GB2239445A

GB2239445A - Coupling for excavator arm

Info

Publication number: GB2239445A
Application number: GB9028003A
Authority: GB
Inventors: Trevor Frederick Frank Hodges
Original assignee: Individual
Current assignee: Individual
Priority date: 1989-12-22
Filing date: 1990-12-24
Publication date: 1991-07-03
Also published as: GB9028003D0

Abstract

Attachment means such as a coupling (12) serve for the detachable attachment of a bucket 11 on the dipper arm 2 of a mechanical earth mover, for example a hydraulic excavator. The attachment device 12 directly attaches to the dipper arm and a tipping link of the excavator at the normal bucket attachment points and in use remains so attached. The device 12 has locating projections 13 which engage and locate relatively to the bucket 11. Latch means 25 are operative to latch the bucket 11 to the attachment device 12 when the device and bucket have boon brought into the correct relative position after said projections 13 have been engaged. <IMAGE>

Description

"ATTACHMENT MEANS" The invention relates to attachment means, and in particular to means for the attachment of a bucket on the so-called "dipper arm" of a mechanical earth mover or "excavator", typical examples of which are the machines which are well known under and colloquially referred to by the trade mark JCB. The bucket of such a machine is normally detachably attached, to allow it to be detached and replaced by a bucket of a different size.

The bucket conventionally has pivot bosses for attachment, by removable pivot pins, separately to the nose end of the dipper arm of the excavator and the controlling "tipping link" which is operated, commonly through a bellcrank lever, by a hydraulic tipping ram. Thus the attachment of a bucket requires manoeuvring it so that two sets of pivot bores, on the machine and bucket, are accurately aligned to permit insertion of the pivot pins by which the bucket is attached. It will be appreciated that this is time consuming and requires considerable effort, particularly with a large bucket which might weigh say up to 10 tonnes.

Accordingly, the changing of a bucket at present frequently requires the combined-efforts of three men, and the invention has for its aim to reduce the time and manpower required to change a bucket.

To this end the invention, according to one aspect thereof, provides a bucket attachment device which attaches to the dipper arm and tipping link of the machine at the normal bucket attachment points and in use remains so attached, which has a locating projection or projections which engage and locate relatively to the bucket, and latch means operative to latch the bucket to the attachment device when the device and bucket are brought into the correct relative position after said projections have been engaged.

According to another aspect thereof the invention provides the combination of a bucket and said attachment device, the bucket having locating means with which said locating projections engage and a keeper structure engageable by a latch member of said latch means to latch the bucket to the attachment device.

The invention according to a further aspect comprises such a bucket for use with an attachment device as described.

The invention also resides in a hydraulic excavator or like machine to the dipper arm of which an attachment device as aforesaid is attached.

The attachment device preferably has two spaced hook-like locating projections which may engage between a cross member at the front side of the bucket and an external bar disposed parallel to and spaced from the cross member, when engaged the projections hooking below the bar as the bucket moves relatively to the attachment device to the bucket-attached position. The keeper structure of the bucket for engagement by the latch means is then preferably disposed centrally at the rear top side of the bucket.

The latch means may comprise a latch bolt mounted at the rear end of the attachment device, and both latching and unlatching movement of the latch bolt are preferably under operator control; alternatively the latch bolt may be spring loaded so that the bucket is automatically latched to the attachment device when fully engaged therewith. The keeper structure may include a striker plate and a locking plate providing a tapered or stepped bore in which the latch bolt engages, the latter then being itself suitably tapered.

The latch bolt may be mounted on, or provided by, the piston rod of a double-acting hydraulic cylinder the appropriate pressurization of which either moves the bolt to latching position or retracts the bolt when it is desired to release a latched bucket. This latch operation may be under the remote control of a driver of the machine, with a latch/unlatch electrical switch in the driver's cab operating a two-way solenoid valve. Desirably the control system of the latch cylinder provides an audible and/or visual warning signal when the latch bolt is retracted, so that the driver will be made aware if an attached bucket is not locked in position by the latch means. With unlatching and latching remotely controlled in this manner the driver can, on his own, drop off a bucket and attach a different bucket without even leaving the cab.This represents a considerable saving in time and manpower as compared with conventional bucket attachment.

When the latch bolt is spring loaded to the latching position it may be mounted on, or provided by, the piston rod of a single-acting hydraulic cylinder the pressurization of which retracts the bolt when it is desired to release a latched bucket. Alternatively, or additionally, a manually-operated lever may be provided for retraction of the latch bolt and this may be a bellcrank lever with one limb thereof engaging a collar on the latch bolt and the other limb providing a latch release handle.

The invention will now be further described with reference to the accompanying drawings which illustrate a conventional bucket attachment and several embodiments of attachment means in accordance with the invention. In the drawings: Fig. 1 illustrates the outer end of the dipper arm of a hydraulic excavator with conventional bucket attachment; Fig. 2 similarly illustrates, to a larger scale, bucket attachment means in accordance with a first embodiment of the invention; Figs. 3 and 4 are respectively diagrammatic side and rear views of an attachment device shown in Fig. 2; Figs. 5 and 6 are similarly side and front views of the bucket of Fig. 2; Fig. 7 shows the manner of initial engagement of the attachment device and the bucket; Fig. 8 is a front view of the attachment device and bucket in the final attached position of the latter.

Figs. 9 to 11 respectively correspond to Figs. 2, 3 and 7 but illustrate a second embodiment of the invention; Figs. 12 to 15 respectively correspond to Figs. 2, 3, 4 and 8 but illustrate a third embodiment; Fig. 16 is a plan view of the third embodiment; and Fig. 17 illustrates a detail thereof.

Fig. 1 shows how in conventional practice a bucket 1 is attached to the dipper arm 2 of a hydraulic excavator. It has laterally spaced pivot bosses 3 with bores aligned with pivot bores in the arm 2, pivotal connection to the later being achieved by the insertion of a pivot pin 4. Similarly, laterally spaced pivot bosses 5 have bores aligned with an end eye of the tipping link 6 of the excavator and a pivot pin 7 is inserted through them.

It can clearly be seen that with a large and heavy bucket the alignment of the two sets of pivot bores to allow insertion of the pins 4 and 7 can be a lengthy procedure with considerable effort being involved. Once the bucket 1 has been attached, tipping movement thereof about the outer nose end of the dipper arm 2 is effected under the control of a hydraulic tipping ram 8 connected to the tipping link 6 via a pivoted bellcrank lever 9.

Fig.2 shows how in accordance with one embodiment of the invention the arrangement of Fig. 1 can be changed to provide a novel bucket attachment which is far less time consuming and less labour intensive, normally being accomplished by the excavator driver who does not require assistance nor need to leave his cab to change a bucket.

The bucket 11 is not now directly attached to the dipper arm 2, but is instead attached through the intermediary of an attachment device 12; and it is the device 12 which is now attached by the pivot pins 4 and 7, to the arm 2 and link 6 respectively. The device 12 remains so attached, and hence attaching or changing a bucket does not involve removal and re-fitting of the pins 4 and 7.

For attachment of the bucket the device 12 has at the front end two laterally spaced and downwardly projecting locating projections 13 which engage a carrying bar 14 at the front side of the bucket 11 in a hook-like manner. At the opposite end the device 12 has latch means 15 which automatically latch to a keeper structure 16 at the rear top edge of the bucket 11, disposed centrally thereof, to lock the bucket 11 in its attached position relatively to the attachment device 12.

Details of the attachment device 12 are more clearly shown in Figs. 3 and 4. It comprises a welded steel fabrication with a main plate 20 from which the projections 13 depend, and two parallel top cheek plates 21 with pivot bosses 22 having bores 22a through which the pins 4 and 7 are fitted. The latch means 15 are mounted on the plate 20 centrally between the plates 21 and comprise a single-acting hydraulic cylinder 23 the piston of which is urged by an internal spring 24 to a latching position. The outer end of the piston rod of the cylinder 23 is formed as a latch/locking bolt 25. In the latching position the bolt 25 projects for latching engagement with the keeper structure 16 of the bucket 11.

The projecting latching/locking position of the latch bolt 25 is illustrated in Fig. 3, and pressurization of the cylinder 23 via a hydraulic connection 26 retracts the latch bolt 25, against the spring 24, to release an attached bucket.

Details of the bucket 11 for attachment to the attachment device 12 are more clearly shown in Figs. 5 and 6. The fabricated steel bucket is of conventional form and shape apart from the attachment features determined by the form of the attachment device 12. Thus, the bucket is provided with the hanging bar 14 and keeper structure 16.

The bar 14 extends parallel to, and spaced outwardly from, a front cross member 30 at the top of the bucket 11, and it passes through four webs 31 to 34 to which it is secured.

The webs 31,32 and 33,34 provide two pairs of cheek plates which form location means between which the two locating projections respectively engage for location laterally of the bucket 11.

The keeper structure 16 comprises a striker plate 35, with an inclined upper end for initial engagement with the projecting latch bolt 25, and a locking plate 36.

Aligned holes in the plates 35 and 36 provide a stepped latch bore 37 in which the tapered nose of the latch bolt 25 engages with a wedging action, the hole in the plate 36 being smaller than that in the plate 35.

Attachment of the bucket 11 will now be described with particular reference to Figs. 7 and 8 of the drawings.

The excavator driver brings his machine up to the front of the bucket to be attached and lowers the attachment device 12 (which may be permanently fitted on the dipper arm 2) at an angular elevation such that the hooked projections 13 engage and locate between the bar 14 and the cross member 30, as illustrated in Fig. 7. With that end of the attachment device 12 located on the bucket 11, by operation of the tipping ram 8 the attachment device 12 is moved in the direction of the arrow A in Fig. 7, ie clockwise in that figure, about an instantaneous pivot centre defined by the bar 14. During such movement the projections 13 hook below the bar 14 for secure attachment of the front end of the bucket 11. This controlled movement is continued until the main plate 20 of the attachment device 12 rests flat on the top of the bucket 11 as shown in Fig. 8.When this position is reached engagement of the latch bolt 25 with the striker plate 35 has moved the bolt 25 initially inwardly until, at the final attached-bucket position, the bolt 25 is aligned with the bore 37, and shoots into latching/locking engagement with the keeper structure 16.

The bucket 11 is now firmly attached to the attachment device 12 and locked in position, the front edge 38 of the plate 20 fitting tightly against the keeper structure 16 to wedge the projections 13 against the bar 14. This provides accurate and firm location for the bucket 11.

Detachment of the bucket 11, again by the excavator driver operating alone whilst remaining in his cab, is achieved by the reverse procedure after remote release of the latch means 15. For this purpose a solenoid valve, operated by a release switch in the cab, is provided in the hydraulic control circuit of the latch cylinder 23.

Visual and/or audible alarm means in the cab indicate to the driver when the latch/locking bolt 25 is retracted and not in full locking engagement with the keeper 16.

The changes effected in the second embodiment are shown in Figs. 9 to 11 and relate to the latch means now identified by reference 115, unchanged parts retaining the original reference numerals. The latch means 115 now comprise a double-acting hydraulic cylinder 123 in place of the single-acting cylinder 23. Movement of the latch bolt 25 to the projecting latching/locking position now results from pressurization of the inner end of the cylinder 123, not spring loading, and alternative pressurization of the outer end of the cylinder 123 retracts the latch bolt 25 to release an attached bucket. Hydraulic pressure and return connections for pressurization of one end or the other of the cylinder 123 are shown diagrammatically at 126.

For attachment of the bucket 11 the excavator driver, with this second embodiment, brings his machine up to the front of the bucket with the latch bolt 25 already retracted. The inclined upper end of the striker plate 35, which is unchanged, ensures smooth engagement with the latch bolt 25 should the latter inadvertently be left projecting. When the position is reached with the bolt 25 aligned with the bore 37, the driver in the cab remotely pressurizes the inner end of the cylinder 123 to shoot the latch bolt 25 into latching/locking engagement with the keeper structure 16.

Thus the driver remotely controls movement of the latch bolt 25 in both directions, and this is controlled by actuation of a two-way latch/release switch in the cab of the machine. This switch controls solenoid valves in turn controlling pressurization of the cylinder 123.

The third embodiment illustrated in Figs. 12 to 17 of the drawings again modifies the latch means 215 which comprise a latch bolt 225 urged by twin springs 224 to the projecting latching position. Thus automatic latching is achieved as in the first embodiment, and no hydraulic actuation is employed. Instead manual latch release is effected, via a bellcrank lever 200 which pivots on a pivot post 201 projecting upwardly from the main plate 20 of the attachment device. The bellcrank 200 is of two-part construction with limbs 202,203 which are separate parts independently mounted on the pivot post 201. The limb 202 is attached at its outer end to a collar 204 on the latch bolt 225, being attached via a pivotal connection 205. The outer limb 203, which provides a manual release lever, has an inturned end portion 203a which engages alongside the limb 202 so that, when the release lever 203 is drawn outwards in the direction of the arrow A (see Fig. 17), the bellcrank 200 turns as a whole about the pivot 201 to retract the bolt 225.

Thus a simple spring-loaded latch mechanism is employed, with the twin springs 224 ensuring that the latch bolt 225 is constantly in locking position. Latching is automatic, and to release the bucket the side lever 203 merely has to be drawn outwards which allows the bucket to swing free. The limb 202 of the bellcrank 200 is provided with lost motion at the pivot 201, so that its effective length can change in accordance with movement of the collar 204. This is achieved by an elongated pivot eye 206 engaged by the pivot post 201.

Claims

CLAIMS:

1. Means for the attachment of a bucket on the dipper arm of a mechanical earth mover, for example a hydraulic excavator, comprising a bucket attachment device which attaches to the dipper arm and a tipping link of the machine at the normal bucket attachment points and in use remains so attached, which has a locating projection or projections which engage and locate relatively to the bucket, and latch means operative to latch the bucket to the attachment device when the device and bucket are brought into the correct relative position after said projections have been engaged.

2. Attachment means according to claim 1, wherein the attachment device has two spaced hook-like locating projections engageable between a cross member at the front side of the bucket and an external bar disposed parallel to and spaced from the cross member, when engaged the projections hooking below the bar as the bucket moves relatively to the attachment device to the bucket-attached position.

3. Attachment means according to claim 2, wherein a keeper structure of the bucket engageable by the latch means is disposed centrally at the rear top side of the bucket.

4. Attachment means according to any one of the preceding claims, wherein the latch means is spring loaded so that the bucket is automatically latched to the attachment device when fully engaged therewith, and unlatching movement of the latch bolt is under operator control.

5. Attachment means according to any one of claims 1 to 3, wherein both latching and unlatching movement of the latch means are under operator control.

6. Attachment means according to any one of the preceding claims, wherein the latch means comprises a latch bolt mounted at the rear end of the attachment device.

7. Attachment means according to claim 6, wherein the latch bolt is mounted on, or provided by, the piston rod of a hydraulic cylinder.

8. Attachment means according to claim 5 and claim 7, wherein the hydraulic cylinder is double-acting so that appropriate pressurization thereof either moves the bolt to latching position or retracts the bolt to release a latched bucket.

9. Attachment means according to claim 8, wherein latch operation is under the remote control of a driver of the machine, with a latch/unlatch electrical switch in the driver's cab operating a two-way solenoid valve.

10. Attachment means according to any one of claims 7 to 9, wherein a control system of the latch cylinder provides an audible and/or visual warning signal when the latch bolt is retracted, so that the driver will be made aware if an attached bucket is not locked in position by the latch means.

11. Attachment means according to any one of claims 6 to 10, wherein the keeper structure engageable by the latch bolt includes a striker plate and a locking plate providing a tapered or stepped bore in which the latch bolt engages, the latter being itself suitably tapered.

12. Attachment means according to claim 4, wherein a manually-operated lever is provided for retraction of the latch bolt.

13. Attachment means according to claim 12, wherein said lever is a bellcrank lever with one limb thereof engaging a collar on the latch bolt and the other limb providing a latch-release handle, the two limbs being separate parts such that on latching said one limb can move with the bolt collar without corresponding movement of the latch-release handle.

14. The combination of a bucket and attachment means in accordance with any one of the preceding claims, wherein the bucket has locating means with which said locating projections engage and a keeper structure engageable by a latch member of said latch means to latch the bucket to the attachment device.

15. A hydraulic excavator or like machine to the dipper arm of which an attachment device in accordance with any one of claims 1 to 13 is attached.

16. Means for the attachment of a bucket on the dipper arm of a mechanical earth mover, constructed and arranged substantially as herein particularly described with reference to Figs. 1 to 8, Figs. 9 to 11, or Figs. 12 to 17, of the accompanying drawings.