4587-1.doc Adapter for a skid steer loader bucket Field of Invention This invention relates to earth moving equipment and more particularly to improving the usefulness of conventional 3 to 8 ton excavators. However the 5 invention is not limited to use with 3 to 8 ton excavators. Background Conventional excavators have a bucket mounted on an articulated arm via a hitch. The hitch allows the bucket to pivot in line with the arm (i.e. about a generally horizontal axis extending across the line of the arm. The hitch may 10 also provide for rotation about an axis in line with the arm, so as to provide sideways angulation of the bucket. The arm itself may be mounted on the excavator body for rotation about a generally vertical axis. Whilst excavators are efficient for digging up soil they are generally not very efficient in moving soil around, particularly when filling trenches or otherwise 15 "cleaning up" because the bucket is a single unit and so must be pushed up against an object to push the soil into the bucket. Skid steer loaders generally have a two piece bucket mounted on a pair of arms that rotate about a horizontal axis. The two part nature of the bucket allows a skid steer loader bucket to efficiently pick up soil or other debris. 20 However, because the bucket is on a single axis, movement of the skid steer bucket requires movement of the entire vehicle. Frequently it is necessary to use a skid steer loader to "tidy up" after using an excavator. Mounting of a conventional skid steer loader bucket to an excavator would 4587-1.doc -2 provide for improved efficiency of the excavator by allowing the skid steer bucket to rotate about more than one axis and avoid the need to use a separate skid steer loader for tidying up. Summary of the Invention 5 In one broad form the invention provides an adaptor for a skid steer bucket for enabling mounting of the skid steer bucket on an excavator hitch, the skid steer bucket having at least one first mounting for mounting to a skid steer loader, the excavator hitch having at least one second mounting for mounting to an excavator bucket, the adaptor having at least one third mounting for 10 engagement with the at least one first mounting of the skid steer bucket and at least one fourth mounting for engagement with the at least one second mounting of the hitch. Preferably the at least one first mounting includes at least one first recess and the at least one third mounting includes at least one first protrusion adapted 15 to be inserted into the at least one first recess. Preferably the at least one first mounting includes at least one first aperture and the at least one third mounting preferably includes at least one second protrusion adapted to pass through a corresponding first aperture. Preferably the at least one first protrusion comprises an angled edge. There 20 may be a single first protrusion that extends transversely across at least part of the width of the adaptor. The protrusion may comprise a top edge of the adaptor. Alternatively, two or more transversely spaced first protrusions may be utilised. The at least one second protrusion preferably comprises one or more pins 25 movable between retracted and extended positions. Preferably the or each pin is biased to the extended position.
4587-1.doc -3 Preferably the at least one fourth mounting includes an elongate pin about the axis of which the adaptor is rotatable when mounted on the hitch. Preferably the at least one fourth mounting includes the at least one actuator mounting, for connection to an actuator mounted on the hitch, whereby the 5 at least one actuator controls the position of the adaptor about the axis of the pin. Preferably the at least one actuator mounting includes two actuator mountings located in a plane spaced from the elongate pin. Preferably the two actuator mountings are either side of a line from the axis perpendicular (90 degrees) to the plane. 10 The fourth mounting may be fixed relative to the third mounting and rotation of the adaptor is via rotation of the excavator hitch. Preferably the adaptor comprises a generally planar plate having a centreline a width, a front surface and a rear surface, an upper edge comprising the at least one protrusion, a lower edge, the at least one protrusion comprising two 15 pins movable between a retracted position in which they are fully or substantially between the upper and lower edges and an extended position in which they extend beyond the lower edge, the two pins being located either side of the centreline, the fourth mounting including an elongate pin about the axis of which the adaptor is rotatable when mounted on the hitch, the 20 elongate pin being parallel to the centreline and two actuator mountings located either side of the centreline, the elongate pin being spaced further from the rear surface than the two actuator mountings. Preferably the plate includes a lower wall extending at least partway along or adjacent to the lower edge. Side wall(s) may extend at least partway along or 25 adjacent to one or both of the side edges. An upper wall may extend at least partway across the width adjacent to the upper edge, most preferably spaced from the upper edge. Each of these walls may be joined to one or more of the 4587-1.doc -4 other walls. Each wall may be discontinuous, so that there are multiple walls extending along or adjacent an edge.The at least one second protrusion preferably passes through or below the lower wall. The at least one second protrusion may extend through or above the upper wall. 5 Brief Description of the Drawings Figure 1 is a schematic perspective view of the adaptor of an implementation of the invention mounted to an excavator hitch. For clarity some components have been omitted. Figure 2 is a perspective view from the rear and top of the adaptor of figure 1. 10 Figure 3 is a plan view from the rear of the adaptor of figure 1. Figure 4 is a side view of the adaptor of figure 1. Figure 5 is a perspective view from the rear and side of the adaptor of figure 1. Figure 6 is a perspective view from the rear and side of a skid steer bucket for 15 use with the adaptor of figure 1. Figure 7 is a plan view from the rear of a variation of the adaptor of figure 1. Figure 8 is a plan view from the rear of an adaptor for use with a powered excavator head. Detailed Description of Preferred and other Embodiments 20 Referring to the drawings there is shown an adaptor 10 to enable connection of a standard skid steer bucket 12 to a conventional excavator hitch 14. The hitch 14 has mounting pins 16, 18, that connect to the arm of the 4587-1.doc -5 excavator (not shown). Typically the hitch 14 may rotate about axis of pin 16 whilst an actuator engages pin 18. Other mounting arrangements may be used. The adaptor 10 has a central pin 20 that is connected to the hitch 14 and, when mounted, the adaptor 10 may pivot about the axis of pin 20. The hitch 5 includes hydraulic rams 22, 24 that are mounted to pins 26 on the adaptor 10. By extending one of the rams and contracting the other the adaptor 10 is caused to rotate about axis of pin 20. The adaptor 10 has a generally planar steel sheet base 30. The width and height of the base are such that it may be connected to a conventional skid 10 steer bucket. In this embodiment the base 30 of adaptor 10 is about 16 mm thick, about 1120 mm wide and about 400 mm tall. A steel sheet wall 32 about 100 mm tall and 16 mm thick extends upwards from the rear face 34 of the base. The wall 32 supports the central pin 20 spaced apart from the rear face 34, preferably about 155 mm from rear face 34. The pins 26 are mounted 15 between flanges 36 that extend between the base 30 and the wall 32. The wall 32 provides structural support to the base 30 and the flanges 36. The wall 32 extends along the lower edge 38 of base 30 and part way along sides 40, about 400 mm. The wall extends across the base between sides 40 spaced from upper edge 42 by about 70 mm. The wall 32 provides strength to 20 the base 30 as well as support to the flanges 36. If desired the base 30 may be formed as a unitary casting or machined block with suitable locations for the pins 26 and with suitable reinforcing/strengthening members. The upper edge 42 is angled, with an angled face 44 about 35 mm long. Located at the bottom edge 38 of the base 30 are two locking pins 46, 25 mounted on mounting 48 within the wall 32 and movable to extend through an aperture 50 in wall 32. The pins may be fully retracted within the perimeter 4587-1.doc -6 of wall 32. The free ends 52 of pins 46 are preferably angled, as seen in figure 5, at about 45 degrees but other angles may be used. Referring to figure 6, a conventional skid steer bucket 60 has a rear portion 62 with an angled recess 64 at an upper end. Two spaced apart pin receiving tabs 5 66 extend rearwards from the base of the mounting plate 62. Apertures 68 in these tabs are sized to receive a securing pin. The adaptor 10 is sized so that the upper edge 42 fits within the upper recess 64 of the conventional skid steer bucket 60 and f tat against the rear of the mounting plate with the securing pins 46 aligned with the apertures 68 in the 10 tabs 66. The adaptor 10 and bucket 60 are secured together by extending pins 46 downwards and through apertures 68. Preferably the pins 46 are spring loaded to an extended position and are caused to partially retract by the action of pivoting the adaptor 10 about the upper recess 64 and bringing the lower edge 15 38 toward the mounting plate, causing the tabs 66 to engage angled faces 52 of pins 46 and urge them inwards until they align with apertures 68, at which point they spring outwards and pass into apertures 68. The bucket is then secured to the adaptor 10. Removal merely requires manual withdrawal of the pins 46 from apertures 68 and rotation of the adaptor 10 so that the pins 46 20 clear the apertures 68, at which point the adapter may be lowered to clear the recess 64 and then withdrawn. The bucket 60 has a jaw 70 movable relative to the rear portion 62. This movement is achieved by use of hydraulic rams (not shown), typically located at either side of the bucket. In the preferred embodiment by spacing the 25 central pin 20 significantly further away from the base plate than the ram pins 26, the rams 22, 24 are caused to be significantly angled relative to the base plate, as seen in figure 1. This provides additional space for hydraulic lines 4587-1.doc -7 feeding the hydraulic rams of the bucket 60. As mentioned above, the central pin 20 is located about 155 mm above the rear face 34. The ratio of this height to width is 155/1120 or about 1:7. Once the bucket is secured to the adaptor 10 it may be used in a conventional 5 manner but with the added degrees of movement provided by the excavator arm and four way hitches. This enables the excavator to pick up debris much more efficiently compared to using a conventional excavator bucket. In addition, the four way hitch allows the skid steer bucket to be easily aligned with a straight edge, such as kerbing. 10 Figure 7 shows an adaptor 110 similar to the adaptor 10 of figures 1 to 6. For clarity the central mounting pin 20, hitch 14 and actuators 22 t 24 are not shown. In this embodiment retaining pins 146 extend from the bottom to the top of the adaptor 110, passing through wall 32. A spring, not shown is mounted on 15 each pin 146 between the upper wall 32 and keeper or flange 158 on pin 146, so as to urge the pin 146 downwards. The top of each pin 146 is connected to a release bar 148 at pivot point 150. The free end 154 of release bar 148 may be rotated about other end 152, which bears against wall 32, to draw pin 146 upwards. Release bar 148 preferably has an aperture tab through which pin 20 156 extends. A safety clip or split pin may be secured to pin 156 to retain the release bars in the position shown and prevent accidental release of the respective retaining pin 146. Lengthening the pins to extend upwards through the upper wall enables the release pins 146 to be easily retracted to disengage the bucket from the adaptor. 25 Whilst the embodiment shown in the figures 1 to 7 designed for use with a conventional excavator which has a simple, non-rotating hitch, the invention may be modified for use with an excavator with a power head. Figure 8 shows 4587-1.doc -8 a modification in which an adaptor 158 is provided with a central mounting 160 for two mounting pins 162 that are the equivalent of pins 16 and 18 of the figure 1 embodiment. These mounting pins 162 allow a powered head to connect to the adaptor 158, with the powered head providing the pivoting 5 function provided by central pin 20 and rams 22 and 24 of the figure 1 embodiment. Unless the context clearly requires otherwise, throughout the description and any claims the words "comprise", "comprising", and the like are to be construed in an inclusive sense as opposed to an exclusive or exhaustive sense; 10 that is to say, in the sense of "including, but not limited to". The features of the invention described or mentioned in this document may be combined in any combination of features where features are not mutually exclusive. It will be apparent to those skilled in the art that many obvious modifications 15 and variations may be made to the embodiments described herein without departing from the spirit or scope of the invention.