coupler. It is also preferred that the second jaw is a single piece jaw, for example a moulded jaw or a welded multi-part fabrication.

It should be noted that the term "jaw" should be interpreted to encompass similar attachment pin receiving members such as grooves, hooks or slots, or other similar terms that are to be found in the art. For example, a hook, a groove or a slot in the main body of a coupler can form a jaw.

Preferably the first latch has a latching face facing in a first direction for bearing against the first attachment pin and a second face facing away from that latching face. Preferably one or more flange is formed on that second face. Then, in its latching position, the third latch preferably rests on one or more of those flanges.

The end of the third latch adapted to rest on those flanges may have one or more stepped surfaces. It would be one or more of those stepped surfaces that would preferably rest on that or those flange(s).

The first latch is adapted to be moveable into a non-latching position from a latching position by retracting it generally in the direction that its second face faces. However, when a pin is not within the first jaw, the first latch is also able to move in the opposite direction beyond the position in which its latching face would have engaged an attachment pin had one been in the first jaw. By that additional range of motion, the flange or flanges on the first latch can be moved clear of the reach of the third latch. As a result the range of available motion for the third latch is also extended.

The present invention also provides a method of attaching an accessory to a coupler on an excavator arm of an excavator, the method comprising: a) providing an excavator with a powered excavator arm having a coupler on an end thereof, the coupler comprising two jaws and a latch for each jaw, one of the latches being powered for movement between a latching position and a non-latching position, and the other being moveable from a latching position into a non-latching position by fully extending the powered latch beyond a latching position, i.e. while there is no pin within that jaw, into a fully extended position while the coupler is in a normal, in use, orientation; b) providing an accessory with two accessory pins thereon sized and spaced to fit into the two jaws of the coupler; c) powering the powered latch to extend it into the fully extended position to move the other latch into a non-latching position; d) manipulating the coupler to locate a first attachment pin of the accessory into the jaw associated with that other latch; e) curling the accessory and coupler, using the excavator arm, so as to invert the coupler, thereby placing the accessory roughly above the coupler; f) reverse powering the powered latch to retract the powered latch for opening its associated jaw, whereupon the second attachment pin locates into that jaw under the weight of the accessory; g) powering the powered latch to extend it to a latching position for securing the second attachment pin in its jaw; and h) uncurling the coupler, using the excavator arm. The attachment is now attached securely to the coupler.

The present invention also provides a method of detaching an accessory from a coupler on an excavator arm of an excavator, the method comprising: a) providing an excavator with a powered excavator arm having a coupler on an end thereof and with an accessory coupled thereto, the accessory having two accessory pins thereon located within two jaws of the coupler, and secured into those jaws by respective latches associated with each jaw, wherein one of the latches is powered for movement between a latching position and a non-latching position, and the other latch is moveable from a latching position into a non-latching position, when an attachment pin is not located within the other jaw, by fully extending the powered latch beyond a latching position into a fully extended position while the coupler is in a normal, in use, orientation; b) curling the accessory and coupler, using the excavator arm, so as to invert the coupler, thereby placing the accessory roughly above the coupler; c) reverse powering the powered latch to retract the latch for opening its associated jaw; d) uncurling the coupler and attachment, using the excavator arm, to position the accessory below the coupler whereupon the attachment pin within the opened jaw exits the opened jaw under the weight of the accessory; e) powering the powered latch to extend it into the fully extended position to move the other latch into a non-latching position to open the other jaw; and f) manipulating the coupler relative to the attachment to remove the other attachment pin of the accessory from that other jaw.

Preferably the act of inverting the coupler and accessory to place the accessory roughly above the coupler serves to move a mechanical stop away from a latching position behind the powered latch.

Preferably the mechanical stop is linked to the other latch.

Preferably the movement of that powered latch into the fully extended position allows the mechanical stop to move beyond its own latching position into a final release position.

These and other preferred features of the present invention will now be described purely by way of example with reference to the accompanying drawings in which: Figure 1 is a cut-away side elevation of a preferred embodiment of the present invention; Figure 2 is a schematic cut-away perspective of a preferred embodiment of the invention with two attachment pins of a bucket (part illustrated) secured within the two-jaws of the coupler; Figures 3 to 8 are schematic cut-away perspectives of the embodiment of Figure 2 illustrating the preferred sequence of operations for firstly attaching an attachment to the coupler (Figs and. 3 to 5 and then for disengaging the attachment from the coupler (Figs. 6 to 8); and Figure 9 is a top perspective view of the preferred coupler, with an attached bucket (in part) illustrating the preferred elements of the coupler roughly in plan.

Referring first of all to Figure 1, a cut-away side elevation of a preferred coupler 10, showing the preferred internal working mechanisms for the coupler 10 of the present invention, is shown. The coupler 10 has a first,. or upper, portion 12 and a second, or lower, portion 14. The coupler also has a front 16 and a rear 18. In normal use the front 16 points towards the cab of an excavator (not shown), whereas the rear 18 points away from the cab.

The upper portion 12 is adapted for connecting the coupler 10 onto the excavbator arm of the excavator and it is displaced slightly forwardly relative to the lower portion 14, as is conventional. In this illustrated embodiment, however, it is displaced further forward than would be conventional. That, however, is optional.

In the upper portion 12, two pairs of holes 2Oare provided, although only one of each pair is shown. Those holes 20 are for attachment of the coupler 10 to the excavator arm of the excavator by using a pair of attachment pins. That attachment is conventional in the art, and thus needs no further discussion.

The lower portion 14, which is instead for coupling onto an accessory, such as an excavator bucket, instead uses a pair of jaws for that attachment. The first jaw, or the rear jaw 22, and the second jaw, or the front jaw 24, conventional as well for that purpose, and thus are sized to receive a further pair of attachment pins, this time fitted to the accessory.

As is conventional now, the rear jaw 22 is a downwardly facing jaw whereas the front jaw 24 is a forward facing jaw. Thus, with this arrangement, the basic principle behind coupling an accessory to the coupler is first to locate a front attachment pin of the accessory within the front jaw 24 and then to swing a rear attachment pin of the accessory into the rear jaw from below. Next, to prevent that second pin from just swinging out of the rear jaw, a pivoting latching hook, or first latch 26, is associated with that rear jaw 22 such that it can be swung about a pivot 28 into a latching position across the rear jaw 22 to secure the second attachment pin within the rear jaw 22. That then secures the accessory firmly onto the coupler 10.

As is also conventional, in this preferred embodiment the pivoting latching hook 26 is driven into that latching position by a mechanical actuator such as a hydraulic ram 32.

However, instead of a hydraulic ram, a pneumatic ram or a screwthread drive, or some other drive device, might be provided.

Further, instead of a pivoting latching hook, a sliding mechanism for that latch might instead be provided.

The present invention is distinguished over prior art couplers, however, by the provision of a unique second latch 34, and an attached third latch, or mechanical stop 36. They are provided to interfere with the above basic principle of operation of the coupler so as to prevent inadvertent, or non-deliberate, disengagement of the accessory from the coupler 10, while still allowing deliberate disengagement of the accessory from the coupler.

The second latch 34 is associated with the front jaw 24 and it is adapted selectively to close the front jaw 24 for securing an attachment pin within the front jaw 24.Because of that latch 34, before the accessory can be decoupled from the coupler 10, steps have to be taken to cause that latch to retract for opening the front jaw 24. Further details of those steps, and the more specific details of that second latch, will now be described in further detail with reference to Figures 2 to 8.

As can be seen in Figure 2, which shows only one half of the second latch 34, the second latch 34 is a pivotal plate connected via a hinge to a third element 36. The plate is generally rectangular with a solid section and is preferably made from steel. Its hinge has a central axis 42.

The second latch 34 can drop in and out of a latching position within the front jaw 24 by sliding generally linearly through a slot defined by two plates 48, 50. It can keeps a generally linear line of movement since it can pivot about its own pivot axis 42, i.e. relative to the third element 36. Further, its interaction with the two plates 48, 50 within that slot defined therebetween, prevents rotation of the second latch 34 relative to main body of the coupler 10, and relative to the front jaw 24.

In an alternative construction, however, the second latch 34 and the mechanical stop 36 may be a single unitary element, thus not needing at least the front plate 48 of the two plates48,50.

The third element 36 is a mechanical stop 36. As more clearly shown in Figure 3, in which the hydraulic ram 32 has been removed for clarity, the mechanical stop 36 is itself also a pivotal member -it is pivotally mounted relative to the main body 38 of the coupler 10 about a pivot pin (not shown) via a bearing hole 40 in the mechanical stop 36.

Thus the mechanical stop 36 can pivot relative to the main body 38 of the coupler 10.

The mechanical stop 36 has a first arm with an end 56 that extends away from the bearing hole 40 away from the second latch 34. It also has a second arm extending away from the bearing hole 40, but instead towards the second latch 34. That second arm carries the pivot axis 42 for the second latch 34 near its end and that axis is located directly above, or in line with, the slot defined between the two plates 48, 50 of the front jaw.

As a result of that geometry (of the mechanical stop relative to the axes and the slot of the front jaw), it is through the pivoting motion of the mechanical stop 36 about the central axis of its bearing hole 40, i.e. relative to the main body of the coupler, that the second latch 34 can be lifted or lowered generally linearly through the slot between the two plates 48, 50.

The pivotal movement of the mechanical stop 36 is illustrated by the arrows 44 in Figure 3.

The generally linear motion of the second latch 34 relative to the front jaw 24 is illustrated by the double headed arrow 46 also in Figure 3.

It is preferred that the first arm of the mechanical stop, i.e. the arm extending from the bearing hole 40 to the end 56, is at least twice as long as the second arm of the mechanical stop 36, i.e. the arm extending from the bearing hole 40 towards the second latch 34. Similarly it is preferred that that first arm of the mechanical stop is at least twice as long as the second latch 34. Those arrangements together should allow the second arm to have a greater moment of inertia about the bearing hole 40 than the second arm combined with the second latch 34. Similarly, or alternatively, the first arm may simply be sufficiently heavier than the second arm and second latch combined to provide the desired greater moment of inertia for that first arm about the bearing hole 40 than the second arm and second latch 34 combined. This moment of inertia arrangement is desired so that gravity can always cause the first arm to drop and the second arm to lift, whenever the orientation of front and rear of the coupler is altered with respect to one another. This is the desired arrangement despite the fact that that arrangement tends to cause the second latch 34 to be permanently biased towards a non-latching position when the coupler 10 is in a normal use orientation, i.e. with the attachment being located underneath the coupler. That is because in normal use the second latch 34 will not be able to lift fully up into the roof of the front jaw 24 for opening the front jaw 24 due to the first latch 26 interfering with the range of motion available to the mechanical stop 36.

Instead, the second latch's normal position during use is as shown in Figure 2 -it extends partially across the opening of the front jaw 24. That is sufficient for "closing" the second jaw for locking an attachment pin within the second jaw. This feature is further explained below with regard to attaching and detaching an accessory to and from the coupler.

Returning, however, to the design of the second latch 34, in preferred embodiments the second latch 34 is painted in a high visibility colour such as orange or red. That is preferred since the second latch is one of the safety features of the coupler that will nearly always be visible from the cab of the excavator -it at least partially extends across the opening of the front jaw 24, and that opening generally faces towards the cab during normal use of accessories. The high visibility second latch 34, therefore, acts as a visible marker for confirming the correct or secure attachment of an accessory to the coupler 10, and that visual aid can be seen by the excavator operator from the within his cab.

For securing the rear attachment pin 54 within the rear jaw 22, however, this preferred embodiment has a first latch 26 in the form of a pivoting latching hook. That pivoting latching hook is mounted for rotation about a pivot pin 28 and is moveable between a latching position and a non-latching position by a hydraulic ram 32. That hydraulic ram 32 is the primary mechanism for holding that first latch 26 in its latching position. To assist with that and to add to the security of that, it is preferred that the hydraulic ram is provided with a check valve to prevent a release of the hydraulic pressure on the ram in the event of a hydraulic failure such as a cut in the hydraulic piping leading to it.

The mechanical stop 36, however, provides a further backup to prevent the inadvertent or non-deliberate release or retraction of the first latch 26 into a non-latching position.

To that end the mechanical stop 36 provides an interference function against that first latch 26, as most clearly illustrated in Figure 5.

For providing that interference function, the first arm of the mechanical stop 36 extends away from the bearing hole 40, and away from the second latch 34, towards the first latch 26. Further its length is long enough to bear against the first latch 26 when the first latch is in a latching position against an attachment pin. However, the first arm is not too long -it needs to be able to swing past the first latch 26 when the first latch 26 is fully extended, i.e. when there isn't an attachment pin within the rear jaw.

Because of the mechanical stop 36, i.e. when the first latch is in a latching position against an attachment pin, the first latch 26 cannot be retracted even by the hydraulic ram 32 until that mechanical stop 36 has been moved from that interference position.

The movement of that mechanical stop 36 is achieved by inverting the coupler 10, as shown in Figure 4, by fully curling the bucket and coupler under the excavator arm using the hydraulics of the excavator arm of the excavator. In that inverted position, due to the moments about the bearing hole 40, the mechanical stop 36 will rotate under the influence of gravity so as to move its end 56 that was in engagement with the first latch 26 away from the first latch 26. That rotational movement is in the direction shown by the downwardly pointing arrow 58 in Figure 4.

It should also be observed that that rotation of the mechanical stop 36 does not open the front jaw 24 since the second latch 34 is still extending partially across the opening of the jaw 24 -it actually closes it further, as shown by the upwards arrow 60 in Figure 4.

Upon that rotation of the mechanical stop, the first latch 26 is free to be retracted from its latching position into a non-latching position by the hydraulic ram 32 (not shown in Figure 4 either, again for clarity). Thus, the rear jaw 22 can be opened (as shown in Figure 4.

Although the basic operations of the three latches have been described above, the preferred method for attaching an accessory, such as a bucket 62, to the coupler 10 will now be described with reference to Figures 3, 4 and 5.

Referring first to Figure 3, the first step in the attachment procedure is the engagement of the front jaw 24 of the coupler onto the front attachment pin 52 of the bucket 62. That is usually done while the bucket 62 sits on the ground and is achieved by manipulation of the coupler 10 relative to the bucket 62, while the coupler is in its normal upright orientation. However, before that can be done, the front jaw 24 needs to be open, i.e. the second latch 34 needs to have been lifted into or above the roof of the front jaw 24.

The front jaw is likely to be open if the last operation with the coupler was the disengagement of the coupler from an accessory. However, if it is not open, to open it the second latch 34 must be lifted. That, however, can only be done while the rear jaw 22 is not accommodating an attachment pin, and only when the first latch has been driven rearwardly to a fully extended position. That can usually be done by using the hydraulic ram 32, as shown in Figure 3.

Once the first latch 26 is fully extended, or while it is being fully extended, the mechanical stop 36 falls clear of the first latch 26 once it is no longer able to reach the first latch 26 to bear against it. That additional rotation of the mechanical stop is then enough to lift the attached second latch 34 clear of the front jaw 24, i.e. fully into or above the roof of the front jaw 24, to open that jaw 24.

Once the front attachment pin 52 of the bucket 62 has then been engaged into the front jaw 24 of the coupler 10, the hydraulics of the excavator arm are then powered up to curl the bucket 62 and the coupler 10 under the excavator, i.e. towards the cab, so as to invert the coupler 10. That positions the bucket 62 roughly above the coupler 10, as shown in Figure 4. During that rotation of the coupler, the mechanical stop 36 will again fall under the influence of gravity to rotate it in the direction shown by the single downward arrow 58 in Figure 4. Thus the end 56 of the mechanical stop passes the first latch 26 again.

Further, as that happens the weight of the bucket will keep the front attachment pin securely in the cradle of the front jaw. Thus the second latch will be able to slide back partially across the opening of the front jaw 24 to close the front jaw 24 for securing the front attachment pin 52 within that front jaw 24.

While the above is happening, the first latch 26 remains fully extended. Thus it prevents the passage of the rear attachment pin 54 of the bucket 62 into the rear jaw 22 of the coupler 10. However, once the above has happened, the first latch 26 can then be retracted by the hydraulic ram 32 to open the rear jaw 22 -the mechanical stop 36 is moved clear of the fist latch so it will not prevent that from happening.

Next, as the first latch 26 is retracted, the rear jaw. opens and eventually the rear attachment pin 54 will fall into that jaw 22 under the weight of the bucket. Then the first latch 26 can be powered back to a latching position by the hydraulic ram. The bucket 62 and coupler 10 can then be reinverted to the position or orientation of Figure 5 -the normal working orientation -by uncurling the arrangement with the excavator arm.

During that uncurling operation the final part of the coupling procedure occurs -the mechanical stop falls back down into an interference position, i.e. with its end 56 bearing against the first latch 26.

From the above it will be appreciated that it is important that the front jaw is openable sufficiently by the movementlrotation of the mechanical stop to allow an attachment pin to be engaged into the front jaw, and also for it to remain sufficiently closed during normal use, i.e. while the mechanical stop is in a latching position, to prevent removal of the attachment pin from the front jaw. That balance is more readily achieved if the latch only extends partially across the front jaw when the mechanical stop is in its latched position. Thus the length of the second latch 34 is preferably chosen such that with the mechanical stop in a latching position, the second latch extends only approximately half way across the opening for the front jaw 24. However, adjusting the relative the lengths of the arms of the mechanical stop 36 will adjust the amount of lift/movement available for the second latch 34 by the rotation of the mechanical stop 36 into its fully dropped position from its latching position. Similarly, adjusting the location of any lower rotation stop for the mechanical stop can adjust the amount of lift/movement available for the second latch 34 by the rotation of the mechanical stop 36 into its fully fully dropped position from its latching position.

In this preferred embodiment the first latch 26 is a hook having an attachment pin facing surface 64 and a back surface 66. The end 56 of the mechanical stop 36 can bear against that back surface 66 when the mechanical stop 36 is in a latching position. However, to provide a more precise latching position for the mechanical stop 36, The back surface 66 of the first latch 26 is provided with a flange 68 having at least one step. This stepped flange 68 provides a seat onto which the mechanical stop's end 56 can sit when it is in its latching position behind the first latch 26. Further, if more than one step is provided, each step provides an alternative seat for the mechanical stop's end 56, whereby attachments with different pin spacings can be accommodated more readily by the coupler 10 -as shown in Figure 3, two or even three steps are preferably provided on the flange 68, with each step providing a corresponding latching position for the mechanical stop 36, depending upon the amount of extension needed by the first latch 26 for its attachment pin facing surface 64 to engage the attachment pin of the respective accessory.

Instead of multiple steps on the flange, the end 56 of the mechanical stop could instead be stepped.

In the illustrated embodiment, the rear jaw is relatively narrow. Thus only a narrow range of accessory pin spacings can be accommodated by that coupler 10. However, that rear jaw 22 could be widened slightly to widen the range of accessory pin spacings accommodatable by the coupler.

The flange 68 also serves a second purpose. It provides more control for the operation of the mechanical stop both in its latching position and between its latching position and it fully dropped position (i.e. for opening the front jaw). By having the flange with the step, the exact state of rotation of the first latch will not define whether the mechanical stop is in a latching position. That is because it is in a latching position whenever it bears onto the step. Thus the mechanical stop will only fall past that latching position when the operator wants it to do so, i.e. by fully powering forward the fist latch 26 when there isn't an attachment pin in the rear jaw 22.

Next, with reference to Figures 6, 7 and 8, the removal of a bucket 62 from the coupler will now be described.

Referring first to Figure 6, the first step in decoupling a bucket 62 from the coupler 10 is to invert the bucket 62 and coupler 10 so as to place the bucket 62 roughly above the coupler 10. That in turn causes the mechanical stop 36 to rotate clear of its latching position behind the first latch 26, as shown by arrow 58. The hydraulic ram 32 can then be powered to retract the first latch 26 for opening the rear jaw 22.

Once that has been done, the bucket 62 and coupler 10 are then reinverted to the normal orientation of Figure 7. That in turn allows the rear attachment pin 54 to swing free from the open rear jaw 22, as shown. The front attachment pin 52, however, is still secured within the front jaw 24 by the second latch 34. Thus even if free swinging, the bucket 62 still will not detach from the coupler 10. Before that can happen it is necessary to release the front attachment pin 52 from that front jaw 24.

To release the front attachment pin 52 from the front jaw 24, the bucket 10 would first normally be seated onto the ground to make it safe. Then the hydraulic ram 32 is again powered, but this time to drive the first latch 26 into its fully extended position, as in Figure 3 above, but as now shown in Figure 8. That in turn allows the mechanical stop 36 to fuiiy drop into the final bucket release position (as shown by arrow 72) in which it lifts the second latch 34 clear up into the roof of the front jaw 24 (as shown by arrow 74). Only then is the front attachment pin 52 also then free to be removed from the front jaw 24.

One final safety feature is incorporated into this coupler. That is the provision of a recess in the floor of the front jaw 24 (see Figure 1). That recess, in this illustrated embodiment has a width of approximately the same length as the height of the jaw's opening. An attachment pin can thus locate into it. That recess 70 makes it even more unlikely that the front attachment pin will disengage from the front jaw unintentionally.

That is because even if the rear attachment pin is already free and the front jaw is open, a free swinging bucket in that open front jaw will still not tend to fall out of the jaw.

Instead the pin will tend to locate into the recess within that front jaw. Further, one in the recess, it will not readily come out of it due to the weight of the bucket. Thus, only when the bucket is on the ground, or shaken vigorously, will the removal of the bucket from that jaw be facilitated. That is because only then will the weight of the bucket 62 be taken off the jaw 24 of the coupler 10. That in turn allows the coupler 10 to be more readily manipulated in a suitable manner relative to the jaw to free the front attachment pin 52 from the front jaw 24.

Referring finally to Figure 9, a top plan view of the working elements of the preferred coupler is provided. From that view it is clearly visible that the second latch 34 lies between a pair of mechanical stops 36. However, other configurations within the scope of the claims as appended hereto would be acceptable as well. The pair of mechanical stops 36, the hydraulic ram 32, the first latch 26 and the second latch 34 have each been shaded with different hash lines to help identify them in the figure.

It can also be noted from Figure 9 that in this preferred embodiment has the hydraulic ram 32 sitting generally between the two mechanical stops 36. That provides a more compact arrangement of the coupler 10 in its height dimension, whereby the bucket's digging capacity will be less compromised by the use of a coupler between the excavator arm and the bucket.

The present invention has been described above purely by way of example. It should be noted, however, that modifications in detail can been made within the scope of the invention as defined in the claims appended hereto.

Claims

CLAIMS1. A coupler for attaching an accessory to an excavator arm of an excavator, the accessory having a first attachment pin and a second attachment pin, the coupler comprising: a frame having a rear jaw that is downwardly facing and a front jaw with an opening that is forward facing and rotated approximately 90 degrees relative to the rear jaw, the rear jaw being adapted to accommodate a range of accessory pin spacings for accommodating different accessories; a mechanical actuator positioned within the frame, the mechanical actuator being a hydraulic ram; a first latch having a first attachment pin engaging surface and being rotatable relative to the frame about a first pivot pin in response to actuation of the mechanical actuator, the first latch being pivotally connected to the hydraulic ram by a second pivot pin; a second latch having a second attachment pin engaging surface; a third element being pivotally mounted relative to the frame about a third pivot pin, the third element being mechanically linked to the second latch such that rotation of the third element about the third pivot pin mechanically actuates the second latch; wherein actuation of the hydraulic ram rotates the first latch about the first pivot pin selectively to engage and disengage the first attachment pin engaging surface against the second attachment pin of the accessory when or if the second attachment pin is received in the rear jaw, and causing the third element to rotate about the third pivot pin causes the second attachment pin engaging surface selectively to latch the first attachment pin of the accessory in the front jaw when or if the first attachment pin is received in the front jaw; the second latch, when in a position to latch the first attachment pin in the front jaw, downwardly extending at least partially across the opening of the front jaw such that the second latch will be visible from within a cab of the excavator when the coupler is attached to the excavator arm of the excavator.
2. A coupler for attaching an accessory to an excavator arm of an excavator, the accessory having a first attachment pin and a second attachment pin, the coupler comprising: a frame having an upper portion adapted to connect the coupler to the excavator arm and a lower portion having a rear jaw that is downwardly facing and a front jaw with an opening that is forward facing and rotated approximately 90 degrees relative to the rear jaw, the rear jaw having an opening adapted to accommodate a range of accessory pin spacings for accommodating different accessories, the opening of the rear jaw being wider than the opening of the front jaw; a mechanical actuator positioned within the frame; a first latch having a first attachment pin engaging surface and being rotatable relative to the frame about a first pivot pin in response to actuation of the mechanical actuator, the first latch being pivotally connected to the mechanical actuator (32) by a second pivot pin; a second latch having a second attachment pin engaging surface; a third element being pivotally mounted relative to the frame about a third pivot pin, the third element being pivotally linked to the second latch such that pivoting of the third element about the third pivot pin causes the second latch to move between a latching position and a non-latching position; wherein actuation of the mechanical actuator rotates the first latch about the first pivot pin selectively to engage and disengage the first attachment pin engaging surface against the second attachment pin of the accessory when or if the second attachment pin is received in the rear jaw, and causing the third element to pivot about the third pivot pin relative to the second latch causes the second attachment pin engaging surface of the second latch selectively to latch the first attachment pin of the accessory in the front jaw when the first attachment pin is received in the front jaw; the second latch downwardly extending at least partially across the opening of the front jaw when it is in the latching position whereby the second latch will be visible from within a cab of the excavator when the coupler is attached to the excavator arm of the excavator.
3. A coupler for attaching an accessory to an excavator arm of an excavator, the accessory having a first attachment pin and a second attachment pin, the coupler comprising: a frame having an upper portion adapted to connect the coupler to the excavator arm and a lower portion having a rear jaw that is downwardly facing and a front jaw with an opening that is forward facing and rotated approximately 90 degrees relative to the rear jaw, the rear jaw having an opening adapted to accommodate a range of accessory pin spacings for accommodating different accessories, the opening of the rear jaw being wider than the opening of the front jaw; a mechanical actuator positioned within the frame; a first latch having a first attachment pin engaging surface and that is rotatable relative to the frame about a first pivot pin in response to actuation of the mechanical actuator, the first latch being pivotally connected to the mechanical actuator by a second pivot pin; a second latch having a second attachment pin engaging surface; and a third element connected to the mechanical actuator, the third element being configured such that it is also mechanically coupled to the second latch and such that movement of the third element simultaneously relative to both the second latch and the mechanical actuator causes the second latch selectively to move between a latching position and a non-latching position; wherein actuation of the mechanical actuator rotates the first latch about the first pivot pin to selectively engage and disengage the first attachment pin engaging surface against the second attachment pin of the accessory when or if the second attachment pin is received in the rear jaw, and moving the second latch into the latching position causes the second attachment pin engaging surface selectively to latch the first attachment pin of the accessory in the front jaw when or if the first attachment pin is received in the front jaw; the second latch downwardly extending at least partially across the opening of the front jaw when it is in the latching position whereby the second latch will be visible within a cab of the excavator when the coupler is attached to the excavator arm of the excavator.
4. The coupler of any one of the preceding claims, wherein the second latch has a hinge and the third element is mechanically linked to the latch via the hinge.
5. The coupler of any one of the preceding claims, wherein the third element is a blocking bar adapted selectively to resist movement of the first latch from a latching position into a non-latching position.
6. The coupler of any one of the preceding claims, wherein the rear jaw is significantly wider in side view than the front jaw.
7. The coupler of any one of the preceding claims, wherein mechanical actuator is a hydraulic ram that is mounted to the frame between and above the rear jaw and the front jaw.
8. The coupler of any one of the preceding claims, wherein the second latch is arranged to pivot about a pivot axis relative to the third element.
9. The coupler of any one of the preceding claims, wherein the second attachment pin engaging surface is generally flat.
10. The coupler of any one of the preceding claims, wherein the first latch is a pivoting latching hook that is movable between a latching position and a non-latching position by the mechanical actuator.
11. The coupler of any one of the preceding claims, wherein the mechanical actuator is a hydraulic ram that includes a check valve to prevent release of hydraulic pressure on the ram in the event of a hydraulic failure.
12. The coupler of any one of the preceding claims when dependent upon claim 5, wherein the first latch has the said first attachment pin engaging surface that defines a latching face facing in a first direction for bearing against the first attachment pin, and the first latch also has a second face, facing away from that latching face, wherein one or more flange is formed on that second face.
13. The coupler of any one of the preceding claims, wherein the third element includes a bearing hole and is pivotally mounted relative to the frame about a fourth pivot pin to permit the third element to pivot relative to the frame.
14. The coupler of any one of the preceding claims, wherein the third element is a third latch that extends between the first and second latches, the third latch, when in a latching position, being adapted to resist movement of the first latch from a latching position into a non-latching position; and when the third latch is in a non-latching position, the first latch is not resisted from moving between a latching position and a non-latching position by the third latch.
15. The coupler of claim 14, wherein the latching position of the third latch is its default position.
16. The coupler of claim 14 or claim 15, wherein the third latch is moveable from a latching position into a non-latching position by means of gravity by at least partially inverting the coupler.
17. The coupler of any one of claims 14 to 16, wherein a biasing member is provided to bias the third latch towards a latching position.
18. The coupler of any one of claims 14 to 17, wherein the third latch, in a latching position, bears against the first latch.
19. The coupler of any one of the preceding claims, wherein one or more of the latches, or the third element, comprises a solid bar.
20. The coupler of any one of the preceding claims, wherein one or more of the latches, or the third element, comprises a hook.
21. The coupler of any one of the preceding claims, wherein one or more of the latches, or the third element, comprises a pair of solid bars.
22. The coupler of any one of the preceding claims, wherein one or more of the latches, or the third element, comprises a pair of hooks.
23. The coupler of any one of claims I to 19, wherein one or more of the latches, or the third element, comprises a bifurcated bar.
24. The coupler of any one of claims 1 to 18, wherein one or more of the latches, or the third element, comprises a bifurcated hook.
25. The coupler of any one of the preceding claims, wherein the second latch is moveable from a latching position into a non-latching position by means of gravity by at least partially inverting the coupler.
26. The coupler of any one of claims 1 to 24, wherein a mechanical actuator is provided for moving the second latch.
27. The coupler of claim 26, wherein the same actuator controls the movements of both the second latch and the third element.
28. The coupler of any one of the preceding claims, wherein a biasing member is provided to bias the second latch towards a latching position.
29. The coupler of claim 28, wherein the biasing member biases both the second latch and the third element.
30. The coupler of any one of the preceding claims, wherein the second latch is pivotally linked to the third element.
31 The coupler of any one of the preceding claims, wherein the second jaw has a recess in its lower half.
32. The coupler of any one of the preceding claims, wherein the first latch comprises a pivoting latching hook.
33. The coupler of any one of the preceding claims, wherein the first latch pivots to move through an arc between a latching position and a non-latching position.
34. The coupler of any one of the preceding claims when dependent upon claim 12, wherein, in its latching position, the third element rests on one of the one or more flanges.
35. The coupler of any one of the preceding claims, wherein the third element is a third latch, the end of which has one or more stepped surfaces.
36. The coupler of any one of the preceding claims, wherein the first latch is adapted to be moveable into a non-latching position from a latching position by retracting it generally away from an attachment pin against which it bears, and is adapted to be moveable in the opposite direction beyond the position in which its latching face would have engaged an attachment pin, had one been in the first jaw, when an attachment pin is not within the first jaw.
37. A method of attaching an accessory to a coupler on an excavator arm of an excavator, the method comprising: a) providing an excavator with a powered excavator arm having a coupler on an end thereof, the coupler being in accordance with any one of the preceding claims and comprising the two jaws and the latch for each jaw, one of those latches being powered for movement between a latching position and a non-latching position; b) providing an accessory with two accessory pins thereon sized and spaced to fit into the two jaws of the coupler; c) manipulating the coupler to locate a first attachment pin of the accessory into the frontjaw; d) curling the accessory and coupler, using the excavator arm, so as to invert the coupler, thereby placing the accessory roughly above the coupler, and locating the second attachment pin into the rear jaw under the weight of the accessory; e) powering the powered latch to extend it to a latching position for securing the second attachment pin in the rear jaw; and h) uncurling the coupler, using the excavator arm.
38. A method of detaching an accessory from a coupler on an excavator arm of an excavator, the method comprising: a) providing an excavator with a powered excavator arm having a coupler on an end thereof and with an accessory coupled thereto, the coupler being in accordance with any one of the preceding claims and the accessory having two accessory pins thereon located within the front and rear jaws of the coupler, and being secured into those jaws by respective latches associated with the front and rear jaws, wherein one of the latches is powered for movement between a latching position and a non-latching position; b) curling the accessory and coupler, using the excavator arm, so as to invert the coupler, thereby placing the accessory roughly above the coupler; c) powering the powered latch to retract it for opening its associated jaw; d) uncurling the coupler and attachment, using the excavator arm, to position the accessory below the coupler whereupon the attachment pin within the opened jaw exits the opened jaw under the weight of the accessory; and e) powering the powered latch to extend it into a fully extended position to move the other latch into a non-latching position to open the other jaw; and f) manipulating the coupler relative to the attachment to remove the other attachment pin of the accessory from that other jaw.
39. The method of claim 37 or claim 38, wherein the act of inverting the coupler and accessory to place the accessory roughly above the coupler serves to move the third element, which is in the form of a third latch, away from a latching position behind the powered latch.
40. The method of any one of claims 37 to 39, wherein the movement of the powered latch into a fully extended position allows the third element to into a final release position, that movement enabling the other latch to be moved into a non-latching position.
41. An excavator, comprising: a powered excavator arm; a cab; a coupler for attaching an accessory to an excavator arm of an excavator, the accessory having a first attachment pin and a second attachment pin, the coupler comprising: a frame having a rear jaw that is downwardly facing and a front jaw with an opening that is forward facing and rotated approximately 90 degrees relative to the rear jaw, the rear jaw being adapted to accommodate a range of accessory pin spacings for accommodating different accessories; a hydraulic ram positioned within the frame; a first latch having a first attachment pin engaging surface and being rotatable relative to the frame about a first pivot pin in response to actuation of the hydraulic ram, the first latch being pivotally connected to the hydraulic ram by a second pivot pin; a second latch having a second attachment pin engaging surface; a third element being pivotally mounted relative to the frame about a third pivot pin, the third element being mechanically linked to the second latch such that rotation of the third element about the third pivot pin mechanically actuates the second latch; wherein actuation of the hydraulic ram rotates the first latch about the first pivot pin selectively to engage and disengage the first attachment pin engaging surface against the second attachment pin of the accessory when or if the second attachment pin is received in the rear jaw, and causing the third element to rotate about the third pivot pin causes the second attachment pin engaging surface selectively to latch the first attachment pin of the accessory in the front jaw when or if the first attachment pin is received in the front jaw; the second latch, when in a position to latch the first attachment pin in the front jaw, downwardly extending at least partially across the opening of the front jaw such that the second latch (34) is visible from within the cab.
42. The excavator of claim 41, wherein the rear jaw is significantly wider in side view than the front jaw.
43. The excavator of claim 41 or claim 42, wherein the hydraulic ram is mounted to the frame between and above the rear jaw and the front jaw, relative to a top and bottom of the coupler.
44 The excavator of claim 41, claim 42 or claim 43, wherein the second latch is arranged to pivot about a pivot axis relative to the third element.
45. The excavator of any one of claims 41 to 44, wherein the second attachment pin engaging surface is generally flat.
46. The excavator of any one of claims 41 to 45, wherein the first latch is a pivoting latching hook that is movable between a latching position and a non-latching position by the hydraulic ram.
47. The excavator of any one of claims 41 to 46, wherein the hydraulic ram includes a check valve to prevent release of hydraulic pressure on the ram in the event of a hydraulic failure.
48. The excavator of any one of claims 41 to 47, wherein the coupler is in accordance with any one of claims 1 to 36.
49. An excavator comprising a coupler substantially as hereinbefore described with reference to any one or more of the accompanying drawings.