Crane Bridge Belt Drive

Abstract

Belt drive apparatus for the bridge of an overhead traveling crane. Multi-V belts are driven by a grooved drive sheave coupled to the main drive shaft. The plurality of apices formed by the multi-V-belt engages a grooveless sheave coaxially secured to a crane drive wheel effecting torque transmission by an axially floating drive relation therebetween. The wheels, in turn, ride on a runway beam defining a track over which bridge travel is to be effected.

Description

BACKGROUND OF THE INVENTION

1. The field of art to which the invention pertains generally includes the art of railway rolling stock and more specifically to bridge drives for traveling overhead cranes.

2. Overhead cranes are commonly used for industrial applications of material handling such as warehousing, heavy manufacturing or the like. A typical crane of this type is disclosed in U.S. Pat. No. 2,997,966. Installation for support of the crane usually includes a pair of elevated and parallel runway beams defining a track over which bridge travel is effected. The bridge, in turn, is suspended from the track and provides a laterally extending trackway between beams for riding movement of the lifting mechanism. By this means, the bridge moves longitudinally in the direction of the runway beams while allowing its operating mechanism to ride on the bridge for shifting laterally therebetween.

As can be appreciated, such installations are not produced on a mass production basis, but are instead custom fabricated for meeting particular requirements of the installation environment. Under those circumstances many uncontrollable variables are encountered such as the spacing of the parallel runway beams, beam shapes, crane capacity and the like. At the same time, the tracking surfaces of runway beams while theoretically parallel and straight in both their horizontal and vertical planes are, as a practical matter, neither parallel nor straight but instead are characterized by various misalignment deflections throughout their length. It is not unusual for the beams to include bends, curves, tipped flanges, or the like resulting from either the mill rolling process or incurred from general handling prior or during installation. Moreover, general open type steel construction employed in warehouses and the like on which such cranes are mounted are themselves subject to deviation from true theoretical dimensions to in turn affect the accuracy of a crane installation being supported thereby. As a consequence, such cranes in traversing the runway beams are subjected to various misalignment deflections and other forms of imperfect movement.

Typical prior art drive construction for these crane bridges has consisted of a positive gearing arrangement connecting motor output directly to the drive wheels of the crane bridge. A typical construction for such an arrangement utilizes a pinion shaft rigidly mounted and coupled to the main drive shaft and engaging gears secured to cantilever mounted drive wheels. These have not been regarded as entirely satisfactory by virtue of the rigidness that the drive pinion mount affords in being inflexible to runway deviations relative to encountered deflections of the drive wheels. Where the deviations are of a significant degree the drive wheels are known to separate from the beam rather than float in compensation therewith. Such separation between one or more wheels from the track can easily cause the remaining wheels to incur the full brunt of drive tracking and load imposed on the crane adversely affecting operability and wear factors to both the wheels and gearing. Moreover, gear drives require extensive lubrication and being generally open and exposed are frequently subject to excessive wear from abrasives or the like in the working environment.

Notwithstanding recognition of the foregoing, manufacturers of these cranes have continued to employ the rigid geared drive as their standard construction despite the obviously apparent drawbacks. At the same time, belt drives as a substitute for gearing have been considered both impractical and unusable for various reasons. Generally they have been characterized as suffering from an inability to transmit adequate driving force from a relatively small drive sheave to a comparably large driven sheave. Also they have been regarded as being unable to tolerate axial cross movement of the belts incurred during traversal of the crane from the aforementioned installation imperfections.

SUMMARY OF THE INVENTION

The invention relates to belt drive apparatus for an overhead traveling crane and more specifically to such a drive affording flexibility for compensating and tolerating imperfection in the crane support. In accordance herewith, a type of multi-V belt is employed, each driven from the main drive shaft by a small diameter grooved drive sheave. In turn, each belt drives a grooveless driven sheave connected to a drive wheel. By virtue of the grooveless driven sheave surface, a floating drive relation is established with the belts enabling them to incur axial shifting where required to compensate for angular misalignment. In the event deflections and/or deviations are encountered by the wheel in the course of runway traversal, axial shifting enables the belts to readily accommodate and insure continuous driving notwithstanding without interfering in the manner of the prior art rigid pinions. At the same time, adequate driving force is constantly maintained as to overcome and eliminate previous difficulties associated with the gear drive units of the prior art.

It is therefore an object of the invention to provide a novel drive structure for an overhead traveling crane.

It is a further object of the invention to provide a novel drive structure for an overhead traveling crane able to tolerate and compensate for expected deviations and deflections in the runway installation supports of such cranes.

It is a still further object of the invention to provide a novel crane bridge structure that is relatively inexpensive as compared to such similar purpose drive structures of the prior art while increasing rather than decreasing performance reliability thereof.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is an isometric illustration of the drive unit viewed from its underside;

FIG. 2 is a plan view of the crane bridge;

FIG. 3 is a fragmentary view as seen substantially along the lines 3--3 of FIG. 2;

FIG. 4 is a sectional elevation taken substantially along the lines 4--4 of FIG. 3;

FIG. 4a is an enlarged fragmentary elevation view, with the belt illustrated in cross-section engaging the driven sheave; and

FIG. 4b is an enlarged fragmentary elevation view, with the belt illustrated in cross-section engaging the drive sheave.

Referring now to the drawings, there is disclosed a crane bridge 10 with which the invention hereof is concerned and that, for example, may be of a general type disclosed in U.S. Pat. No. 2,997,966. Briefly, bridge 10 comprises a cross-girder 11, laterally secured between a pair of spaced-apart end trucks 12 and 13. Girder 11 is preferably of a wide flange I-beam cross section and is provided with capping in the form of a pair of angles 14 and 15 secured to the top flange thereof. A motor drive shaft 18 for effecting bridge movement, as will be understood, is suitably supported for rotation in displaced journals 19. Supporting the journals displaced from the girder are spaced-apart arms 20, bolted to the girder via bolts 21. A drive pulley 25 secured to the motor drive shaft laterally intermediate the end trucks is driven by a belt 26 from pulley 27 on the output shaft of motor 28 for transmitting the motive drive force as will be described.

Forming the runway drive tracks for the crane bridge are a pair of parallel spaced-apart supporting runway beams 32 and 33 on which to receive end trucks 12 and 13 respectively. Each beam is preferably of a wide flange I cross-section for which the lower flange upper surfaces 34 and 35 define the driving trackway. For advancing the bridge on the trackway to longitudinally position its crane (not shown), each of the end trucks 12 and 13 are provided with a pair of opposed support wheels 38 and 39 and a pair of opposed drive wheels 40 and 41 displaced longitudinally therefrom. Each of the latter wheels are appropriately contoured on their outer rims for drive tracking engagement with flange surfaces 34 and 35.

Providing cantilevered support for the wheels in this relation is a frame attached to the end truck and consisting of a pair of parallel channel members 45 and 46 connected at their ends by a cross-plate 47. Included in the cross-plate is a cut-out 48 to enable passing of the runway beam. The drive wheels themselves are each supported on a pair of ball bearings 51 and 52, mounting them on the reduced end 53 of lateral pin 54. Each pin in turn extends through a boss 55 welded and aligned with channel aperture 56. A slotted brace 57 welded to the pin receives bolts 58 and 59 and their corresponding hex nuts enable wheel spacing adjustment to accommodate beam size variations.

To drive the crane bridge in accordance with the invention hereof, drive wheels 40 and 41 include comparatively large grooveless driven sheaves 62 and 63 respectively integrally juxtaposed therewith. Drivingly engaging the latter sheaves are V-belts 64 and 65 of preferably multi-V cross section forming a sawtooth driving face of alternating peaks 68 and valleys 69. Belt compositions of that type have high friction characteristics being disclosed for example in U.S. Pat. Nos. 2,620,016, 2,728,239 and 2,746,308 and are commercially marketed under the trademark "Poly-V". In turn driving the belts, is an elongated drive shaft 66 constituting the drive sheave to be described and secured directly via coupling 67 to motor driven shaft 18. Supporting drive shaft 66 for rotation are a pair of spaced-apart bearings 72 and 73 each secured by means of an open ended cradled bearing cap 74 to the underside of side plates 75 and 76 depending from side channels 45 and 46 respectively.

Appropriate belt tension is maintained by means of an intermediately located cylindrical idler 79 supported on a central shaft 80 extending through matched vertical slots 81 in each of the side plates. Outwardly beyond the side plates, the ends of shaft 80 are received in the lower looped end of depending rods 82. The rods in turn extend vertically upward through the adjacent side channel flange for resilient suspension via coil spring 85 compressed between washers 86 and 87 by a hex nut 88 threaded to the upper end of the rod. Through adjustment applied via the hex nut, appropriate belt tension can be applied as desired.

The effective driving portion of sheave 66 is a reduced diameter grooved portion 90 at each end between the side plates and separated by an intermediate enlarged diameter portion 91. The number of grooves in portion 90 is usually more than required by belts 64 and 65 to allow for adjustment in wheel spacing. At the same time sheaves 62 and 63 are grooveless and of axial width on the belt running surface greater than the belt widths. In this manner, the belts are enabled to axially float on the driven sheaves while maintained in driving engagement therewith in the course of bridge travel whereby to accommodate misalignment deflection encountered by wheels 40 and 41 as they traverse the runway beams. With this arrangement any angular or elevated deviation caused by the encountered misalignment will not produce discontinuance in the drive connection since the grooveless surface of sheaves 62 and 63 can accommodate belt shift or the like otherwise apt to result in a loss of drive transmitted to the wheels. Although the belt apices are engaging a smooth cylindrical drive surface on the driven sheaves, apparently sufficient flattening of the apices occurs enabling drive traction to be maintained.

By the above description, there is disclosed novel apparatus for driving the bridge of an overhead traveling crane. Through the use of V-belts driven from a grooved drive sheave in a floating drive relation with a grooveless driven sheave, the belts are enabled to float axially in accommodating misalignment deflection encountered by the drive wheels. By virtue of this feature, the wheels themselves are able to accommodate the misalignment deflections without causing the belt drives to incur loss in drive relation from either the driving or driven sheave. A relatively simple belt drive structure is therefore able to replace the previously cumbersome and handicapped positive gearing drives employed for similar purposes in the prior art. Not only is the reliability of this form of drive achieved readily and simply, but it likewise affords the other attendant property of increased quietness, reduced lubrication, and reduced maintenance associated with belts as compared to geared drives of the prior art. Whereas, the drive hereof has been described as having principal use in conjunction with an overhead traveling crane, this is not intended as a limitation since it could obviously be used in various forms of overhead conveying devices.

Since many changes could be made in the above construction and many apparently widely different embodiments of this invention could be made without departing from the scope thereof, it is intended that all matter contained in the drawings and specification shall be interpreted as illustrative and not in a limiting sense.

Claims

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In an overhead conveying apparatus for travel on a runway track support, drive means comprising in combination:

a. motor means having an output drive shaft;

b. a pair of spaced-apart drive wheels mounted on said conveying apparatus in drive tracking engagement with said track support;

c. drive sheave means operatively connected to said motor output shaft;

d. driven sheave means operatively connected to each of said drive wheels and having a substantially smooth belt drive surface thereon; and

e. V-belt means having a V-faced driving surface which transmit driving force from the drive surface of said drive sheave means to said driven sheave means by at least one apex of said V-face of said belt means bearing against said substantially smooth drive surface thereof.

2. In an overhead conveying apparatus according to claim 1 in which the drive surface of said drive sheave has a predetermined axial extent for accommodating anticipated deflection in the alignment of said runway support.

3. In an overhead conveying apparatus according to claim 2 in which said drive sheave means comprises a grooved surface sheave of smaller diameter than said driven sheave and of width greater than said belt means to facilitate spacing adjustment of said wheels.

4. In an overhead conveying apparatus according to claim 1 in which said conveying apparatus comprises the bridge of an overhead traveling crane, said track support comprises a pair of spaced-apart runway beams and said drive means is duplicated for a driving engagement with each of said beams.

5. In an overhead conveying apparatus according to claim 4 including adjustable tensioning means for presetting a desired tension level of said V-belt means.

6. In an overhead conveying apparatus according to claim 5 in which said tensioning means comprises an idler roller spring loaded against said belt means.

7. In an overhead conveying apparatus according to claim 4 in which said V-belt means comprises an endless belt having a plurality of parallel juxtaposed V-grooves on its drive transmitting surface.

8. In an overhead conveying apparatus according to claim 7 in which the belt drive surface of said driven sheave is engaged by the apices of said V-grooves.

9. In an overhead conveying apparatus according to claim 8 in which said drive wheels extend cantilever supported from said conveying apparatus for maintaining said drive tracking engagement.

10. In an overhead conveying apparatus according to claim 9 including adjustable tensioning means for presetting a desired tension level of said V-belt means.

11. In an overhead conveying apparatus according to claim 10 in which said tensioning means comprises an idler roller spring loaded against said belt means.