System And Method For Removable Installation Of Swing Circle For Large Crane

Abstract

The superstructure for large material handling apparatus is removably mounted to a bed by means of a swing circle which includes a bearing having an outer race secured to the bottom of the superstructure and an inner race with a plurality of depending slotted tangs. The tangs are placed through slots in the bed of the apparatus, and wedges are forced into the slots of the tangs to secure the tangs beneath the lower surface of the bed. The wedges are then locked in place, and means are provided for bracing the tangs against the frame of the apparatus to prevent turning of the inner race during operation.

Description

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to large material handling systems; and more particularly, it relates to a system and method for removably mounting a superstructure to the bed of a mobile crane.

A large mobile crane of the type with which the present invention is concerned includes a vehicle which provides a flat bed on which there is mounted a crane superstructure. The superstructure houses the prime mover, usually a diesel engine, and a movable boom and gantry are attached to the superstructure.

In operation, the superstructure is mounted on the bed of the vehicle for rotation about a vertical axis. The bearing which interconnects the superstructure to the vehicle bed is sometimes referred to as a slue ring or "swing circle."

In order to avoid exceeding the maximum load limit permitted on public highways, it is desirable to remove the superstructure, boom, gantry and winches from the vehicle and transport them on a separate vehicle from site to site. In order to accomplish this, it has been the practice to remove the entire swing circle with the superstructure to prepare the system for transportation to another site.

2. Known Systems

Threaded bolts and nuts have been used to mount a crane superstructure to a vehicle bed. That is, one of the races of the bearing forming the swing circle is bolted directly to the horizontal bed of the vehicle on which the crane is mounted during operation. This has proved satisfactory even for the largest size of mobile crane that has heretofore been commercially available. This technique does, however, have practical limits for cranes of very large size -- for example, a 250 ton crane which has been developed and for which the present invention has particular applicability.

For example, if bolts were used to mount the superstructure of the above-mentioned 250 ton crane to the vehicle bed, at least 30 bolts having a diameter of two inches would be required. Further, to properly fasten the bolts, a torque wrench should be used to apply a predetermined torque. Although tools are readily available for torquing down nuts for smaller diameter bolts, tools for larger diameter bolts are expensive and difficult to handle, and thus impractical in use. This difficulty is further accentuated by the fact that some of the bolts would have to be located in positions which are almost inaccessible beneath the swing circle and beneath the vehicle bed. Thus, the present invention is concerned with a method and system for connecting a slue ring to a vehicle bed which has fewer connections than the previous bolt systems between the bearing and the vehicle bed (resulting in a reduction in the amount of space allocated to these connections) and to alleviating the necessity of using large tools which are hard to handle.

SUMMARY

In the present invention, the bearing which forms the swing circle includes an outer race which is connected to the crane superstructure and rotates as the superstructure turns, and an inner race which is adapted to be fixedly, but removably mounted on the bed of the vehicle. Thus, by disconnecting the inner race, the entire swing circle may be removed from the vehicle bed with the superstructure.

The inner race of the bearing is provided with a plurality of depending tangs, each defining a slot elongated horizontally and having a lower, inclined surface. The tangs are placed through corresponding slots in the bed of the vehicle, and a wedge is forced into each of the slots of the tangs beneath the vehicle bed. That is, the wedge is located between the inclined surface of a tang slot and the lower surface of the vehicle bed. The wedges are then locked in place, and means are provided for bracing the tangs against the frame of the vehicle to prevent turning of the inner race during operation.

The wedges may be forced into place by a hydraulic jack or simply by using a sledge hammer -- thus obviating the need for torque wrenches and the like. Further, only 10 such tang and wedge connections need be made for the very large 250 ton crane mentioned above. A smaller number of tangs, for example, six or eight, could be used for a crane designed for a smaller capacity.

Although pairs of the tangs should be located diametrically, adjacent ones of the tangs need not be located at equal angular increments about the bearing. This enables the tangs to be located in positions of greater access.

Other features and advantages of the present invention will be apparent to persons skilled in the art from the following detailed description of a preferred embodiment accompanied by the attached drawing wherein identical reference numerals will refer to like parts in the various views.

THE DRAWING

FIG. 1 is a perspective view of a material handling apparatus incorporating the present invention with portions of the boom and vehicle cab removed;

FIG. 2 is a perspective view of the underside of the superstructure, showing the swing circle;

FIG. 3 is an upper perspective view of the vehicle bed showing the slots for receiving the tangs on the swing circle;

FIG. 4 is a side elevational view showing the swing circle mounted on the vehicle bed;

FIG. 5 is a plan view illustrating the mounting of the swing circle on the vehicle bed with portions broken away;

FIG. 6 is a cross-sectional view taken through the sight line 6--6 of FIG. 5;

FIG. 7 is a detailed side view taken through the sight line 7--7 of FIG. 5;

FIG. 8 is an end view illustrating one tang mounted beneath the vehicle bed;.

DETAILED DESCRIPTION

Turning first to FIG. 1, reference numeral 10 generally designates a large mobile material handling apparatus including a crane generally designated 11 mounted on a wheeled vehicle 12.

The vehicle 12 includes a horizontal flat bed 13 on which a crane superstructure 14 is mounted by means of a swing circle or slue ring generally designated 15. The swing circle 15 is provided with bearings to permit rotation of the superstructure about a vertical axis, as will be described in greater detail below.

The crane superstructure includes a boom 16, only a portion of which is shown, pivotally mounted for rotation about a horizontal axis to raise and lower the boom. Boom 16 may be elevated by appropriate means such as a cable assembly including a gantry partially seen at 17.

The vehicle 12 is provided with laterally extensible outriggers 19 for stabilizing the vehicle and crane in operation to increase the tipping circle.

Turning now to FIG. 2, the base or bottom of the superstructure 14 is a horizontal plate 20, to which the swing circle 15 is secured. The swing circle 15, as mentioned, is a bearing permitting rotation of the superstructure relative to the vehicle bed 13. The swing circle 15 includes an outer race 21 and an inner race 22. The outer race 21 of the swing circle may be formed in upper and lower sections, best seen in FIG. 8 and designated 23 and 24 respectively. When secured together, the upper and lower sections 23, 24 of the outer race 21 form an annular channel having an upper bearing surface 23a, a lower bearing surface 24a, and a side bearing surface 25.

The sections 23, 24 of the outer race are held together, and the combination secured to the base plate 20 of the superstructure by means of bolts 27. There are 30 separate bolts 27 holding the two sections of the outer race 21 together, as seen in FIGS. 2 and 4. These bolts also are connected to the superstructure.

Returning again to FIG. 8, the inner race 22 of the swing circle has a generally cylindrical shape, and it includes a peripheral thrust flange 29 and an inner gear 30 which forms a reaction base for driving the superstructure in rotation relative to the bed 13 of the vehicle. The thrust flange 29 is received in the annular channel formed in the outer race 21. A split upper roller bearing 31 is located between the bearing surface 23a of the upper section 21 of the outer race and the upper surface of the thrust flange 29. Similarly, a split roller bearing 32 is located between the lower surface of the thrust flange 29 and the bearing surface 24a. A retainer member 33 holds the upper split roller bearings 31 in place and a similar retainer member 34 holds the lower split roller bearings 32 in place. A side roller bearing 35 is located between the side of the thrust flange 29 and the bearing surface 25 formed in the annular channel of the outer race. A plurality of such roller bearing arrangements are located about the entire thrust flange 29 to maintain a low friction engagement between the outer and inner races 21, 22.

A plurality of tongues (herein referred to as tangs) 37 depend from the inner race 22 of the bearing. For the large 250 ton crane, there are 10 tangs 37 located about the periphery of the inner race 22. The tangs 37 are arranged to form diametrically opposed pairs, but the angular spacing between adjacent tangs need not be the same throughout. This allows placement of the tangs 37 in those locations to which access is most easily gained, depending upon the frame beneath the bed 13 of the vehicle.

Each of the tangs 37 is provided with a horizontally elongated slot 38, and each of the slots 38 has a lower inclined bearing surface 39. Some of the bearing surfaces 39 are inclined upwardly as viewed looking toward the center of the swing circle, and others are inclined downwardly when so viewed. The slots 38 are adapted to receive a wedge 40, and the different inclinations of the bearing surfaces 39 is to permit insertion of the wedges 40 from different directions, as viewed in side section. For example, in FIG. 8, the center of the swing circle is to the left of the illustration, and the wedge 40 is inserted from outside the inner race 22 of the bearing. The wedge 40 has an inclined surface 41 for engaging the bearing surface 39 of the slot 38, and the wedge 40 is interposed between the bearing surface 39 and the lower surface of the bed 13 of the vehicle. It will be appreciated that the upper surface of the slot 38 is located above the lower surface of the bed 13 when the swing circle is in assembled relation with the bed so that the wedging action is maintained between the tangs 37 and the bed 13. The tangs 37 are received in corresponding slots 43 (as best seen in FIG. 3) formed in the bed 13 lying in the general shape of a circle. The upper surface of the bed 13 is machined in a flat angular path 44 to form flat surface for the race 22 to rest on between the tangs 37.

Turning now to FIG. 7, each of the tangs 37 is provided with a pair of internally threaded apertures located to either side of the slot 38 for receiving bolts 48 which secure a cross bar 49 against the outer side surface of the wedge 40 after it is forced in place by a hydraulic jack or sledge hammer. It is an important advantage of the present invention that no special tools or force-measuring devices are needed for the proper insertion of the wedges 40. EAch of the wedges 40 includes a central tapped aperture 50 in its outer surface to which a tool may be threaded for removing the wedge when it is desired to disassemble the superstructure from the bed of the vehicle.

Referring now to FIGS. 5 and 6, a frame comprising a grid of interconnected braces or support bars is shown in dashed line and generally designated by reference numeral 52. The frame 52 is located beneath the vehicle bed 13, and this framework is so arranged that a pair of spaced bars 53, 53a is located on either side of the slots 43 which are located at the 3 o'clock and nine o'clock positions. Each of the tangs may have associated with it a pair of frame bars as at 53,53a, or, alternatively, there may be only one such frame bar associated with a tang, as at 54 and 55 which are associated with adjacent tangs. The frame bars 53, 53a, 54 and 55 serve as braces for preventing rotation of the inner race 22 of the bearing. For example, referring to FIG. 7, a hole 56 is formed in the brace bar 53 and a corresponding hole 57 is formed in the brace bar 53a. A threaded bolt 58 extends through the hole 56 and is provided with a nut 59 and a washer 60 which engages the inner surface of the brace bar 53. After the wedges have been properly installed in their associated tang slots, the bolt 58 is turned while the nut 59 is held until the bolt 58 engages the end of the tang 37, thereby forcing the washer 60 against the brace bar 53 and preventing the tang 37 from moving to the right. Similarly, associated with the hole 57 in the brace bar 53a is a bolt 62, a nut 63 and a washer 64. The bolt 62 is tightened to engage the left end of the tang 37.

For the tang locations at the 6 o'clock and 12 o'clock positions in FIG. 5, only one such brace bar and locking mechanism is associated with each tang; however, these locking mechanisms, generally designated by reference numerals 67 and 68 act in opposing directions on the inner race 22 so as to prevent relative rotational movement between that inner race and the vehicle bed 13.

As will be further observed from FIG. 5, the wedges associated with the upper and lower pairs of tangs are inserted from the inside of the slue ring, whereas the three wedges on each side of the illustration are inserted from outside the slue ring. The lower bearing surfaces (identified by reference numeral 39 in FIG. 8) are inclined in corresponding directions to fully engage the inclined surface 41 of their associated wedges, depending upon the direction of insertion of the wedge. Attached to the inner wall of the inner race 22 is a bottom pan 70 (see FIG. 5) which forms a bottom cover for the swing circle when it is removed from the vehicle bed.

In assembling the swing circle to the vehicle and preparing it for operation, the tangs 37 of the inner race are placed through the slots 43 which have sufficient clearance to permit easy insertion of the slots. Next, the wedges 40 are inserted into the apertures 38 of the tangs 37 in their intended direction, as with a sledge hammer or hydraulic jack.

Next, the cross bars 49 are assembled to their associated tangs by means of the bolts 48 to hold the wedges firmly in place. Next, the side locking mechanisms are inserted in the ribs forming the framework beneath the vehicle bed to engage the ends of the tangs and prevent rotation of the inner race of the swing circle during operation.

In removing the swing circle, the disassembly includes the reverse steps to those just described, except that in removing the wedge itself, a threaded bolt is inserted in the aperture 50 to the wedge 40 to facilitate hydraulic withdrawal of the wedge.

Thus, the present invention provides for a system for mounting a slue ring onto the bed of a vehicle wherein only 10 individual connections need be made between the vehicle bed and the slue ring, and these connections are simply and easily made without the need for tools which are expensive or hard to handle. Further, there are no critical adjustments or measurements to be made during installation.

Having thus described in detail a preferred embodiment of the invention, persons skilled in the art will be able to modify certain of the structure that has been illustrated and to substitute equivalent elements for those which have been disclosed, and it is, therefore, intended that all such modifications and substitutions be covered as they are embraced within the spirit and scope of the appended claims.

Claims

I claim:

1. A system for removably mounting a crane superstructure to a bed comprising: an annular bearing having an inner race and an outer race; means for securing one of said inner and outer races to said superstructure, the other of said inner and outer races having a plurality of depending tangs; said bed defining a plurality of elongated slots adapted to receive said tangs, said tangs projecting beneath said bed when said bed and bearing are in assembled relation and each tang defining a slot extending beneath said bed; and a wedge adapted to be forced into the slot of each tang between the lower surface of an associated slot and the lower surface of said bed when said bearing is assembled to said bed.

2. The system of claim 1 wherein the lower surface of each tang slot is tapered upwardly in the direction of insertion of an associated wedge, thereby to cause greater frictional engagement with an inserted wedge.

3. The system of claim 1 further comprising means for locking each of said wedges to an associated tang in which it is inserted.

4. The system of claim 3 wherein each of said locking means comprises a transverse bar adapted to engage a wedge, said bar extending beyond the width of said wedge and including side holes; and bolt means adapted to pass through the side holes of said cross bar and be threadably received in an associated tang for holding a wedge in engagement with a tang.

5. The system of claim 4 wherein each wedge is provided at its rear surface with a threaded aperture adapted to receive a tool to facilitate the removal of a wedge.

6. The system of claim 1 wherein each of said tangs defines end surfaces, said system further comprising frame means beneath said bed, and side locking means for interconnecting said frame means to associated tangs to prevent rotational movement between said other race of said bearing and said bed frame.

7. The system of claim 1 characterized in that said plurality of tangs is an even number of tangs and said tangs are arranged in an associated pair located at diametrically opposite locations relative to the center of said bearing.

8. The system of claim 7 wherein said inner race of said bearing is provided with said tangs and said outer race is secured to said superstructure.

9. In a mobile crane including a superstructure and a vehicle providing a bed for said superstructure, a system for rotatably and removably mounting said superstructure to said bed comprising: means associated with said bed for providing a plurality of slots elongated in a generally circular pattern; a swing circle including an annular bearing having an inner race and an outer race, one of said inner and said outer races being fixedly secured to said superstructure and the other of said inner and outer races defining a plurality of depending tangs adapted to be received in associated ones of said slot in said bed, each tang extending beneath said bed when said superstructure is in assembled relation therewith and including a slot; a wedge for each of said slots in said tangs and adapted to be wedged between the lower surface of a slot and the vehicle bed to rigidly secure said tangs beneath said bed; and means connected to a frame supporting said bed for engaging at least some of said tangs to prevent relative rotational movement between said other bearing race and said vehicle bed.

10. The system of claim 9 further comprising means for locking said wedges to an associated tang after said wedges have been forced between a tang and said vehicle bed.

11. The system of claim 9 wherein said inner race is provided with said tangs, said inner race further comprising a laterally extending thrust flange, said outer race defining an annular channel for receiving said thrust flange, said swing circle further comprising roller bearing means in said channel for receiving said thrust flange in rolling engagement.

12. A method of removably mounting a crane superstructure to a vehicle bed, said superstructure including a bearing having an inner race and an outer race for permitting rotation of said superstructure about a vertical axis when in assembled relation with said vehicle bed, comprising: providing a plurality of depending tangs on one of said inner and outer bearing races and a corresponding set of slots in said vehicle bed for receiving said tangs, each tang further defining a slot at least partially located beneath said vehicle bed when said superstructure is in assembled relation with said bed; placing said tangs in their associated slots in said bed; then forcing wedges into the slots of said tangs between said vehicle bed and the lower surface of an associated tang slot; and then locking said wedges in place.

13. The method of claim 12 further comprising the steps of bracing the ends of at least some of said tangs against a frame beneath said bed to resist rotational movement between said other bearing race and said vehicle bed.