US3493064A - Walking mechanism for dragline excavators and the like - Google Patents

Description

Feb. 3, 1970 WALKING MECHANISM Filed Dec. 26, 196'? E; c. WILSON 3,493,064 FOR DRAQLINE EXCA VATORS AND THE LIKE 2 Sheets-Sheet 1 INVENTOR ELLIS C. WILSON ATTORNEY Feb. 3, 1970 E. c. WILSON WALKING MECHANISM FOR DRAGLINE EXCAVATORS AND THE LIKE Filed Dec. 26, 1967 '2 Sheets-Sheet 2 I 1 I I I J Ill! U IIIT lllul INVENTOR ELLIS c. WILSON n ATTORNEY United States Patent 3,493,064 WALKTNG MECHANISM FOR DRAGLINE EXCAVATORS AND THE LIKE Eliis C. Wilson, South Milwaukee, Wis., assignor to Bucyrus-Erie Company, South Milwaukee, Wis.,

a corporation of Delaware Filed Dec. 26, 1967, Ser. No. 693,204 Int. Cl. B62d 57/02, 51/06 US. Cl. 180-8 6 Claims ABSTRACT OF THE DISCLOSURE This disclosure relates to a walking dragline of the type having walking shoes on opposite sides of the machine which have a slide and slideway connection with the machine to allow for relative longitudinal movement during a stepping action. According to the invention, the slideways on the walking shoes are pivotally mounted to allow for rotation of the machine relative to the walking shoes to compensate for uneven ground conditions; and spring biased equalizer bars are provided on the shoes and engage the slideways to urge the shoes toward aligned positions parallel to the machine.

This invention relates to a walking mechanism for dragline excavators and the like. More particularly, it resides in an improved walking mechanism of the type where there is a slide and slideway connection between a walking shoe and the machine, the primary improvement residing in mounting the slideway pivotally on the shoe to compensate for uneven ground conditions.

A walking dragline usually has two shoes or sets of shoes on opposite sides of the main frame of the machine. When the machine is walking over uneven terrain, one shoe may contact the ground before the other. Even on fiat surfaces, one shoe may be on firmer ground than the other shoe. Whenever the machine encounters such uneven conditions, there is a tendency for the machine to rotate relative to one or both shoes. If the mechanical connection between the machine and shoes does not allow for at least some relative rotation, the walking mechanism or the entire machine will be subjected to severe torsional and bending forces and stresses which can result in serious damage or destruction. This problem exists in all machines of this general type, but is particularly serious in extremely large and heavy machines. The machine disclosed therein, for example, has a working weight of approximately million pounds, and is equipped with 21 2'20 yard bucket and a boom in excess of 300 feet in length. The stresses which might be encountered in moving a machine of such proportions are enormous. Further, with a machine of this size the shoes are spaced so far apart that the likelihood of encountering uneven ground conditions is quite great.

The walking mechanism described in US. Patent No. 3,265,145 to Beitzel provides one workable solution to the problem of relative rotation. The machine therein described is provided with walking shoes having slideways rigidly mounted thereon, and slides on the machine proper which are slidably received in the slideways. To compensate for ground irregularities, the slideways are constructed so as to provide a loose fit for the slides and this allows for lateral, angular rotation of the shoes with respect to the machine. It is also important to provide a means for aligning the shoes prior to the beginning of a walking step, however, and to accomplish this, the Beitzel patent calls for slideways which are tapered at one end, the slides being intended to be in the narrowest part of the slideway just prior to the beginning of a step when the shoes are still off the ground. Although the "ice Beitzel structure is quite satisfactory, for various reasons it has been found that as a practical matter the lateral, angular rotation of the shoes in either direction is limited to about 2". There are times when this degree of rotation is not enough, and it becomes necessary to provide for considerably greater rotation of the shoes. Further, where there are uneven ground conditions, it is possible with the tapered slideway for the slide to still be in the narrowed part of the slideway after the beginning of a walking step when the shoes are on the ground and weight is being put on them. In this case there is no room for relative rotation when it is most needed.

SUMMARY OF THE INVENTION In accordance with this invention, an improved walking mechanism for a dragline excavator is provided which includes a walking shoe capable of greatly increased lateral, angular rotation in either direction with respect to the machine proper. This is accomplished primarily by providing a pivotally mounted slideway on the walking shoe.

It is the general object of this invention to provide an improved walking mechanism which includes such a pivotal slideway to provide for increased rotatability. In

the particular embodiment shown, for example, the walking shoe is capable of up to as much as 6 to 8 lateral, angular rotation in either direction.

It is another object of this invention to provide an improved walking mechanism which includes means for aligning the walking shoe with respect to the machine at the beginning of a walking step.

It is still another object of the invention to provide a walking mechanism having the foregoing advantages which is adaptable for use in various types of walking machines.

It is still another object of the invention to provide an improved mechanism which has the several cited features and advantages which is quite strong and readily adaptable to very large machines while still being relatively simple and inexpensive to manufacture and maintain.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a somewhat schematic side view in elevation showing a walking dragline excavator provided with a walking mechanism constituting a preferred embodiment of the invention,

FIG. 2 is an enlarged fragmentary top view through the plane 22 shown in FIG. 3, with parts shown broken away and in cross-section, further illustrating the walking mechanism of FIG. 1,

FIG. 3 is an enlarged fragmentary side view, with parts shown broken away and in cross-section, taken in the plane 3-3 shown in FIG. 2, and

FIG. 4 is an enlarged fragmentary end view taken in the plane 44 shown in FIG. 3.

DESCRIPTION OF THE PREFERRED EMBODIMENT The dragline excavator shown in FIG. 1 is generally conventional and, for this reason and since the walking mechanism of this invention is equally useful for other types of machines, is shown somewhat schematically and will be described only briefly. It includes, in general, a main or revolving frame 1 which is revolvably mounted on a central supporting base or tub 2 and which supports a main boom 3 and usual appurtenant elements. A pair of identical walking shoes 4, only one of which can be seen, are disposed alongside the frame 1 and base 2 on opposite sides and are connected to the frame 1 as will be described to be revolvable with it.

The connections between the frame 1 and shoes 4 constitute the walking mechanisms, which are generally as shown and described in the said US. Patent No. 3,265,-

145. Again, however, only one set of connections or mechanism can be seen and will be described, but the mechanism on the other side of the machine is the same.

The walking mechanisms are driven by means of a shaft 5 which extends outwardly on both sides of the frame 1 and is driven by suitable motors (not shown). Each walking mechanism includes a circular driving disc 6 eccentrically mounted on the shaft 5 and a walking frame designated generally by the reference numeral 7 which is rotatably mounted on the disc 6. The walking frame 7 includes an upper part 8, which actually receives the disc 6, and a lower part 9, with a hinge connection 10 therebetween. The lower part 9 is provided with laterally extending flanges 11 to have an inverted T-configura tion, and serves as a slide as will be described.

A longitudinally extending slideway designated generally by the reference numeral 12 is provided on the flat upper surface of the shoe 4, and slidably receives the slide part 9 of the walking frame 7. In the embodiment shown, the slideway 12 is of unitary construction and includes a flat base portion 13 against the shoe 4 and opposite, facing angle portions 14 which overhang the slide flanges 11. The slideway, could, of course, also be made up of separate parts bolted or otherwise connected together.

A rigid link 15 has one end pivotally connected to the shoe 4 at a point 16. The other end of the link 15 is pivotally connected to the disc 6 at a point 17 that is generally diametrically opposite from the shaft 5.

The operation of the walking mechanisms is as described in the aforesaid Beitzel patent. Rotation of the shaft 5 causes the frame 7 to be moved in what would be a circular path were the shoe 4 suspended in space. At the same time, the link 15 causes the shoe 4 to slide forwardly and rearwardly with respect to the frame 7, this motion being additive to give a resultant thoretical elliptical path to the shoe 4. In actual operation, the shoe 4 is moved forwardly and downwardly until it contacts the ground, and further rotation of the shaft 5 causes the leading edge of the tub 2 to be lifted and the machine proper to be moved in the same direction as the shoe. The tub 2 is then lowered and the shoe 4 picked upwardly and moved forwardly again. The net result of repeated rotations is a stepping type of action in which the machine moves in a direction away from the boom 3, or to the left as seen in FIG. 1.

A large circular pivot pin 18, seen most clearly in FIG. 3, is fixed to the underside of the slideway base portion 13, at a suitable point as will be described, and is received in a circular opening 19, which is provided with a suitable bearing surface, in the top of the shoe 4, so that the entire slideway 12 is pivotally mounted on the shoe 4 to be movable in a horizontal plane. A split retaining collar 20 received in an annular recess 21 near the outer end of the pin 18 and disposed in an enlarged chamber 22 below the opening 19 holds the slideway 12 against vertical movement.

The ends of the slideway base portion 13 extend beyond the angle portions 14 to define toe portions 23 which are generally arcuate. A spaced set of retaining blocks 24 are rigidly mounted on the top of the shoe 4 at either end of the slideway 12 and include lip portions 25 which overhang the toe portions 23 to further hold the slideway 12 against vertical movement off the shoe 4.

It will be appreciated that the pivotal mounting of the slideway 12 allows, in effect, for relative rotation between the machine proper and the shoes 4 in the event of uneven ground conditions. In the embodiment shown, up to 6 to 8 of rotation is possible, which represents a substantial improvement over known prior arrangements. The hinge connection 10 is also helpful in the event of uneven ground conditions since it provides for movement of the shoes in a vertical plane transverse to the line of movement of the machine.

In the embodiment shown, the pin 18 is approximately at the longitudinal center of the slideway base 13. The

location of the pivot pin 18 with respect to the slide 9 and disc 6 constantly changes during walking since the shoe 4 is constantly moving with respect to the frame 7. To insure maximum effectiveness, the pin 18 should be located so that it is approximately directly under the center line of the disc 6 when the shoe 4 is placed on the ground at the beginning of a step, or in other words at about the time when the tub 2 begins to be raised.

As can be seen in FIGS. 2 and 3, the right-hand toe portion 23 of each slideway 12 is provided with cast teeth 26. The teeth 26 mesh with a rack segment 27 at one end of a lever arm 28 which has its other end fixedly connected by means of a vertical pin 29 to an equalizer bar 30 disposed in a cavity 31 in the shoe 4. Rods 32 are fastened to each end of the bar 30, and constant biasing forces of equal magnitude are applied to the rods 32 by means of springs 33 which operate between brackets 34 in the shoe 4 and retainers 35 fixed to the rods 32. These elements constitute an aligning means which exerts a constant force resisting the relative pivotal movement between the shoe 4 and slideway 12 in either direction. Thus, the shoe 4 is urged toward a parallel relationship with the slideway 12, the slide 9, the frame 7 and the main frame 1, the two shoes 4 also being urged toward a parallel relationship with one another.

The alignment provided by the arm 28 and bar 30 and their associated elements insures that the shoes 4 will be properly positioned at the beginning of each step. The aligning elements are effective only when the shoe 4 is raised ofl? the ground, however, and are overridden when the machine proper is being lifted or moved. They do not, therefore, interfere with the desired compensating pivotal movement of the slideway 12.

Thus, the embodiment of the invention shown and described herein provides an improved walking mechanism which provides for substantially increased rotatability of the shoes 4. It will be obvious that the arrangement shown is relatively simple and easily adaptable to even very large machines.

Although a preferred embodiment of the invention has been shown, it will be obvious that various modifications are possible without departure from the spirit of the invention. The invention is of course not necessarily limited to dragline excavators, and may be useful in other types of walking machines. Nor is the invention limited to the particular basic type of walking mechanism shown. the copending application of Kraschnewski et al. Ser. No. 506,207, filed Nov. 3, 1965, and noW Patent No. 3,375,892 for example, shows a walking arrangement involving vertical and horizontal hydraulic cylinders to effect the desired motion. The Kraschnewski et a1, arrangement also includes a slide and slideway connection between walking shoes and a machine and the pivotal slideway herein could be advantageously incorporated therein.

Further, changes could be made in the specfic embodiment shown. The particular slide and slideway arrangement in which the slide 9 has an inverted T-configuration and the slideway 12 has the overhanging angle portions 14 is not critical; and a reverse arrangement could be used with the slideway having an upright T-configuration and the slide having inwardly extending flanges under the crossbar portion thereof. Other aligning arrangements for the shoes 4 could also be provided, or the particular arrangement shown could be provided at both ends of each slideway 12.

What is claimed is:

1. In a walking mechanism for a dragline excavator and the like having a revolving frame, a slide operatively connected to the revolving frame, a shoe alongside the revolving frame, and a slideway on the shoe that slidably receives the slide to allow for relative longitudinal movement between the shoe and the revolving frame,

the improvement wherein the slideway is pivotally mounted on the shoe to be movable in a horizontal plane.

2. The walking mechanism of claim 1 wherein the slideway comprises a base portion and there is a pivot pin attached to the underside of the base portion which is received in the shoe to pivotally mount the slideway thereon.

3. The walking mechanism of claim 1 wherein the slideway has a toe portion at each end thereof; and there is a spaced set of facing retaining blocks mounted on the shoe, said blocks overhanging respective toe portions of the slideway.

4. The walking mechanism of claim 1 which includes means for aligning the shoe with respect to the slideway prior to the beginning of a walking step.

5. The Walking mechanism of claim 4 wherein the aligning means comprises bias means operative between the shoe and slideway to exert a constant force resisting relative pivotal movement in either direction.

6. The Walking mechanism of claim 5 wherein there are teeth provided on at least a portion of at least one of the toe portions; and there is a lever arm having a rack segment at one end which meshes with said teeth; and there is an equalizer bar, the other end of the lever arm being fixedly connected to the equalizer bar intermediate the ends of the bar; and the bias means acts against the ends of the bar.

References Cited UNITED STATES PATENTS 2,399,375 4/ 1946 Mullins. 2,399,417 4/1946 Wilson et al. 3,265,145 8/1966 Beitzel. 3,375,892 4/ 196 8 Kraschnewski.

LEO FRIAGLIA, Primary Examiner

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