A quick coupler

Abstract

Discloses a quick coupler for use with a working machine. It comprises a coupler body with a first 14 and second 16 recesses for receiving attachment pins. There is a first 22 and second 24 locking me

Description

A Quick Coupler FIELD The present teachings relate to a quick coupler for attaching a work implement to a working arm of a working machine. BACKGROUND Working machines, also known as off-highway vehicles, typically have a working arm pivotally mounted to the body of the machine, and a working implement, such as a bucket or a grabber, attached to the end of the arm via a coupling device. Attachment of the working implement enables the working machine to perform working operations. It is common for such coupling devices to include a so-called quick coupler to connect a variety of working implements to the working arm. Quick couplers tend to include an actuator-operated locking mechanism, which is capable of selectively locking and unlocking two attachment pins of a working implement with respect to the quick coupler, to enable the working implement to be connected to and disconnected from the quick coupler respectively. The present invention seek to provide an improved quick coupler. SUMMARY The present invention provides a quick coupler for connecting a working implement to a working arm of a working machine according to the appended claims. The present disclosure provides a quick coupler comprising a coupler body comprising first and second recesses configured to respectively receive first and second attachment pins of a working implement therein. The first and second locking members may be moveable between unlocked and locked positions for locking first and second attachment pins in the first and second recesses, respectively. An actuator may be configured to move the first locking member between the unlocked and locked positions. A biasing arrangement may be configured to bias the first locking member into the locked position in the event of the actuator failing. The biasing arrangement may be further configured to move the second locking member into the locked position as the first locking member is moved into the locked position. Using the biasing arrangement which provides a fail safe for the actuator and first locking members allows the actuating force for the second locking members to be conveniently provided. Further, the actuating force achieved with the biasing arrangement may be limited to prevent the second locking members being forced in the event that one of the attachment pins is misaligned. The actuator may be configured to move the second locking members from the locked position to the unlocked position. Hence, the second locking members may be movable in a first direction, e.g. unlocked to locked, using the biasing arrangement, and a second direction, e.g. locked to unlocked, using the actuator. This is advantageous as any dirt or debris which has collected in or around the lock during use may be easily displaced using the relatively large force of the actuator. The biasing arrangement may be independently movable of the actuator. Hence, the actuator may be moved to engage the first locking member when the biasing arrangement is prevented from moving, for example, where the second locking member is jammed or prevented from becoming fully locked. The biasing arrangement may only engage the first locking member when the second locking member is fully engaged in the locked position. The first locking members may be subjected to an actuating force determined by the actuator. When moving from the locked to the unlocked position, the second locking members may be subjected to an actuating force determined by the biasing arrangement. The actuating force of the actuator may be greater than the actuating force of the biasing arrangement. A maximum actuation force for moving the second locking member from the unlocked position to the locked position may be the maximum actuator force, e.g. the spring force, of the biasing arrangement. As such, the maximum actuation force applied to the second locking mechanism may be restricted compared to the first locking members driven by the actuator. The biasing force of the biasing arrangement may be less than the actuation force of the actuator. The biasing arrangement may comprise a compression spring. The second locking member may comprise a clasp. The clasp may be pivotally mounted to the coupler body. The clasp may be configured to pivot into the second recess when moving into the locked position and out of the second recess when moving from the locked position to the unlocked position. Providing a pivoting clasp reduces the actuation force required to move the second locking member into the locked position, which is better suited to the use of the biasing member. A mover may extend between the biasing arrangement and the clasp. The mover may be configured to pivot the clasp under the influence of the biasing member. The biasing arrangement may be configured to linearly displace the mover away from the second locking member to move the second locking member from the unlocked to the locked position. The linear displacement of the mover under the influence of the biasing member may cause a rotation of the clasp about the pivot member. The mover may comprise a lock bar which is located radially outwards of the second locking member when in the locked position. The lock bar may be provided at a fixed radial separation from the recess when in the locked position, such that the lock bar is configured to prevent movement of the second locking member into the unlocked position. The mover may be restricted to move linearly in relation to the second recess. The linear movement may be a tangential movement with respect to the second recess. The pivotable clasp may comprise a running surface on a radially outer thereof. The clasp may comprise a plate-like member. The running surface may be provided by an edge of the plate-like member. The clasp may be located in a plane which is normal to the longitudinal axis of the second recess / second attachment pin. The lock bar may pivot in the normal plane. The pivot axis may be aligned with the longitudinal axis of the second recess / second attachment pin. The lock bar may engage with the running surface during linear displacement of the lock bar to effect pivoting of the clasp. The running surface may comprise a curved profile. The curvature of the running surface may comprise a gentle curve. The mover may comprise a recess in which the clasp resides when in the unlocked position. The recess may be located on a proximal side of the lock bar relative to the first locking member. Hence, the lock bar may be distally located in relation to a central portion of the coupler body. The lock bar may be the distal most portion of the clasp. The second locking member may be biased into an unlocked position. As such, when the first locking member is retracted into the coupler body by the actuator and the biasing force of the biasing arrangement is removed from the second locking member, the second locking member may be opened via a second locking member biasing element. For example, the clasp may be opened using a clasp biasing element which may be, for example a torsion spring. The clasp biasing element may be configured to pivotably urge the clasp radially outwards into the unlocked position. The quick coupler may further comprise an actuation axis along which the first locking member moves between the unlocked and locked positions. The first locking members may be elongate and extend along the direction of the actuation axis. The first recess and second recess may respectively define a front and rear of the quick coupler. The actuation axis may extend fore-aft with respect to the front and rear. The compression spring may comprise a longitudinal axis which is aligned with the actuation axis of the first locking members. The actuator may comprise a linear actuator, e.g. a hydraulic cylinder. The actuation direction of the linear actuator may be along the actuation axis. The hydraulic cylinder may comprise a body and a rod having a drivable piston mounted within the body. The rod may be aligned with the actuation axis. The hydraulic cylinder may be connected to the first locking member via a trunnion. The rod may be connected to the first locking member, optionally via an intermediate structure such as a carriage. The full bore end of the cylinder may be mounted proximal to the second locking members. The full bore end may be mounted to the coupler body via a trunnion. The quick coupler may further comprise a pair of laterally displaced first locking members. The first locking members may each comprise an elongate body (which may be referred to as pins or rods). The elongate bodies may be provided proximal an edge of the coupler body. The actuator may be located between the pair of laterally displaced first locking members. The actuator may lie along a centreline of the quick coupler. The first locking members may be connected by a carriage. The carriage may comprise an elongate member which extends width wise across the quick coupler and attach to the first locking members at the ends thereof. The actuator may extend between the coupler body and the carriage. The biasing arrangement may comprise a biasing member which extends between the carriage and the coupler body. The biasing arrangement may urge against a rear side of the carriage. The locking members may be attached to the front side of the carriage. The quick coupler may comprise a pair of first locking members and a pair of second locking members. Each pair of the first and second locking members may comprise a respective biasing member of the biasing arrangement. The biasing members may be aligned with the actuation axis. The biasing members may be aligned with the longitudinal axis of the first locking members. The biasing members may be coaxial with the first locking members. The first locking member may comprise an elongate body having a locking portion and a guide extending rewards thereof. The guide may extend along a longitudinal axis of the locking portion, that is, be coaxial with the locking portion. The guide may comprise a rod which is received within a guide aperture for at least part of the stroke of the first locking member. The guide aperture may be provided at a distal end of the guide. The guide aperture may be provided in the coupler body, optionally in a plate member of the coupler body. The guide aperture may be proximate the second locking members. Each respective biasing member may be located around a first locking member guide. The quick coupler may comprise an indicator arrangement configured to indicate when at least one of the first and second locking members is in the unlocked and / or locked position. The indicator arrangement may comprise the second locking member or the lock bar. The present disclosure provides a working machine comprising: a body; a ground engaging propulsion structure supporting the body; and a working arm mounted to the body. The quick coupler many be mounted to a distal end of the working arm. The body may comprise an undercarriage supported by the ground engaging propulsion structure and a superstructure, e.g. a rotatable superstructure, connected to the undercarriage. The working arm is mounted to the superstructure. The quick coupler may be used to attach a tilt rotator attachment to the end of a working arm. The working machine may be an excavator. The working machine may be a backhoe loader, a slewing excavator, a tracked excavator or a wheeled excavator. The working machine may be any working machine comprising a working arm which can usefully utilise the quick coupler of the disclosure. The skilled person will appreciate that except where mutually exclusive, a feature described in relation to any one of the aspects, embodiments or examples described herein may be applied mutatis mutandis to any other aspect, embodiment or example. Furthermore, except where mutually exclusive, any feature described herein may be applied to any aspect and / or combined with any other feature described herein. BRIEF DESCRIPTION OF THE DRAWINGS Embodiments will now be described with reference to the accompanying drawings, in which: Figures 1 and 2 show isometric underside views of a quick coupler according to the present disclosure; Figure 3a to 3c show sectional views of the quick coupler of Figures 1 and 2 in respective unlocked, locked and partially locked positions Figure 4 shows an exploded view of the quick coupler of Figures 1 and 2; and Figure 5 shows a side view of a working machine which may include the quick coupler of the present disclosure. Detailed Description General In the following detailed description, numerous specific details are set forth in order to provide a thorough understanding of various embodiments and the inventive concept. However, those skilled in the art will understand that: the present invention may be practiced without these specific details or with known equivalents of these specific details; that the present invention is not limited to the described embodiments; and, that the present invention may be practiced in a variety of alternative embodiments. It will also be appreciated that well known methods, procedures, components, and systems may have not been described in detail. With reference to Figures 1 to 4, there is provided a quick coupler 10 is connectable to a working arm of a working machine (510, Figure 5) so as to connect a working implement 552 to the working machine. The quick coupler 10 comprises a coupler body 12 comprising first and second pair of recesses 14, 16 for receiving first and second attachment pins 18, 20 of a working implement therein. The quick coupler 10 also comprises first and second pairs of locking members 22, 24 which are moveable between locked and unlocked positions for locking first and second attachment pins 18, 20 in the respective first and second recesses 14, 16. An actuator 26 is configured to move the first locking members 22 between the locked and unlocked positions. A biasing arrangement 28 is configured to bias the first locking members 22 into the locked position in the event of the actuator 26 failing. Further, the biasing arrangement is configured to move the second locking members 24 into the locked position as the first locking members 22 are moved into the locked position with actuation of the actuator 26. Before proceeding further it should be noted that the isometric views of Figures 1 and 2 include the first and second locking members 22, 24 simultaneously in both the locked and unlocked positions for ease of comparison. Thus, in Figures 1 and 2, it can be seen that one of the first locking members 22a protrudes from the coupler body 12 to obstruct the respective portion of the first recess 14, and the other of the first locking members 14b is in a retracted, unlocked position. Similarly, the second locking member 24a which corresponds to the first locking member 22a is shown in a locked position with the other 24b shown in the unlocked position. It will be appreciated that, in practice, the locking members 22, 24 would work in unison with both the first and second locking members 22, 24 being operable in conjunction with each other, rather than separately. Thus, the two first locking members 22 will ordinarily protrude into the first recesses 14 and be retracted into the coupler body 12 together when the actuator 26 is actuated in either direction. Similarly, the second locking members 24 will ordinarily protrude into the second recesses 14 and be retracted into the coupler body 12 by similar amounts together when the actuator 26 is actuated in either direction. That said, it will be appreciated that the second locking members 24 may be individually actuated by separate biasing members 28a and 28b, as shown and described in connection with Figure 3c. As will be appreciated by the skilled person, the orientation of the quick coupler 10 in use will be dependent on the orientation of the working arm of the working machine. For the purpose of the disclosure, the front of the quick coupler comprises the first recess with the rear comprising the second recess as indicated in Figure 3a. The bottom of the quick coupler 10 may be taken to be the side on which the work implement is mounted, with the top being the side which connects to the working arm. The coupler body 12 may be integrally formed, e.g. integrally cast, as a unitary component. It will be appreciated that in alternative arrangements, the coupler body 12 may be fabricated, forged, or may be formed from any suitable manufacturing method. The coupler body 12 includes the first recess 14 and a second recess 16 at opposing ends thereof. As noted, the first recess 14 is arranged to receive a first attachment pin 18 of a working implement therein, and the second recess 16 is arranged to receive a second attachment pin 20 of the working implement therein. The spacing and size of the recesses may be conventional with a view to receiving conventional attachments. As can be seen from Figures 1 and 2, the recesses 14, 16 may be formed by suitably shaped channels or cut-outs in the coupler body 12. The recesses 14, 16 may include one or more surfaces for contacting the attachment pins 18, 20 and may be any suitable shape capable of receiving and retaining the attachments pins 18, 20 when locked in position with the locking members 22. The contacting surfaces may be continuous across the width of the coupler body 12 or discrete at a central portion or the lateral edges of the coupler body 12. The contacting surfaces may be provided by one or more lugs local to the locking members 22, 24, for example. The recesses 14, 16 may comprise a U-shaped or J-shaped channel so that the attachment pins 18, 20 can only be received from specific directions. As can be seen in Figures 1 and 2, the first and second recesses 14, 16 each comprise a continuous contact surface which extends across the full width of the coupler body 12 and additionally comprises lugs to provide additional contacting surfaces local to the locking members 22, 24. The first recesses 14 are provided with a J-shaped profile (when viewed side-on) which contacts approximately half of the attachment pin 18 with the locking member 22 obstructing the open side when in the locked position to prevent withdrawal of the attachment pin 18. The second recesses 16 comprise a U-shaped channel. The second locking members 24 extend radially through a wall of the U-shaped channel, again to obstruct the opening and prevent withdrawal. It will be appreciated that the specific arrangement of the recesses 14, 16 and the corresponding locking members 22, 24 may vary across embodiments and the variants shown and described herein are not limiting. As noted above, the first locking members 22 are moveable between a locked position, which is shown in Figures 1, 2, 3b and 3c, and an unlocked position, which is shown in Figures 1, 2 and 3a. The second locking members 24 are moveable between a locked position, which is also shown in Figures 1, 2 and 3b, and an unlocked position, which is shown in Figures 1, 2 and 3a. Figure 3c shows the second locking member 24 in a partially locked state in which the second attachment pin 20 is not fully received within the second recess 16 thereby preventing a full stroke. The arrangement of the actuator 26, first locking members 22 and biasing arrangement 28 may be such that the actuator 26 and first locking members 22 are biased into the locked position by the biasing arrangement 28. Hence, to move from the locked position to the unlocked position, the actuator 26 must operably overcome the biasing force of the biasing arrangement 28 to retract the first locking members 22. Once in the unlocked position, the actuator 26 can be locked to maintain the position against the biasing force of the biasing arrangement 28. For example, in the case of an actuator 26 in the form of a hydraulic cylinder, a valve (not shown) can be operated to prevent the flow of hydraulic fluid and movement of the actuator 26. When moving from the unlocked to the locked position, the direction of actuation of the actuator 26 may be reversed such that the first locking members 22 protrude from the coupler body 12 to extend into the recess 14. The first locking members 22 may be primarily actuated by the actuator 26 with the biasing arrangement 28 merely providing some redundancy in the event of a failure. However, in some embodiments, the biasing arrangement 28 may be sufficient to actuate the first locking members 22 without the aid of the actuator 26. That is, the function of the actuator 26 may, in some embodiments, be limited to unlocking the first locking members 22 only. The second locking members 24 may be actuated by the biasing arrangement 28 when the first locking members 22 and actuator 26 are moved between the unlocked position to the locked position. As noted, the actuation of the biasing arrangement 28 may be controlled and / or restricted by the position of the actuator 26 such that the second locking members 24 require the actuation of the main actuator 26 to operate. However, the actuation force acting on the second locking members 24 is provided only by the biasing arrangement 28. That is, the second locking members 24 may be driven by the biasing arrangement 28 in conjunction with or subsequent to the movement of the first locking members 22 from the unlocked to the locked positions. When moving from the locked to the unlocked position, the second locking members 24 may be directly actuated by the actuator 26 as it retracts the first locking members 22 and moves the biasing arrangement 28 rearwards. The first attachment pin 18 of a working implement can be locked in the first recesses 14 by first receiving the first attachment pin 18 in the first recesses 14 with the first locking members 20 in the unlocked position, then moving the first locking members 20 to the locked position. With the first attachment pin 18 locked in the first recesses 14 as described, it is prevented from separating from the coupler body 12, and is thus connected to the coupler body 12. The first attachment pin 18 can be unlocked from the first recesses 14 by moving the first locking members 20 from the locked position to the unlocked position, enabling the first attachment pin 18 to be removed from the first recess 14. The second attachment pin 20 of the working implement can be locked in the second recesses 16 by first receiving the second attachment pin 20 in the second recess 16 with the second locking members 24 in the unlocked position, then moving the second locking members 24 to the locked position. With the second attachment pin 20 locked in the second recess 15 as described, it is prevented from separating from the coupler body 12, and is thus connected to the coupler body 12. The second attachment pin 20 is then unlocked from the second recess 16 by moving the second locking members 24 from the locked position to the unlocked position, enabling the second attachment pin 20 to be removed from the second recess 16. It will be appreciated that, due to the respective shape of the first and second recesses 14, 16 of the embodiment shown in the drawings, the second attachment pin 20 may be required to be received within the second recess 16 prior to first attachment pin 18 being received within the first recess 14 due to the separation of the attachment pins 20 being fixed. In the illustrated embodiment, the first locking member 20 comprises a pair of elongate pins extending along respective longitudinal axes 22-2. The first locking members 22 are slidably received in respective bores defined in the coupler body 12. The first locking members 20 and the bores have corresponding profiles such that movement of the first locking member 20 relative to the coupler body 12 is constrained to the longitudinal axis 22-2 of the first locking member 20. As shown in the exploded view of Figure 4, the bore may comprise a liner bearing in some embodiments. The first locking members 22 may comprise a locking portion 22-1 which extends forwards and a guide 32 which extends rearwards from the locking portion 22-1. The first locking members 22 are illustrated as being connected by a carriage 30 which is movable by the actuator 26 to actuate the first locking members 22. In the illustrated embodiments, each of the first locking members 22 comprise a guide 32. However, it will be appreciated that the guide 32 may be omitted or may additionally or alternatively be provided on the carriage 30. Each guide 32 extends between locking portion 22-1 along the longitudinal axis 22- 2 and a guide aperture 34 in the coupler body 12. The guides 32 are arranged to be slidably received within the guide aperture 34 as the first locking members 22 are retracted into the coupler body 12 when moving to the fully retracted, unlocked position. The guides 32 may be separated from the guide aperture 34 when the first locking members 22 are in the extended positions to allow some movement of the locking portion 22-1 during the engagement with the attachment pin 18. However, this is not a limitation and the guides 32 may have sufficient length relative to located within the guide aperture 34 irrespective of position. The carriage 30 may comprise a body which extends between each of the pair of first locking members 22 and which is movable along the longitudinal axes 22-2 of the first locking member 22 under the influence of the actuator 26. In the embodiment shown, there is provided a single actuator 26 which is connected to the mid-point of the carriage 30 between the two locking members 22a, 22b. However, this is not a limitation and the actuator 26 may be located elsewhere in relation to the carriage 30 and there may be a plurality of actuators in some embodiments. For example, in some embodiments, each of the first locking members 22a,b may be provided with its own actuator. The locking members 22 may be provided as a unitary body which includes the locking portion 22-1 and guide 32. The locking portion 22-1 may comprise a generally cylindrical body having a diameter which is greater than the guide 32, the two portions being separated by a shoulder which abuts the carriage 30. It will be appreciated that in some embodiments, the locking portion 22-1 and guide 32 may be formed from separate components which are assembled and attached to one another to provide the unitary structure. The first locking members 22 may be attached to the carriage 30 using any suitable attachment. In the example shown, the first locking members 22 comprise a threaded portion to the rear of the carriage for receiving a nut 36. When tightened, the nut 36 urges the carriage 30 against the shoulder of the locking portion 22-1 thereby securing the two components together. The guide aperture 34 may be provided by a wall of the coupler body 12 or a guide plate 38 which is received by and / or attached to the coupler body 12. In the embodiment show, the guide aperture 34 is provided by a guide plate 38 which is received in a corresponding seat which may be provided between opposing portions, e.g. flanges, of the coupler body 12. The seat and locating plate 38 may comprise suitable locating features, such as the curved lateral edges, which ensure the plate 38 is correctly aligned with the guide 32. In the embodiment shown in the drawings, the guide plate 38 includes a short circumferential boss 40 around the guide aperture 34. The boss 40 projects forwards towards the locking portion 22-1 and locates the biasing member 28, as described in more detail below. The quick coupler 10 includes an actuator 26 configured to move the first locking members 20 between the locked and unlocked positions. The actuator 26 is configured to operate in conjunction with the biasing member 28 to move the second locking members 24 between the locked and unlocked positions. The actuator 26 may be located within a cavity in the coupler body 12 and may be interposed between the first locking members 22. In the illustrated embodiment, the actuator 26 is a linear hydraulic actuator in the form of a hydraulic cylinder. The actuator 26 includes an actuator body 26-1 and a rod 26-2 on which there is a mounted a piston (not shown) to define one or more working chambers on either side thereof, as well known in the art. The actuator 26 is configured to selectively extend and retract the rod 26-2 relative to the actuator body 26-1 in order to move the first locking members 22 between the locked and unlocked positions along an actuation axis which corresponds to the longitudinal axes 22-1 of the first locking members 22. In alternative embodiments (not shown), the actuator 26 may be an electronic or pneumatic actuator. The actuator 26 is generally elongate and extends between the carriage 30 and an attachment on the coupler body 12. The actuator 26 may be mounted in any suitable way such as, for example, a trunnion mount at the full bore end and a trunnion mount between the rod 26-2 and carriage 30, as shown. Other mounting methods as well-known in the art are possible. The actuator 26 is centrally mounted between the two first locking members 22 and provided in a plane defined by the two first locking members 22 arranged on either side thereof. It will be appreciated that providing a planar arrangement of the actuator 26 and first locking members 22 helps reduce the depth of the quick coupler 10 which is generally advantageous. However, in some instances, the actuator may be offset from the plane which extends between the two first locking members 22. As noted, each of the first locking members 22 are biased into the locked position via a biasing arrangement 28 which provides a biasing force to the rear of the locking portion 22-1 so as to urge the first locking members 22 into a locked position. Thus, when the actuator 26 applies no force to the first locking member 22, for example when the actuator 26 loses power or fails, the biasing arrangement 28 is configured to maintain the locking members 22 in the locked position using the spring force of the biasing arrangement 28. As such, the actuator 26 is required to overcome the biasing arrangement 28 to move the first locking member 22 from the locked position to the unlocked position. The biasing arrangement 28 may include a pair of biasing members 28a, 28b configured to bias each of the first locking members 22 into the locked position. In the illustrated embodiments, the biasing members 28a,b extend longitudinally between the first locking members 22 and the coupler body 12. Thus, there is shown a first end 28-1 of the biasing member 28a which engages the coupler body 12 and a second end 28-2 which engages the first locking member 20 to the rear of the carriage 30. As shown, the biasing members 28a, 28b may be resilient elements such as a compression spring, but in alternative embodiments any suitable biasing element or arrangement may be used. The use of a compression spring is particularly advantageous as it can be received over the guide 32 such that the biasing force is coaxial with the longitudinal axis of the locking members 22 and actuating axis. Compression springs also provide a robust and predictable mechanical force. The first and second ends 28-1, 28-2 of the biasing members 28a,b may be attached in any suitable way. In the embodiment shown, a first end 28-1 of the compression springs are mounted over the boss 40 provided around the guide aperture 34 which is sized to aid radial location of the compression spring. The second end 28-2 of the compression spring is urged against the rear side of the carriage 30. As described below, the biasing member 28 may be operatively attached to the second locking members 24 such that an extension or retraction of the biasing member 28 causes the second locking member 24 to move between the locked and unlocked positions. The biasing members 28 are arranged so as to from a first higher compressed state when the first and second locking members 22, 24 are unlocked, to a second lower compressed state when the first and second locking members 22,24 are in a locked position. It will be appreciated that a significant amount of compressive force is provided by the biasing members 28 when the first locking members 22 are in a locked position in order to provide the back-up actuation force described above. The second locking members 24 may comprise a pivotally mounted clasp which is configured to rotate relative to the respective recess and partially encircle or otherwise engage with or obstruct the attachment pin 20 when correctly located in the second recess 16. Thus, relative to the second recess 16, the clasp may move from a radially outer position when the second locking member 24 is unlocked, to a radially inward position when the second locking member 24 is locked. The clasp lies and pivots in a plane which is generally normal to the central axis of the recess 16 (which corresponds to a longitudinal axis of the attachment pin 20). The pivoting axis may generally parallel to the longitudinal axis of the attachment pin 20 such that the clasp moves radially and in the normal plane of the attachment pin 20. In the orientation shown, the clasp is provided above the attachment pin 20, that is, on the working arm side, but this is not a limitation and other orientations are possible. The pivot mount 43 is illustrated as being above and to the rear of the guide aperture 34, however, the location may vary. In the embodiment shown, the clasp is movably received within a slot 44 provided in the coupler body 12 and flanked by lateral walls. The clasp may be biased in an open configuration by a clasp biasing member 46. The clasp biasing member 46 may be any suitable device which urges the clasp into the open / unlocked position. In the illustrated embodiment, the clasp biasing member 46 comprises a torsion spring. The illustrated torsion spring has a main body 46-1 which includes a central passageway centred on a boss coaxially with the pivot mount 43 and a pair of spring arms 46-2 configured to engage opposing surfaces of the coupler body 12 and an attachment point on the clasp. The biasing member 46 is tensioned so as to hold the clasp in the unlocked position when the actuator 26 and first locking members 22 are retracted in the unlocked position. As the clasp is moved into the locked position the clasp is pivoted against the spring force of the biasing member 46. The quick coupler 10 comprises a pair of second locking members 24, each of one the pair corresponding to one of the first locking members 22. Hence, the biasing member 28a associated with the first locking member 22a is configured to actuate the second locking member 24a, and the biasing member 28b associated with the first locking member 22b is configured to actuate second locking member 24b. A mechanical linkage between the respective biasing members 28a,b and second locking members 24a,b is provided by mover 48. The mover 48 is configured to move linearly between a first position corresponding to the unlocked position of the second locking member 24 and a second position which corresponds to the locked position. The movement of the mover 48 is effected by the movement of the respective biasing member 28 as they expand and contract with movement of the actuator 26. The mover 48 comprises an elongate body 48-3 having at a first end an attachment portion 48-1 which is attached to the biasing member 28 and at a second end a clasp portion 48-2 which driveably engages with the clasp so as to move it between the locked and unlocked positions during actuation of the biasing member 28. The actuation of the mover 48 and the engagement with the clasp may be any suitable to effect the movement of the clasp. In the illustrated embodiment, the mover 48 is generally linearly displaceable along the longitudinal axes 22-2 of the first locking members 22. The mover 48 provides a direct link such that the movement of the biasing member 28 results in a corresponding movement of the clasp. Hence, as the biasing members 28 expand when moving from the unlocked to the locked position, the mover 48 is drawn into the coupler body 12. The clasp portion 48-2 may comprise a lock bar 48-4 which is located on a radially outer surface of the clasp such that it contacts and moves the clasp from the unlocked position to the locked position as the mover 48 is retracted linearly into the coupler body 12. Once in the locked position, the lock bar 48-4 resides on the radially outer surface of the clasp thereby restricting outward movement and ensuring the attachment pin 20 restrained within the recess 16. The lock bar 48-4 comprises an axial length having a leading edge 48e which engages with the upper surface of the clasp. Upstream of the leading edge 48e, there is provided an opening or recess 48-5 in which the clasp can be received when in the unlocked position so as to allow the clasp to move radially outwards from the recess 16 under the influence of the clasp biasing member 46. In the illustrated embodiment, the running surface 45 which engages the lock bar 48-4 is angled relative to the actuation axis of the mover 48 when in the unlocked position such that the linear rearwards movement of the mover 48 along the running surface 45 causes the radial displacement of the clasp. The shape of the running surface may be variously modified to suit a desired actuation motion. In the illustrated embodiment, the running surface 45 comprises a curve but an angled surface comprising one or more facets may be preferable in some variants. Once in the locked position, the running surface 45 is located beneath, i.e. radially inwards to the lock bar 48-4 and aligned with the actuation axis 22-2. In the illustrated embodiment, the clasp portion 48-2 comprises a pair of arms which extend from the body 48-3 towards the terminal end. The lock bar 48-4 joins the ends of the arms. The separation of the arms upstream of the lock bar 48-4 defines the opening / recess in which the clasp 48 is received when in the unlocked position. In addition to the lock bar 48-4 and opening / recess, the clasp may comprise an elongate channel 42 which receives the running surface 45 of the clasp so as to retain some engagement therebetween and maintain alignment when in the unlocked configuration. The mover 48 may take any suitable form which enables the connection between the biasing members 28 and the clasp. In the illustrated embodiment, the mover 48 comprises a generally L-shaped member in which the attachment portion 48-1 is provided by the leg of the L shape, and the body 48-3 is provided stem which is horizontally aligned. The attachment portion 48-1 comprises a through-hole in which the guide 32 of the respective first locking member 22 is received. The attachment portion 48-1 is provided upstream of the biasing member 28, e.g. between the biasing member 28 and carriage 30 or locking portion 22-1, such that when the second end of the biasing member 28 moves, the mover 48 is shifted relative to the clasp to actuate the second locking member 24. The mover 48 and first locking member 22 are provided in a floating arrangement such that the mover 48 is not moved by first locking member 22 or actuator 26 if the clasp or biasing member 28 is not able to move. Hence, in the event that the actuator 26 is operated and the first locking members 22 move into the locked position but the clasp is blocked, for example, if the attachment pin 20 is not properly inserted into the recess 16, the actuator can continue to operate without forcing the clasp. That is, the actuating force on the second locking member 22 is limited to the spring force of the biasing member 28. Figures 3a to 3c show the operation of the quick coupler 10. In Figure 3a the coupler 10 is shown in an unlocked state in which the attachment pins 18, 20 are located in the recesses 14, 16, but the actuator 26 is not operating to actuator the first and second locking members 22, 24. Hence the first locking member 22 is shown in a retracted position and housed within the coupler body 12. Similarly, the second locking member 24 is held in an unlocked configuration in which it is received within the recess 48-5 of the mover 48 and held in the open position under the influence of the clasp biasing member 46. Figure 3b shows the quick coupler 10 in a locked configuration in which the actuator 26 has been operated to move the first locking members 22 out of the coupler body 12 into the first recess 16, thereby partially obstructing the recess 14 and preventing the removal of the attachment pin 20. Due to the movement of the actuator 26 and associated displacement of the first locking members 22, the biasing member 28 is free to expand thereby displacing the mover 48 and lock bar 48-4 to urge against and move the clasp radially inwards to capture the second attachment pin 18. The mover 48 and clasp will stay in this position under the influence of the biasing member 28 until the actuator 26 is operated in the opposing direction to overcome the biasing force and withdraw the first locking member 22 and mover 48 back to the positions shown in Figure 3a. Figure 3c shows a partially received attachment pin 21 in the second recess 16. In conventional quick couplers, if the attachment pins 20 are not correctly received within the recesses 16 prior to actuation, the locking members 24 may be forced directly on to the attachment pins 20 causing damage to either or both. One benefit of operating the second locking members 24 using a spring force is that it detaches the actuation from the full force of the actuator and limits the actuation force on the clasp to that of the biasing member 28 expanding against the mover 48. Hence, as shown in Figure 3c, the actuator 26 has driven the first locking member 22 into a position allowing the biasing member 26 to expand. However, the movement of the clasp is obstructed by the attachment pin 20, thereby limiting the inwards displacement of the clasp. As such, the clasp fails to lock the attachment pin in place but also prevents any significant damage due to the limited force which can be applied by the biasing member 26. As noted above, the mover 48 may comprise a recess 48-5 in which to the clasp may be received when in the unlocked position. In the illustrated embodiment, the recess 48-5 comprises an aperture which extends fully through the body 48-3 of the mover 48 such that the clasp may be visible from a radially outside position. When the mover 48 is fully engaged, the clasp is located beneath the lock bar 48- 4. In some embodiments, an indicator aperture 50 may be provided in the coupler body 12 above the clasp such that the position of the clasp can be revealed to an operator sat in a machine cab or external to the machine. In doing so there is provided an indicator which may be used by the operator or a banksman to determine whether a successful engagement has been achieved. It will be appreciated that other indicators as known in the art may also be possible. A further advantage of providing an aperture 48-5 which extends fully through the mover 48 is that it helps prevent the build-up of dirt and debris between the mover 48 and the clasp, thereby helping to ensure reliable operation of the clasp during an unlock operation. Referring to Figure 5, there is illustrated a working machine 510. In the present embodiment, the working machine 510 may be considered to be an excavator. The working machine 510 could be any type of working machine such as an excavator having any operating weight, a loader, a telehandler etc. Such working machines may be denoted as off-highway vehicles. The ground engaging propulsion structure includes a first, or front, axle Al and a second, or rear, axle A2, each axle being coupled to a pair of wheels 562, 564. In other embodiments, the ground engaging propulsion structure may include a pair of endless tracks. One or both of the axles Al, A2 may be coupled to a drive arrangement (not shown) configured to drive movement of the ground engaging propulsion structure (i.e. the axles Al, A2). The drive arrangement causes movement of the working machine 510 over a ground surface. The drive arrangement includes a primer mover and a transmission. The prime mover may be an internal combustion engine, an electric motor, or may be a hybrid comprising both an internal combustion engine, an electric motor. The working machine 510 has a body 566 supported on the ground engaging propulsion arrangement. The body 566 of the working machine 510 includes an undercarriage 568 supported on the ground engaging propulsion arrangement. A superstructure 570 is connected to the undercarriage 568. The superstructure 570 is connected to the undercarriage 568 by a mounting arrangement 572. In the arrangement shown, the mounting arrangement 572 is a slewing mechanism in the form of a slewing ring. The mounting arrangement 572 permits unrestricted rotation of the superstructure 570 relative to the undercarriage 568 in this embodiment. In alternative arrangements it will be appreciated that the superstructure 570 may not be able to rotate relative to the undercarriage 568. A cab 574 from which an operator can operate the working machine 510 is mounted to the superstructure 570. The cab 574 includes an operator seat (not shown). It will be appreciated that in some arrangements, the working machine 510 may not include a cab 574 and the operator seat may be directly mounted on the body 566 of the working machine 510. The working machine 510 includes a working arm 576. The working arm 576 is connected to the body 566 and is provided for performing working operations. The working arm 576 is connected to the body 566. In the arrangement shown, the working arm 576 is connected to the superstructure 570. The working machine 510 includes a counterweight 578 having a mass for counterbalancing the working arm 576. The counterweight 578 is provided on the superstructure 570. In alternative arrangements, it will be appreciated that the counterweight may be omitted. A working implement 580 in the form of a bucket is attached to the end of the working arm 576 via a coupling 582. The working implement 580 comprises the attachment pins 18, 20 for being received by the recesses 14 and 16 of the quick coupler 10. Thus, in use, the quick coupler may be attached to the end of the working arm 576 and used to engage the working implement 580. Although the teachings have been described above with reference to one or more preferred embodiments, it will be appreciated that various changes or modifications may be made without departing from the scope as defined in the appended claims.

Claims

Claims 1. A quick coupler for connecting a working implement to a working arm of a working machine, the quick coupler comprising: a coupler body comprising first and second recesses configured to respectively receive first and second attachment pins of a working implement therein; first and second locking members moveable between unlocked and locked positions for locking first and second attachment pins in the first and second recesses, respectively; an actuator configured to move the first locking member between the unlocked and locked positions; and a biasing arrangement configured to bias the first locking member into the locked position in the event of the actuator failing, wherein the biasing arrangement is further configured to move the second locking member into the locked position as the first locking member is moved into the locked position by the actuator.

2. The quick coupler of claim 1, wherein actuator is configured to move the second locking members from the locked position to the unlocked position.

3. The quick coupler of claims 1 or 2, wherein the biasing arrangement is independently movable with respect to the actuator. 4, The quick couple of any preceding claim, wherein a maximum actuator force for moving the second locking members from the unlocked position to the locked position is the actuation force of the biasing arrangement.

5. The quick coupler of any preceding claim, wherein the biasing arrangement comprises a compression spring.

6. The quick coupler of any preceding claim, wherein the second locking member comprises a clasp pivotally mounted to the coupler body.

7. The quick coupler of claim 6, further comprising a mover which extends between the biasing arrangement and the clasp, wherein the mover is configured to pivot the clasp under the influence of the biasing member.

8. The quick coupler of claim 7, wherein the biasing arrangement is configured to linearly displace the mover away from the second locking member to move the second locking member from the unlocked to the locked position.

9. The quick coupler of claim 8, wherein the mover comprises a lock bar which is located radially outwards of the second locking member when in the locked position to prevent movement of the second locking member into the unlocked position. 10.The quick coupler of claim 9, wherein the pivotable clasp comprises a running surface on a radially outer edge thereof, and wherein the lock bar engages with the running surface during the linear displacement of the mover to effect pivoting of the clasp.

11. The quick coupler of claim 10, wherein running surface is curved.

12. The quick coupler of any of claims 7 to 11, wherein the mover comprises a recess in which the clasp resides when in the unlocked position, wherein the recess is located on a proximal side of the lock bar relative to the first locking member. 13.The quick coupler of claims 6 to 12, further comprising a clasp biasing element, optionally a torsion spring, configured to pivotably urge the clasp radially outwards into the unlocked position.

14. The quick coupler of any preceding claim, further comprising an actuation axis along which the first locking members move between the unlocked and locked positions. 15.The quick coupler of claim 14 when dependent on claim 5, wherein the compression spring comprises a longitudinal axis which is aligned actuation axis of the first locking members.

16. The quick coupler of any preceding claim, wherein the actuator comprises a linear actuator, e.g. a hydraulic cylinder. 17.The quick coupler of any preceding claim, further comprising a pair of laterally displaced first locking members, the first locking members being connected by a carriage. 18.The quick coupler of claim 17, wherein the actuator extends between the coupler body and the carriage wherein, optionally, the biasing arrangement urges against a rear side of the carriage which is opposite to the first locking members.

19. The quick coupler of any preceding claim, comprising a pair of first locking members and a pair of second locking members, each pair of the first and second locking members comprising a respective biasing member of the biasing arrangement.

20. The quick coupler of any preceding claim, wherein the first locking member comprises an elongate body having a locking portion and a guide extending rewards along a longitudinal axis of the locking portion, wherein the biasing arrangement comprises a compression spring coaxially arranged on the guide. 21.The quick coupler of any preceding claim, comprising an indicator arrangement configured to indicate when at least one of the first and second locking members is in the unlocked and / or locked position, wherein the indicator arrangement comprises the second locking member or, when dependent on claim 9, the lock bar.

22. A working machine comprising: a body; a ground engaging propulsion structure supporting the body; and a working arm mounted to the body, wherein a quick coupler of any one of claims 1 to 21 is mounted to a distal end of the working arm.

23. The working machine according to claim 22, wherein the body comprises an undercarriage supported by the ground engaging propulsion structure and a superstructure, e.g. a rotatable superstructure, connected to the undercarriage, and wherein the working arm is mounted to the superstructure.

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