US 3257968 A
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Description (OCR text may contain errors)
J. E. MINTY ETAL 3,257,968
CRANE TRUCK 4 Sheets-Sheet 1 June 28, 1966 Filed Sept. 20, 1962 June 28, 1966 J. E. MINTY ETAL CRANE TRUCK 4 Sheets-Sheet 2 Filed Sept. 20, 1962 June 28, 1966 J. E. MlNTY ETAL 3,257,968
CRANE TRUCK Filed Sept. 20, 1962 4 Sheets-Sheet 3 J0 a7 a/ A? 73&
June 28, 1966 Filed Sept. 20, 1962 J. E. MINTY ETAL CRANE TRUCK 4 Sheets-Sheet 4 if JW United States Patent 3,257,968 CRANE TRUCK John Minty, North Muskegon, and Walter A. Paulssen,
Spring Lake, Mich., assignors, by mesne assignments, to
Dresser Industries, Inc., Dallas, Tern, a corporation of Delaware Filed Sept. 20, 1962, Ser. No. 225,001 4 Claims. (Cl. 105-163) This invention relates generally to wheel assemblies for supporting heavy cranes, hoists or the like and is more particularly concerned with a dual wheel assembly for mounting such devices on a pair of closely spaced parallel rails.
In recent years, high-capacity cranes and hoists have been developed for lifting and transferring heavy articles and materials in manufacturing and assembly plants as well as for loading and unloading materials at dock sites, in ship yards and on large construction sites. Typically, high-capacity lifting devices of this nature must be provided with a supporting nail structure to bear the heavy weight of both the crane and the material which is being lifted or transferred. As this supported weight has increased, it has become necessary to place more wheels on each rail for supporting the load bearing carriage. This has usually been accomplished by mounting front and rear wheels in equalizer truck assemblies at spaced intervals along the carriage. However, this construction necessitates separate axles for each wheel of the truck assembly, and since the load which is supported by the truck is disposed centrally between its track-engaging wheels, the load bearing carriage is limited in its approach to the track end.
In order to overcome these difficulties, wheel assemblies have been developed which mount two wheels on each end of a common shaft or axle to travel on two closely spaced rails beneath each side of the carriage. In this way the carriage can approach the end of the rail structure to a point limited only by the effective radius of the supporting wheels. To equalize the load borne by each of the wheels, it is customary to journal the common axle in a spherical bearing between the wheels and thus permit limited rocking movement of the axle. However, the wheels of travelling cranes, which are journalled in this manner, have a tendency to walk or become skewed since the spherical bearing also permits limited front and rear twisting of the axle. Moreover, since the dual wheels are engaged between two closely spaced rails, this skewing effect sets up large binding forces between the wheels and the rails and greatly increases the power required to drive the carriage along the rails.
Accordingly, the primary aim of the present invention is to provide a dual wheel assembly for mounting a load bearing carriage on a rail structure which effectively equalizes the load on each Wheel and yet which prevents skewing of the wheels on the rail structure.
It is also an object to provide a dual wheel assembly of the above type which may be easily and economically installed on standard-type carriage frames without expensive alterations or modifications. Moreover, it is a related object to provide such a dual wheel assembly which is inexpensive to manufacture and yet dependable and long-lasting in operation even under prolonged periods of heavy use.
Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which:
FIG. 2 is a front elevation with portions broken away of the carriage as seen from line 2-2 in FIG. 1;
FIG. 3 is a side elevation as seen from line 3-3 in FIG. 1;
FIGS. 4, 5 and 6 are enlarged sections taken respectively along lines 4-4, 5-5 and 6-6 of FIG. 1;
FIG. 7 is an enlarged side elevational View of the guide frame shown in FIGS. 1, 2 and 4, as seen substantially along the line 7-7 in FIG. 2.
FIG. 8 is a top plan view of the wheel and axle assembly shown in FIG. 6 as seen from line 8-8 in FIG. 3; and
FIG. 9 is a partial section of the wheel and axle assembly shown in FIG. 5, with one wheel removed, as seen from line 9-9 in FIG. 5.
While the invention will be described in connection with certain preferred embodiments, it will be understood that we do not intend to limit the invention to those embodiments. On the contrary, we intend to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined by the appended claims.
Turning now to the drawings, there is shown in FIG. 1, a load bearing carriage 10 which embodies the present invention. In the illustrated embodiment, the carriage 10 is in the form of a bridge assembly for a travelling crane and includes a pair of spaced, parallel cross frame members or girders 11 which are connected at their opposite ends to a pair of parallel side frame members or carriage trucks 12. Each of the trucks is provided with front and rear wheel and axle assemblies 13 and 14, respectively, which are disposed under the sides of the carriage and adapted to engage a rail structure in the form of two closely spaced, parallel rails 15 and 16 (see FIG. 2). A rail sweep 17 is mounted on each end of the trucks 12 to clear the rails ahead of the wheel and axle assemblies.
It will be understood that the rail structures are suitably mounted on fixed supports in order to define a track for the travelling crane bridge carriage 10 which in the present instance is illustrated as the overhead type. Similarly, a laterally extending track for the rail engaging wheels of the crane mechanism (not shown) is provided by a pair of closely spaced, parallel rails 18 and 19 mounted on the upper surface of each of the cross frame members 11. It will now be appreciated that the crane bridge carriage is adapted to move along the rails 15, 16 in a longitudinal direction and the carriage has rails 18, 19 for movement of the crane mechanism in a lateral direction. End stops.
20 are also mounted on the cross frame members 11 to prevent the crane mechanism from running off the side of the carriage 10. Such bridge assemblies have found particular utility in factory installations and at dock sites where exceedingly heavy loads must be transferred from one point to another.
In order to equalize the weight of the bridge carriage 1t and its supported load on each of the rails 15, 16, the front wheel and axle assemblies 13 each include a pair of closely spaced, flanged rail engaging wheels 21 and 22 keyed on a common axle 23 which is journalled in a spherical type roller bearing 24 Similarly, the rear wheel and axle assemblies 14 each have a pair of rail engaging wheels 25 and 26 mounted at opposite ends of a common axle 27 which is also journalled in a spherical type roller bearing 28. To secure the wheels to their respective axles 23, 27, large lock nuts 29 are threaded on the axles.
posed between the wheels to permit free rotation of the axles as well as to allow limited rocking movement of the wheels, on the rails 15, 16. Thus, even if one rail is slightly lower than the other, the wheel and axle assembles will tilt slightly so that each wheel carries a substantially equalized load.
It will be understood that the spherical bearings are dis- The spherical bearings 24, 28 are each mounted in an eccentric bearing cage 30 and are retained in place by means of a retainer plate 31 which is secured to the cage by bolts 32. To keep out the dirt and to retain lubrication within the bearing, both the cage 30 and plate 31 are provided with seal elements 33, which abut an inwardly extending hub 34 on each of the wheels. The bearing units are also provided with suitable fittings 35 for admitting lubrication into the bearings.
For supporting the carriage on the wheel and axle assemblies 13, 14, the side trucks are provided at their opposite ends with semi-circular recesses 36 and 37 which are adapted to overlie the eccentric bearing cages 30. A retaining strap 33, also having a semi-circular face is bolted to the truck frame to completely retain the eccentric bearing cage 30. It will be understood that rotation of the eccentric bearing cage 30 in the recess 36, for example, will adjustably position the axle 23. To lock the bearing cage 30 against accidental rotation at the selected position in the recess 36, a key 39 is bolted to the face of the recess to engage one of a plurality of transverse keyways 40 which are cut in the periphery of the bearing cage.
To move the crane bridge carriage 10 along the rails '15, 16, a driving mechanism indicated generally at 45 is secured to the carriage on a platform 46. In the present instance, a single drive mechanism is connected to the front Wheel and axle assemblies 13, but it will be appreciated that a second drive mechanism could be installed at the rear of the carriage, if desired. The drive mechanism 45 includes an electric motor 47 having a drive shaft 48 coupled to an input shaft 49 of a gear train enclosed within a housing 50. The opposite end of the motor shaft 48 is provided with a brake device 51 and the gear train input shaft 49 extends through the housing 50 and is also provided with a brake device 52. The brakes 51, 52 are, of course, operable to resist rotation of their. respective shafts and thereby serve to stop the rolling movement of the carriage 10.
The gear train has dual-output shafts 53 which project laterally from the sides of the housing 50 and each output shaft is connected to a floating drive shaft 54 by a universal coupling element 55. A second universal coupling element 56 connects the drive shaft 54 to a stub shaft 57 formed integrally with the axle 23 of each of the front wheel and axle assemblies 13. Thus, it will be appreciated that the floating drive shaft 54 and universal couplings make it possible to drive the front wheel and axle assemblies 13 even when they are slightly tilted to equalize the supported load on uneven rails. 15, 16.
It will also be understood by those skilled in this art that spherical roller bearings 24, 28 of the type illustrated have an imaginary center point which defines the origin of three mutually perpendicular intersecting axes. These axes are respectively: a horizontal rotating axis generally concentric with the bearing and extending substantially perpendicular from the frame 12; a horizontal tilting axis extending through the bearing at right angles to the rotating axis; and a vertical skewing axis extending through the hearing at right angles to both the rotating axis and the tilting axis. Therefore, not only does the spherical bearing permit free rotation of the wheel and axle assembly, but it also allows limited universal pivoting movement of the assembly in the form of tilting movement in a general vertical plane and skewing or twisting movement in a generally horizontal plane.
In accordance with the present invention, the wheel and axle assemblies 13, 14 are provided with means for limiting skewing movement of the wheelsv so that frictional forces between the wheels and the supporting rails are minimized. In both of the two illustrated embodiments, the limiting means includes a restraining member secured to the frame 12 and extended downwardly with one enddisposed a spaced distance from the bearing .center point substantially in the horizontal plane defined by the intersecting rotating and tilting axes. Preferably the lower end of the restraining member includes friction reducing means in the form of a bearing element for engaging the wheel and axle assembly which permits rotation and tilting movement but limits skewing movement so that the Wheel and axle assemblies do not bind on the rails.
For restraining skewing movement of the wheel and axle assembly 13, a guide frame 60 with a depending leg portion 61 is secured to the side truck 12. As shown in FIGS. 1 and 4, theframe and leg are reinforced by a pair of upstanding, angled rib members 62 and a pair of cross ribs 63 which rigidize the depending leg 61. The lower end of the leg preferably extends downwardly past the plane of the intersecting horizontal axes of the wheel and axle assembly 13 and defines a reinforced downwardly opening slot 65 which slidingly retains a bushing 66 on the stub shaft 57. Thus, the leg 61 permits the bushing 66 to move up and down in the slot 65 as the wheel and axle assembly tilts to equalize the load on uneven rails, but prevents the assembly from twisting or skewing about its vertical axis. Therefore, the tendency of the wheels to walk on the rails is largely minimized and consequently the extreme binding forces are greatly reduced.
To prevent skewing movement of the rear wheel and axle assembly 14, where there is no extending stub shaft, a different type of restraining means is used which includes a frame element 70 secured to the side truck 12 so as to extend downwardly between the two wheels 25, 26 adjacent their peripheries. The element 70 mounts a cross shaft 72 disposed in the horizontal plane extending through the rotating axis of the wheel and axle assembly 14. In this embodiment, the shaft 72 includes a pair of eccentric journal portions 72a and 72b which mount a pair of antifriction bearing 73a and 73b for journalling a pair of rollers 73 that engage the surface of the rail engaging wheels 25, 26. The roller shaft 72 is rotatably positioned by means of an adjusting plate 75' so that the rollers 73 bear against the wheels which are positioned by the eccentric bearing cage 30. It will now be understood that the rollers 73 permit the wheels to vertically adjust to the rails 15, 16 but restrains them from skewing movement. The rollers are lubricated through an internal passageway in the shaft 72 which carries a suitable fitting 76.
It will now be appreciated that the restraining means for the respective Wheel and axle assemblies 13, 14 each include a frame member 60 or 70 that extends downwardly a spaced distance from the bearing center point and intersects the horizontal plane defined by the rotating and tilting axes of the bearing. Moreover, each of the restraining means includes friction reducing means 66 and 73 adapted to engage its respective Wheel and axle assembly 13, 14. Thus, by locating the restraining means at right angles to the vertical skewing axis and at a spaced distance from the bearing center point the wheel and axle assemblies 13, 14 are effectively prevented from front and rear twisting. Accordingly, even if the rails 15, 16 are at uneven heights, the carriage wheels each carry an equalized load and the restraining means described above prevent the wheels from walking or binding on the rails.
It is also a feature of the invention that the restraining means may be installed on conventional crane bridge carriages 10 having dual wheel and axle assemblies 13, 14, without expensive alterations to the carriage. Thus, by merely adding the frame member 60 and slotted leg 64 to engage the bushing 66, the assembly 13 is restrained from skewing. Similarly, the wheel and axle assembly 14 is restrained from skewing movement by the simple and inexpensive addition of the frame 70 and rollers 73 which engage the wheels. Moreover, it will also be apparent that the individual parts of these restraining means are simply formed and that they may be manufactured without great expense.
We claim as our invention: I
1. A supporting mechanism for a load bearing carriage having a frame adapted for movement on a pair of closely spaced, parallel rails adjacent each side of said frame, comprising, in combination, a wheel and axle assembly including a pair of laterally spaced rail engaging wheels adjacent each side of said frame for supporting said carriage on said rails, a spherical type roller bearing mounted on each side of said frame for universally journalling said respective wheel and axle assemblies, said wheel and axle assemblies each having an axis of rotation concentric with saidcooperating bearing and extending from said frame in a generally horizontal plane, each ofsaid wheel and axle assemblies also having a tilting axis extending through said cooperating bearing at right angles to said axis of rotation in a generally horizontal plane and having a skewing axis extending through said cooperating bearing in a generally vertical plane at right angles respectively to said axis of rotation and said tilting axis, and a restraining member secured to said frame adjacent each side thereof and carrying a bearing element spaced apart from said spherical bearing substantially in said generally horizontal plane of said tilting axis for engaging said respective wheel and axle assembly independently from said spherical roller bearing to limit skewing movement thereof about said skewing axis while permitting rocking movement about said tilting axis so that said respective wheel and axle assembly does not bind on said rails.
2. A supporting mechanism for a load bearing carriage having a frame adapted for movement on a pair of closely spaced, parallel rails adjacent each side of said frame, comprising, in combination, a Wheel and axle assembly including a pair of laterally spaced rail engaging wheels adjacent each side of said frame for supporting said carriage on said respective pairs of rails, a spherical type roller bearing mounted on each side of said frame having a center point defining the origin of three mutually perpendicularly oriented intersecting axes including a horizontal rotating axis, a horizontal tilting axis, and a vertical skewing axis, said wheel and axle assembly journalled in said spherical bearing for rotation about said rotating axis and for limited rocking and skewing movement about said tilting and skewing axes, respectively and a restraining member secured to said frame adjacent each side thereof and extending downwardly therefrom with one end disposed a spaced distance from said center point substantially in the horizontal plane defined by said intersecting rotating and tilting axes, said restraining member having a bearing element on said end in horizontally spaced relationship with said spherical bearing for engaging said wheel and axle assembly independently from said spherical roller bearing to permit rotation and rocking movement thereof while resisting skewing movement about ,said vertical skewing axis so that said wheel and axle assembly does not bind on said rails.
3. For use in supporting a load bearing carriage having a frame adapted for movement on a pair of parallel, closely spaced rails disposed beneath each side of said carriage and extending along the line of travel thereof, the combination comprising, a pair of rail engaging wheels adjacent each side of said carriage for supporting said carriage on said rails, said pair of wheels mounted on a common axle journalled in a spherical type roller bearing secured to said frame to equalize the load on each of said wheels, said axle having a portion extending beyond one of said wheels and carrying a bushing thereon, and a leg member extending downwardly from said frame adjacent said extending axle and having a slotted opening in the lower end thereof, said bushing being retained in said slotted opening to permit limited vertical movement while restraining horizontal skewing movement of said axle so that said wheels do not bind on said rails.
4. For use in supporting a load bearing carriage having a frame adapted for movement on a pair of parallel, closely spaced rails disposed beneath each side of said carriage and extending along the line of travel thereof, the combination comprising, a pair of rail engaging wheels adjacent each side of said carriage for supporting said carriage on said rails, said pair of wheels mounted on a common axle journalled in a spherical type roller bear ing secured to said frame to equalize the load on each of said wheels, a leg member secured to said frame and extending downwardly therefrom to a point horizontally disposed from said bearing and adjacent the periphery of said wheels, and a pair of rollers journalled on the lower end of said leg member for peripherally engaging said pair of wheels adjacent said point to restrain horizontal skewing movement of said wheels and axle so that said wheels do not bind on said rails.
References Cited by the Examiner UNITED STATES PATENTS 907,964 12/1908 Brown 163 X 1,335,759 4/1920 Schneider 105-215 X 1,576,702 3/1926 Ackerman 105163 X 1,884,689 10/1932 Hilpert 105-163 X 2,547,710 4/1951 Lee 105138 ARTHUR L. LA POINT, Primary Examiner.
R. H. BRAUNER, LEO QUACKENBUSH, Examiners.
R. B. SANCHEZ, H. BELTRAN, Assistant Examiners.