GB2250529A

GB2250529A - Screed plate finisher for paving machine

Info

Publication number: GB2250529A
Application number: GB9026358A
Authority: GB
Inventors: Dennis Anthony Hills
Original assignee: Blaw Knox Construction Equipment Co
Current assignee: Blaw Knox Construction Equipment Co
Priority date: 1990-12-04
Filing date: 1990-12-04
Publication date: 1992-06-10
Also published as: GB9026358D0; DE69124967D1; EP0493889A1; DE69124967T2; EP0493889B1

Description

2230529 IMPROVEMENTS IN AND RELATING TO PAVING MACHINES This invention

relates to a paving machine for laying concrete and pulverulant materials such as asphalt on substrates such as road foundations or the ground. In particular, the present invention relates to a screed plate finisher for use in conjunction with a paving machine.

Paving machines may be self propelled or constitute an accessory constructed for mounting on a vehicle. Self propelled paving machines normally employ a hopper for carrying hot asphalt for distribution using augers over an area to be paved. During movement of the machine a screed plate serves to strike-off and leveloff deposited asphalt prior to compaction of the so laid asphalt by, for example, tamping or rolling. In order to produce a cambered, or, reverse cambered - a so called gulley two or more screed plates may be used and, by adjusting the screed plate relative to a substrate foundation the thickness of asphalt laid may be varied in a direction transverse to the direction of laying.

British Patent No. 1,560,469 Joseph Vogele A.G. describes and claims an extensible screed plate finisher for concrete or bituminous paving materials comprising a main plate fixed on support arms of the finisher, 'and at least one extra plate which is disposed behind the main plate in the direction of operation and which extends approximately over half the length of the main plate and which is connected to the main plate by means of guides and is laterally extensible by means of a displacement drive, and wherein the main plate carries a guide tube for receiving guide means connected to the extra plate, two guide elements are provided in spaced superposed relationship at the outer rear end of the main plate, and a rail fixed on the extra plate is guided between said guide elements. The guide means used in the Vogele finisher are constructed in the form of a telescopic tube and the guide elements are rollers disposed on eccentrics. ' 2 In the embodiment described in the above Patent GB 1560,469 both the inner and outer surfaces of the outer guide tube needed to be machined accurately and the rail had a projecting web, both surfaces of which needed to be machined accurately flat and parallel.

It is an object of the present invention, which is defined in the appended claims, to provide a paving machine with a supporting mechanism for the extending plates which is improved in these respects.

The invention will be further described with reference to the accompanying drawings in which Figure 1 is a simplified plan view of the supporting mechanism for the extending plates.

Figure 2 is a vertical section along the line A A of Figure 1 and Figure 3 is.a detail showing an adjustable bearing pad.

Each of these figures is diagrammatic and very much simplified, showing only components relevant to the present invention.

Referring first to Figure 1, the main screed plate assembly is in two halves only one of which, the left hand half, is shown in the Figure. It is supported between two end plates, 1, 2 which are held spaced apart and parallel to each other by a tube 3 of rectangular section and by a structure comprising a pair of rectangular section rails 4, 5 and a tube of circular section 6, which is the guide tube for the extension plate and forms the outermost of a set of three telescopic tubes. The main screed plate itself appears at 7 in Figure 2.

The extension screed plate 8 which is also to be seen in Figure 2, is likewise supported between end frames 9, 10 spaced apart by a tube 11 of rectangular section carrying a rail 12. The outer end plate 9 carries the innermost tube 13 of the telescopic tubes working within the guide tube 6. The extension plate is extended or retracted by means of a hydraulic jack 14 operating between the outer end plate 9 of the extension screed plate assembly and the inner plate 2 of the assembly carrying one half of the -main screed plate.

The inner end plate 10 of the extension screed plate assembly carries a boss 15 with a central opening 16 which clears the outside of the guide tube 6 and which has a pair of pressure pads 17, 18, one of which 17 engages the machined under surface of the rail 4 and the other of which 18 engages the machined upper surface of the rail 5. The surfaces of these rails not engaged bv the pressure pads do not need to be machined accurately parallel or flat. The action of the pressure pads on these rails supports the weight of the extension screed-plate assembly when it is clear of the ground. The rails 4 and 5 must be rigid enough for this purpose and they may themselves be supported on tubes or struts between the end plates, or, as indicated in Figure 2, rebated slightly into grooves milled in the sides of the guide tube 6.

The rectangular tube 11 of the extension tube assembly, as already described carries a rail 12 which is machined on its upper surface, and this surface engages a pressure pad 19, shown in more detail in Figure 3. It comprises a block 20 of low friction material supported by a pair of adjusting screws 21, 22.

The pressure of the block 20 on the rail 12 supports the reaction of the ground against the extension screed plate less the weight of the extension itself, and as wear takes place the screws can be advanced to compensate. This adjustment is well clear of the internal mechanism of the extension support assembly and readily accessible and the bearing surface of the rail 12 itself is readily accessible for cleaning.

Claims

CLAIMS 1. A paving machine having a main screed plate and at least one

extension screed plate mounted to the rear of the main screed plate and extendible laterally outwards and in which the main screed plate assembly carries a guide tube receiving guide means attached to the or each extension plate and with means provided for supporting the extension plate against rotation about the axis of the guide tube, characterised in that the means for preventing such rotation comprises a pair of guide rails 4,5, fixed in relation to the main screed plate 7 and attached or closely adjacent to the guide tube 6, with pressure pads 17, 18, fixed in relation to the extension screed plate and bearing on the guide rails in such a sense as to oppose rotation of the extension plate about the axis of the guide tube under its own weight, and with a further guide rail 12 fixed in relation to the extension screed plate and with a pressure pad 19 fixed in relation to the main screed plate bearing on the rail ' in such a sense as to oppose rotation of the extension screed plate assembly due to pressure against the ground.
2. A paving machine according to claim 1, in which the guide rails of the pair are rebated into grooves in the guide tube.
3. A paving machine according to claim 1 or claim 2, in which the pressure pad 19 bearing on the rail of the extension screed plate assembly is provided with adjustment means.