GB2180522A - Lateral-offset arrangement for a digging machine knee - Google Patents

Abstract

Apparatus is provided for laterally offsetting a knee (30) on a vehicle-mounted digging machine, or, as shown, on the rotatable superstructure of a mobile digging machine, in order to leave the knee on the extended longitudinal axis (74) of the vehicle for those digging jobs which most commonly arise, or to bring it, easily and quickly, into a laterally offset working position, (broken lines), or also into a limiting offset position, so as to slew the sub-assembly comprising a boom, a dipper arm and a digging tool to a transverse position and to fold it up. The knee (30) is articulated to the digging machine via two preferably parallel arms (22, 24), and can be shifted between limiting lateral-offset positions by means of a positioning drive (70), while being lockable in any intermediate position. In at least one limiting offset position, the knee (30) may be located within the line defining the lateral outline of the digging machine, or within an extension of this outline (Fig. 3). <IMAGE>

Description

SPECIFICATION Lateral-offset arrangement for a digging machine knee This invention relates to a lateral-offset arrangement for a knee on a vehicle-mounted digging machine, or on the rotatable superstructure of a mobile digging machine, this knee serving as the means of mounting a slewing column which can be rotated about a generally vertical axis and which carries a boom in a manner such that it can be luffed about a generally horizontal axis.

Knees are known which are attached to the frame of a vehicle-mountable digging machine either at a fixed position, or in a manner permitting lateral shifting, the digging machine being fastened, in its turn, to a vehicle which may be either wheeled or tracked, this fastening being permanent, or such that the digging machine may be exchanged for another accessory appliance. A slewing column is mounted on the digging-machine knee, this column carrying the digging-machine boom, together with operating cylinders and the digging tool, and being rotatable about a vertical axis, in most cases through 1800, this rotation being effected by means of a slewing mechanism.

Digging-machine knees which are attached to the frame at a fixed position are generally located centrally in relation to the longitudinal axis of the vehicle and, when designed in this way, are particularly suitable for digging trenches along the extended longitudinal axis of the vehicle, or for carrying out other kinds of earthmoving work along this axis. Trenches which are offset from the longitudinal axis of the vehicle are dug with the aid of those types of digging machine, vehicle-mounted or mobile (self-propelled), which possess laterallyshiftable knees.

In known arrangements, knees of the above mentioned type are designed as sliders, the operation of shifting them laterally calling for manual actions which are not always easy to perform under the harsh working conditions which generally prevail in the construction industry. This association with harsh conditions creates a disadvantage in that a slider which must not be made in a manner such that it fits its guides closely, owing to the ever-present need to allow for dirt ingress, and which thus needs a very large amount of play in order to be shifted, must first be clamped before the digging machine is brought into operation. Furthermore, it is disadvantageous that, in order to shift the slider, the arm of the digging machine must be placed on the ground, and propped, which is possible only if there is enough room.Expensive, automatic slider-drive mechanisms are otherwise necessary, which exhibit a dangerous tendency to jam.

Lastly, vehicle-mounted digging machines are also known, in which the digging-machine knee is designed as an intermediate boom which is mounted in a manner such that it can rotate about a vetical axis on the attachmentframe. The intermediate boom can be considered as being a transverse swinging arm so that, in the case of this design, the slewing column is located at one end of this arm, while the bearing about which a swinging movement takes place is located in the attachment-frame, at the other end of the arm.This design of digging machine departs from the conventional ones, acknowledged as belonging to the state of the art, by virtue of the fact that, in order to obtain a lateral offset, the digging-machine knee is not shifted parallel to itself, on a slider, but is slewed by means of the intermediate boom so that, in the limiting positions, a conventional slewing range, totalling 1800, no longer permits the boom to reach slewed positions which are necessary or attractive for certain types of work, unless the boom slewing range were to be increased by providing an expensive slewing mechanism.

The object underlying the present invention is to simplify a lateral-offset arrangement for a knee of the type referred to above, this simplification being aimed towards the operation and construction of the knee while at the same time improving it to an extent such that, in situations involving working on the extended longitudinal axis of the vehicle-which account for approximately 90% of digging jobs-the digger driver experientes no difficulties either in leaving the knee in the central position, or in moving it quickly sideways for jobs involving a lateral offset.Furthermore, there is no difficulty in bringing the knee, again quickly, into a limiting offset position when the intention is that the sub-assembly comprising the boom, the dipper arm and the digging tool should be slewed into a transverse position and folded-up in front of the rotatable superstructure in the case of a mobile digging machine, or in front of the attachment-frame in the case of a vehiclemounted one, this being the state which is assumed when the mobile machine or other vehicle has to be transferred to another location.

According to the present invention, there is provided lateral-offset apparatus for a knee on a vehicle-mounted digger, or on the rotatable superstructure of a mobile digging machine, the knee serving as the means for mounting a slewing column which can be rotated about a generally vertical axis, and which carries a boom in a manner such that it can be luffed about a generally horizontal axis, wherein the knee is supported on the digging appliance by being articulated to it by means of two arms and movable, by a positioning drive, parallel to itself and between limiting lateral-offset positions, while being lockable in any intermediate position.

In the case of this comparatively simple design, albeit one which is, above all, easy to operate at all times, swinging the parallel arms through even less than 1800 causes the digging-machine knee to move, parallel to itself (i.e. maintained in a constant orientation), through a portion of a circular arc, and causes it to become laterally offset without altering the parallelism with the longitudinal axis of the vehicle or rotatable superstructure, as the case may be.In the case of a symmetrical form of construction, the two limiting lateral offset positions can correspond to those of a slider which is mounted on a guide frame, but without having to accept the disadvantages of the slider guideway, namely play which is conditioned by the manner in which the slider has to function, a special clamping device, and the room which is needed for setting down the arm of the digging machine so that it can be propped in order to enable the slider to be pushed sideways.

Although in the case of the known slidermounted knee, the inconvenience involved in manhandling it to the central position, from the limiting laterally-offset position where it will still be situated as a result of this being the state assumed for transferring the vehicle to its current location, will induce the digger driver to dispense with knee-shifting, he will no longer experience these hindrances when using the lateral-offset apparatus according to the invention, since he needs merely to switch an automatic positioning drive on and off in order to obtain the lateral offsetting movements.For this reason, the maximum attainable working efficiency of a digging machine can be increased many times over, because the optimum knee position, whether central or laterally offset, can be set for each type of work and, moreover, the digger driver no longer has to spend time, at the end of a job, on slewing the folded boom sub-assembly into the transverse position in front of the digging appliance, in order to assume the state required for moving the vehicle, or vice versa at the beginning of a job.

In one embodiment of the invention, the arms can have a swinging range which is less than 1800 and, by reason of their ability to swing transversally, and/or by virtue of their length, can be set up in a manner such that the knee can reach at least one limiting lateraloffset position, when it becomes possible for a boom, equipped with a digging tool and extending longitudinally from the knee, to work in the region of the extended track lines defined by the wheels or tracks which are provided beneath the chassis of either a mobile digging machine or a vehicle carrying an attachment frame, as the case may be. Because the parallel arms swing through a limited range, one or more simple hydraulic cylinders can be used as the positioning drive.In the case of digging appliances of conventioanl size, the swinging range can, for example, be approximately 1200, for which a single hydraulic cylinder may in some instances be sufficient. The limiting offset position of the knee is usually defined by a convention according to which the outer edge of a digging tool, attached to the boom, should be approximately in line with the outer edge of the chassis or attachment-frame when the boom is set to point longitudinally of the machine. However, it is also possible, within the scope of the present invention, to displace the limiting knee-offset position even further outwards in the lateral direction, either by enlarging the swinging range of the parallel arms and/or by lenthening the arms.

According to another feature of the invention, it is preferred, regarding the lateral-offset arrangement, that the lateral distance between the two axes about which the arms pivot, at the knee and at the vehicle, should be made large enough to enhance the stiffness of the articulation system. It can be expedient if the two axes about which the arms pivot at the knee are separated by a distance not less than approximately one third of the arm length.

According to another feature, the distance between the vertical axes at which the arms are articulated to the vehicle and to the knee, in conjunction with a limitation of the angle through which these arms swing, results in the distance between the arms remaining large enough, even in the limiting offset position, to route hydraulic hoses through between them, in order to make the connections to the hydraulic cylinders associated to the boom subassembly. In this way, the hydraulic lines can be provided with useful protection from the effects of the harsh conditions under which digging machines operate. The arms may consist of a torsionally stiff box structure, the height of which is considerably greater than the width.

In a preferred embodiment of the lateral offset arrangement, the knee also has a torsionally stiff frame on which upper and lower mounting fittings are provided for rotatably mounting a slewing column, on the one hand, and for pivotably attaching the arms, on the other hand, while a slewing mechanism for the slewing column is also provided on the knee above the mounting fittings. The wide knee, which favours effective support and absorption of working forces when the boom is slewed, at the same time enables an aperture to be provided in the knee frame, between its upper and lower ends, through which aperture the hydraulic hoses for the boom sub-assembly can be routed.

In the case of a mobile digging machine, the knee articulation system according to the invention can be installed on a suitable frame on the front of a rotatable superstructure, to one side of the driver's cab and, if appropri ate, laterally offset in relation to the longitudinal centreline of the superstructure, so that, for example only a slight lateral offset is needed, in conjunction with allowing the arms to swing through a range of about 60 , in order to bring the knee into one of the limiting offset positions, namely one which is approximately on the longitudinal centreline of the superstructure, while the other limiting offset position is used mainly for folding the boom sub-assembly across the front of the superstructure, this being the state which is assumed for transferring the digging machine to another location.Other advantageous designs of the lateral-offset arrangement are of course conceivable within the scope of the invention, in the context of a mobile digging machine, examples being designs involving a larger transverse swinging range, and/or the installation of the parallel arms at a central position.

With a mobile digging machine of this type, laterally-offset digging is rendered possible by rotating the superstructure until the slewing column has the required lateral offset in relation to the longitudinal axis of the chassis, this capability being independent of the particular manner in which the knee is articulated.

The arms supporting the knee may be parallel and may be arranged to form part of a parallelogram. Alternatively, the arms may be of unequal length.

The present invention will now be described in greater detail, by way of example, with reference to the accompanying drawings, in which: Figure 1 shows a side view of a vehiclemounted digging machine, with an attachment frame represented in partial section, Figure 2 shows a plan view of the vehiclemounted digging machine of Figure 1, Figure 3 shows a plan view, similar to Figure 2, but also including the vehicle carrying the attachment frame, and with the knee situated in a limiting lateral-offset position, Figure 4 shows a diagrammatic plan view of a mobile digging machine possessing a lateraloffset arrangement, in which the knee is situated in the principal digging position, and Figure 5 shows the knee in the same plan view as Figure 4 but in the other limiting offset position, in which the boom sub-assembly is accommodated approximately within the circle enveloping the rotatable superstructure.

In the illustrative embodiment shown in Figures 1, 2 and 3, the subject matter of the invention is put into practical effect in the form of a vehicle-mounted digging machine.

This machine comprises an attachment-frame 10, consisting essentially of vertical frame portions 12, horizontal frame portions 16, and supporting legs 14 which are adjustably guided inside the vertical portions 12. Upper and lower push-in connecting tongues 18 are fixed to the rear of the attachment-frame 10, these tongues 18 serving to connect the digging appliance to the vehicle which is to carry it, this connection being made, for example, into corresponding mountings, and secured by push-in pins.

Reinforcing members 20 are fastened to the rear surfaces of the horizontal frame portions 16, one being fastened to the upper portion and another to the lower portion, these reinforcing members 20 serving as mountings and supports for the pivot axes or, rather, pivot pins 26, 28 about which two parallel arms 22 and 24 can be swung, these arms preferably being of the same length.

Figure 1 shows the height of the arms 22, 24, which considerably exceeds their width (Figures 2 and 3). In a practical design, the transverse swinging arms 22, 24 consist of a torsionally stiff box structure and are articulated, at their front ends, to a digging-machine knee 30, so that each can pivot about a vertical axis 32 and 34 respectively. The distance between the vertical pivot axes 26 and 28 is exactly equal to the distance between the pivot axes 32 and 34 on the knee 30, so that the two arms 22, 24 combine with the knee 30 in forming a parallelogram in every position into which they can be swung.The arms 22, 24 extend forwards through an opening in the attachment frame 10 and carry pairs of lateral connection lugs 36 at their front ends, connecting eyes of piston rods belonging to respective hydraulic cylinders 38 being connected between the pairs of lugs 36 as best seen in Figure 4. As Figures 2 and 3 show, the ends of the hydraulic cylinders 38 are pivotably mounted on the upper rear reinforcing member 20 of the attachment-frame 10, by means of vertical pivot pins 40.

The knee 30 consists of a box structure, possessing upper and lower bearing plates 42 and 44, respectively, a so-called slewing column 48 being rotatable about a generally vertical axis 46 at the front ends of the bearing plates, and serving as the means for holding a boom 50 and a boom cylinder 52. A swanneck or dipping arm 54 is attached to the boom 50 in the usual way, together with a digging tool 56, inclusive of its operating cylinder.

A slewing mechanism 58 serves to rotate the slewing column 48 so as to produce the slewing movements, this mechanism 58 being installed in a mounting structure which can, for example, be fixed on top of the knee 30 and comprising, in this case, two pivotably mounted hydraulic cylinders, the ends of their piston rods of which act on pivot pins 61, 62 belonging to the slewing column 48. Figure 2 shows the knee 30 in its central position, which coincides with the longitudinal axis of both the vehicle and the digging machine, and from which the boom sub-assembly can slew the digging tool 56 to either side, in each case through about 90 in order, for example, to pick up excavated material in the central area and then to dump it to one side or the other.

Figure 3 shows the knee 30 in a limiting lateral-offset position, in which it is situated near the prolongation of one of the track lines of the carrier vehicle. This limiting position is, for example, defined by the convention that when the boom 50, with the digging tool 56, is set parallel with the longitudinal axis of the vehicle, it should be possible to dig exactly as far to either side as the vehicle track line, or the lateral extremity of the attachment-frame.

A still larger lateral offset could be obtained by lengthening the arms 22, 24, and/or by enlarging the angular range through which they swing, for example by articulating the drive cylinder 38 differently, or by coupling them at a different position on the frame, or by mounting the arms 22, 24 further forwards on the attachment-frame. Figure 3 shows, moreover, that the lateral separation of the pivot axes 26, 28 and 32, 34, is sufficiently large, even in the limiting offset position, to leave room for routing hydraulic supply lines (not shown) between the arms 22, 24, leading these hydraulic lines through the attachment frame 10 and a longitudinal aperture in the knee frame, for connecting a pressure oil system on the carrier vehicle to the operating cylinders belonging to the boom sub-assembly.Figure 1 shows that the cylinders 38 for swinging the arms 22, 24 are pivotably mounted, at their respective ends, in clevisstyle lugs which extend from the attachment frame reinforcing member 20, and from the front end of each swinging arm respectively.

In their turn, the arms 22, 24 can be mounted on pivot axes or, rather, on the pivot pins 26, 28 which extend between the reinforcing members 20, and between the upper and lower mounting plates 42, 44 belonging to the knee 30, or else they can be mounted on upper and lower, axially parallel pins, as shown in Figure 1, in the case of the mounting of the slewing column 48, by way of an example.

In Figure 3, the boom sub-assembly 50, 54, 56, resembling the one shown in Figure 1 is in the folded state, and has been slewed to a transverse position in front of the attachmentframe 10, corresponding to the road-transport p6sition of the digging machine when it is mounted on a vehicle. The same, folded, state could also be assumed if the mirror-image slewing movement were to be executed, i.e. if the knee 30 were to be situated on the righthand side of the attachment-frame when in the limiting lateral off- set position. The hydraulic cylinders 38 swing the arms 22, 24 into any position within their swinging range, and lock them there. When digging at right angles to the longitudinal axis of either a vehicle or a rotatable superstructure, the swing travel of the arms 22, 24 can be utilised for executing an additional digging movement.

The illustrative embodiment depicted in Figures 4 and 5 shows how the knee-articulation system according to the invention is applied to a mobile (self-propelled) digging machine. A superstructure 64 is mounted on a tracked chassis 66, in a manner such that it can execute a 360-degree rotation about a vertical axis 65, and is located to one side, and at the front, of the driver's cab 72 and to one isde of the longitudinal centreline 74 of the machine, a mounting frame 68 which carries and supports the vertical pivot axes or, rather, the pivot pins 26, 28 for the two parallel arms 22, 24, the arrangement resembling that of the illustrative emobdiment shown in Figures 1 to 3.The mounting frame 68 additionally carries a pivotal connection 40 for a simple hydraulic cylinder 70, which in the present embodiment extends between the two arms 22, 24 and is pivotably fastened to an inner connection 76 belonging to one of them, namely to the arm 24. In the illustrative embodiment of Figures 4 and 5, the knee 30 is provided with a lateral-shift range corresponding to approximately 60", between the limiting offset positions shown in Figures 4 and 5, and implemented by means of the arms 22, 24 and their drive cylinder 70. In the limiting positions shown in Figure 4, the knee 30 is situated near the longitudinal centreline 74 of the rotatable superstructure 64, so that the digger driver then has the best possible view of the boom sub-assembly and digging tool.

In the second limiting offset position, shown in Figure 5, the knee 30 has been shifted from the central position, through a distance such that the boom sub-assembly, which has been folded up, still remains within the lateral limits of the chassis after having been slewed into a position across the front of the rotatable superstructure 64, and is also accommodated within the enveloping circle 78 which is defined by the rear portion of the super-structure. In further respects, the construction of both the knee 30 and the slewing column 48 corresponds essentially to that of the embodiment of Figures 1 to 3. For the sake of clarity, the slewing mechanism 58 for the slewing column 48 is omitted from Figures 4 and 5 but it is in fact installed on the knee 30.

The knee and boom position shown in Figure 4, as indicated by the continuous lines, is adopted for digging trenches along the longitudinal axis 74 of the vehicle, this type of work accounting for at least 90% of all jobs, and while the knee position indicated by the broken lines can be used for digging laterallyoffset trenches, at the left-hand side of the chassis, it is, however, particularly useful for assuming the folded-up position shown in Figure 5, in which the boom sub-assembly remains within the outline of the vehicle or rotatable superstructure 64, as the case may be, and can, moreover, be brought inwards until it is situated at least within the enveloping circle 78.

Claims (20)

1. A lateral-offset apparatus for a knee on a vehicle-mounted digger, or on the rotatable superstructure of a mobile digging machine, the knee serving as the means for mounting a slewing column which can be rotated about a generally vertical axis, and which carries a boom in a manner such that it can be luffed about a generally horizontal axis, wherein the knee is supported on the digging appliance by being articulated to it by means of two arms and movable, by a positioning drive, parallel to itself and between limiting lateral-offset positions, while being lockable in any intermediate position.

2. Apparatus according to claim 1, wherein the arms have a swinging range which is less than 1800 and, by reason of their ability to swing, and/or their length, can be set up in a manner such that the knee can reach at least one limiting lateral offset position at which it becomes possible for a boom, equipped with a digging tool and extending longitudinally from the knee, to work in the region of an extended track line, as defined by the wheels or tracks which are provided beneath a chassis of either a mobile digging machine or a vehicle carrying the apparatus as the case may be.

3. Apparatus according to claim 1 or 2, wherein when the knee is in a limiting lateraloffset position, a boom sub-assembly remains within the lateral limits of the chassis once having been slewed into a position across the front of an attachment frame, or across the front of the rotatable superstructure as the case may be.

4. Apparatus according to any of the preceding claims, wherein the lateral distance between the two arms is made large enough to enhance the stiffness of the knee-articulation system.

5. Apparatus according to claim 4, wherein the lateral distance between the two arms is not less than approximately one third of the length of the arms.

6. Apparatus according to any of the preceding claims, wherein the arms each consist of a torsionally stiff box structure, the height of which is greater than the width.

7. Apparatus according to any of the preceding claims, wherein the distance between the generally vertical axes at which the two arms are articulated to an attachment frame and to the knee, in conjunction with limitation of the angle through which these arms swing, results in the distance between the arms remaining large enough, even in the limiting offset position, to route hydraulic hoses through between them, in order to effect connections to hydraulic cylinders associated with a boom sub-assembly.

8. Apparatus according to any of the preceding claims, wherein the parallel arms extend through an opening which is formed by upper, lower, and lateral portions of an attachment-frame and are mounted on pivot pins which are fixed to the attachment-frame behind the opening, in horizontal load-bearing members.

9. Apparatus according to any of the preceding claims, wherein connecting means is fastened to each of the two arms and a hydraulic cylinder acts on each connecting means, each hydraulic cylinder being articulated to the digging applicance.

10. Apparatus according to any of claims 1 to 8 wherein a single hydraulic cylinder is provided as the positioning drive for the arms, the hydraulic cylinder being located between the arms and acting on connecting means associated with the arms.

11. Apparatus according to any of the preceding claims, wherein at least one limiting knee-offset position is provided, such that when the knee reaches it, a boom sub-assembly once slewed into a position across the front of the rotatable superstructure, or across the front of an attachment frame, as the case may be remains within the lateral limits of the chassis or attachment frame, as the case may be.

12. Apparatus according to any of the preceding claims, wherein the knee has a torsionally stiff frame on which upper and lower mounting fittings are provided for rotatably mounting a slewing column, on the one hand, and for pivotably attaching the parallel arms on the other hand, while a slewing mechanism for the slewing column is also mounted on the knee, above the mounting fittings.

13. Apparatus according to claim 12, wherein the f rame of the knee contains an aperture between its upper and lower ends for the routing therethrough of hydraulic hoses for the boom sub-assembly.

14. Apparatus according to claim 12 or 13, wherein the mounting fitings for rotatably mounting the slewing column and for pivotably attaching the arms are attached to upper and lower mounting plates associated with the knee, the mounting plates forming portions of the knee frame.

15. Apparatus according to any of the preceding claims, wherein the two arms supporting the knee are parallel.

16. Apparatus according to claim 15, wherein the two arms form part of a parallelogram.

17. Apparatus according to any of claims 1 to 14, wherein the two arms are of unequal length.

18. Apparatus according to any of the preceding claims, wherein, at least in one limiting offset position, the knee is situated in the region of a line defining the lateral outline of the digging machine, or in the region of an extension of this outline.

19. Lateral-offset apparatus for a knee of a digging appliance substantially as herein particularly described with reference to Figures 1 to 3 or to Figures 4 and 5 of the accompanying drawings.

20. A vehicle fitted with apparatus according to any of the preceding claims.