WO1988000897A1

WO1988000897A1 - A vehicle turntable

Info

Publication number: WO1988000897A1
Application number: PCT/AU1987/000251
Authority: WO
Inventors: Hiliary Maxwell Irvine; Kenneth George Coles; Kenneth John Arnold
Original assignee: K. G. Coles & Co. Pty. Limited
Priority date: 1986-08-08
Filing date: 1987-08-07
Publication date: 1988-02-11

Abstract

A vehicle turntable comprising a central bearing assembly (11) and a platform (10) formed by a stressed skin cover plate (19) structurally combined with a grillage of supporting beams (17). The platform deflects with load and means (21, 27) are provided to prevent rotation of the turntable at a predetermined deflection.

Description

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A VEHICLE TURNTABLE

FIELD OP THE INVENTION

This invention relates to turntables for vehicles, particularly road vehicles, of the kind employed to enable such vehicles to be turned in confined spaces, such as at loading docks. The object of the invention is to provide turntables of a more economic construction than those of the prior art.

BACKGROUND ART

The prior art contains many approaches to the design of such turntables. A characteristic which such prior art turntables have in common, is the use of a supporting frame which provides substantially all of the strength of the turntable in supporting the load. Typically such turntables comprise a rigid frame of steel structural sections supporting an upper surface onto which the vehicle is to be driven, the rigid frame being supported either at the periphery of the turntable, or at its centre.

As a result of this approach to construction, prior art turntables are inefficient in their use of steel and motive power, and as a result are unnecessarily expensive.

SUMMARY OF THE INVENTION

Turntables of the present invention are characterised by the use of a method of construction which is lighter than those used previously, in conjunction with means for the support and braking or deactivation of the turntable in the event of overloading.

In one broad form, the present invention resides in a vehicle turntable comprising a central bearing assembly, a turntable body mounted for rotation about said bearing assembly, said body comprising a grillage of supporting beams and a cover plate fixed to said grillage so as to form a structural stressed skin thereon.

Preferably, the grillage comprises a plurality of pairs of parallel beams, the beams of each pair intersecting beams of at least one other pair, and the cover plate comprises at least one steel plate attached by welding to the grillage over substantially all of the extent of the grillage.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will now be described in relation to two embodiments thereof, illustrated in the accompanying drawings, in which :

Fig. 1 is a plan view of a turntable in a first embodiment of the invention, with the cover plates partially removed; Fig. 2 is a cross-sectional side elevation of the turntable of Fig. 1; Fig. 3 is a fragmentary cross-section showing the central mounting of the turntable of Fig. 1; Fig. 4 is a fragmentary cross-sectional elevation showing the turntable and associated installation at the periphery; Fig. 5 is a plan view of a turntable in a second embodiment of the invention, with the cover plates partially removed; Fig. 6 is a fragmentary cross-sectional side elevation of the turntable of Fig. 5; and Fig. 7 is a cross-sectional side elevation of the central bearing assembly of the turntable of Figs. 5 and 6. DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The installation illustrated in Figs. 1 to 4 comprises a turntable platform 10 mounted on a central bearing 11 for rotation within a pit 12. The bearing 11 suitably comprises a slewing ring the lower half 13 of which is fixed to the concrete base 14 of the pit 12, the upper half 15 of the slewing ring supporting the platform 10 at its central region, where the platform is provided with radial members 16.

Structurally, the platform 10 consists of three pairs of parallel beams, in this embodiment of rectangular hollow section, arranged to form a grillage within an outer circle of boxed channels 18. A steel cover plate 19 is welded onto the grillage formed by the beams 17 so that it constitutes a stressed skin to support the weight of the vehicles. The cover plate 19 is suitably of a light chequer plate, and is welded to the grid at all junctions with the underlying beams.

This combination of underlying grillage and stressed skin cover eliminates the need for a large number of welded stiffening members under the cover plates as used in the prior art, and results in a platform of greatly reduced weight.

The central portion of the platform 10, above the radial members 16, is provided with a removable cover plate (not shown) to allow access to the bearing assembly.

Compared with prior art turntables, the stressed skin and grillage construction employed in the present invention has greater flexibility, and the centrally supported embodiment of the invention illustrated in Figs. 1 to 4 allows for significant deflection at the edges of the turntable. It is preferred that a peripheral landing be provided beneath the platform 10 to support the platform against excessive deflection in the case of overload, and in the illustrated embodiment such a landing is provided by the upper flange of a peripheral channel 20, which may be provided with a rubber pad 21. Upon contact between the platform 10 and the rubber pad 21, the friction will be sufficient to stop the drive unit rotating the turntable.

If desired, provision may be made for vertical adjustment of the spacing of the landing below the platform. For example, the channel 20 may be mounted on shims. Alternatively, adjustable feet may be provided at spaced locations around the periphery of the platform, with rubber pads for engagement with the landing.

The drive unit employed may consist of a motor and gearbox of conventional construction mounted on a pivoted frame with a polyurethane-tyred drive wheel frictionally engaging the outer ring of the turntable under spring force.

The turntable of Figs. 1 to 4 may be pre-assembled in major sub-assemblies, comprising the central bearing, the central structure of radial members 16, and the inner portions of the beams 17, and two "D" shaped assemblies of the outer portions of beams 17, the major portions of the outer ring 18 and of the cover plate 19, with final assembly of these components being carried out at the installation site.

The embodiment illustrated in Figs. 5, 6 and 7 is suitable for greater load-carrying than the embodiment of Figs. 1 to 4. In this embodiment, the platform 10 is supported at its periphery rather than at the centre. The general construction of the platform 10 in this embodiment is similar to that of the previously described embodiments, with a grid of pairs of parallel beams 17, peripheral channels 18 and cover plate 19, the latter again acting as a stressed skin.

Around the periphery of the platform 10 at equally spaced locations there are provided support wheels 22 mounted on radial axles extending between the outer circle 18 and chordal support beams 23. These wheels 22 run on a circular track provided, in this embodiment, by inverted railway rails 24 having their lower ends embedded in the concrete footing of the pit 12. The wheels 22 are tapered and their axles cambered, the angle of taper passing through the centre point of the turntable and the plane of the upper surface of the rail 24, to provide a true conical rolling surface on the horizontal top of the rail 24, thereby providing low rolling friction and turning forces with resultant wear-free and smooth running of the turntable.

Not shown in Fig. 5, a central assembly of radial members 16 is attached at its centre to a central bearing 25 (Fig. 7). The bearing 25 does not support the platform 10, but acts only to take horizontal braking loads and to locate the turntable. In the embodiment shown in Fig. 7, the central bearing shaft 26 is capable of vertical movement within a sleeve 27, and at the point of overload of the turntable, the upper bearing assembly 28 will contact the upper end of the sleeve 27, and a limit switch (not shown) will be actuated to remove power from the drive motor.

Although the support of the turntable in this embodiment is shown as being at the periphery, it will be appreciated that the support rollers may, if desired, be located somewhat inboard of the outer edge of the turntable. While the invention has been described in relation to two presently preferred embodiments, it will be appreciated that the principles of construction may be embodied in other ways, and that the invention is not limited to the particular embodiments described. For example, the combination of stressed skin and underlying grid may be realised with many different patterns of beams, and bearing and support arrangements of other kinds may be employed.

Claims

CLAIMS ;

1. A vehicle turntable comprising a central bearing assembly, a turntable body mounted for rotation about said bearing assembly, said body comprising a grillage of supporting beams and a cover plate fixed to said grillage so as to form a structural stressed skin thereon.

2. A vehicle turntable according to claim 1 wherein said grillage comprises a plurality of pairs of parallel beams, the beams of each pair intersecting beams of at least one other pair.

3. A vehicle turntable according to claim 2 wherein said cover plate is attached to said beams at substantially all points of contact between them.

4. A vehicle turntable according to claim 2 comprising three pairs of parallel beams, the beams of each pair passing one on either side of said central bearing assembly, each pair being disposed at substantially equal angles to the beams of the other pairs.

5. A vehicle turntable according to claim 1 wherein said cover plate comprises at least one steel plate attached by welding to said grillage over substantially all of the extent of said grillage.

6. A vehicle turntable according to claim 5 wherein said cover plate comprises a first section extending between a first peripheral portion of said turntable and a beam of one of said pairs of beams, said beam being located on the same side of said bearing assembly as said peripheral portion, said first section being attached to said beam along substantially its length and to such portions of other beams of said grillage as lie beneath said section.

7. A vehicle turntable according to claim 6 wherein said cover plate comprises a second section extending between a further peripheral portion of said turntable and the other beam of said pair, said second section being attached to said other beam along substantially its length and to such portions of other beams as lie beneath it.

8. A vehicle turntable according to claim 1 wherein said turntable is supported on said central bearing assembly, said turntable further comprising support means underlying the periphery of said turntable and spaced below said periphery such that upon the occurrence of a predetermined overload on said turntable, said turntable deflects into contact with said support means for support thereby.

9. A vehicle turntable according to claim 8 and further comprising turntable drive means, wherein the opposed surfaces of said periphery and said support means are such that the friction between them upon said predetermined overload is sufficient to prevent rotation of the turntable by said drive means.

10. A vehicle turntable according to according to claim 9 further comprising means for adjusting the vertical position of said support means.

11. A vehicle turntable according to according to claim 1 wherein said turntable is supported at or adjacent its periphery, said bearing assembly functioning to locate the turntable and to resist horizontal forces thereon.

12. A vehicle turntable according to according to claim 11 wherein said bearing assembly allows vertical deflection of said turntable under load, said turntable further comprising drive means and means detecting vertical deflection of a predetermined extent and means responsive to such detection to disable said drive means.