Vibrating Comb Structure For A Road Surface Layer

Abstract

The comb structure is adaptable to different road surface layers and is easily mounted on any type of road finisher. It comprises two articulated girders in end-to-end relation and movable together along their axes. A transmission system having two eccentric rollers imparts to the girders two reciprocating movements of different frequences which are superimposed on each other. Each girder carries a comb carrier which is adjustable in height and in inclination and carries a comb having teeth which rake the road surface layer.

Description

Most roads are constructed in a satisfactory manner by means of an evenly spread composition based on bitumen admixed with gravel. However, when there is required a road surface having enhanced antiskid qualities, for example on bridges and in bends, it is necessary to make the gravel project to a greater extent so as to inpart increased roughness to the surface layer. This is achieved in an effective manner by employing a composition including more bitumen and raking the gravel immediately after spreading the composition. There is then employed a special road surface finisher provided with a vibrating comb which causes the sharp face of the gravel to project.

Unfortunately this procedure is costly since it requires several types of finisher in accordance with the surface layer to be produced.

An object of the present invention is to avoid this drawback by providing a comb structure whose movements and adjustment are controlled independently and which can therefore be easily mounted on all types of existing finishers and may be removed when the finisher must be employed alone.

The invention provides a vibrating comb structure for a road surfacing machine and comprising a frame, combined with means rigidly fixing the frame to a road surface finisher or like machine and with slideways supporting two girders which are in articulated end-to-end relation but movable together along their longitudinal axes, a comb carrier mounted on each one of the girders, a motor secured to the frame and a system including eccentric rollers for converting the movement of rotation of the motor into two simultaneous reciprocating movements of the girders along the slideways.

In said system, one eccentric roller makes it possible to add to a first movement of vibration produced by a second eccentric roller a second movement which has a different amplitude and frequency and which is combined with the first movement. The two movements may be produced simultaneously or independently so as to impart to the surface layer different appearances while maintaining the qualities of roughness. Means for regulating the position of the comb carrier with respect to the girders and means for varying the inclination of the teeth of the comb are advantageously mounted on the girders.

The comb thus undergoes a vibratory movment transverse to the direction of displacement of the finisher and moreover has a position which is adjustable in height with respect to the road surface layer so that the teeth penetrate to the desired depth into the layer. The adjustment of the inclination of the teeth completes the precision of the work effected and ensures that the gravel is raked to a well determined depth so as to impart to the road surface the required antiskid features.

However, the presence of all these controls entails no modification in the finisher itself which merely supports the comb structure for moving over the road surface as the surface layer is being spread.

Further features and advantages of the invention will be apparent from the ensuing description with reference to the accompanying drawings.

In the drawings:

FIG. 1 is a diagrammatic side elevational view of a vibrating comb structure mounted on a road surface finisher;

FIG. 2 is a front elevational view of the comb structure shown in FIG. 1;

FIG. 3 is a plan view of the comb structure and of the control circuit controlling its reciprocating movement;

FIG. 4 is a perspective view, to an enlarged scale, of the centre part of the comb structure showing the various adjusting systems;

FIG. 5 is an enlarged view, with a part cut away, of the right part of the comb structure shown in FIG. 2, and

FIG. 6 is a front elevational view of the part of the comb structure shown in FIG. 5 showing the system controlling the inclination of the comb teeth .

Road surface layers are usually spread by means of a finisher or like machine which usually comprises a vehicle 1 carrying a hopper filled with a surface layer composition and means for spreading this composition which are shown very diagrammatically in FIG. 1. Mounted at the rear of this vehicle is a comb structure 2 adapted to rake the road surface and spread the gravel.

According to the invention, this comb structure is supported by an adaptor plate or frame 3 fixed to the rear of the finisher vehicle 1 in a position transverse to the direction of displacement of the latter, preferably by bolting to angle irons which are permanently fixed to the platform or base 5 or the finisher. This comb structure is in two parts and includes two girders 4 and 6 which have a square or like section (FIG. 2) and are mounted in end-to-end relation and interconnected by an articulation 7 which ensures that they move together in the direction of their lengths parallel to the plate 3 but allows them to become out of alignment in the vertical plane. Each of these girders 4 and 6 supports a half-comb 18 and 20 provided with teeth which are parallel to each other and are inclined with respect to the surface of the road. The girders are supported by the plate 3 through slideways 8, two of which are provided for each girder in the embodiment shown in the Figures. Each slideway 8 comprises (FIG. 3) two horizontal pins 10 and 12 mounted between two L-shaped members 14 which are fixed to be perpendicular to the plate 3 by one arm of the L-shaped members 8. Mounted on each pin 10, 12 is a sleeve 16, 17 (FIG. 6) which is integral with one of the sides of the girder 4,6 and has a bore whose diameter is such that it is freely slidable on the pin 10, 12, this movement being solely limited by the length of the pins between the members 14.

The two girders may therefore undergo a reciprocating movement in a direction perpendicular to the displacement of the finisher and are movable with respect to the plate 3 independently of the movement of the finisher.

The half-combs 18 and 20 are fast with the girders 4 and 6 as concerns their movements on the slideway 8. Indeed, fixed to each of the girders 4 and 6, as shown in FIGS. 2 and 4, are two girder members 22 which are perpendicular to the corresponding girder and a guide 24 is mounted on these girder member. The guide 24 is constituted by two parallel blocks 25 which are interconnected in their upper and lower parts by two parallel plates 26 and 28. The plate 28 has extending therethrough a vertical screw 30 which is prevented from moving axially in two opposite walls of the girder 22 but is rotatable with respect to these walls and with respect to a fixed nut 32 carried by the plate 28. Rotation of the screw 30, for example by means of a crank 34, causes the guide 24 to slide on the girder member 22 and permits a variation in the position of the guide 24 in height with respect to the girder 4. On each girder, the guides 24 have on their confronting faces bearings 36, 37 in which is journalled a spindle 38 which carries, through two pairs of rigid arms 40, a half-comb 20 or 18. Displacement of the guides 24 causes the displacement of the spindle 38 and adjusts the position of the corresponding half-comb in height with respect to the corresponding girder.

Each half-comb 20 or 18 is constituted by two L-section members 41, 43 (FIGS. 4 and 6) which are fixed in back-to-back relation and carry a plate 42 carrying the series of teeth 44 and 46 which are symmetrical with respect to the plane of assembly of the two L-section members.

The member 43, which is the nearer to the girder 4 or 6, is integral with the pair of arms 40 and consequently with the spindle 38. However, each of the arms 40 is provided with an aperture 48 into which extends a pin 50. The two pins 50 cooperate with the apertures 48 in the arms of the same pair and are integral with the end 52 of a screw-threaded rod 54 which extends through an extension portion 29 of the upper plate 28 of the guide 24 and is maintained above this plate by a nut 56 which is held axially in position but is rotatable with respect to the plate 29 (FIGS. 5 and 6).

A crank or any other system (not shown), which may be manual or automatic, rotates the nut 56 and thus causes the rod 54 to move with respect to the nut 56 and shifts the pins 50 in the apertures 48. This displacement causes the arms 40 to pivot and also causes the spindle 38 to rotate in the bearings 36 and 37. The members 41 and 43 also pivot. The inclination of the plate 42 and consequently of the series of teeth 44 and 46 with respect to the girder 4 or the direction of displacement of the finisher is thus modified.

Owing to the conbination of the guides 24 whereby it is possible to regulate the height of the teeth of the comb and the pivoting arms 40 which permits modifying the inclination of the teeth, it is possible to cause the comb to penetrate exactly to the desired depth in accordance with the type of surface layer and in particular in accordance with the grain size of the gravel particles.

In the course of spreading, the comb, which has just been adjusted, must be made to undergo a vibrating movement which is superimposed on the displacement of the finisher. This movement is obtained by means of a motor 60 (FIG. 3) which is mounted above the plate 3 on a frame fixed to the machine 1. This motor drives through a speed-reducing device 62 a shaft 64 which is perpendicular to the girders 4 and 6 and on which is mounted in an eccentric manner a roller 66 (FIGS. 3 and 4). The roller 66 rotates with the shaft 64 and moves inside a fork or, in the illustrated embodiment, a rectangular frame 68 whose two vertical walls are always in contact with the roller. The frame 68 is supported by one, or preferably two, rods 70 which are freely slidable in a support 72 integral with one of the girders, for example, in the presently-described embodiment, the girder 4 supporting the half-comb 18. The height of the frame 68 is moreover sufficient to permit its upper and lower walls to be at a slight distance from the roller irrespective of the angular position of the latter.

On the other side of the support 72, the rods 70 are fixed to a second frame 74 which is similar to the frame 68 and, in the same way as the frame 68, is in contact by its vertical walls with two diametrally opposed points of an eccentric roller 76 which is rotated by a shaft 78 parallel to the shaft 64. The shaft 78 is rotatable in two plates 80 fixed to the girder 4 and it transmits to this girder the longitudinal movement produced by the rotation of the roller 66 so that this girder slides along the slideways 8.

The shaft 78 is connected through a speed-reducing device 90 to a hydraulic motor 82 which drives it in rotation. The motor 82 is fed with fluid through a flow regulator 84 and a hydraulic distributor 86, by a pump 88 associated with a fluid tank 89, the fluid being, for example, oil. the pump 88 is driven by the motor 60 driving the roller 66. The speed-reducing device 90, interposed between the hydraulic motor 82 and the roller 76, enables the rotational speed of this roller to be reduced. The speed of rotation of the roller 76 is regulated by means of the flow regulator 84.

The size of the roller 66, as the size of the roller 76, is so chosen that its eccentricity is less than the length of the spindles 10 and 12 between the plates 14 of the slideways 8. Consequently, when the roller 66 is rotated by the motor 60, it drives the frame 68, guided by the rods 70, in a reciprocating movement perpendicular to the direction of displacement of the machine 1. This movement is transmitted to the shaft 78 and the plates 80 through the girder 4 which moves along the corresponding slideways 8. The girder 6 is also driven in this movement owing to the effect of the articulation or hooking system 7 which renders the girders interconnected as concerns longitudinal movements. The teeth 46 of the comb rake the surface layer in paths in the form of narrow lines such as those shown at A in FIG. 4.

When the hydraulic motor 82 is also operating, it being brought into operation or stopped by means of the distributor 86, the roller 76 imparts to the frame 74, which already undergoes a reciprocating movement produced by the roller 66, a second reciprocating movement which is also perpendicular to the direction of displacement of the finisher. This second movement has preferably a frequency and amplitude which are distinctly different from those of the first movement and are super-imposed thereon so that the teeth 46 supported by the girders rake the surface layer by forming herring-bone shaped lines such as those shown at B in FIG. 4.

The amplitude of these herring-bone shaped lines may be easily adjusted by modifying the speed of rotation of the shaft 64 and/or shaft 78 by acting on the speed of rotation of the motor 60 or on the flow regulator 84.

Preferably, the member 41 of each half-comb carries a tube 92 which is held in position by fins 93 and provided with a longitudinal slot 94. One end of the tube is associated with a burner (not shown in the drawing) which is supplied with a source of gas or like fuel. The tube 92 thus performs the function of a heating jet for the teeth of the comb, hot gases issuing from the burner by way of the slot 94 along the tube 92 so as to heat the comb teeth 46.

The comb is adapted to the effective or working width of the finisher by the addition of extension elements to a width of construction identical to the comb support 18 or 20. The lengths of these elements are in accordance with the dimensions of the standard extra width elements equipping any type of finisher. These extra width elements are fixed by bolting to the end of the comb 18 and/or 20.

Thus it is possible to cause the gravel particles to project to the desired height owing to the penetration of the teeth, this penetration being optionally facilitated by the heating of the comb teeth.

The vibrating comb structure is entirely independent since its movement of reciprocation is produced by a drive system independent of the finisher. Moreover, the adjustment in height of the comb teeth and the adjustment of their inclination are not dependent on the construction of the finisher. The whole of the comb structure may therefore be easily adapted to different types of finisher or like machine, the adaptor plate 3 being in an appropriate form depending on the machine to which it is fixed.

In some cases, for example, the comb structure may be secured directly to the platform of the finisher with no special members.

The comb structure may be removed when necessary so as to facilatate its servicing and the servicing of the finisher.

Various modifications may be of course made to the comb structure just described. In particular the plate 3 may support between the slideways 8 L-section members supporting silent blocks or like elastic systems which affords a flexible connection between the girders 4 and 6 and facilitates the sliding of the girders.

Moreover, the cranks or handles 34 controlling the vertical position of the combs may be connected in pairs so as to ensure that the displacement of each half-comb is strictly parallel to itself. The eccentric rollers 66 and 76 may be similar or have diameters or eccentricities which are different, depending on the desired amplitudes of movement.

The plate 42 carrying the teeth 44 and 46 is fixed to the members 41 and 43 in any suitable manner which enables it to be easily removed, for example to permit turning it round after use of one series of teeth 46 and using the second series of teeth 44.

The comb assembly with its motor and its transmission means may be constructed on a second platform which is independent of the finisher and is articulated to the rear of the latter so as to be towed along.

This second platform is merely disposed on the coating, all the other previously described means being retained.

Claims

Having now described our invention what we claim as new and desire to secure by Letters Patent is:

1. A vibrating comb structure for a road surfacing machine and comprising a frame for connecting to a road surface finisher or like machine, slideways carried by the frame, two girders slidably mounted on the slideways, means for articulating the girders in end-to-end relation so that they are movable together along their longitudinal axes, a comb carrier mounted on each one of the girders, a comb carried by each carrier, a motor secured to the frame and having a rotary output shaft, and a transmission system for converting the movement of rotation of the motor output shaft into two simultaneous reciprocating movements of the girders along the slideways.

2. A comb structure as claimed in claim 1, wherein each comb carrier comprises two members carried by each girder and substantially perpendicular to the corresponding girder, a guide substantially vertically slidable on each member, a half-comb being carried by each guide and means for controlling said sliding and adjusting the vertical position of said guide and the associated half-comb.

3. A comb structure as claimed in claim 2, comprising for supporting each half-comb on the guides two bearings integral with the guides, a spindle rotatable in the bearings and means for adjusting the angular position of said spindle in said bearings.

4. A comb structure as claimed in claim 3, wherein each comb carrier is integral with two pairs of parallel arms integral with the rotatable spindle and defining apertures for the passage of a spin shifted by a screw-and-nut device controlling the inclination of said arms and therefore the inclination of the teeth of the comb.

5. A comb structure as claimed in claim 4, wherein each comb carrier comprises two L-section members parallel to the girder and in back-to-back relation to each other, a plate mounted on the L-section members and two rows of teeth on the plate.

6. A comb structure as claimed in claim 1, wherein each comb carrier comprises two L-section members parallel to the girder and in back-to-back relation to each other, a plate mounted on the L-section members and two rows of teeth on the plate.

7. A comb structure as claimed in claim 1, comprising alongside each comb carrier a system for heating the teeth of the comb.

8. A comb structure as claimed in claim 1, comprising extension elements mounted relative to the girders whereby it is possible to adapt the comb structure to different working widths of one or of various finishers.

9. A vibrating comb structure for a road surfacing machine and comprising a frame for connecting to a road surface finisher or like machine, slideways carried by the frame, two girders slidably mounted on the slideways, means for articulating the girders in end-to-end relation so that they are movable together along their longitudinal axes, a comb carrier mounted on each one of the girders, a comb carried by each carrier, a motor secured to the frame and having a rotary output shaft, and a transmission system including eccentric rollers for converting the movement of rotation of the motor output shaft into two simultaneous reciprocating movements of the girders along the slideways.

10. A comb structure as claimed in claim 9, wherein the eccentric roller system comprises a first eccentric roller, a first rotatable shaft carrying the first roller and perpendicular to the girders, means for operatively connecting the first roller to one of the girders through a second of said eccentric rollers, a second shaft carrying the second roller, the second shaft being only rotatable and carried by the girder, the two rollers being adapted to produce reciprocations at different frequencies which are superimposed.

11. A comb structure as claimed in claim 10, wherein the same girder carries the second shaft and a support, said connecting means comprising sliding rods slidable in the support and means defining two pairs of rubbing surfaces interconnected by the rods, each pair of rubbing surfaces being co-operative with one of the two rollers.

12. A comb structure as claimed in claim 11, comprising a hydraulic motor, connected to drive the second eccentric roller, and a pump, the motor secured to the frame driving the first eccentric roller and being connected to drive the pump.

13. A comb structure as claimed in claim 9, wherein means are provided for selectively actuating the two eccentric rollers independently and simultaneously.