GB2527353A

GB2527353A - Quick hitch

Info

Publication number: GB2527353A
Application number: GB1410983.9A
Authority: GB
Inventors: Edwin James Ratcliffe; Daniel James Smail
Original assignee: JC Bamford Excavators Ltd
Current assignee: JC Bamford Excavators Ltd
Priority date: 2014-06-19
Filing date: 2014-06-19
Publication date: 2015-12-23
Anticipated expiration: 2034-06-19
Also published as: GB2527353B; GB201410983D0

Abstract

A quick hitch(10) comprising; a movable hook (16) and a manually operated locking mechanism(12) this comprises, a sliding locking plate/panel(18) where the locking plate(18) is configured to retain the movable hook(16) in a closed position. The locking plate(18) is mounted with a torsion spring(fig.5, 26) which biases a rocking arm(20) that pivots on the same coupling pin(24) as the rotating hook(16). The retaining mechanism is biased to keep the hook(16) closed and is released mechanically by the use of a lever inserted into an aperture(fig.7a, 252). Excessive movement of the locking plate(16) is prevented by stoppers(30) on the internal walls of the coupler. The blocking plate(18) can be substantially H, Y, M or U shaped.

Description

Quick Hitch

FIELD OF THE INVENTION

[01] The present invention relates to a quick hitch comprising a locking mechanism, in particular to a quick hitch comprising a manually operated locking mechanism.

[02] The present invention also relates to a manually operated locking mechanism for a quick hitch.

BACKGROUND OF THE INVENTION

[03] Quick hitches, also known as quick release couplers, are generally used on working machines, e.g. excavators, to allow the rapid change of an attachment on the machine, such as a bucket, hydraulic breaker etc. [04] Pin system quick hitches are quite versatile and take advantage of the two pins that are used to attach a standard' type attachment (ie. bucket) to the working arm of the working machine.

[05] Depending on how a pin system quick hitch is designed to mechanically operate in practice, it can be placed in one of three classifications, namely: a manual system, a semi-automatic system and a hilly-automatic system.

[06] Quick hitches generally comprise a latch mechanism that is utilised to retain the attachment to the quick hitch, and a safety locking mechanism is required to secure the latch mechanism in order to avoid inadvertent disconnection of the latch mechanism, [07] The International Standard ISO/DIS 1303 1:2013 outlines the current standards for the safety of quick hitches for earth moving machinery. The Standard states that for manual quick hitches, the locking mechanism or system shall be activated manually from the location where the engagement system is operated, or as an automatic action during the engagement process. Any socking device used must be retained on the quick hitch so that it cannot be removed without the use of tools.

[08] The Standard also states that manual and mixed quick hitches (i.e. semi-automatic systems) shall be designed such that disengagement can only be carried out at the quick hitch itself [09] In addition, the Standard requires that for a manual quick hitch, the design shall ensure that the engagement system can only be activated from the location where the tO locking mechanismlsystem is activated.

[10] In current manual excavator quick hitches, the safety locking mechanism is generally in the form of a manually inserted safety pin retained by a lynch pin to prevent accidental release of the engagement system. The safety pin has to be removed before the latch mechanism is released in order to be able to move the rear hook (engagement system) to disengage from the attachment's rear pin. This is reliable and safe if used in accordance with the manufacturer operating instructions.

[11] However, in real life use it is often the case that the safety pin is not fitted or the lynch pin is lost. As a result, there have been numerous occasions where an operator of a working machine has been found operating the working machine without the safety pin fitted.

[12] As mentioned above, current legislation states that the locking device used, hence the safety pin, must be retained on machines, It is envisaged that future quick hitch legislation will require the lynch pins to also be retained on working machines.

[13] One current method of retention of the safety pin and lynch pin on the working machine is with a chain. However, there are a number of problems associated with the use of a chain. For example: -chains are easily snagged in use; -the rattling of the chain causes damage to paint work and/or annoyance; -replacement of a damaged safety pin or lynch pin is hampered by the chain; -the hanging safety pin and lynch pin can snag when hitching up an attachment.

[14] The safety pin can be retained by an additional device allowing it to be cleared of the mechanism but preventing it being separated from the quick hitch. However, this generally leaves the safety pin exposed during the coupling or decoupling process of and attachment, and accidental contact of the exposed safety pin during the process may cause damage to the safety pin rendering it useless.

[15] It is desirable to provide a quick hitch and a manually operated locking mechanism for a quick hitch which addresses one or more of the problems and disadvantages identified above.

SUMIvIARY OF THE INVENTION [16] A first aspect of the invention provides a quick hitch comprising: a movable hook arranged to move between a locked position and a fully unlocked position; and a manually operated locking mechanism comprising a locking plate configured to move between a first position and a second position, wherein the locking plate is configured to retain the movable hook in the locked position when in the first position.

[17] By means of the invention, there is provided a quick hitch comprising a manually operated locking mechanism which removes the need for a safety pin locking system as in currently used in manual quick hitches, thus avoiding the problems associated with the use of a safety pin locking system.

[18] In addition, the locking mechanism provides a locking system which may be operated by a single motion thus making the locking system of the invention simpler and easier to use that known safety pin locking systems. The single motion will lift the locking plate out of the first position, and in use permit the pivoting of the movable hook.

[19] Preferably, the locking plate is securely connected to the movable hook.

[20] In exemplary embodiments, the locking plate is configured to retain the movable hook in the locked position by restricting rotational movement of the movable hook.

For example, the locking plate may be arranged to restrict rotational movement of the movable hook by blocking or obstmcting a rotational path of the movable hook towards the fully unlocked position.

[21] Preferably, the locking plate when in the second position is configured to release the movable hook from the locked position.

[22] In exemplary embodiments, the locking plate when in the second position does not block or obstruct the rotational path of the movable hook towards the fully unlocked position.

[23] Preferably, the locking plate comprises a width greater than a width of the movable hook.

[24] In exemplary embodiments, the locking plate is substantially H-shaped, substantially Y-shaped, substantially NI-shaped or substantially U-shaped.

[25] The locking plate may be biased towards the first position.

[26] In exemplary embodiments, the locking mechanism further comprises a rocking lever coupled to the locking plate, wherein the rocking lever is configured to bias the locking plate towards the first position.

[27] In embodiments comprising a rocking lever, the rocking lever may be configured to be operably coupled to a pivot pin of the movable hook of the quick hitch.

[28] In this way, the locking mechanism may be associated with the engagement system of the quick hitch thus ensuring that the locking mechanism is utilised, [29] The rocking lever may be coupled to the rocking plate by a coupling pin.

[30] In exemplary embodiments wherein the rocking lever is coupled to the rocking plate by a coupling pin, the locking plate is preferably suspended from the coupling pin so as to allow free movement of thc locking plate about the coupling pin.

[31] In exemplary embodiments comprising the rocking lever, the quick hitch may further comprise a spring arranged to facilitate the rocking lever in biasing the locking plate towards the first position.

[32] In exemplary embodiments comprising the rocking lever, the rocking lever may be centrally mounted on a pivot pin of the movable hook of the quick hitch.

[33] In exemplary embodiments, the locking mechanism may further comprises a stopper arranged to restrict movement of the locking plate when in the first position.

[34] Preferably, the stopper is mounted on an internal wall of the quick hitch.

[35] In exemplary embodiments, the quick hitch comprises a stopper mounted on opposing internal walls of the quick hitch.

[36] Preferably, the stopper(s) comprise a check at a distal end thereof, the check arranged to resifict the movement of the movable hook in the fully unlocked position.

[37] In exemparv embodiments, the quick hitch further comprises a retainer configured to control the movement of the locking plate from the first position towards the second position.

[38] The retainer may comprise a pair of hooks mounted on an outer surface of the movable hook and arranged to engage with the locking plate.

[39] Alternatively, the retainer may comprise a substantially T-shaped block having outwardly extending arms arranged to engage with the locking plate.

[40] In exemplary embodiments wherein the quick hitch comprises a retainer, the quick hitch may further compise a spring mechanism arranged to bias the retainer towards engagement with the locking plate.

[41] In yet another alternative embodiment, the retainer may comprise at least one fastener.

[42] The quick hitch in accordance with the invention may be a manual quick hitch or a semi-automatic quick hitch.

[43] A second aspect of the invention provides a manually operated locking mechanism for a quick hitch comprising: a locking plate configured to move between a first position and a second position; wherein the locking plate is arranged such that when the locking mechanism is incorporated in a quick hitch, the first position is configured to retain a movable hook of the quick hitch in a locked position and the second position is configured to release the movable hook from the locked position.

[44] In exemplary embodiments, the locking plate of the locking mechanism is substantially H-shaped, substantially Y-shaped, substantially M-shaped or substantially U-shaped.

[45] In exemplary embodiments, the locking mechanism further comprises a rocking lever coupled to the locking plate, wherein the rocking lever is configured to bias the locking plate towards the first position.

[46] Preferably, the rocking lever is configured to be operably coupled to a pivot pin of the movable hook of the quick hitch. For example, the rocking lever may be coupled to the locking plate by a coupling pin.

[47] Preferably, in embodiments wherein the rocking lever is coupled to the locking plate by a coupling pin, the locking plate is suspended from the coupling pin so as to allow free movement of the locking plate about the coupling pin.

[48] In exemplary embodiments, the locking mechanism further comprises a spring arranged to facilitate the rocking lever in biasing the locking plate towards the first position.

[49] In exemplary embodiments, the locking mechanism further comprises a stopper arranged to restrict movement of the locking plate when in the first position.

BRIEF DESCRIPTION OF THE DRAWINGS

[50] Embodiments of the invention %vill now be described with reference to the accompanying drawings, in which: [5]] Figure Ia is an exploded view ofan embodiment ofa quick hitch in accordance

with the prior art;

[52] Figure lb is a schematic view of the quick hitch of figure lain assembled form; [53] Figure 2 is a schematic view of an embodiment of a manually operated locking mechanism in accordance with a first aspect of the invention incorporated in a first embodiment of a quick hitch in accordance with a second aspect of the invention; [54] Figures 3a and 3b are schematic views showing the relative positioning of the movable hook and the stoppers in the quick hitch of figure 2; [55] Figure 4 is a schematic view of another embodiment of a manually operated locking mechanism in accordance the invention incorporated in a second embodiment of a quick hitch in accordance vith the invention; [56] FigureS is a cross sectional view of the quick hitch of figure 4; [57] Figures 6a to 6d are schematic views of the stages of releasing the movable hook from its locked position to its (lilly unlocked position; [58] Figures 7a and 7b are schematic views of a movable hook and locking mechanism forming part of a third embodiment of a quick hitch in accordance with the invention, and [59] Figure 8 is a schematic view of a working machinc incorporating a quick hitch in S accordance with the invention.

DETAILED DESCRIPTION OF EMBODIMENT(S)

[60] The preceding discussion of the background to the invention is intended only to facilitate an understanding of the present invention. It should be appreciated that the discussion is not an acknowledgement or admission that any of the material refered to was part of the common general knowledge as at the priority date of the application.

[61] Throughout the description and claims of this specification, the words "comprise" and "contain" and variations of the words, for example "comprising" and "comprises", mean "including but not limited to", and is not intended to (and does not) exclude other components, integers or steps.

[62] Throughout the description and claims of this specification, the singular encompasses the plural unless the context otherwise requires. In particular, where the indefinite article is used, the specification is to be understood as contemplating plurality as well as singularity, unless the context requires otherwise.

[63] Features, integers or characteristics, and compounds described in conjunction with a particular aspect, embodiment or example of the invention are to be understood to be applicable to any other aspect, embodiment or example described herein unless incompatible therewith.

[64] Referring to figures la and ib, an embodiment of a quick hitch 1 in accordance

with the prior art is shown.

[65] The quick hitch 1 comprises a movable hook 2 and a fixed hook 3 located at opposing ends of a body 8, The movable hook 2 is pivotably mounted to the body 8 and is movable between a locked position and a frilly unlocked position (not shown).

[66] The fixed hook 3 is configured to engage with a front pivot pin of an attachment S and the movable hook 2 is configured to engage with a rear pivot pin of an attachment.

[67] The quick hitch is configured to be attached to the working arm of a working machine by means of hitch pins 6 located within eyelets 9 in the body 8.

[68] The embodiment shown in figures a and th is of a manual quick hitch system and relies on the attachment, once engaged, being retained by the use of a manual latch mechanism, such as a screw operated latch (operated using a ratchet), or a sprung latch (operated using a detachable lever, called a tommy-bar').

[69] A safety pin 4 is manually inserted into a side of the quick hitch to stop the movable hook 2 from opening inadvertently. The safety pin 4 is held in place by a lynch pin 5.

[70] A central spring 7 is provided for biasing the movable hook 2 towards the locked position.

[7]] Refering to figure 2, an embodiment of a manually operated locking mechanism 12 in a first embodiment of a quick hitch 10 in accordance with the invention is shown.

[72] The quick hitch 10 is a manual quick hitch and relies on the attachment, once engaged, being retained by the use of a manual mechanism (not shown), such as a screw operated latch (operated using a ratchet), or a sprung latch (operated using a detachable lever, called a tommy-bar').

[73] In common with quick hitches known in the art, the quick hitch 10 of the invention also comprises a fixed hook 14 configured to engage with a front pivot pin of an attachment (not shown) and a movable hook 16 configured to engage with a rear pivot pin of an attachment (not shown). The movable hook 16 is arranged to move between a socked position and a fully unlocked position, with the screw operated latch or spmng latch is operably linked to the movable hook 16 to retain the hook lÔin the S locked position and/or engagement with the rear pivot pin in use.

[74] The term "locked position" is used to denote the position of the movable hook 16 where it is arranged to close off a recessed area 33 in the body 31 of the quick hitch 10 configured to receive the rear pivot pin of an attachment therein, h this position, in use, the movable hook 16 will engage with the rear pivot pin and retain it within the recessed area 33, thus coupling the rear pivot pin to the quick hitch 10.

[75] The term "filly unlocked position' is used to denote the position of the movable hook 16 where it is arranged not to obstruct access to the recessed area 33 in the body 31. In this position, the rear pivot pin of an attachment may be inserted into or removed from the recessed area 33.

[76] The body 31 of the quick hitch comprises a pair of opposing side support plates having a first section 37a and a second section 37b. In figure 2, the left hand side second section has been omitted and the left hand side first section is drawn as being transparent for clarity. The recessed area 33 is configured to receive the rear pivot pin of an attachment is located on the first section 37a, The first section 37a also comprises a recessed area 39 configured to receive the front pivot pin of an attachment.

[77] The quick hitch 10 is arranged to be coupled to the working arm of the working machine by means of hitch pins (not shown) located within eyelets 28 located on the quick hitch 10 on an opposite side thereof to the side of the quick hitch 10 that engages with the attachment. In the embodiment shown, the eyelets 28 are located on the second section 37b of the side support plates 35 defining the body 31, The arrangement is similar to that known in the art and as such will not be discussed any further.

II

[78] The locking mechanism 12 comprises a locking plate 18 configured to move between a first position and a second position. The locking plate 8 when in the first position is configured to retain the movable hook 16 in the locked position and in use prevent the movable hook 16 from inadvertently releasing the rear pivot pin in use, as described in more detail below. The locking plate 18 is also configured to release the movable hook 16 from the locked position when in the second position.

[79] The locking plate 18 is of a width that is greater than the width of the movable hook 16. In the embodiment shown, the locking plate 18 is substantially H-shaped, although it would be understood that the locking plate 18 may be any suitable shape and is not limited to the shape shown in the figures.

[80] The locking mechanism 12 further comprises a rocking lever 20 coupled to the locking plate 18. The rocking lever 20 is configured to bias the locking plate 18 towards the first position.

[81] The rocking lever 20 is facilitated to bias the locking plate 18 by at least one spring (not shown). In the embodiment shown, the rocking lever 20 is facilitated by two springs in the form of torsion springs. In this way, should one of the springs fail, the rocking lever 20 will still bias the locking plate 18 towards the first position.

[82] While the locking mechanism 18 is described with two torsion springs, it is to be understood that a single torsion spring or more than two torsion springs may be utilised to facilitate the rocking lever 20 in biasing the locking plate 18 towards the first position. In addition, the springs may instead be in a different form, for example in the form of compression springs rather than torsion springs.

[83] While the locking mechanism 8 has been described comprising springs, the rocking lever 20 may instead be assisted by any suitable means that is capable of facilitating the rocking lever 20 in biasing the locking plate 8 towards the first position and is not limited to one or more springs.

U

[84] The rocking lever 20 is coupled to the locking plate 18 by a coupling pin 22. In the embodiment shown, the locking plate 18 is suspended from the coupling pin 22 so as to allow free movement of the locking plate 18 about the coupling pin 22.

[85] The rocking lever 20 is operably coupled to a pivot pin 24 of the movable hook t6. In the embodiment shown, the rocking lever 20 is centrally mounted on the pivot pin 24. It would be understood that it is not essential for the rocking lever 20 to be centrally mounted on the pivot pin 24, and may be mounted at any position on the pivot pin 24.

[86] The locking mechanism 12 further comprises a stopper 30 arranged to restrict tO movement of the locking plate t8 when in the first position. The stopper 30 is arranged such that it is configured to restrict fill rotational movement of the locking plate 18 about the coupling pin 22 when the locking plate 18 is in the first position.

[87] In the embodiment shown, the locking mechanism 12 comprises a pair of stoppers 30, each mounted on opposing internal walls 32 of the quick hitch 10. The stoppers 30 are fixed to and positioned on the internal walls 32 such that each stopper lies in the path of the rotational movement of the locking plate 18 about the coupling pin 22 when the locking plate 18 is in the first position. Rotational movement of the locking plate 18 when in the first position will be prevented by the legs 19 of the H-shaped locking plate 18 abutting against the fixed stoppers 30. Figure 3a shows a schematic representation of the abutment of the legs 19 of the locking plate 18 against the stoppers 30. Figure 3a is for illustration purposes only and is not drawn to scale.

[88] The stoppers 30 are sized and arranged such that the part of the stoppers 30 that comes into contact with the locking plate 18 does not prevent movement of the movable hook 16 towards the fully unlocked position when the locking mechanism 12 is released.

[89] Each stopper 30 comprises a check 34 at a distal end thereof Each check 34 is arranged to restrict the movement of the movable hook 16 in the filly unlocked 1-, Ii position. That is to say, the checks 34 will restrict the amount of rotation that the movable hook 16 may achieve about the pivot pin 24 once the movable hook 16 is released from the locked position. Figure 3b shows a schematic representation of the abutment of the movable hook 16 of the checks 34 of the stoppers 30. The legs of the locking plate are shown in phantom for clarity. As in the case of figure 3a, figure 3b is for illustration purposes only and is not drawn to scale. As can be seen, the movable hook 16 is narrower than the locking plate 18 so will not come in contact with the part of the stoppers 30 that comes into contact with the locking plate 18.

[90] In the embodiment shown, the checks 34 are in the form of tabs extending towards the interior of the quick hitch 10 having a surface for engagement with the movable hook 16.

[91] The quick hitch 10 further comprises a retainer 36 configured to control the movement of the locking plate 18 from the first position towards the second position.

The retainer 36 controls the movement of the locking plate 18 such that the initial movement of the locking 18 from the first position towards the second position is in a substantially linear direction.

[92] In the embodiment shown, the retainer 36 comprises a pair of hooks 38 mounted on an outer surface of the movable hook 16 and arranged to engage with each leg 19 the locking plate 18. It would be understood that the hooks 38 may be of a different shape and/or design depending on the shape and/or design of the locking plate 18.

[93] The hooks 38 may be integrally formed with the movable hook 16 or be fixedly attached to the movable hook 16.

[94] The quick hitch 10 further comprises a spring mechanism 42 for biasing the movable hook 16 towards the locked position (shown in a frilly retracted position). Tn the embodiment shown, the spring mechanism 42 is arranged to engage with the outer surface of the movable hook 16 at a section between the hooks 38 of the retainer 36.

In this way, the spiing mechanism 42 also acts to bias the retainer 36 towards engagement with the locking plate 18. Pt

[95] Referring to figures 4 and 5, a second embodiment of a quick hitch 100 in accordance with the invention is shown. Various components of the quick hitch 100 are not shown in figure 5 for clarity.

[96] The second embodiment is similar to the first embodiment and the same reference numerals have been used for identical features. The reference numerals for similar features of the second embodiment to those of the first embodiment have been increased by 100 for convenience. For example, the movable hook which was identified with reference numeral 16 in the first embodiment, is identified with reference numeral 116 in the second embodiment.

tO [97] As previously described, in relation to the first embodiment, the rocking lever 20 is facilitated to bias the locking plate 18 by two springs 26 in the form of torsion springs (see figure 5).

[98] The main difference between the first and second embodiments is in the design of the retainer and the spring mechanism.

tS [99] In the second embodiment, the retainer 136, rather than comprising a pair of hooks, comprises a substantially T-shaped block having outwardly extending arms 146 arranged to engage with the locking plate 8, The arms 146 work in a similar manner to the hooks 38 of the first embodiment.

[100] The retainer 136 is coupled to the movable hook 116 by means of fasteners 148.

In the embodiment shown, the fasteners 148 are in the form of bolts but it would be understood that any suitable fastener may be used or the retainer 136 may instead be fixed to the movable hook 116 by other means such as welding etc. [101] In the second embodiment, the spring mechanism 142 is also arranged to bias the movable hook 116 towards the locked position. However, rather than engaging with the outer surface of the movable hook 116, the spring mechanism 142 engages with a latch 144 that is configured to engage with the retainer 136 mounted on the movable hook 116.

[102] A cap 123 may be provided and located on a side of the locking plate 118 to ensure that the coupling pin 22 may be inserted from one side of the locking plate 118 only. The cap may be integrally formed with the locking plate 118, or separately formed and rigidly secured to the locking plate 118.

[103] With particular reference to figures 6a to 6d, the working of the locking mechanism 12 in use will now be described.

[104] When the locking plate 18 is in the first position and the movable hook 116 is in the locked position (see figure 6a), the locking mechanism 12 prevents the release of the movable hook 116 from the locked position to a frilly unlocked position should the manual mechanism (i.e. screw operated latch or sprung latch) fail or not be engaged.

This is due to the fact that the legs 19 of the locking plate 18 will come into engagement with the stoppers 30 (as shown in figure 3a). In this position, the legs 19 of the locking plate 18 sit within the arms 146 (or hooks 38 in the first embodiment) ofthe retainer 136.

[105] In order to move the movable hook 116 towards the fully unlocked position, a user first manually lifts the rocking lever 20 which in turn will cause the legs 19 of the locking plate 18 to be lifted into the second position (see figure 6b). The legs 19 of the locking plate 18 may be lifted such that a lower end thereof is partially retained within the arms 146 (or hooks 38 in the first embodiment) as shown in figure 6b or such that they are frilly lifted out of the arms 146 (or hooks 38 in the first embodiment).

[106] A stop plate (not shown) may be provided on the movable hook 16 and a free end of the rocking lever 20 (i.e. the end opposite the end with the coupling pin 22) is configured to come into contact with the stop plate, if provided, to indicate to the user when the rocking lever 20 has been lifted sufficiently such that it clears both the arms 146 (or hooks 38 in the first embodiment) and the stoppers 30.

[107] The screw operated latch or sprung latch is then released in order to allow the movement of the movable hook 116. The method of releasing and operation of the screw operated latch or sprung latch is known in the art and as such will not be discussed in any detail.

[108] Once released, the movable hook I 6 is moved towards the frilly unlocked position (scc figure 6c).

[109] Once in the frilly unlocked position, the rocking lever 20 may be released and once released, will bias the locking plate 18 towards the stoppers 30. The legs 19 of the locking plate 18 end up resting on top of the stoppers 30, and also sitting within the arms 146 (or hooks 38 in the first embodiment), as shown in figures 3b and 6d.

[1101 In order to be able to move the movable hook 116 from the filly unlocked position towards the locked position, in the case of a screw operated latch, the screw operated latch is operated to move the movable hook 116 towards the locked position.

The locking plate 8 will move with the movable hook 116 and along the stoppers 30.

When the locking plate 18 no longer rests on the stoppers 30 it will drop back to a position wherein rotational movement of the locking plate t8 is once again prevent by the stoppers 30.

[11] With reference to figures 7a and 7b, an embodiment of a locking mechanism 212 forming part of a quick hitch 200 in accordance with a third embodiment of the invention will now be described.

[112] The quick hitch 200 is similar to the first embodiment described above, with the main differences being the design of the locking mechanism 212 and the design of the movable hook 216.

[113] Like the previously described embodiments, the quick hitch 200 comprises a fixed hook (not shown) configured to engage with a front pivot pin of an attachment (not shown), a movable hook 26 configured to engage with a rear pivot pin of an attachment (not shown) and arranged to move between a locked position and a fully unlocked position, a body comprising a pair of opposing side support plates having a F' first section arid a second section (not shown), and a spring mechanism (not shown) for biasing the movable hook 216 towards the locked position.

[114] As in the previously described embodiments, the locking mechanism 212 comprises a locking plate 218 configured to move between a first position and a second position, and at least one stopper (not shown) arranged to restrict movement of the locking plate 218 when in the first position.

[115] The locking plate 28 is biased towards the first position, but instead of being biased by a rocking lever as in the previously described embodiments, the locking plate 218 is biased by gravity towards the first position or may be biased by a spring tO or similar mechanism towards the first position.

[116] The purpose of the locking plate 218 and the stopper(s) are the same as outlined in relation to the earlier described embodiments.

[117] In an exemplary configuration, a pair of stoppers fixed and positioned on opposing the internal walls of the quick hitch 300 as described above are utilised.

[118] Similarly to the previously described embodiments, the locking plate 218 is operably coupled to the movable hook 216. The way in which the locking plate 2 t 8 is operably coupled to the movable hook 216 will be described in further detail below.

[119] As in the previously described embodiments, the locking plate 218 is ofa width that is greater than the width of the movable hook 216. In the embodiment shown, the locking plate 218 is substantially M-shaped, although it would be understood that the locking plate 218 may be any suitable shape and is not limited to the shape shown in the figures.

[120] The locking plate 218 is operably coupled to the movable hook 216 by means of fasteners 248 and is configured to slide relative to said fasteners 248 between the first and second positions. The fasteners 248 therefore act in a similar fashion to the retainers 36)36 of the earlier described embodiments, in that they are configured to control the movement of the locking plate 218 from the first position towards the second position. The location and positioning of the fasteners 248 control the movement of the locking plate 218 such that the movement of the locking 218 from the first position towards the second position is in a substantially linear direction.

[121] The way in which the locking plate 218 is coupled to the movable hook 216 means that the locking plate 218 will move with the movable hook 216 as the movable hook rotates.

[122] As a result, rotational movement of the movable hook 216 will be prevented by the locking plate 218 when the locking plate 218 is in the first position (as shown in figure 7a) due to the legs 219 of the M-shaped locking plate 218 abutting against the fixed stoppers.

[123] Manually sliding the locking plate 218 to the second position (as shown in figure 7b) will move the legs 219 of the M-shaped locking plate 218 out of the path of the stoppers, thus allowing the movable hook 216 to move from the locked position (i.e. when movement is restricted by the locking plate 218) towards the fully unlocked position.

[124] In the embodiment shown, the movable hook 216 comprises a cavity or opening 252 configured to receive part of a tool (not shown) therein in order to facilitate the movement of the locking plate 218 from the first position towards the second position.

The tool may be any suitable tool, for example a tommy bar, capable of imparting a force to the locking plate 218 greater than the biasing force acting on the locking plate 218.

[125] Referring to figure 8, an embodiment of a working machine 300 incorporating a quick hitch 10, 100, 200 in accordance with the invention is shown.

[126] The quick hitch 0, 100, 200 is utilised to couple an attachment 304 in the form of a bucket to the working arm 302 of the working machine 300 by way of hitch pins 306.

[127] While the locking mechanism 12, 212 in accordance with the invention has been described installed in a manual quick hitch system, it is not limited to such applications and may also be installed in semi-automatic quick hitch systems.

[128] With a scmi-automatic quick-hitch system the attachment is retained with a hydraulically operated latch, but the locking mechanism provides additional security.

[129] In essence, the locking mechanism 12, 212 in accordance with the invention may be utilised in any quick hitch system wherein a safety pin is currently used to stop the inadvertent release of the movable hook from the rear pivot pin of the attachment.

[130] The locking mechanism 12, 212 in accordance with the invention has a number of advantages over known safety pin locking systems. Firstly, the issues associated with the misplacement of a key component of the locking system are removed.

[131] In addition, since the locking mechanism 12, 212 is designed to be built into the quick hitch, it is more protected from damage than a safety pin locking system. It also can be easily inspected for damage.

[132] Furthermore, the locking mechanism 12, 212 is designed such that when incorporated into a quick hitch, the operation of the quick hitch does not change thus not imparting any additional burden to an operator in use.

[133] Although the invention has 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 of the invention as defined in the appended claims.

[134] In addition, the invention is not restricted to the details of any foregoing embodiments. The invention extends to any novel one, or any novel combination, of the features disclosed in this specification (including any accompanying claims, abstract and drawings), or to any novel one, or any novel combination, of the steps of any method or process so disclosed.

Claims

Claims A quick hitch comprising: a movable hook arranged to move between a locked position and a fully unlocked position; and a manually operated locking mechanism comprising a locking plate configured to move between a first position and a second position, wherein the locking plate is configured to retain the movable hook in the locked position when in the first position.
2. A quick hitch as claimed in claim I, wherein the locking plate is securely connected to the movable hook.
3, A quick hitch as claimed in claim I or 2, wherein the locking plate is configured to retain the movable hook in the locked position by restricting rotational movement of the movable hook.
4. A quick hitch as claimed in claim 3, wherein the locking plate is arranged to restrict rotational movement of the movable hook by blocking or obstructing a rotational path of the movable hook towards the frilly unlocked position.
5. A quick hitch as claimed in any one of claims I to 4, wherein the locking plate when in the second position is configured to release the movable hook from the locked position.
6. A quick hitch as claimed in claim 5 when dependent on claim 4, wherein the locking plate when in the second position does not block or obstruct the rotational path of the movable hook towards the frilly unlocked position.
7. A quick hitch as claimed in any one of claims Ito 6, wherein the locking plate comprises a width greater than a width of the movable hook.
8. A quick hitch according to any one of claims Ito 7, wherein the locking plate is substantially H-shaped, substantially Y-shaped, substantially M-shaped or substantially U-shaped.
9, A quick hitch according to any one of claims Ito 8, wherein the locking plate is biased towards the first position.
10. A quick hitch according to any one of claims I to 9, wherein the locking mechanism further comprises a rocking lever coupled to the locking plate, wherein the rocking lever is configured to bias the locking plate towards the first position.
11. A quick hitch as claimed in claim 10, wherein the rocking lever is configured to be operably coupled to a pivot pin of the movable hook of the quick hitch.
12. A quick hitch as claimed in claim 10 or claim II, wherein the rocking lever is coupled to the rocking plate by a coupling pin.
13. A quick hitch as claimed in claim 12, wherein the locking plate is suspended from the coupling pin so as to allow free movement of the locking plate about the coupling pin.
14. A quick hitch as claimed in any one of claims 10 to H, further comprising a spring arranged to facilitate the rocking lever in biasing the locking plate towards the first position.
15. A quick hitch according to any one of claims 10 to 14, wherein the rocking lever is centrally mounted on a pivot pin of the movable hook of the quick hitch.
16. A quick hitch as claimed in any one of the preceding claims, wherein the locking mechanism further comprises a stopper arranged to restrict movement of the locking plate when in the first position.
17. A quick hitch according to claim 6, wherein the stopper is mounted on an internal wall of the quick hitch.
18. A quick hitch according to claim 16, comprising a stopper mounted on opposing internal walls of the quick hitch.
19. A quick hitch according to claim 17 or claim 18, wherein the stopper(s) comprise a check at a distal end thereof, the check ananged to restrict the movement of the movable hook in the frilly unlocked position.
20. A quick hitch according to any onc of claims 1 to 19, furthcr comprising a retainer configured to control the movement of the locking plate from the first position towards the second position.
21. A quick hitch according to claim 20, wherein the retainer comprises a pair of hooks mounted on an outer surface of the movable hook and arranged to engage with the locking plate.
22. A quick hitch according to claim 20, wherein the retainer comprises a substantially T-shaped block having outwardly extending arms arranged to engage with the locking plate.
23. A quick hitch according to claim 21 or claim 22, further comprising a spring mechanism arranged to bias the retainer towards engagement with the locking plate.
24. A quick hitch according to claim 20, wherein the retainer comprises at least one fastener.
25. A quick hitch according to any one of claims Ito 24, wherein the quick hitch is a manual quick hitch.
26. A quick hitch according to any one of claims I to 24, wherein the quick hitch is a semi-automatic quick hitch.
27. A manually operated locking mechanism for a quick hitch comprising: a locking plate configured to move between a first position and a second position; wherein the locking plate is arranged such that when the locking mechanism is incorporated in a quick hitch, the first position is configured to fin Li retain a movable hook of the quick hitch in a locked position and the second position is configured to release the movable hook from the locked position.
28. A locking mechanism as claimed in claim 27, wherein the locking plate is substantially H-shaped, substantially Y-shapcd, substantially M-shapcd or substantially U-shaped.
29. A locking mechanism as claimed in claim 27 or claim 28, further comprising a rocking lever coupled to the locking plate, wherein the rocking lever is configured to bias the locking plate towards the first position.
30. A locking mechanism as claimed in claim 29, wherein the rocking lever is configured to be operably coupled to a pivot pin of the movable hook of the quick hitch.
31. A locking mechanism as claimed in claim 29 or claim 30, wherein the rocking lever is coupled to the locking plate by a coupling pin.
32. A locking mechanism as claimed in claim 3], wherein the locking plate is suspended from the coupling pin so as to allow free movement of the locking plate about the coupling pin.
33. A locking mechanism as claimed in any one of claims 29 to claim 32, further comprising a spring arranged to facilitate the rocking lever in biasing the locking plate towards the first position.
34. A locking mechanism as claimed in any one of claims 27 to 33, further comprising a stopper arranged to restrict movement of the locking plate when in the first position.
35, A locking mechanism as generally hereinbefore described with reference to and/or illustrated in figures 2 to 7b of the accompanying drawings.
36. A quick hitch as generally hereinbefore described with reference to and/or illustrated in figures 2 to 7b of the accompanying drawings.