THIS invention relates to an apparatus for applying substances to a ground surface, particularly, but not limited to, a road surface e.g. to repair cracks therein or apply lines thereto.

A road surface which has developed cracks can be refurbished either by completely resurfacing the road or by individually repairing the cracks. For economic reasons, the latter option is often preferred. Crack repair is traditionally carried out by melting blocks of bitumen in a large heating vessel and then transporting the melted bitumen to the site of a crack in a smaller container. At the crack site, the bitumen is poured into the crack and allowed to set.

A disadvantage of the traditional procedure is the necessity to heat up large quantities, often of the order of thousands of litres, of bitumen in the large heating vessel. Apart from the fact that it may take several hours each day to melt the bitumen to an adequately fluid state, heat must continuously be applied to the vessel throughout the day to maintain the molten condition. This is extremely wasteful of heating energy, particularly if only a limited crack repair operation is to be carried out.

Fran a first aspect of the present invention there is provided a road crack repair apparatus cαrprising:

a sealant container which can be charged with unmelted sealant,

a sleigh base which contacts the road surface and which can be moved in a forward direction over that surface along the length of a crack which is to be repaired, the sleigh base being at a lower elevation than the sealant container and including a sealant distribution shoe which comprises a pair of rearwardly divergent members defining a gap between them, the width of the gap increasing in a rearward direction, and

means for applying heat to the sealant to cause it to melt and for directing the molten sealant into the gap between the divergent members of the distribution shoe with the shoe then distributing the molten sealant in a controlled manner into the crack and onto the road surface adjacent the crack.

Conveniently, the means for applying heat to the sealant, which is typically bitumen, to cause it to melt comprises at least one gas-fired heater. The apparatus may carry its own supply of LP gas for supplying the heaters. Typically there will be a pair of gas-fired heaters mounted on opposite sides of the sealant container.

In the preferred embodiments, the sealant container includes a porous basket arranged to discharge molten sealant through the pores thereof. The basket will conveniently be of downwardly tapering shape to facilitate directional gravitational discharge of the molten sealant.

Preferably, the sealant container comprises a basket having a solid upper portion and a lower discharge portion which is at least partially porous. Such an arrangement is particularly advantageous since the sealant or other material may be melted at the lower end of the basket and allowed to run straight off through the pores therein. This avoids problems that can occur with systems which aim to melt a whole body of material at once, especially where the material has a low thermal conductivity, when the outer layers of the material can scorch before sufficient heat is transferred to the inner material to melt it. This is a problem which can occur with bitumen used to repair cracks in a road surface.

This ability of the invention to melt small amounts of material at a time also allows small pieces of aggregate to be mixed into the material without the aggregate settling to the bottom as would occur if the whole body of the material was melted at once. As long as the pieces of aggregate are smaller than the pores in the bottom of the basket, then the mixture will be applied by the apparatus of the invention in substantially the same proportion in which it was mixed. By mixing in small pieces of aggregate, for example the sealant used to repair a road may be made more skid resistant and therefore may be safely over-banded.

The sealant container need not actually be used for containing a sealant such as bitumen. Instead it might contain a mixture of sealant and solid particles e.g. aggregates, or even a completely different material such as paint for painting lines on a road surface. Such an arrangement is novel and inventive in its own right and

from another broad aspect the invention provides an apparatus for applying a molten substance to a road surface, said apparatus including a container for receiving solid material, said container having a solid upper portion and a tapering lower portion which is at least partially porous, heating means for melting the material in the container and a distribution shoe for receiving the molten substance and distributing the material on the ground in a controlled manner. It will be appreciated that such an apparatus may have any of the preferred features set out herein or in the attached claims.

Preferably also, the apparatus incorporates means for controlling the thickness of the sealant distributed onto the road surface adjacent the crack. In one embodiment of the invention, the thickness controlling means comprises a restraining member spanning between the divergent members of the distribution shoe, the restraining member having a lower edge which can be set at a predetermined height above the road surface. In this case, the restraining member typically comprises a flap spanning between the divergent members of the distribution shoe at a variable inclination to the road surface. In another embodiment, thickness can be controlled by the provision of means, for example a pivoted chute, which is mounted beneath the basket to collect the molten sealant and direct it into the gap between the divergent members of the distribution shoe. In one embodiment, the apparatus is entirely supported, for sliding movement over the road surface, on the distribution shoe. In another embodiment, the apparatus is supported both by the distribution shoe and by a road-engaging wheel. In either case, it is preferred that the apparatus include a handle by means of which the apparatus can be pulled manually over the road surface, along the length of the crack.

The invention will now be described in more detail, by way of example only, with reference to the accompanying diagrammatic drawings in which:

Figure 1 shows a plan view of a first embodiment of the invention;

Figure 2 shows a side elevation of the apparatus seen in Figure i;

Figure 3 shows a cross-section at the line 3-3 in Figure 2;

Figure 4 shows a cross-section at the line 4-4 in Figure 1 ;

Figure 5 illustrates the repair of a crack in a road surface;

Figure 6 shows a side elevation of a second embodiment of the invention;

Figure 7 shows a view of the second embodiment looking in the direction of the arrow 7 in Figure 6; and

Figure 8 shows a plan view of the second embodiment.

The illustrated embodiments are used to repair a crack, such as the crack 10 seen in Figure 5, with bitumen 12.

Referring to Figures 1 to 3, the first embodiment 14 of the invention has, as its major components, a sleigh base 16, a basket 18 and a pair of heaters 20 located on opposite sides of the basket. The sleigh base 16 incorporates a bitumen distribution shoe including two angle iron members 24 which are connected to one another at a pointed leading end 26 of the base. The members 24 diverge from one another in a rearward direction as illustrated in Figure 1. A support frame 28 is mounted transversely on the members 24 and supports the basket 18 and the heaters 20. A shaft 30 extends rotatably between the members 24 at a position located rearwardly of the support frame. A restraining member in the form of a planar flap 32 is connected rigidly to the shaft 30 between the members 24. The ends of the shaft are threaded and project through holes in the members 24. Wingnuts 34 can be tightened up on the projecting ends of the shaft to anchor the shaft at a selected rotational position and hence to set the flap at a chosen inclination to the vertical.

The basket 18 is made of expanded metal and has an upper portion 36 of rectangular cross-section and a lower portion 38 which tapers in cross- section to a lower extremity 40 as illustrated in Figure 3. The basket is fixed between cross-members 42 of the support frame 28.

At their opposite ends, the cross-members 42 support the lower ends of the heaters 20. Although illustrated only diagrammatically in the drawings, each heater is typically made up of a series of conventional ceramic, gas-fired heating panels. In practice, the heating panels are supplied with LP (liquid petroleum) gas from a conventional LP gas cylinder (not illustrated in the drawings).

Gas is supplied to the panels through appropriate hoses (also not illustrated). As illustrated, the heaters oppose one another on opposite sides of the lower portion 38 of the basket 18.

The legs of a U-shaped handle 44 are connected to the members 24 as illustrated, with the handle extending forwardly beyond the leading end 26 of the sleigh base.

In use the basket 18 is charged with billets or slugs of bitumen, in solid form, and of appropriate size. The sleigh is positioned on the road surface 46, in the vicinity of the crack 10, such that the crack extends on the line of an imaginary bisector of the (bitumen distribution shoe, i.e. the, members 24. LP gas flow to the heaters 20 is established and is ignited at the heaters. The intense heat generated by the heaters and directed against the sides of the basket causes rapid melting of the bitumen in the lower portion 38 of the basket 18. The molten bitumen flows out of the basket through the openings in the expanded metal and accumulates on the road surface in the triangular enclosure defined by the members 24 and the flap 32 ,of the distribution shoe,

The sleigh base is now pulled over the road surface in the direction of the arrow 50, along the length of the crack 10. As the sleigh base moves along the crack, a layer of bitumen 12 is left on the road surface, filling the crack and a zone on each side of the crack as illustrated in Figure 5. In practice, the application of bitumen to the road surface extends over the full length of the crack 10 and for some distance beyond the ends of the crack.

It will be appreciated that the application of the bitumen 12 to the road surface takes place in a controlled manner because of the action of the distribution shoe. The width of the layer of bitumen is determined by the length of the flap 32, and its thickness by the elevation of the lower edge of the flap above the road surface. The thickness can be varied merely by loosening off the wingnuts 34 and adjusting the orientation of the flap and so the elevation of the lower edge of the flap above the road surface. In the illustrated case, the width of the bitumen layer is fixed, but in a modified foπn of the invention a series of flaps of different length can be provided with different attachment points along the length of the members 24. In this case, the appropriate flap is selected and mounted to the sleigh base at the appropriate orientation to give a bitumen layer of required width and thickness.

Figures 6 to 8 illustrate a second embodiment 100 of the invention. In this embodiment, there is a round cylindrical bitumen slug holder 102 which is mounted in a round cylindrical retainer 104 and which has a solid wall 105 at its upper end and a conical basket 106 of porous construction at its lower end. The basket 106 may, for instance, be formed of expanded metal.

The lower end of the retainer 104 is mounted on a rectangular chimney 108 which has gas-fired heaters 110 mounted on opposite sides thereof. The heaters 110 are directed inwardly into the chimney, towards the basket 106, through appropriate openings in the sides of the chimney. A stub axle 112 projects horizontally from the lower end of one side 114 of the chimney and supports a rotatable, ground-engaging wheel 116.

A discharge chute 118 (omitted from Figure 8 in the interests of clarity of illustration) projects through an opening in the opposite side 120 of the chimney. The chute includes a collector portion 122 located beneath the basket 106 and is pivoted to the chimney at a horizontal pivot axis 124. The pivotal mounting of the chute allows it to swivel in a vertical plane as indicated by the arrow 126 in Figure 7.

Projecting from the side 120 of the chimney, at a position beneath the chute 118, is a support arm 128 including a clevis frame 130. A sleigh base 132 is mounted between the arms 134 of the clevis frame 130 as illustrated. The sleigh base 132 incorporates a bitumen distribution shoe including two members 136 which diverge from one another in a rearward direction as seen in Figure 8. The members 136 have outwardly flared upper walls 138 as seen in Figure 7 and are mounted on a base 140 which has a generally triangular opening matching the gap 142 between the members.

The embodiment of Figures 6 to 8 uses bitumen cartridges (not illustrated) in which a predetermined volume of cold, solid bitumen is supplied in a round cylindrical tin or other container which is dimensioned to fit into the bitumen slug holder 102 with an open end of the tin facing downwardly.

With the gas-fired heaters operational, heat is directed into the chimney 108 and moves upwardly in the chimney by convection. The heat softens the bitumen and allows it to slide out of the tin or other container into the basket 106. Continued application of heat by the heaters 110 melts the bitumen to a fluid state in which it can drop through the openings of the basket and into the collector portion 122 of the chute 118. The molten bitumen then flows along the chute which discharges it into the divergent gap 142 between the members 136 of the distribution shoe, the outwardly flaring nature of the upper walls 138 of the members facilitating the collection of the bitumen in the gap.

The apparatus 100 also includes a forwardly projecting handle 144 by means of which it can be pulled over the road surface, along the length of a crack 10 such as that seen in Figure 5. It will be appreciated that the apparatus is supported during towing movement by the wheel 116 and by the base 140.

The divergent nature of the members 136 of the distribution shoe ensures that the molten bitumen is spread evenly over the road surface, filling the crack 10 and covering the road surface for a limited distance on either side of the crack. The width of the bitumen coverage is determined by the lateral spacing of the members 136 at their rear ends. The bitumen solidifies on the road surface in and adjacent the crack, thereby repairing it.

An advantage of the embodiment of Figures 6 to 8 is the fact that as soon as the bitumen has softened and moved out of the tin or other container into the basket 106, the empty container can be extracted and replaced by another similar container accommodating a fresh slug of bitumen, thereby ensuring a continuous bitumen feed.

A further advantage is the pivotal nature of the chute 118. Upward pivoting of the chute, i.e. reducing the angle of inclination of the chute surface relative to the horizontal, reduces and can even stop the flow rate of the bitumen discharged by the chute. Thus the operator has a simple means for controlling the application rate of bitumen. By varying the inclination of the chute and varying the speed at which the apparatus is towed over the road surface, the operator is able to control the thickness of the bitumen application within close limits.

The apparatuses described above will, it is believed, be eminently suitable for repairing road surface cracks or any other appl ication where a molten substance is applied to a ground surface. It is also believed that the use of either apparatus as described will be substantially more econojnica3 to use than a conventional large volume heating vessel as described at the outset, particularly in relatively small-scale crack repair operations.

It will be appreciated that in either embodiment, the LP gas cylinder for supplying the heaters 20, 110 can be mounted on the apparatus itself. It also be appreciated that while specific reference has been made to bitumen as the sealant which is used to fill and repair cracks in a road surface, any other conventionally used sealant, such as pitch, tar or asphalt could also be used in either embodiment.