GB2076978A - Weighbridge - Google Patents

Abstract

A weighbridge utilising load cells 2 has a unitary prestressed concrete platform 1 manufactured either as a single monolithic structure in a single cast or as a plurality of units or sections subsequently bonded together to form an effectively monolithic structure, said manufacture being effected under controlled conditions remote from the site of installation and including the provision of pre-positioned and aligned locating and abutment plates 8 for the load cells so as to reduce on-site work. <IMAGE>

Description

SPECIFICATION Weighbridge This invention relates to weighbridges, for exam ple for weighing vehicles.

It is known to provide weighbridges utilising load cells and having load bearing platform structure through which the load to be weighed is distributed and applied to the cells. Said structure may incorporate concrete members, one such example being described in British Patent 1402901 in which a weighbridge platform is assembled from premanufactured concrete elements including at least one element formed of pre-stressed concrete.

It is also known to provide a monolithic concrete weightbridge platform by casting and forming it on the site of intended installation or by assembling concrete deck slabs on site to a steel platform framework, the loading being applied to the load cells through the latter as exemplified in British Patent 1038669.

Casting or assembly of the platform on site has to be carried out under field conditions, usually out of doors, and with the need to achieve the necessary accuracy of alignment and calibration using portable equipment Components or assemblies which are found to be defective following assembly have to be corrected on site or removed and replaced which may be costly in terms of time and transport costs.

The object of the present invention is to provide a weighbridge construction which can be installed and calibrated with a minimum of work on site and to give consistent and reliable operation.

According to one aspect of the invention a weighbridge comprises a plurality of load cells and a load carrying platform supported on the cells on assembly, said platform being a substantially unitary prestressed concrete structure when formed which can be at least partly formed under controlled manufacturing conditions remote from the site of installation and transported to the latter, said platform having locating and abutment formations forthe load cells which are positioned and aligned to the required operative accuracy when the platform is formed and before it is placed in its operative position.

According to another aspect of the invention a method of manufacturing a weighbridge includes the steps of forming a substantially unitary prestressed concrete load carrying platform having locating and abutment formations for load cells of the weighbridge positioned and aligned to the required operative accuracy at the time of formation and before the platform is placed in its operative position, forming foundations including supports for the load cells to align them with said formations, and assembling the weighbridge with the load cells positioned between the foundations and the said formations.

Preferably the platform is of generally inverted channel section having at least two integral longitudinally extending spaced parallel downwardly depending beams or webs, said formations being attached at opposite end portions of each said beam or web and the load cells used being four in number each at a respective corner portion of the platform.

One practical embodiment of the invention is now more particulariy described with reference to the accompanying drawings wherein: Figure 1 is a diagrammatic side elevation of an installed weighbridge (part broken away); and Figure 2 is a lateral section on line 2-2 of Figure 1.

The weighbridge shown is a standard pattern provided in a range of lengths appropriate to weighing capacities suitable for road vehicles to correlate to loadings laid down by vehicle use legislation, typically having a platform 3 metres wide in lengths from 12 to 18 metres.

The drawings show the complete installation comprising a monolithic pre-stressed concrete platform 1 supported on a plurality, in this particular example four, load cell units 2 disposed generally at corner regions of the platform, said units resting on foundations 3 in a pit 4 which is about 1.20 metres deep.

Platform 1 is preformed under controlled manufacturing conditions remote from the installation site and is designed to provide maximum strength and rigidity with minimum quantity of materials for economy of installation and ease of transport to site.

The platform comprises a generally planartable portion 5 the major portion of which is some 150 mm in thickness and incorporating longitudinally extending pre-stressing wires. The corners and end edges of the platform surface are protected by metal capping (not shown).

The platform structure further includes integral downwardly depending beams or webs 6 extending its full length and spaced apart, each centred at about 360-400mm from the side edges of the platform.

The maximum depth below the platform top surface of webs 6 is 950mm but end portions 7 are reduced to 575mm depth.

At the time of manufacture of platform 1, locating and alignment plates 8 are accurately mounted on the concerete structure, the appropriate surfaces being readily accessible and alignment and accuracy being tested and ensured using factory available equipment. Plates 8 are ready to receive the load cell units without further adjustment after leaving the factory.

Installation and assembly on site is speedily carried out with the minimum of equipment. The accuracy of the platform abutments for the load cells has already been checked and is ensured, thus it is only necessary to ensure that the cell foundations 3 are accurate, corrections to these can be made fairly readily on site and their alignment can be easily checked before the platform is lowered into place.

The unitary structure of platform 1 avoids much on-site assembly and avoids any problems due to curing of the concrete and supervision of its proper reinforcement and pre-stressing.

A pair of man holes (not shown) may be provided between webs 6 adjacent to the load cell units 2 for access to the latter following assembly.

The load cells will be interconnected with approp riate indicating or read-out equipment (not shown) in known manner.

While the platform described above is formed in a single cast incorporating its prestressing wires and is transported to site as a unitary structure the invention further comprises a platform formed as a plurality of individual units or sections which are transported to site and assembled by being bonded together at the assembly stage, the end result being a unitary platform which is effectively monolithic.

This procedure may be used to reduce transport and handling problems. It is contemplated that the same mould may be used to cast the platform either in a single cast or in units or sections according to requirements.

On sloping sites the unitary platform oftheinven- tion may be adapted by the use of tapered packing pieces so that the load cell units act vertically.

Claims (15)

1. Aweighbridgecomprising a plurality of load cells and a load carrying platform supported on the cells on assembly, said platform being a substantially unitary pre-stressed concrete structure when formed which can be at least partly formed under controlled manufacturing conditions remote from the site of installation and transported to the latter, said platform having locating and abutmentforma tionsforthe load cells which are positioned and aligned to the required operative accuracy when the platform is formed and before it is placed in its operative position.

2. Aweighbridge as in Claim 1 wherein thy entire platform is formed in a single cast as a monolithic structure.

3. A weighbridge as in Claim 1 wherein the platform is formed as a plurality of individual units or sections assembled by being bonded together to form a unitary platform which is effectively monolithic.

4. Aweighbridge as in Claim 1,2 or3 wherein the platform is of generally inverted channel section having at least two integral longitudinallyextending spaced parallel downwardly depending beams or webs.

5. Aweighbridge as in Claim 4whereinthere are four locating and abutment formations positioned at respective opposite end portions of two of said beams or webs.

6. A weighbridge as in Claim 5 wherein said end portions are reduced in depth relative to intermediate portions of the beams or webs.

7. Aweighbridge as in Claim 4,5 or6 wherein the platform has a table portion which is of substantially uniform thickness except in the areas of said beams or webs.

8. Aweighbridge as in any one preceding claim including a manhole in the platform for access to the load cells following installation.

9. A weighbridge substantially as hereinbefore described with reference to and as shown in the accompanying drawings.

10. A method of manufacturing aweighbridge including the steps of forming a substantially unitary pre-stressed concrete load carrying platform having locating and abutment formations for load cells of the weighbridge positioned and aligned to the required operative accuracy at the time of formation and before the platform is placed in its operative position, formingfoundations including supports for the load cells to align them with saiclformations, and assembling the weighbridge with the load cells positioned between the foundations and the said formations.

11. A method as in Claim 10 wherein the entire platform is formed ina a single cast as a monolithic structure under said manufacturing conditions.

12 A method as in Claim 10 wherein the platform is formed and transported to the site as a plur alitf of individual units or sections which are subsequentlyassembled by being bonded togetherto form a unitary platform which is effectively mono lithic,

13. Amethod as in Claim 11 or 12 including the step of providing a mould which is adaptable to cast the platform either in a single cast or in units or sections.

14. A method as in any one of Claims 10 to 13 wherein there are four load cells, each disposed at a respective corner region of the platform.

15. A method of manufacturing a weighbridge substantially as hereinbefore described with reference to-the accompanying drawings.