AU714190B2 - Improved attachment for skid steer loader - Google Patents

Description

AUSTRALIA

PATENTS ACT 1990 COMPLETE SPECIFICATION FOR A STANDARD PATENT 9*

ORIGINAL

Name of Applicant: Actual Inventor: Address of Service: Invention Title: IAN CLIVE POLLARD IAN CLIVE POLLARD SHELSTON WATERS MARGARET STREET SYDNEY NSW 2000 IMPROVED ATTACHMENT FOR SKID STEER LOADER Details of Associated Provisional Application No. PN8512 dated 7 March, 1996 The following statement is a full description of this invention, including the best method of performing it known to me/us:- The present invention relates to the field of skid steer loaders and attachments therefor.

Although the invention has been developed primarily for use as an excavation attachment which is manipulated using existing controls associated with a skid steer loader, it will be appreciated that the invention is not limited to this field of use.

Skid steer loaders are well known in the construction industry, and are widely used in situations where small size and high manoeuvrability are desirable. As well as being capable of performing standard digging and grading jobs, many skid steer loaders are 10 also configured to be fitted with back hoes, angle blades, earth augers, pallet forks and other attachments, each suited to a particular task.

Of particular usefulness is the back hoe attachment, especially for digging *0•8 trenches, foundations and the like. Unfortunately, existing back hoe attachments tend to be relatively complex pieces of machinery, requiring up to seven additional hydraulic rams to work effectively. These rams along with associated hoses and multiple jointed arms can place considerable additional structural and hydraulic loads on the skid steer oo loader.

Furthermore, in use the relatively heavy attachment is mounted to the main lifting arms of the loader, which are generally locked in a relatively low position when the attachment is being used. The high mass of the attachment and its forward position means that stabilising legs are often required to ensure that the loader remains steady during excavation. This adds considerably to the cost, weight, and complexity of the loader, whilst making it relatively inconvenient to drive the loader with each excavated load to a remote pile or truck. This, to some extent, reduces the advantages of using a small manoeuvrable loader in confined environments.

Yet another problem is the relatively low digging power and speed offered by such attachments, since powerful rams such as those used on the lifting arms of the loader itself tend to be relatively expensive. Furthermore, for reasons similar to those above, the relatively high weight of such large rams would make the loader even less stable in use.

Existing back hoe designs also require the operator to control the back hoe using "levers and other controls mounted adjacent the back hoe itself, rather than from the safety cage on the loader. This is relatively inconvenient, puts the operator at additional a. a risk of accident, and once again increases the complexity and cost of the attachments.

~It is an object of the present invention to overcome or at least substantially one or more of the disadvantages of the prior art.

Accordingly, the present invention provides an excavating attachment for a skid steer loader having a pair of lifting arms hingedly each being hingedly connected at a first end to a skid steer chassis, the excavating attachment including: a boom having a connection end and an attachment end remote therefrom, the connection end being releasably connectable to respective ends of the lifting arms remote from the first ends; a bucket hingedly connected to the attachment end of the boom for relative rotation between an extended position and a retracted position; and a first ram extending between the bucket and the boom, selectively to rotate the bucket between the extended and retracted positions.

-4- Preferably, the attachment is controllable substantially by standard control mechanisms associated with the skid steer loader.

Desirably, the connection end of the boom includes a rigid frame for hinged connection to the ends of the lifting arms.

Preferably, the ends of the lifting arms include downwardly depending brackets terminating in respective free ends, the frame being hingedly connected to the free ends of the brackets for rotation about a hinge axis with respect to the lifting arms. It is further preferred that the frame is generally planar and depends downwardly from the boom to define a lower free edge. In this embodiment, the boom is attached to the free ends of the brackets adjacent the free edge.

Preferably, a second ram extends between the frame and a support member extending between the lifting arms. Desirably, the second ram forms part of the standard hydraulic circuit of the skid steer loader.

In a preferred embodiment, the frame includes a transverse rail arrangement, and the boom includes a carriage mounted to the rail arrangement for transverse sliding movement with respect thereto. It is further preferred that the frame includes a 0 1 transverse rack, the rack including a series of spaced apart rack teeth. In this embodiment, the carriage includes pawl means selectively to engage the rack teeth, thereby selectively to prevent transverse movement of the carriage with respect to the rail.

Desirably, drive means associated with the pawl means are provided to transversely move the carriage with respect to the rail, thereby transversely moving the boom with respect to the skid steer loader.

Preferably, the pawl means includes a pair of spaced apart pawls, each having a plurality of spaced apart pawl teeth for complementary engagement with adjacent rack teeth. Preferably, each of the spaced apart pawls is adapted respectively to drive the rack in a transverse direction opposite to that of the other pawl.

It is desirable that control means are provided to selectively alter the direction of travel of the carriage with respect to the rack in response to actuation of the drive means.

In a preferred embodiment, the drive means includes a drive lever mounted for reciprocating rotational movement. Preferably, manual reciprocation of the lever causes sequential driving of the rack, retraction of the pawls from the rack, transverse movement of the pawls in a direction opposite to previous driving movement, and reengagement of the pawls with the rack.

oA preferred embodiment of the invention will now be described, by way of example only, with reference to the accompanying drawings in which: Figure 1 is a side elevation of a prior art back hoe excavation attachment mounted on a skid steer loader; "Figure 2 is a side elevation of an excavating attachment according to the invention attached to a skid steer loader, showing the range of movement available; Figure 3 is a side elevation of the attachment shown in Figure 2; Figure 4 is a schematic plan view of the attachment shown in Figure 3; and Figure 5 is a detailed schematic view of a pawl associated with the attachment shown in Figure 4.

Referring to the drawings, and in particular to Figure 2, an excavating attachment 1 for a skid steer loader 2 having a pair of lifting arms 3 hingedly connected to a skid steer -6chassis 4 includes a boom 6. The boom 6 has a connection end 8 and an attachment end remote therefrom. The connection end 8 is releasably connectable to respective ends 12 of the lifting arms 3 remote from the chassis 4.

A bucket 14 is hingedly connected to the attachment end 10 of boom 6 for relative rotation between an extended position (not shown) and a retracted position (as illustrated). A first ram 18 extends between bucket 14 and boom 6, selectively to rotate the bucket between the extended and retracted positions.

As best shown in Figure 3, the connection end 8 of boom 6 includes a rigid frame for hinged connection to the ends of the lifting arms. The frame 20 is generally planar and depends downwardly from the boom 6 to define a lower free edge 22.

The respective ends 12 of the lifting arms 3 include downwardly depending i" .brackets 24 terminating in respective free ends 26. The free edge 22 of frame 20 is hingedly connected to the free ends 26 of the brackets 24 for rotation about a hinge axis :o°.28 with respect to the lifting arms 3.

A support member (not shown) extends between the lifting arms 3. A second ram (not shown) extends between the support member and the frame 20, the second ram oS

S

being operable to rotate the frame 20 and thereby the boom 6 between an upper position A and a lower position B with respect to the lifting arms 3. In the upper position A, the frame 20 is generally parallel with and adjacent to the free ends 26 and the lifting arms 3, whilst in the lower position B, the frame 20 is angularly displaced from the free ends 26 of the lifting arms 3. The second ram forms part of the standard hydraulic circuit of the skid steer loader 2.

-7- As best shown in Figure 3, the first ram 18 has a first end 30 hingedly connected to a raised mounting point 32 on the boom 6. The first ram 18 also has a second end 34 hingedly connected to a formation on the bucket 14 via connection means shown generally as 36. Preferably the connection means 36 includes a pivot member 38 having first and second pivot ends 40 and 42 respectively, and a linkage member 44. The first pivot end 40 is hingedly connected to the second end 34 of the first ram 18, whilst the second pivot end is hingedly connected to the boom 6. The linkage member 44 extends between the first pivot end 40 and the bucket 14.

In the embodiment illustrated, the frame 20 includes a transverse rail arrangement 46, as best shown in Figures 3 and 4. The boom 6 includes a carriage 48 mounted to the rail arrangement 46 for transverse sliding movement with respect thereto. The frame i °"°further includes a transverse rack 50 including a series of spaced apart rack teeth 52.

The carriage 48 includes pawl means in the form of a pair of spaced apart pawls 54, each having a plurality of spaced apart pawl teeth 56 for complementary engagement with 4.*e adjacent rack teeth 52. The pawls 56 are mounted for movement about pawl axis 57, and ~are biased towards the rack 50 by spring arrangement 59.

4 Q The attachment further includes drive means including a drive lever 58 mounted for reciprocating rotational movement about axis 60. Manual reciprocation of the drive lever 58 causes selective transverse driving of the carriage 48 with respect to the rail arrangement 46.

In use, the excavation attachment is mounted to the lifting arms 3 of the skid steer loader 2 by suitable connection means. It is preferred that this connection is achieved by means of standard attachment means such as those currently used to secure existing -8attachments to such loaders. For example, the attachment may be configured to use the "Bob-Tach System" typically used with Bob Cat loaders and the like. However, any other suitable attachment means may be used.

Once the attachment is securely mounted to the loader, an operator may control it using the existing hydraulic control systems. For example, the bucket may be raised or lowered simply by using pre-existing foot pedal controls located on the floor of the loader's cabin. Rotational movement of the boom with respect to lifting arms may be effected by another foot pedal located near the operator. In one standard configuration, :the raising and lowering motion is controlled by a left foot pedal, whilst rotational 10 movement of the boom may be controlled by a right foot pedal.

•Slewing of the attachment to the left or right is achieved using the pre-existing skid i* steer feature of the loader. In this way, use of a left hand steering lever (LHSL) and right hand steering level (RHSL) enables slewing of the entire skid steer loader, and thereby the excavation attachment.

S

The bucket may be rotated about the attachment end of the boom by means of the 5555 first hydraulic ram. With a typical Bob Cat loader, this movement may be effected by S. S movement of the RHSL to the left or right. Such movement causes selective extension and retraction of the first ram, thereby causing the bucket to be rotated with respect to the boom.

In some situations, the transverse movement capabilities of the attachment may be useful. In one embodiment, the racket and pawl mechanism merely acts as a powerful lock to prevent undesirable transverse movement of the attachment in use. In this embodiment, operation of the lever causes disengagement of the pawls from the rack, -9which enables the boom to slide along the rail and carriage assembly in response to the operator pushing the boom.

Even more advantageously, the lever may be operated to sequentially drive each pawl with respect to the rack. Reciprocating the lever will cause each pawl to sequentially disengage the rack, retract in the same direction as the boom is desired to be moved, re-engage the rack, then drive the boom in the desired direction. In this way, even very heavy loads can be moved sequentially along the rack in a transverse direction by manipulation of the drive lever. Control means (not shown) enable the direction of *o.

drive to be changed, as well as allowing the entire mechanism to be locked in one transverse position.

The present invention provides a number of advantages over prior art excavation attachments. In its broadest form, the invention allows the use of powerful pre-existing rams associated with the lifting arms. In most cases, only one additional ram to control rotation of the bucket with respect to the boom will be required, which vastly simplifies the attachment itself. The reduction in complexity and cost ensures that this aspect of :the invention alone provides a significant commercial advantage over prior art attachments. In the preferred embodiment, the additional feature of the ratchet operated transverse rail and carriage arrangement allows for powerful transverse movement of the boom in use, without expensive additional hydraulics. For these reasons, the present invention represents a commercially significant advance over prior art excavation attachments for use with skid steer loaders.

Although the invention has been described with reference to a specific example, it will be appreciated by those skilled in the art that the invention may be embodied in many other forms.

Claims (19)

1. An excavating attachment for a skid steer loader having a pair of lifting arms hingedly each connected at a first end to a skid steer chassis, the excavating attachment including: a boom having a connection end and an attachment end remote therefrom, the connection end being releasably connectable to respective ends of the lifting arms remote from the first ends; a bucket hingedly connected to the attachment end of the boom for relative rotation "between an extended position and a retracted position; and a first ram extending between the bucket and the boom, selectively to rotate the bucket between the extended and retracted positions.

2. An excavating attachment according to claim 1, wherein the attachment is controllable substantially by standard control mechanisms associated with the skid steer loader. •°oo

3. An excavating attachment according to claim 1 or claim 2, wherein the connection end of the boom includes a rigid frame for hinged connection to the ends of the lifting °.E arms.

4. An excavating attachment according to claim 3, wherein the ends of the lifting arms include downwardly depending brackets terminating in respective free ends, the frame being hingedly connected to the free ends of the brackets for rotation about a hinge axis with respect to the lifting arms.

I 1 -11- An excavating attachment according to claim 4 wherein the frame is generally planar and depends downwardly from the boom to define a lower free edge, the boom being attached to the free ends of the brackets adjacent the free edge.

6. An excavating attachment according to claim 5, further including a support member extending between the lifting arms, and a second ram extending between the support member and the frame, the second ram being operable to rotate the frame and thereby the boom between an upper position and a lower position with respect to the lifting arms, such that, in the upper position the frame is generally parallel with and adjacent to the free ends of the lifting arms, and in the lower position the frame is angularly displaced from the free ends of the lifting arms.

7. An excavating attachment according to claim 6, wherein the second ram forms part °°of the standard hydraulic circuit of the skid steer loader.

8. An excavating attachment according to any one of the preceding claims, wherein the first ram has a first end hingedly connected to a raised mounting point on the boom. oogo

9. An excavating attachment according to claim 8 wherein the first ram has a second end hingedly connected to a formation on the bucket via connection means.

An excavating attachment according to claim 9 wherein the connection means includes a pivot member having first and second pivot ends, and a linkage member, wherein the first pivot end is hingedly connected to the second end of the first ram and the second pivot end is hingedly connected to the boom, and wherein the linkage extends between the first pivot end and the bucket.

11. An excavating attachment according to any one of the preceding claims wherein, in use, the bucket is moveable laterally with respect to the lifting arms. -12-

12. An excavating attachment according to any one of claims 4 to 10 wherein the frame includes a transverse rail arrangement, and the boom includes a carriage mounted to the rail arrangement for transverse sliding movement with respect thereto.

13. An excavation attachment according to claim 12 wherein the frame further includes a transverse rack, the rack including a series of spaced apart rack teeth, and wherein the carriage includes pawl means selectively to engage the rack teeth 52, thereby selectively to prevent transverse movement of the carriage with respect to the rail.

14. An excavation attachment according to claim 13 further including drive means i: associated with the pawl means, wherein operation of the drive means causes the pawl means engaged with the rack teeth to transversely move the carriage with respect to the rail, thereby transversely moving the boom with respect to the skid steer loader.

•15. An excavation attachment according to claim 14 wherein the pawl means includes a pair of spaced apart pawls, each having a plurality of spaced apart pawl teeth for complementary engagement with adjacent rack teeth. *555

16. An excavation attachment according to claim 15 wherein each of the spaced apart •e pawls is adapted respectively to drive the rack in a transverse direction opposite to that of the other pawl.

17. An excavation attachment according to claim 16 further including control means to selectively alter the direction of travel of the carriage with respect to the rack in response to actuation of the drive means.

18. An excavation attachment according to any one of claims 15 to 17 wherein the drive means includes a drive lever mounted for manual reciprocating rotational movement, such that reciprocation of the lever causes sequential driving of the rack, 13- retraction of the pawls from the rack, transverse movement of the pawls in a direction opposite to previous driving movement, and re-engagement of the pawls with the rack.

19. An excavating attachment according to any one of the preceding claims, wherein the lifting arms are hingedly connected to respective supports extended upwardly from a rearward portion of the chassis. An excavating attachment substantially as herein described with reference to any one of the embodiments of the invention shown in the accompanying drawings. DATED this 20th Day of May, 1997 10 IAN CLIVE POLLARD Attorney: JEFFREY B. SWEETMAN Fellow Institute of Patent Attorneys of Australia 15 of SHELSTON WATERS o o* o°