Patent Application
20070157492
This application claims priority to GB 0525379.4, filed Dec. 13, 2005 and GB 0617394.2 filed Sep. 4, 2006 and expressly incorporated by reference.
Not applicable.
Not applicable.
1. Field of the Invention
The present invention relates to a jaw of a coupler for coupling attachments, such as buckets, to the excavator arm of a digger.
2. Description of Related Art
Attachments used to be, and still sometimes are, attached directly to the excavator arm of diggers by using bucket (or coupler) pins, hereinafter called “pins”. They extend through holes both in the end of the excavator arm and in the attachments. The pins link them together such that they are relatively pivotable by manipulation of the arm.
The insertion of those pins through the holes has always proved to be difficult or inconvenient, especially in view of the heavy weight of some attachments. This is made worse by the fact that all of the holes need to be carefully aligned in order for the pins to be passed through them. To avoid this problem, therefore, automated or “quick” couplers have been developed. They enable the operator of the digger to couple the attachment to the excavator arm from within the cab of the digger—the coupler is already attached to the arm, usually by two more pins.
Some quick couplers also allow that coupling to be secured, i.e. made safe from accidental disengagement. See, for example, the couplers disclosed in GB2330570 (to Miller UK), GB2359062 (to Miller UK), EP1318242 (to Geith), GB2332417 (to Redrock Engineering) and U.S. Pat. No. 6,699,001 (to JRB), all of which have such a safety feature.
GB2330570 discloses a coupler in which, in addition to the two holes for coupling the coupler to the excavator arm, there are two jaws for fitting onto the bucket pins. One of the jaws is forward facing (for engaging a first pin of an attachment). The other jaw is downwardly facing (for dipping down onto a second pin of the attachment once the first pin is in the forward facing jaw). A pivoting latching hook is associated with the downwardly facing jaw. It is for latching the second pin in that downwardly facing jaw. A blocking bar can then swing into a position behind the hook to block the hook—the blocking bar prevents the hook from pivoting backwards (i.e. out of its latched position).
The coupler disclosed in U.S. Pat. No. 6,699,001 also uses a blocking bar. However, in place of the pivoting latching hook, a sliding plate is provided.
GB2359062 also discloses a coupler having a blocking means. However, the blocking means in that coupler is instead in the form of a manual safety pin that is inserted behind the latching hook by the operator, or his assistant, through the sidewalls of the coupler.
The couplers in GB2332417 and EP1318242 instead have a latch for each jaw. The latches are linked together such that either one or the other of the latches will remain in a latched position while the coupler is in use.
Despite the provision of safety features, an operator might still use the coupler incorrectly. Therefore it would be desirable to provide an integral or automatic safety feature for the couplers whereby the likelihood of an accidental disengagement of an attachment from the coupler can be further reduced, even where the coupler is used incorrectly.
These and other features of the present invention will now be described in more detail with reference to the accompanying drawings in which:
FIGS. 6 to 10 are sectional views through preferred front jaw configurations.
The present invention therefore provides an excavator coupler having a top either that is attached to, or that is for attachment to, an excavator arm of a digger, the coupler having a bottom to which an attachment, such as a bucket, can be, or is, connected, the attachment having at least one pin, wherein the coupler comprises a front jaw for engaging that pin, the jaw having an opening for the pin, the opening facing generally longitudinally relative to the length of the coupler and the jaw comprising an interior space, and lips that partially occlude the interior space so as to provide a profile for the jaw that has a widened interior relative either to the gap between the lips or to the opening of the jaw, if narrower, and wherein one lip is provided on an upper wall of the jaw and the other lip is provided on a lower wall of the jaw.
Preferably the jaw's interior space has an intermediate portion behind the lips that is widened relative to the gap between the lips and also widened relative to a back portion of the interior space.
Preferably the back portion defines a seat for the pin. The pin can then sit in that seat when the attachment is secured properly to the coupler.
Preferably the back portion of the jaw is generally circular or radiused, i.e., defining a semi-tubular profile. That feature provides a seat for a round bucket pin of an appropriate size (which will be fractionally smaller than the radius of the back portion), whereby the pin can sit firmly or securely within the back portion of the jaw.
The radiused portion may comprise a curve with more than one radius whereby two or more differently sized round pins can sit firmly or securely within the back portion of the jaw. The two or more radiused curves may be distinctly formed or might instead be blended together.
Preferably the coupler is provided with another jaw which is downwardly facing, i.e. away from the excavator arm, in use. It is for receiving a second pin of the attachment.
Preferably the downwardly facing jaw has a latching hook or a latching plate associated with it. The hook or plate is for locking the second pin within the downwardly facing jaw upon movement or advancement of that latching hook or plate into a latched position.
Preferably the front jaw is a solid member that extends across the full width of the coupler, and preferably with a substantially constant cross section. However, it may be a bifurcated jaw, e.g. by being formed by cutting or forming the jaw's profile into two side plates of the coupler. Additionally or alternatively, it might have a taper, usually on its bottom half, e.g. to form (or partially form) a beak or a point. The taper can ease or facilitate the engagement of the jaw with the first pin.
If the coupler is made of a cast body, preferably milling provides some of the finished surfaces of the coupler. The jaws may be formed or finished by that milling process, or may be formed by the casting. However, the jaws may instead be pre-formed as a separate component, e.g. from a tougher material than the coupler's main body. The jaw may then be welded or otherwise joined to that body. That separate fabrication technique for the jaw, however, is also preferably used when the coupler's main body is made from plate stock, rather than by a casting technique.
Preferably the depth dimension of the partially occluded jaw is oriented in a direction that is inclined from parallel to the longitudinal direction of the coupler. The depth dimension of the jaw may, however, be parallel to that longitudinal direction of the coupler. Most preferably, however, the angle of inclination faces upwards. The angle may be up to 20° from the parallel direction, but most preferably it is about 10° from the parallel direction.
Preferably the front jaw has a width that is less than the widest width of the coupler—the width of the front jaw is measured in a lateral direction of the coupler.
Preferably the downwardly facing jaw has two longitudinally spaced end walls. Preferably the gap between the end walls is wider than the depth of the first jaw—the width of the gap is measured along the longitudinal direction of the coupler)
Preferably the gap of the downwardly facing jaw is at least one and a half times wider than the diameter of a second pin of an attachment suitable for attaching to the coupler. The width of the gap might even be two or three times wider than such a pin. This feature allows the coupler to be used for attaching a wide range of different attachments to the same excavator arm, the attachments having a range of different pin spacings, i.e. the spacing between the pin centers on the attachments).
Preferably the downwardly facing jaw has a profile that comprises two sides and a top that extends between the two sides. The top preferably comprises two concave end portions and a central convex portion between the two concave end portions. Those portions may be blended together so as to provide a top for the jaw with a smooth profile or shape.
Preferably the convex portion has a radius, the centre of which lies substantially on the pivoting axis of the hook (when the coupler has a pivoting latching hook for the downwardly facing jaw).
Preferably the two sides are profiled so as partially to occlude the opening of the downwardly facing jaw. The sides may be rounded off at that opening, and may also be blended with the concave end portions of the top of the jaw.
The lips of the front jaw may extend sharply inward from the upper and lower walls of the jaw, like teeth. More preferably, however, the inside wall of each lip has a curve that blends the upper or lower wall so as to give a smooth profile.
The tips of the lips may be rounded or squared off.
Preferably the lips of the front jaw (or each half of it, if bifurcated) are integrally formed with the rest of the front jaw, thereby making the jaw a unitary structure.
The lips provide two dams that can resist movement of the first pin out of that jaw (i.e. after it has been located into the jaw by passing it through the opening (i.e. through the gap between the lips).
Prior art front jaws usually have no lips, or no more than a small ridge. As a result, in prior art front jaws, a pin would normally be free to fall out of the jaw if it was allowed to slide in the jaw (i.e. if it was not secured into the back of the jaw by the engagement of the latching hook (or plate) against the other pin). The dams of the present invention prevent that freedom to fall out of the jaw.
It is noted, however, that FIG. 1 of GB2332417 shows a front jaw having a lip on its bottom wall. That coupler, however, also requires a latch for closing that jaw. The present invention therefore also provides: an excavator coupler having a top either that is attached to, or that is for attachment to, an excavator arm of a digger, the coupler having a bottom to which an attachment, such as a bucket, can be, or is, connected, the attachment having at least one pin, wherein the coupler comprises a front jaw for engaging that pin, the jaw having an opening for the pin, the opening facing generally longitudinally relative to the length of the coupler and the jaw comprising an interior space, and at least one lip that partially occludes the interior space so as to provide a profile for the jaw that has a widened interior relative to the opening of the jaw, the lip being provided on either an upper wall of the jaw or on a lower wall of the jaw, the front jaw not being associated with a latching means.
The present invention also provides: an excavator coupler having a top either that is attached to, or that is for attachment to, an excavator arm of a digger, the coupler having a bottom to which an attachment, such as a bucket, can be, or is, connected, the attachment having at least one pin, wherein the coupler comprises a front jaw for engaging that pin, the jaw having an opening for the pin, the opening facing generally longitudinally relative to the length of the coupler and the jaw comprising an interior space, and at least one lip that partially occludes the interior space so as to provide a profile for the jaw that has a widened interior relative to the opening of the jaw, the lip being provided on a lower wall of the jaw and the front jaw being associated with a gravity operated latching means, that latching means being provided on an upper wall of the jaw and being arranged to operate under the influence of gravity such that it will fall under the influence of gravity from a normal latching position, in which it partially occludes the interior space, into a non-latching position, upon inverting the coupler.
Preferably, in the non-latching position, the latching means retracts fully from the opening of the jaw such that it no longer occludes the interior space.
Preferably the profile of the intermediate portion of the interior space is stepped outwardly relative to both the back portion and or each lip, and more preferably both in the upper and lower walls of the jaw. The intermediate portion may, however, be stepped outwardly only from the or each lip, or from the or each lip and just one of the upper wall or the lower wall of the back portion.
The height of the or each lip is preferably between 8 and 20 mm, and more preferably between 10 and 17 mm. Preferably the height of the or each lip is between one eighth and one third of the diameter of the pin for which the jaw was designed (or higher), or between one eighth and one third of the height of the opening of the jaw (or higher) or between one eighth and one third of the height (or diameter) of the back portion of the jaw. Most preferably, however, it is about one quarter of the diameter of the pin for which the jaw was designed, or about one quarter of the height of the opening of the jaw or about one quarter of the height (or diameter) of the back portion of the jaw.
Preferably, if a line was to extend across the opening of the jaw, that line would extend substantially perpendicularly between the top and the bottom of the coupler. More preferably, however, the lower half of the jaw projects further outward than the upper half of the jaw, whereby that line would be angled by 10°, or more, from that perpendicular. Then, where two lips are provided, a pin jumping around in the jaw (i.e. when the attachment and coupler are inverted such that the attachment is on top of the coupler, e.g. when the excavator arm and the attachment are in the crowd position) would not readily jump from behind the lip in the upper wall (i.e. the one that is now lowermost due to the inversion) to a position on top of the opposite lip, but instead would jump to a position behind that opposite lip. This makes the pin even less likely to jump out of the jaw. It should be appreciated, however, that that jumping problem does not occur with the coupler and attachment oriented the normal way up (i.e. with the attachment below the coupler). That is because the weight of the attachment will keep the pin behind the bottom lip.
Preferably, the intermediate portion having the widened dimension is defined by cut-outs in either or both of the upper and lower walls of the jaw. The cut-outs extend across the full width of the jaw (i.e. laterally across the coupler). The lips and the back portion are then the parts of the jaw that lie forward and rearward, respectively, of those cut-outs.
Preferably the intermediate portion is defined by a cut-out having a depth and a width, the width (measured longitudinally relative to the coupler) being at least twice the depth. More preferably, the width is more than three times the depth, and most preferably the width is more than four times the depth. This arrangement is to allow the pin to fall full depth into the cut-out, rather than being prevented from doing so because the cut-out is too narrow.
Preferably the cut-out is between 8 and 20 mm deep (whereby a lip height of between 8 and 20 mm is provided). More preferably, the cut-out is between 12 and 17 mm deep.
Preferably the cut-out is between 40 and 80 mm long. More preferably the cut-out is between 46 and 72 mm long.
The present invention also provides an excavator coupler having a top either that is attached to, or that is for attachment to, an excavator arm of a digger, the coupler having a bottom to which an attachment, such as a bucket, can be, or is, connected, the attachment having at least one pin, wherein the coupler comprises a front jaw for engaging that pin, the jaw having an opening for the pin, the opening facing generally longitudinally relative to the length of the coupler and the jaw comprising an interior space, and at least one lip that partially occludes the interior space so as to provide a profile for the jaw that has a widened interior relative to the jaw's opening, the lip being provided on an upper wall of the jaw.
Preferably no moving latch or catch is provided for the front jaw.
Preferably the downwardly facing jaw is associated with a latch or catch. That latch or catch is preferably a pivoting latching hook, although it might instead slide between its open and closed positions.
A safety pin or a blocking bar might be provided for the latch or catch.
The present invention also provides a combination of an attachment (such as a bucket) and a coupler, the coupler having a front jaw and the attachment having a pin for engagement with the front jaw, the front jaw having a front opening extending generally in the longitudinal direction of the coupler relative to the length of the coupler, the jaw having an upper wall with a cut-out therein defining a back portion rearward thereof and a lip forward thereof.
In each embodiment of the present invention, the opening should face no more than 20° from that longitudinal direction of the coupler, but more preferably no more than 15° from that longitudinal direction of the coupler. The longitudinal direction extended between the front and rear ends of the coupler, i.e. generally parallel to the top, the bottom and the sides of the coupler.
Couplers, both of the prior art and of the present invention, usually have a side plate that is positioned nearer the top of the coupler than the jaw, which side plate lies in a plane that is laterally stepped outwardly from the side of the coupler's front jaw. That step-out defines a step-face that faces downwardly, i.e. towards the two jaw. It is preferred that the couplers of the invention similarly have such a step-face.
In conventional attachments, e.g. buckets, the front pin, i.e. the pin for the front jaw of a coupler, is mounted substantially perpendicularly between two plates. Each plate has an upper surface (or is capped by something having an upper surface). In use that upper surface faces the step-face. Preferably, therefore, in accordance with another aspect of the present invention there is provided a combination comprising a coupler of the present invention (as defined above) having both a front jaw and a step-face and an attachment having both a upper surface and a front pin for engagement in the front jaw, wherein the upper surface, in use, faces the step-face, and wherein the front jaw of the coupler is spaced sufficiently downward from the step-face to allow the upper surface of the attachment, in use, to be spaced from the step-face both when the front jaw and the pin are properly seated together, and when the pin is sitting behind the lip in the upper wall, perhaps in a cut-out that defines that lip. This stops any rubbing occurring between the coupler and the attachment, and will prevent the engagement of the upper surface with the step-face from preventing the pin from falling into the cut-out, or from falling behind the lip.
Referring first of all to
Instead of a bucket 16, some alternative excavator attachment might be secured to the excavator arm 12 of the digger 10 by the coupler 14.
As shown in FIGS. 2 to 5, the coupler 14 comprises a top portion 18, a bottom portion 20, and two ends 22, 24. In normal use, the front end 24 is the one that is shown to the right in
The top portion 18 comprises two pairs of holes 26 for attaching the coupler 14 to the excavator arm 12 by using pins, as shown in
The first jaw 28 faces downwardly. It is called the downwardly facing jaw 28. The second jaw 30 faces longitudinally out of the front end 24 of the coupler 14. It is called the front jaw 30.
The coupler is also provided with a lifting eye 36, which can be used to attach things to the coupler for example with a rope or a chain.
Although not shown, the first jaw 28 is associated with a pivoting latching hook, as in GB2330570. It will be appreciated, however, that a sliding plate or sliding hook might be substituted for the pivoting latching hook, as in U.S. Pat. No. 6,699,001.
The latching hook pivots about a pivot hole 34 on a rod (not shown), and its operation is known from GB2330570. A detailed discussion of the operation of that latching hook is therefore not required in this application.
The second, or front jaw 30 faces towards the front end 24 of the coupler 14 (almost parallel to the longitudinal dimension of the coupler—it is inclined at an angle of just 10° in the illustrated embodiments). It opens at that end 24 at an opening, as shown in
The opening of the jaw is partially occluded by both a top lip 38 and a bottom lip 40. Further, those lips 38, 40 extend across a significant part of the width of the coupler 14. In an alternative embodiment, however, the lips 38, 40 may be intermittent across the width of the coupler, like spaced-apart teeth.
The jaw is made as a solid one piece jaw of a toughened steel. The body is made by casting. The jaw is then welded into that cast body. That construction might be replaced, however, with an additional number of components that are welded together. For example, there might be a bifurcated jaw formed from two appropriately shaped side plates that are welded onto a frame, the side plates having two matching jaws cut into them. The lips then might extend just across the widths of those sidewalls.
The lips provide the jaw with a new profile, when compared to the front jaw in GB2330570.
The profile of the jaw includes the lips 38, 40, a substantially semi-circular back portion 42 and an intermediate portion 44. The lips 38, 40 have opposing flat faces that are parallel to each other, whereby there is a constant gap between them. The opposing faces might instead be rounded, however.
The gap between the top and bottom lips 38, 40 of the jaw 30 defines the diameter of the back portion 42 of the jaw 30.
Between the lips 38, 40 and the back portion 42 there is the intermediate portion 44. The intermediate portion 44 is widened relative to them both. This makes the lips 38, 40 partially occlude the interior space defined by the back portion and the intermediate portion.
The intermediate portion is both widened relative to the dimension of the gap between the lips and widened relative to the diameter of the back portion of the jaw 30. It might, however, only be widened relative to the gap between the lips—the back portion would then not be distinct from the intermediate portion. Nevertheless, in the illustrated embodiment, the intermediate portion 44 is widened relative to the back portion and the lips by two stepped out portions (or cut-outs). One is in the upper wall 46 of the jaw. The other is in the lower wall 48 of the jaw 30. Those cut-outs each comprises an angled step 50 (the two steps are substantially opposite each other, although the step 50 in the lower wall 48 is slightly further forward than the step 50 in the upper wall 46). The step 50 (more clearly seen in
The transitions between the back portion 42, the angled steps 50, the flat wall sections 52, the rounded or blended section 54 and the lips 38, 40 can be sharp. However, they are more preferably blended so as to avoid stress concentrations. The backsides of the lips 38, 40, however, have a straight section after the blended section 54. The straight section butts up to the flattened tips of the lips, which flattened lips define the opening. That transition may also be rounded, as can the opening. Indeed, the tips of the lips can be rounded.
As discussed above, a lip is provided for the lower wall of the front jaw of the coupler shown in FIG. 1 of GB2332417. That jaw, however, does not have a cut-out that defines a back portion for its jaw. The present invention is additionally differentiated from that prior art coupler's front jaw by having a lip also on the upper wall 46 of the jaw 30. Yet further, the preferred embodiments of the present invention do not have a moving closing mechanism (e.g. a catch or a hook) for the front jaw. The front jaw in GB2332417, however, does require a moving closing mechanism.
In alternative embodiments of the present invention, only a single cut-out might be provided, either in the upper wall or in the lower wall, or the transitions between the various parts of the jaw might be more or less blended than that illustrated, or the back portion 42 might be wider or narrower than the gap between the lips, or even the intermediate portion 44 may be either more or less pronounced (i.e. more or less widened relative to either the lips or the back portion or both of them).
The jaw configuration of the present invention, in use, enables a pin to retain its location within the front jaw 30 even in the event that the latching hook provided for the other jaw (i.e. the downwardly facing jaw 28) is inadvertently withdrawn from a latched position to an open or unlatched position, whereby the pin would normally have been free to fall out of the front jaw since the longitudinal position of the pin was no longer restrained by that hook. There are two scenarios where that inadvertent decoupling might have happened:
1. If the coupler is in its upright position, i.e. above the bucket, the pin in the downward facing jaw would be free to swing out of that downwardly facing jaw if the coupler was to be lifted by rotation of the bucket about the pin in the front jaw. Once swinging freely (i.e. once the bucket is also lifted, only the front jaw would be holding the weight of the bucket, via the pin in that front jaw. Naturally, while the pin remains in the back portion of the front jaw, the bucket will be carried. However, if the front jaw was to be pointed downwardly by rotating the coupler, then the pin in that front jaw would be likely to slide out of that back portion. Without the lip, the pin would then fall out of the coupler. The lip of the present invention, however, catches the pin before it falls out, thereby preventing the pin from failing out. That lower lip, in other words, forms a dam over which the bucket pin is unlikely to be able to pass without violent shaking or careful manipulation of the excavator arm.
2. If the coupler was the other way up, i.e. in the “crowd” position, then it is the other lip that forms the dam. However, in that orientation, the pin in the “downwardly facing” jaw (i.e. the one now pointing upwardly since the coupler is inverted) will not try to disengage from that jaw as readily anyway since the weight of the bucket holds the pin in that jaw, which in turn restricts the amount of sliding available to the pins to, at most, the free width of that downwardly facing jaw. Unfortunately, however, that free width can be sufficiently long in couplers designed to fit to attachments having a very wide range of pin spacings to allow disengagement of the front pin from the front jaw. The dam, therefore, again serves to prevent that disengagement. The lip in that upper wall, therefore, is of particular benefit for universal couplers, i.e. couplers designed to fit attachments having a wide range of different pin centre spacings.
The lips also provide the advantage that no latching means (or other moving part) for the front jaw is needed in order to resist the disengagement of a pin from that front jaw in the event of an inadvertent disengagement of the latching hook for the downwardly facing jaw. The jaw, therefore, provides an inherent safety feature, i.e. one involving no moving parts that can fail.
Referring now to
The jaw in
The two cut-outs will both allow a 80 mm pin to fall into them to a depth that is about one quarter of the diameter of the pin (actually 17/80 of the diameter). The jaw is also angled upward from the longitudinal direction of the coupler by 10°.
The jaw in
The jaw in
Then there is the jaw of
As with the other jaws, this jaw is also angled upward from the longitudinal direction of the coupler by 10°.
Referring finally to
The toggle is a feature provided in the couplers disclosed in GB0617394.4, the full contents of which are incorporated herein by way of reference, and from which this case claims the benefit of priority.
As disclosed therein the toggle 60 is mounted within a hole 64 in the upper wall 63 and is mounted for rotation about a pivot axis, as defined by a peg or bolt 66 that passes through the hole 64 in a transverse direction (i.e. transverse to the sides of the coupler). The bolt may be held in position by a bolt head and a nut.
The toggle 60 may pivot about the bolt 66 between an open or non-latching position in which the toggle 60 sits fully within the hole 34, i.e. so as not to partially occlude the opening 31 of the front jaw 30, and a closed or latching position, as shown in
That toggle is mounted off-center relative to the bolt 36, whereby it is balanced so that in a normal orientation of the coupler 10, i.e. in an in-use orientation in which the front and rear jaws (and therefore also any attachment pins held therein) are generally level to each other, the toggle's center of gravity will cause it to rotate under the influence of gravity into that latter closed position in which the nose or end 62 descends into the front jaw so as to partially close the opening 31 of the front jaw 24.
By having this arrangement, in normal use an attachment pin within that front jaw will only be able to be removed from the front jaw through the opening 31 of the jaw if the toggle was to rotate out of its way. That is because attachment pins have a size corresponding generally to the height of the front jaw. However, further rotation of that toggle is not possible due to the configuration of the toggle, the bolt and the hole. The toggle in its closed position has a wall 78 that bears against a front wall member 72 of the hole 64. Further, preferably that front wall member 72, the bolt 66 and the toggle 60 are all reinforced, toughened or hardened as well, whereby they should be able to resist even a significant attempt to force an attachment pin out of the jaw.
The toggle 60 preferably comprises at its first end (surrounding the bolt) two perpendicular walls 74, 78 that tangentially extend from a curved section 76. There is also a third wall 79 that extends parallel to and perpendicular to the two other walls 74, 78, respectively. Further, that first end has an aperture therein through which the bolt 66 passes for pivotally mounting the toggle 60 within the hole 64 of the front jaw 30. The aperture is between the two parallel walls 78, 79 and runs parallel to all three walls 74, 78, 79.
The hole 64 in the upper wall 63 of the front jaw 30 has a flat bottom 81 and the inside surface of the front wall member 72 extends perpendicular to that flat bottom 81. That inside surface also is flat.
The bolt 66 is arranged through the hole 64 of the first jaw 30 in a position that is spaced from, yet parallel to, both the flat bottom 81 and the inside surface of the front wall member 72. The distance of the bolt 66 from the inside surface is slightly greater than the radius of the curved section 76 of the toggle. The distance of the bolt 66 from the flat bottom is greater than its distance from the inside surface.
The aperture in the toggle is arranged concentrically to the curved section 76 of the toggle. As a result, the toggle will be free to rotate within the hole 64 through a full 90° range of angles, i.e. between its open and closed positions. In the open position, the first of the two perpendicular walls 74, 78 will bear against the front wall 72 to provide a first rotation limitation for the toggle. In the closed position, the second of the two perpendicular walls 74, 78 will bear against the front wall 72 to provide a second rotation limitation for the toggle. Changing the angle between these two perpendicular walls 74, 78 will therefore change the available range of angles of rotation for the toggle.
In addition, the toggle comprises the opposite end 62—the end 62 that extends out of the hole 64 when the gravity-operated member 60 is in its closed position. That end 62 comprises a curved wall 90 that will face towards an attachment pin when one is within the front jaw and when the member 60 is in its closed position. That curved surface, although optional, provides an increased area of surface contact between the attachment pin and the toggle in the event of an attempt to remove the attachment pin from the front jaw through the opening of the jaw when the member is in its closed position. As a result, forces are less concentrated on the toggle.
No biasing member is provided for the toggle, whereby it relies purely upon gravity for its orientation. However, as a result it is free to rotate within that 90° range if it is acted upon by an external force. Accordingly, although the toggle will prevent the withdrawal of an attachment pin from the front jaw, the toggle will rotate to allow an attachment pin to be inserted into the jaw.
By positioning the aperture for the bolt in the first end of the toggle, the centre of gravity of the toggle is arranged towards the second end of the toggle relative to its pivot axis. Thus the gravity-operated member will default to a closed position whenever the coupler is level. However, the toggle can be moved to its open or non-latching position by rotating the coupler through an angle of about 90°, i.e. into the crowd position.
The present invention has been described above purely by way of example. However, modification in detail to the present invention may be made within the scope of the invention as defined in the claims appended hereto.
| Number | Date | Country | Kind |
|---|---|---|---|
| GB 200525379.4 | Dec 2005 | GB | national |
| GB 200617394.2 | Sep 2006 | GB | national |
