CA2249929A1

CA2249929A1 - Device for compacting

Info

Publication number: CA2249929A1
Application number: CA 2249929
Authority: CA
Inventors: Scott Milton
Original assignee: Individual
Current assignee: Individual
Priority date: 1998-09-25
Filing date: 1998-10-14
Publication date: 2000-03-25

Abstract

Disclosed herein is a device for compacting a road surface, comprising a plurality of load bearing wheels, each wheel being arranged to roll under a predetermined load along a corresponding longitudinal portion of the road surface, the load being sufficient to compact the road surface, wherein each of the wheels is capable of following the an uneven road profile, while maintaining contact with the road surface, so as to delivery the load thereto.

Description

DEVICE FOR COMPACTING
TECHNICAL FIELD
The present invention relates to devices and techniques for compacting road surfaces.
BACKGROUND ART
Though more and more urban roads are covered with pavement, most local rural roads remain as 'gravel' roads. Vehicle tires tend to shift the gravel causing bumps and potholes. Part of the maintenance of these roads during summer months involves grading the road with a scrapper which smooths off the bumps and randomly distributes the scraped gravel to lower regions on the road surface such as potholes and then is treated with a dust suppressant. With continuing budget cuts, local governments, till now, have not bothered to incur the additional cost of manpower and machinery to compress the gravel on the freshly graded road surface to a denser form. As a result, the fresh gravel is easily shifted again by vehicle tires. The loose gravel is also easily saturated by rain water causing dangerous driving conditions, and a loss of gravel through splashing of mud by vehicle tires and run oil' In those limited cases where these gravel roads are compacted, the compacting machines normally used carry out the compacting procedure with a steel drum, which has the tendency to ride on the already dense relatively higher areas of the road surface and not compress the relatively lower areas such as in potholes.
A gravel road surface which has been graded but not compacted can create hazardous visibility problems in view of blowing dust, hazardous driving conditions due to loose gravel, and a faster deteriorating road surface leading to pot holes, wash boarding, and wheel rutting.
It would be desirable to provide a technique to compact the road surface after it is graded, without the expense of having a separate vehicle.
It is therefore an object of the present invention to obviate or mitigate these disadvantages.
DISCLOSURE OF THE INVENTION
Briefly stated, the present invention involves a device for compacting a road surface, comprising a plurality of compression members, each being arranged to be displaced along a corresponding longitudinal path on said road surface and under a compacting load, wherein each of said compression members is capable of following an uneven road profile, while maintaining contact with said road surface, so as to deliver said compacting load thereto.
In another aspect of the present invention, there is provided a road grading vehicle comprising a motor-driven undercarriage supporting a road-scraping blade and a road-compacting assembly coupled with said undercarriage and trailing said blade, said road-compacting assembly including a number of compression members, each being arranged to deliver a compacting load to a road surface, each of said compression members being further arranged to follow the contour of said road substantially independent of the other compression members.
In still another aspect of the present invention, there is provided a device for use with a road grading vehicle comprising:
- a plurality of compression members to engage a road surface behind said vehicle along a road surface and under a compacting load, - a frame for carrying said compression members; and - displacement means for displacing said frame between an operative position with said compression members delivering said compacting load to said road surface and an inoperative position.
In yet a further aspect of the invention, there is provided a method for compacting a road surface, comprising the steps of - providing a plurality of compression members, - orienting each of said compression members to follow a longitudinal path on said road surface;
- delivering a compacting load on each of said compression members, and - arranging each of said compression members so that each is capable of following an uneven road profile, while maintaining contact with said road surface, so as to deliver said compacting load thereto.
BRIEF DESCRIPTION OF THE DRAWINGS
Several preferred embodiments of the present invention will now be described, by way of example only, with reference to the appended drawings in which:
Figure 1 is a perspective view of a road grading vehicle including a device for compacting;

Figure 2 is a perspective view of the device of figure 1;
Figure 3 is another perspective view of the device of figure I ;
Figure 4 is a side perspective view of the device of figure 1;
Figure 5 is a schematic view of one portion of the device of figure 1;
Figures 6, 7 and 8 are photographs of another device for compacting;
Figures 9a through 9c are schematic views of several devices for compacting.
Figure 10 is an exploded view of one portion of the device of figure 6; and Figure 11 is a side view of a road grading vehicle of figure 6.
BEST MODE FOR CARRYING OUT THE INVENTION
The term 'compacting load' refers to the forces or pressures being exerted by each of the compression members on the road surface, which are sufficient to cause the material on the road surface to be compacted to a reasonable.
As will be described below, there is provided a device shown at 10 for compacting a road surface having an uneven profile, comprising a plurality of compression members in the form of load bearing wheels 12, each wheel having a pneumatic tire and being arranged to roll along a corresponding longitudinal path of the road surface and under a compacting Ioad. As will be described, the compacting load may be, if desired, preset according to the road surface, so that the load is sufficient to compact the road surface, wherein each of the wheels is capable of following the uneven profile and maintaining contact with the road surface, so as to deliver the load thereto.
The pneumatic tire is particularly useful in the device 10 since it can assists in providing a relatively more even load or pressure over the area of the path the wheel follows and can better accommodate such things as small rocks and other obstructions, than with other compression members with inflexible or more rigid road-contacting surfaces. Nonetheless, there may be instances where more rigid road-contacting surfaces can nonetheless provide improved results over conventional techniques.
Examples include sliding pads or blocks or members having partial rolling capability.
The device has a frame means 14 for carrying the wheels, the frame being attachable to a road grading vehicle (also known as a 'grader').
A displacement means, in this case in the form of a pair of linear actuators, in this case hydraulic rams 18, are provided for displacing the frame between an operative position with the wheels in contact with the road surface, as shown in solid lines in the figure 3, and an inoperative position wherein the wheels are unable to deliver a compacting load to the road surface. In this latter case, the wheels are spaced from and above the road surface, as shown in dashed lines in figure 3. A plurality of suspension assemblies are provided as shown at 22, wherein each independently suspend a group of wheels, such as one or two wheels. In this case, each suspension assembly supports a pair of wheels, for example wheels 12a, 12b supported by suspension assemblies 22a as shown in figure 2.
The frame has a laterally oriented beam member 24 and each of the suspension assemblies, includes a spring arm arrangement 26 extending outwardly from the beam.
Each of the arm arrangements has a distal end region 26a and an axle member 28 is mounted on the distal end region, so as to form a pair of axle portions outwardly extending in opposing directions from each of the axle portions supporting a corresponding wheel. In this case, each suspension member includes a number of stacked leaf springs, wherein the longest thereof is secured to the axle portion at its distal end. In this case, the wheels are positioned parallel to one another and are spaced apart to allow the spring to be connected. The other end of the spring is secured to the frame. When assembled the tires are evenly spaced apart and in a substantially straight line. A pair of support members 30 extend outwardly from the beam member and each of the hydraulic rams is coupled to a corresponding one of the support members.
The frame means includes a harness assembly 36 fixed on the grader, and the hydraulic rams are mounted between the support arms and the harness assembly.
The harness is provided with pivot points allowing a frame to be raised or lowered by the two hydraulic rams or cylinders mounted parallel to each other on each side to the rear of the grader. One end of the frame, namely at the support arms, is pivoted to the harness, with another pivot location near a mid-point in the support arms, which is connected to the piston end of the ram. The barrel end of the ram is connected to a pivot point on the harness. When in use the tool will follow the path of the driven tool, the grader, compressing the loose gravel to a denser form by a controlled amount of pressure delivered through a valve to the cylinders.
As is shown in figure 5, the device also has a controller 50 for controlling the magnitude of the compacting load to be exerted by each of the wheels. In the case of the device 10, the controller works in conjunction with a hydraulic fluids source, in this case the hydraulic pump and reservoir 52, 54 on board the grader, a supply line 56 joining the source with the hydraulic rams as well as a return line 58 to return the fluids from the supply line to the source. The controller functions to control the amount of hydraulic fluids being delivered to the hydraulic rams. To do this, the controller has a monitoring means 60 for monitoring pressure in the supply line and a diverter means, in the form of a diverter valve 62 is responsive to the monitoring means for diverting hydraulic fluid from the supply line to the barrel end of the hydraulic ram via line 64 (in the case of extending the ram, as would be done, for instance to transfer the wheels to their operative position, according to a desired compacting load) and alternatively to the ram end as shown at 66 (for retracting the ram, as would be done, for instance to transfer the wheels to their inoperative position). The monitoring means is also operable to maintain the pressure in the supply line below a predetermined maximum value and above a predetermined minimum value, for reasons to be explained. The controller also has a switch, for example a three position toggle switch as shown at 68, which can be mounted in the cab of the grader and provide a first position 'A', corresponding to the inoperative position, a second position 'B' corresponding to the operative position and a central 'neutral' position 'C', corresponding to a 'operation constant' position.
A compacting load adjustment means is also provided which is in communication with the diverter means for adjusting the compacting load, the adjustment means including a solenoid 72 for actuating the diverter and a power adjustment unit 74 for adjusting power being delivered to the solenoid. In this case, the adjustment means may be provided in the form of an adjustable scale, such as a linear or rotary scale, which can be placed adjacent the control switch.
In one mode, the control unit thus functions to direct a predetermined portion of the hydraulic fluid from the supply line to the barrel end of the hydraulic rams. The greater the pressure to be exerted, or the greater the displacement of the ram, the greater the quantity of fluid to be diverted. The magnitude of the compacting force will be related to the pressure in the ram multiplied by the operative cross sectional area of the ram, multiplied by the number of hydraulic rams (in this case two) and divided by the number of wheels. The compacting force will of course depend on the geometry of the support arms and the suspension assemblies. The pressure being exerted by each wheel will thus equal the force being exerted by the wheel over area of the 'foot print' of the wheel on the road surface.

The device functions as follows. First, assuming the device is in its a position with the wheels resting on the ground surface, the operator activates the hydraulic system causing pressure to be established in the supply line. The operator then toggles the switch from its neutral position to its 'inoperative' position, which in this case causes the diverter to redirect hydraulic fluid from the supply line to the ram end of the hydraulic rams, in this case causing the rams to retract and bring the wheels to their inoperative position. The operator may then proceed to a particular road surface, select the compacting load to be delivered by the wheels, that is by adjusting the rotary dial, and then transferring the toggle switch to its first position, causing the diverter to divert fluids to the barrel end of the ram, thereby causing it to be extended and thus bringing the wheels to their operative position. The monitoring means functions to bring the wheels to within a predetermined range of compacting load as represented, say, by a range of pressures being present in the supply line, say to within a few percent, or more or less depending on the sensitivity required. The operator may then operate the grader in the normal fashion, meanwhile causing the wheels to roll, under load, along their respective longitudinal paths and compacting the road surface as a result. The degree of the compacting can of course depend on the magnitude of the compacting load and the number of passes of the wheels along the road surface.
Figure 9a) shows, schematically, four groups of two wheels each on a relatively flat road surface. Figure 9b) shows, schematically, eight groups of one wheel each, that is each independently suspended along and, in this case, traveling over a relatively irregular road surface. Figure 9c) shows, schematically, four groups of two wheels each, traveling over a relatively irregular road surface. This case be seen by a combination of the torsional rotation of the suspension along with varying degrees of vertical translation of each axle relatively to the others.
Although, the spring assemblies in the device 10 support a pair of wheels, they nonetheless allow the wheels to follow the road contour in a substantially independent manner, since the spring assemblies have a torsional and vertical resiliency, as shown by arrows Rt and Rv in figure 3. Of course, this independence can be enhanced by providing a suspension assembly for each individual wheel, if desired. Should the wheels encounter a substantial obstruction, such as a large rut or hump, or should the vehicle pass over a relatively sharp or pronounced crest or valley in the road surface, the wheels may in fact cause a momentary change or fluctuation in the pressure in the supply lines.
In this case, the monitoring means detects the pressure change and, should the change exceed the predetermined range of allowable fluctuations, the monitoring means communicates with the diverter to adjust the quantity of hydraulic fluid being present in the supply line accordingly.
A particular feature of the control system is that the hydraulic fluid is constantly flowing through the supply line and the return line, the proportion actually being returned to the reservoir depending on the particular operating phase of the device.
This allows the controller to constantly monitor and tailor the position of the wheels and the compacting loads exerted thereby on the road surface.
The device is useful in that it is able to utilize the weight of the grader to, in effect, pre-load the suspension assemblies, thereby increasing the applied pressure, and thus the compacting load, to the gravel on the road surface. The device may have an extension to be used for a wider area to be rolled. The device also utilizes the grader's hydraulic system to supply to the valve pressure, and thus the compacting load to the wheels, by action of the hydraulic rams. The valve is controlled from within the cab of the grader by means of a switch and a control knob.
Thus, when used with a grader, the device 10 provides a modified road grading comprising a motor-driven undercarriage supporting a road-scraping blade and a road-compacting assembly coupled with said undercarriage and trailing said blade, said road-compacting assembly including a number of compression members, each being arranged to deliver a compacting load to a road surface, each of said compression members being further arranged to follow the contour of said road substantially independent of the other compression members.
It will be seen that, in the case of device 10, the wheels have collinear rolling axes and are independently mounted on the frame and with substantially collinear axes in the operative position shown in figure 9a. The frame is movable relative to the undercarriage in order to adjust the compressive force, the higher the force, the greater its ability of compressing loose gravel or dirt to a higher density, thereby to lengthen the useful life of a road between repairs.
Referring to figures 7 to 10, there is provided another device shown at 100 for compacting a road surface having an uneven profile, comprising a plurality of compression members in the form of load bearing wheels 112 carried by a frame means 14, the frame being attachable to a grader. A displacement means, in this case in the form of a pair of linear actuators, in this case hydraulic rams 118, are provided for displacing the frame between an operative position with the wheels in contact with the road surface and an inoperative position wherein the wheels are unable to deliver a compacting load to the road surface, the inoperative position being one wherein the wheels are spaced from the road surface as shown by figure 7. As with the earlier device 10, a plurality of suspension assemblies are provided as shown at 122, wherein each independently suspend a group of wheels, such as one or two wheels, again in this case two wheels 112a, 112b supported by suspension assemblies 22a as shown in figure 6.
The frame has a laterally oriented beam member 124 and each of the suspension assemblies, includes a spring arm arrangement 126 extending outwardly from the beam.
Each of the arm arrangements has a distal end region 126a and an axle member 128 is mounted on the distal end region, so as to form a pair of axle portions outwardly extending in opposing directions from each of the axle portions supporting a corresponding wheel.
The detail of the suspension members is shown in figure 9 and includes a number of stacked spring plates 126b held at one end by a ring clamp 126c which includes a pair of U-bolts 126d and mating nuts 126e, themselves engaging a base plate 126f.
The distal end 126a of the longest of the plates has mounted thereon another ring clamp 127 to embrace the axle portion 128 and is similar in construction to the ring clamp 126c, apart from the use of a central bolt 127a extending through the spring plate to secure the clamp 127 in position. The piston end of each of the two hydraulic rams 118 are pivoted to a flange shown at 114a which is welded to the upper face of the frame member.
The devices are believed to be particularly useful because the series of load-bearing compression members, preferably wheels, more preferably with pneumatic tires, follow the grader while grading a road. During use, the grader will be driven over the road surface a number of times to provide an optimum profile. This allows the wheels to run into the pot-holes and wheel ruts many times, thereby improving the compression of the road surface, particularly in these depressions, still further. It is believed that the use of the device will greatly increase the span between road grading treatments and will decrease the need for dust suppressants, while still achieving a longer lasting road surface and decreasing the negative effects on the environment. It could be said that the device is an 'environmentally friendly' tool.
While the above embodiments make use of compression members in the form of load bearing wheels, it will be understood that other wheels can also be used including those filled with other fluids such a water for are solid wheels, for example.
In addition, compression members may also be used such as rollers, or load bearing skid pads that are arranged to slide along the road surface. In addition, other suspension arrangements are envisaged for supporting the wheels such as in the use of other springs such as compression springs, pneumatic bladders or other arrangements which allow each of the compression members to follow the contour of the road substantially independent of the others.
Thus, the device provides an attachment which can be secured to the rear of a grader. It may be hydraulically operated by two cylinders in order to raise or lower it to the ground, or alternatively operated with pneumatic or electrical circuits instead of the hydraulic circuit above mentioned. The device 10 is compact and uses the weight of the grader to pre-load springs connected to tires which roll the road surface to a higher density. Also the amount of weight applied to the device can be adjusted simply by the turn of a dial. In addition, while the device 10 makes use of a controller capable of controlling the compacting load, other controllers are contemplated which do not necessarily do so, including those used in standard hydraulic, pneumatic and electronic control systems.
When used with a grader, the device allows for the compaction of gravel roads to be carried out simultaneously while being graded. Among its advantages, the device 10 can be relatively easy to operate and be used the same time the grader is being operated.
The device can have relatively low maintenance costs, and can be made to attach easily to the grader.
The device can in some cases be made to be compact, easy to use, cost effective, require relatively little maintenance. Furthermore, the device may be configured to rely on the hydraulic system on the grader in order to operate it between its operative and inoperative positions, thereby to achieve the compaction necessary for improving the life of gradable road surfaces. The device can be made to be relatively adaptable to fit a number of different models of grader and can be made with relatively accessible materials.
It is also believed that there may be some road surfaces where the device 10 may not be as useful as in others. For example, the device may not show significant results when used on roads covered with larger aggregate such as that known colloquially as "rip rap".
While the device 10 is movable to an inoperative position which is characterized by the compression members actually being physically spaced from the road surface, there are other positions available for the compression members which can be considered to be inoperative, such as the position where the wheels are still in contact with the road surface, but are essentially 'floating' on the road surface because the load being exerted on them is essentially zero, or nonzero but still clearly not sufficient to compact the road surface by any reasonable measure.

Claims

1. A device for compacting a road surface, comprising a plurality of compression members, each being arranged to be displaced along a corresponding longitudinal path on said road surface and under a compacting load, wherein each of said compression members is capable of following an uneven road profile, while maintaining contact with said road surface, so as to deliver said compacting load thereto.

2. A device as defined in claim 1, wherein each of said compression members is a wheel.

3. A device as defined in claim 1 wherein each of said wheels includes a pneumatic tire.

4. A device as defined in claim 2, further comprising frame means for carrying said wheels, said frame means being attachable to a road grading vehicle.

5. A device as defined in claim 4, further comprising displacement means for displacing said frame means between an operative position and an inoperative position.

6. A device as defined in claim 5 wherein said wheels are spaced from said road surface in said inoperative position.

7. A device as defined in claim 5, further comprising a plurality of suspension assemblies, each for suspending a group of wheels.

8. A device as defined in claim 7 wherein each group includes one or two wheels.

9. A device as defined in claim 7 wherein said frame means further comprises a laterally oriented beam member, each of said suspension assemblies further comprising a spring arm expending outwardly from said beam member.

10. A device as defined in claim 9, wherein each of said arms has a distal end region, further comprising a pair of axle portions outwardly extending from opposing sides of said distal end region, each of said axle portions supporting a corresponding wheel.

11. A device as defined in claim 10 further comprising a pair of support members extending outwardly from said beam member, said displacement means further comprising a pair of linear actuator assembles, each of which is coupled to a corresponding one of said support members.

12. A device as defined in claim 11 wherein said frame means includes a harness assembly for attachment to said road grading vehicle, said linear actuator assemblies being mounted between said support arms and said harness assembly.

13. A device as defined in claim 12 wherein said linear actuator assemblies are hydraulic rams.

14. A road grading vehicle comprising a motor-driven undercarriage supporting a road-scraping blade and a road-compacting assembly coupled with said undercarriage and trailing said blade, said road-compacting assembly including a number of compression members, each being arranged to deliver a compacting load to a road surface, each of said compression members being further arranged to follow the contour of said road substantially independent of the other compression members.

15. A vehicle as defined in claim 14 wherein said compression members include wheels having collinear rolling axes.

16. A vehicle as defined in claim 15 wherein said wheels are independently mounted on a frame which is movable relative to said undercarriage in order to adjust said compacting load.

17. A device for use with a road grading vehicle comprising:
- a plurality of compression members to engage a road surface behind said vehicle along a road surface and under a compacting load, - a frame for carrying said compression members; and - displacement means for displacing said frame between an operative position with said compression members delivering said compacting load to said road surface and an inoperative position.

18. A device as defined in claim 17 wherein said compression members are spaced from said road surface in said inoperative position.

19. A device as defined in claim 18 wherein said compression members are wheels.

20. A device as defined in claim 19, wherein said displacement means further comprises control means for controlling the magnitude of said compacting load.

21. A device as defined in claim 20 wherein said displacement means includes at least one hydraulic ram, an hydraulic fluids source and a supply line joining said source with said at least one hydraulic ram for delivering hydraulic fluid thereto.

22. A device as defined in claim 21 wherein said control means further includes monitoring means for monitoring pressure in said supply line.

23. A device as defined in claim 22, further comprising a return line for returning recirculating hydraulic fluid from said supply line to said source, and diverter means responsive to said monitoring means for diverting hydraulic fluid from said return line to said hydraulic ram, according to a desired compacting load.

24. A device as defined in claim 23 wherein said monitoring means is operable to maintain said pressure below a predetermined maximum value.

25. A device as defined in claim 24 wherein said monitoring means is operable to maintain said pressure above a predetermined minimum value.

26. A device as defined in claim 23 further comprising adjustment means in communication with said diverter means for adjusting said compacting load, said adjustment means including a solenoid for actuating said diverter and a power adjustment unit for adjusting power being delivered to said solenoid.

27. A method for compacting a road surface, comprising the steps of - providing a plurality of compression members, - orienting each of said compression members to follow a longitudinal path on said road surface;
- delivering a compacting load on each of said compression members, and - arranging each of said compression members so that each is capable of following an uneven road profile, while maintaining contact with said road surface, so as to deliver said compacting load thereto.