(12) INTERNATIONAL APPLICATION PUBLISHED UNDER THE PATENT COOPERATION TREATY (PCT)
`
`(19) World Intellectual Property Organization
`International Bureau
`
`( 43) International Publication Date
`13 March 2008 (13.03.2008)
`
`PCT
`
`(51) International Patent Classification:
`E02F 3/36 (2006.01)
`
`11111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111111
`
`(10) International Publication Number
`WO 2008/029112 A2
`Greenwood, Southview, Fatfield, Washington, Tyne &
`Wear NE38 8AH (GB).
`
`(21) International Application Number:
`PCT/GB2007 /003324
`
`(22) International Filing Date:
`4 September 2007 (04.09.2007)
`
`(25) Filing Language:
`
`(26) Publication Language:
`
`English
`
`English
`
`(30) Priority Data:
`0617394.2
`0711428.3
`
`4 September 2006 (04.09.2006) GB
`13 June 2007 (13.06.2007) GB
`
`(71) Applicant (for all designated States except US): MILLER
`UK LIMITED [GB/GB]; Bassington Industrial Estate,
`Bassington Lane, Cramlington, Northumberland NE23
`8AD (GB).
`
`(72) Inventors; and
`(75) Inventors/Applicants (for US only): MILLER, Gary
`[GB/GB]; 9 Camoustie, Usworth, Washington, Tyne
`& Wear NE37 1ND (GB). MILLER, Ronald, Keith
`[GB/GB]; Kenton House, 13 kenton Avenue, Gosforth,
`Newcastle upon Tyne NE3 4JD (GB). PENDLETON,
`Gary [GB/GB]; 27 Badgers Wood, Stanley, County
`Durham DH9 OHR (GB). REAY, Howard [GB/GB]; 2
`
`(74) Agents: TUNSTALL, Christopher, Stephen eta!.; Carp(cid:173)
`maels & Ransford, 43-45 Bloomsbury Square, London
`WC1A 2RA (GB).
`
`(81) Designated States (unless otherwise indicated, for every
`kind of national protection available): AE, AG, AL, AM,
`AT, AU, AZ, BA, BB, BG, BH, BR, BW, BY, BZ, CA, CH,
`CN, CO, CR, CU, CZ, DE, DK, DM, DO, DZ, EC, EE, EG,
`ES, FI, GB, GD, GE, GH, GM, GT, HN, HR, HU, ID, IL,
`IN, IS, JP, KE, KG, KM, KN, KP, KR, KZ, LA, LC, LK,
`LR, LS, LT, LU, LY, MA, MD, ME, MG, MK, MN, MW,
`MX, MY, MZ, NA, NG, NI, NO, NZ, OM, PG, PH, PL,
`PT, RO, RS, RU, SC, SD, SE, SG, SK, SL, SM, SV, SY,
`TJ, TM, TN, TR, TT, TZ, UA, UG, US, UZ, VC, VN, ZA,
`ZM, ZW.
`
`(84) Designated States (unless otherwise indicated, for every
`kind of regional protection available): ARIPO (BW, GH,
`GM, KE, LS, MW, MZ, NA, SD, SL, SZ, TZ, UG, ZM,
`ZW), Eurasian (AM, AZ, BY, KG, KZ, MD, RU, TJ, TM),
`European (AT, BE, BG, CH, CY, CZ, DE, DK, EE, ES, Fl,
`FR, GB, GR, HU, IE, IS, IT, LT, LU, LV, MC, MT, NL, PL,
`PT, RO, SE, SI, SK, TR), OAPI (BF, BJ, CF, CG, CI, CM,
`GA, GN, GQ, GW, ML, MR, NE, SN, TD, TG).
`
`Published:
`without international search report and to be republished
`upon receipt of that report
`
`(54) Title: COUPLER
`
`-iiiiiiiiiiii
`
`!!!!!!!! -
`
`iiiiiiiiiiii ----iiiiiiiiiiii -
`----iiiiiiiiiiii
`iiiiiiiiiiii ----
`
`6
`
`M
`,..-.!
`,..-.!
`0\
`M
`0 .........
`~ (57) Abstract: Couplers (10, 110) for attaching an accessory to an excavator arm of an excavator. Couplers comprise a first side
`0
`for attaching the coupler to the excavator arm and a second side onto which the accessory will be coupled. The coupler comprises a
`M
`latch (26, 34, 130, 154) for selectively securing and releasing an attachment pin (52, 54) of the accessory in a jaw, groove, hook or
`0 slot in the second side of the coupler. The coupler is fully controllable from within the cab of the excavator and it allows improved
`> security in the securement of the accessory to the coupler, i.e. preventing accidental decouplings, but while still allowing intentional
`
`~ decoupling operations to be carried out without undue burden.
`
`Page 1 of 85
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`CATERPILLAR EXHIBIT 1005
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`wo 2008/029112
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`PCT/GB2007/003324
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`1
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`COUPLER
`
`This application claims priority from both GB0711428.3 and GB0617394.2, the whole
`
`contents of which are incorporated herein by way of reference for supporting the
`
`5 disclosure of this application. In brief, however, the present invention relates couplers
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`for attaching an accessory, such as an excavator bucket, to an excavator arm of an
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`excavator. Generally a coupler will comprise one or two jaws (or grooves, hooks or
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`slots) and one or two latches for selectively securing (or releasing) one or two
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`attachment pins of the accessory in the or each jaw (or groove, hook or slot).
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`10
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`Many couplers have been developed in the art. Some are fully automatic, i.e. fully
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`operable from within the cab of the excavator for both coupling and decoupling an
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`accessory to or from the coupler and some are part automatic I part manual, requiring
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`many or most operations for coupling and decoupling of an accessory to or from the
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`15 coupler to be carried out from within the cab, but with one or more operations needing to
`
`be done instead at the coupler itself.
`
`A part automatic and part manual coupler is disclosed in GB2359062. The coupler is
`
`attached remotely to the accessory, i.e. from within the cab of the excavator. However,
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`20
`
`that attachment is made more secure by an additional manual step - the insertion of a
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`safety pin into a position behind a pivoting latching hook of the coupler.
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`A fully automatic coupler is disclosed in GB2330570. It has a gravity operated blocking
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`bar that is designed to fall behind the rear latching hook during normal use, whereby
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`25 when the coupler is in use, and therefore in a normal, in-use or upright, orientation, the
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`latching hook is prevented from being retracted by the presence of the blocking bar
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`behind the latching hook. To release the accessory, however, that blocking bar is lifted
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`from that blocking position either by a second hydraulic ram (i.e. one that is not
`
`connected to the latching hook) or simply by inverting the coupler, i.e. by moving the
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`30 excavator arm and coupler into either the crowd position or to a position curled above
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`the excavator arm (an unconventional position for an excavator arm to assume). In that
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`inverted orientation, the blocking bar will fall away from its blocking position to allow
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`2
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`the latching hook for the rear attachment pin then to be retracted by the latching hook's
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`own hydraulic ram.
`
`There are also many other couplers, either fully automatic or part automatic and part
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`5 manual. See, for example, the couplers disclosed in the following publications:
`
`Australian Patent AU557890, German Utility Model DE20119092U, European Patent
`
`Applications EP0405811 and EP1318242, GB Patent Application GB2332417, US
`
`Patents US5692325 and US6132131, and PCT Publication W099/42670.
`
`10 The majority of prior art couplers have a first (or top) half that is for attaching the
`
`coupler to the excavator, and that attachment is generally to an excavator arm of the
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`excavator. The coupler of EP0405813, however, is instead for attaching a digger bucket
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`to the front end loader of the excavator. The couplers then have on the other or opposite
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`side of the coupler two attachment pin engaging jaws, grooves, hooks or slots, whereby
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`15 an accessory having a pair of attachment pins (such as an excavator bucket) can be
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`attached to that coupler via the pair of attachment pins: one of the jaws, grooves, hooks
`
`or slots is for engaging a first or front attachment pin of the accessory and the other jaw,
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`groove, hook or slot is for engaging the second or rear attachment pin of the accessory.
`
`20 Couplers are also known for attaching accessories that have only one attachment pin.
`
`Those couplers have just one jaw, groove, hook or slot. Typically, however, the
`
`accessory then has the other jaw, groove, hook or slot for engaging a second attachment
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`pin, which is instead positioned on the coupler.
`
`25 Despite the existence of numerous designs of coupler, there is still an ever increasing
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`demand upon the industry for the provision of even more security for fully automatic
`
`couplers, and for which couplers no manual steps need to be carried out by the user on
`
`the coupler for completing the securement or detachment of an accessory. A purpose for
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`this drive is that it allows the user to remain within the safe environment of the cab of the
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`30 excavator. This is important since accessories and couplers are typically quite large and
`
`heavy pieces of equipment, and thus they are potentially dangerous when being
`
`manipulated by an excavator.
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`3
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`For couplers having a pair of jaws, one of the jaws usually faces downwards, i.e. away
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`from the first half of the coupler, and that jaw is usually referred to as the rear jaw- it is
`
`normally located, in use, the furthest away from the cab, and excavator arms usually
`
`5 extend from a rear of the excavator. Due to its position, and the way it faces in use, often
`
`that jaw is not visible from the cab. The other jaw, however, usually faces away from
`
`that rear jaw and towards the cab. It generally is also rotated by approximately 90°
`
`relative to the rear jaw, i.e. instead of pointing downwards, it usually points forwards. It
`
`is usually, in use, nearer to the cab than the rear jaw and thus it is usually referred to as
`
`10
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`the front jaw.
`
`In many such prior art couplers a pivoting or sliding latching hook or latching plate is
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`provided for the rear jaw for locking an attachment pin within that jaw. Thus, to couple
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`the accessory to the coupler, a first or front attachment pin is first engaged into an open
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`15
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`front jaw of the coupler, and the coupler is then rotated or manipulated relative to the
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`accessory to position the second attachment pin into the coupler's open rear jaw. Then
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`the latching hook or latching plate is driven rearwardly, for example by a hydraulic
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`piston or a screwthread, to close the rear jaw to lock the rear attachment pin within the
`
`rear jaw. That in turn locks the front attachment pin in the front jaw.
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`20
`
`Such a securement of the accessory to the coupler is entirely secure, subject to there
`
`being no failure of the respective components of the coupler. However, users of such
`
`couplers additionally demand back-up safety mechanisms to be incorporated into those
`
`couplers to provide assurances that an accessory cannot accidentally be decoupled from
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`25 a coupler, even if the drive mechanism for the latching hook or the latching plate is
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`accidentally retracted or in the event of a mis-use of the coupler, or even in the event of a
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`failure of a component of the coupler or the accessory. Further, there is a drive towards
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`making the back-up safety features both automatic to implement and visible from within
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`the cab. By being automatic, they cannot be omitted or forgotten by the user, and by
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`30 being visible from the cab it is possible to assess their status from the cab, i.e. to carry
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`out a remote visual check as to whether the safety features have adopted their correct
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`back-up safety position for ensuring a backed-up securement between the coupler and
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`4
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`the accessory. Further, the demand is for such couplers that still allow fully automatic
`
`coupling and decoupling of the accessory from the coupler.
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`It should also be observed that many prior art couplers have the provision for
`
`5 accommodating different accessories, i.e. ones having different distances between their
`
`respective attachment pins. That allows accessories from different manufacturers, or
`
`from different product ranges, to be accommodated by the coupler (it is commonplace
`
`for different buckets and other accessories from different manufacturers to have different
`distances between their pairs of attachment pins, i.e. different pin spacings). Prior art
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`10 couplers generally achieve that by the provision of either a screwthread drive system or a
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`hydraulic ram mounted between the two jaws, grooves, hooks or slots. The screwthread
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`or a hydraulic ram can then move one or both of the jaws, grooves, hooks or slots
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`relative to a frame of the coupler to accommodate the different pin spacings. Generally
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`speaking, however, just one of the jaws, grooves, hooks or slots is moved by the
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`15
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`screwthread or hydraulic ram, and that one is most frequently the rear one (or the latch
`
`associated therewith).
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`The securement of the two attachment pins within the two jaws is generally by a relative
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`separation of the two pin-engaging components. That securement of the two fixed
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`20 attachment pins of the accessory within the two jaws of the coupler can be referred to as
`
`a primary securement since it alone provides a securement of the accessory to the
`
`coupler. Such primary securement mechanisms are strong and thus are generally reliable
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`since it is most unlikely that a component of it, such as either the screwthread or the
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`hydraulic ram, or the hook or jaw themselves, will fail. That is because these items are
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`25 all designed to meet the demands of the usual environment of use for the coupler.
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`Indeed, these items are often "over-engineered" to provide a significant overload buffer).
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`Despite that, however, it is usual to provide the above mentioned back-up safety (or
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`failsafe) mechanisms to prevent the accessory from decoupling from the coupler in the
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`unlikely event of such a failure.
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`30
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`Such safety back-up mechanisms, as known in the art, include at a most simple level,
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`just a cover for the actuation circuit (usually in the cab of the excavator). That prevents
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`accidental access to the actuation switches during use of the accessory. However, there is
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`5
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`a demand for additional security. As such, failsafe mechanisms are provided in or on the
`
`coupler itself. See, for example, the coupler of EP1318242. It has a spring driven hook
`
`for the front jaw, which hook defaults to a closed state for securing a front attachment
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`pin within the front jaw of the coupler. Therefore, even if the rear hook fails, the
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`5 accessory is secured within the coupler. A problem with that coupler, however, is that if
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`the decoupling command is given accidentally, the spring driven hook will automatically
`
`be retracted by the hydraulic ram as the sliding rear jaw reaches a fully retracted
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`position. US6132131 and US5692325 similarly provide a latching hook for the front jaw
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`that is driven by the rear jaw's hydraulic ram, and as such they also have that same
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`10 problem.
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`In GB2332417, however, a toggling dual-hook arrangement is provided -
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`there are two moving hooks that are interconnected by a toggling arrangement to ensure
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`that as one hook opens the other hook closes, and vice versa. This prevents both hooks
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`from opening simultaneously. However, if either the link or one of the hooks fails, the
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`coupling between the accessory and the coupler becomes vulnerable.
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`15
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`20
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`The present invention, therefore, seeks to provide coupler designs that are both fully
`
`controllable from within the cab, and that will allow improved security in the securement
`
`of the accessory to the coupler, i.e. preventing accidental decouplings, but while still
`
`allowing intentional decoupling operations to be carried out without undue burden.
`
`According to a first aspect of the present invention there is provided a coupler for
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`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,
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`25 wherein:
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`the second portion has two jaws, one for receiving a first attachment pin of an
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`accessory and the other for receiving a second attachment pin of the accessory;
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`a first latch is associated with the first jaw for securing the first attachment pin
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`within the first jaw when the first latch is in a latching position;
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`30
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`a second latch is associated with the second jaw for securing the second
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`attachment pin within the second jaw when the second latch is in a latching position;
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`6
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`a third latch is provided that extends between the first and second latches, the
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`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
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`when the third latch is in a non-latching position, the first latch is not resisted
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`5
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`from moving between a latching position and a non-latching position by the third latch.
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`Preferably the second latch is linked or connected to the third latch.
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`Preferably the second latch is pivotally linked to the third latch. They may, however, be
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`10 an integrally formed member.
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`In another arrangement, the second and third latches are separate components that are
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`selectively engageable with each other by movements of one or both of those latches,
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`and wherein the third latch also resists movement of the second latch from a latching
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`15 position into a non-latching position when it is itself in a latching position but wherein it
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`will not resist movement of the second latch from a latching position into a non-latching
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`position when it is in some other predetermined position. Preferably that predetermined
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`position cannot be assumed by the third latch while a first attachment pin is secured
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`within the first jaw by the first latch. Preferably that is achieved by the provision of a
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`20
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`flange on the first latch that restricts movement of the third latch while a first attachment
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`pin is secured within the first jaw by the first latch.
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`Preferably the latching position of the third latch is its default position, i.e. the position it
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`assumes during normal use of the coupler (i.e. non-inverted and with an attachment
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`25 attached thereto).
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`Preferably the third latch is moveable from a latching position into a non-latching
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`position by means of gravity by at least partially inverting the coupler. Alternatively, or
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`additionally, a mechanical actuator may be provided for moving the third latch.
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`30
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`A biasing member may be provided to bias the third latch towards a latching position.
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`Preferably the third latch, in a latching position bears against the first latch.
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`7
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`One or more of the latches may comprise a solid bar and/or a hook.
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`One or more of the latches may comprise a pair of solid bars and/or hooks.
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`One or more of the latches may comprise a bifurcated bar or hook.
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`Preferably the first latch is moveable from a latching position into a non-latching
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`position by a mechanical actuator, such as a hydraulic ram.
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`Preferably the second latch is moveable from a latching position for the second jaw into
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`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
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`provided for moving the second latch.
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`A biasing member may be provided to bias the second latch towards a latching position.
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`5
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`10
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`15
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`The same biasing member and/or mechanical actuator may control the movements of
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`both the second latch and the third latch since those latches are linked or connected
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`20
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`together.
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`Preferably the second jaw has a recessed groove in its lower half.
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`Preferably the coupler can accommodate a range of pin spacings between the two
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`25 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
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`size of coupler). In this manner, accessories from different manufacturers, with different
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`pin spacings, can be attached to the coupler without modification of either the coupler or
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`the accessory.
`
`30
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`For adjusting the first latch, the mechanical actuator is preferably a hydraulic ram. It
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`might, however, be a pneumatic ram or a screwthread drive mechanism.
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`8
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`Preferably the mechanical actuator is mounted within the confines of the coupler,
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`generally between and slightly above the two jaws.
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`Preferably the first latch is a pivoting latching hook, or a pair of pivoting latching hooks.
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`5
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`Preferably the first latch pivots to move through an arc between a latching position and a
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`non-latching position. In other embodiments it might be a plate that slides such that it
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`moves linearly between a latching position and a non latching position.
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`10 Each jaw may be bifurcated. It is preferred, however, that the first jaw is a pair of jaws
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`formed in the two sidewalls of the coupler. It is also preferred that the second jaw is a
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`single piece jaw, for example a moulded jaw or a welded multi-part fabrication.
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`It should be noted that the term "jaw" should be interpreted to encompass similar
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`15 attachment pin receiving members such as grooves, hooks or slots, or other similar terms
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`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.
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`Preferably the first latch has a latching face facing in a first direction for bearing against
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`20
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`the first attachment pin and a second face facing away from that latching face. Preferably
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`one or more flange is formed on that second face. Then, in its latching position, the third
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`latch preferably rests on one or more of those flanges. Preferably the predetermined
`
`position lies beyond the position that the third latch assumes when resting upon that
`
`flange.
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`25
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`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).
`
`30 The first latch is adapted to be moveable into a non-latching position from a latching
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`position by retracting it generally in the direction that its second face faces. However,
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`when a pin is not within the first jaw, the first latch is also able to move in the opposite
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`direction beyond the position in which its latching face would have engaged an
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`9
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`attachment pin had one been in the first jaw. By that additional range of motion, the
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`flange or flanges on the first latch can be moved clear of the reach of the third latch. As a
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`result the range of available motion for the third latch is also extended. That enables the
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`third latch to be extended into the predetermined position, if desired.
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`5
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`The present invention also provides a method of attaching an accessory to a coupler on
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`an excavator arm of an excavator, the method comprising:
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`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
`
`10 being powered for movement between a latching position and a non-latching position,
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`and the other being moveable from a latching position into a non-latching position by
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`fully extending the powered latch beyond a latching position, i.e. while there is no pin
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`within that jaw, into a fully extended position while the coupler is in a normal, in use,
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`orientation;
`
`15
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`b) providing an accessory with two accessory pins thereon sized and spaced to fit
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`into the two jaws of the coupler;
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`c) powering the powered latch to extend it into the fully extended position to
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`move the other latch into a non-latching position;
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`d) manipulating the coupler to locate a first attachment pin of the accessory into
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`20
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`the jaw associated with that other latch;
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`e) curling the accessory and coupler, using the excavator arm, so as to invert the
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`coupler, thereby placing the accessory roughly above the coupler;
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`f) reverse powering the powered latch to retract the powered latch for opening its
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`associated jaw, whereupon the second attachment pin locates into that jaw under the
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`25 weight of the accessory;
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`g) powering the powered latch to extend it to a latching position for securing the
`
`second attachment pin in its jaw; and
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`h) uncurling the coupler, using the excavator arm. The attachment is now
`
`attached securely to the coupler.
`
`30
`
`In an alternative an·angement, the present invention provides a method of attaching an
`
`accessory to a coupler on an excavator arm of an excavator, the method comprising:
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`10
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`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, each latch being
`
`selectively moveable between a latching position and a non-latching position, wherein
`
`one of the latches is powered for movement between a latching position and a non-
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`5
`
`latching position, and the other is selectively resisted from movement from a latching
`
`position into a non-latching position by a third latch, wherein that third latch can be
`
`moved into a predetermined, non-latch-resisting position upon extending the powered
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`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,
`
`10
`
`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 for
`
`moving the third latch into its predetermined, non-latch-resisting position;
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`d) manipulating the coupler to locate a first attachment pin of the accessory into
`
`15
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`the jaw associated with the other latch;
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`e) curling the accessory and coupler, using the excavator arm, so as to invert the
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`coupler, thereby placing the accessory roughly above the coupler;
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`f) reverse powering the powered latch to retract the powered latch for opening its
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`associated jaw, whereupon the second attachment pin locates into that jaw under the
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`20 weight of the accessory;
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`g) powering the powered latch to extend it to a latching position for securing the
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`second attachment pin in its jaw; and
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`h) uncurling the coupler, using the excavator arm. The attachment is now
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`attached securely to the coupler.
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`25
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`The present invention also provides a method of detaching an accessory from a coupler
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`on an excavator arm of an excavator, the method comprising:
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`a) providing an excavator with a powered excavator arm having a coupler on an
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`end thereof and with an accessory coupled thereto, the accessory having two accessory
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`30 pins thereon located within two jaws of the coupler, and secured into those jaws by
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`respective latches associated with each jaw, wherein one of the latches is powered for
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`movement between a latching position and a non-latching position, and the other latch is
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`moveable from a latching position into a non-latching position, when an attachment pin
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`is not located within the other jaw, by fully extending the powered latch beyond a
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`latching position into a fully extended position while the coupler is in a normal, in use,
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`orientation;
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`b) curling the accessory and coupler, using the excavator arm, so as to invert the
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`5 coupler, thereby placing the accessory roughly above the coupler;
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`c) reverse powering the powered latch to retract the latch for opening its
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`associated jaw;
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`d) uncurling the coupler and attachment, using the excavator arm, to position the
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`accessory below the coupler whereupon the attachment pin within the opened jaw exits
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`10
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`the opened jaw under the weight of the accessory;
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`e) powering the powered latch to extend it into the fully extended position to
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`move the other latch into a non-latching position to open the other jaw; and
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`f) manipulating the coupler relative to the attachment to remove the other
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`attachment pin of the accessory from that other jaw.
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`15
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`Preferably the act of inverting the coupler and accessory to place the accessory roughly
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`above the coupler serves to move a mechanical stop away from a latching position
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`behind the powered latch.
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`20 Preferably the mechanical stop is linked to the other latch.
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`Preferably the movement of that powered latch into the fully extended position allows
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`the mechanical stop to move beyond its own latching position into a final release
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`position, or the above mentioned predetermined position, whereupon the other latch is
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`25
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`released to be free to move into a non-latching position.
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`In an alternative arrangement, the present invention provides a method of detaching an
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`accessory from a coupler on an excavator arm of an excavator, the method comprising:
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`a) providing an excavator with a powered excavator arm having a coupler on an
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`30 end thereof and with an accessory coupled thereto, the accessory having two accessory
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`pins thereon located within two jaws of the coupler, and secured into those jaws by
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`respective latches associated with each jaw, each latch being selectively moveable
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`between a latching position and a non-latching position, wherein one of the latches is
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`powered for movement between a latching position and a non-latching position, and the
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`other latch is selectively resisted from movement from a latching position into a non(cid:173)
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`latching position by a third latch, wherein that third latch can be moved into a
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`predetermined, non-latch-resisting position upon extending the powered latch beyond a
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`5
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`latching position, i.e. while there is no pin within that jaw, into a fully extended position
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`while the coupler is in a normal, in use, orientation;
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`b) curling the accessory and coupler, using the excavator arm, so as to invert the
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`coupler, thereby placing the accessory roughly above the coupler;
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`c) reverse powering the powered latch to retract the latch for opening its
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`10 associated jaw;
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`d) uncurling the coupler and attachment, using the excavator arm, to position the
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`accessory below the coupler whereupon the attachment pin within the opened jaw exits
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`the opened jaw under the weight of the accessory;
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`e) powering the powered latch to extend it into the fully extended position to
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`15 move the third latch into its predetermined, non-latch-resisting position;
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`f) moving the other latch into a non-latching position; and
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`g) manipulating the coupler relative to the attachment to remove the other
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`attachment pin of the accessory from that other jaw.
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`20 Preferably step f) is achieved by recurling the accessory and coupler, using the excavator
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`arm, so as partially to invert the coupler, thereby placing the accessory in a position that
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`is substantially level with the coupler. That then allows the other latch to fall into a non(cid:173)
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`latching position under the influence of gravity if it is free to do so. It should be
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`appreciated, however, that that other latch might instead be power operated, e.g. it may
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`25 have its own actuator, such as a hydraulic ram.
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`It would also be desirable to provide just a simple supplementary failsafe or securement
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`mechanism for couplers. Preferably
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`the supplementary failsafe or securement
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`mechanism will be able to ensure that an accessory will still be retained upon the coupler
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`30 until that supplementary failsafe or securement mechanism is released even in the event
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`of a catastrophic failure of the primary securement mechanism, e.g. the hydraulic ram or
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`the screwthread, or even a moveable jaw, groove, hook or slot, or even in the event of an
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`accidental or inadvertent release of that primary securement mechanism by the operator.
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`According to a further aspect of the present invention, therefore, there is provided a
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`coupler for coupling an accessory to an excavator arm of an excavator, the accessory
`comprising at least one attachment pin for use in the coupling, the coupler comprising a
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`5
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`first side for attaching the coupler to an excavator arm of an excavator and the coupler
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`having a second side onto which the accessory will be coupled, the second side
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`comprising a jaw for receiving the attachment pin of the accessory for connecting the
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`accessory to the coupler by the engagement of the jaw with the attachment pin, wherein
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`the jaw comprises a gravity-operated member having a first state- the jaw-open or jaw-
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`10 unlocked state, and a second state -
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`the jaw-closed or jaw-locked state, the gravity(cid:173)
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`operated member at least partially closing the jaw of the coupler when it is in its first
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`state, said first state being achieved by the gravity-operated member when the coupler
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`(and, when connected, the accessory) is in a n