US3066582A - Road surfacing - Google Patents

Description

E. F. CUTLER ROAD SURFACING Dec. 4, 1962 4 Sheets-Sheet 1 Filed Dec. '7, 1959 E. F. CUTLER ROAD SURFACING Dec. 4, 1962 4 Sheets-Sheet 2 Filed Dec. 7, 1959 E. F. CUTLER ROAD SURFACING Dec. 4, 1962 Dec. 4, 1962 E cu 3,066,582

ROAD SURFACING Filed Dec. '7, 1959 4 Sheets-Sheet 4 aesassz ROAD SURFACING Earl F. Cutler, 8401 W. 119th t, lalos Park, llll. Filed Dec. 7, 1959, Ser. No. $557,613 7 Claims. (6i. 9439) Asphalt concrete pavement is used as a riding surface in various types of highway construction. Its outstanding serviceablility under a wide variety of weather and traffic conditions have made it one of the dominant types of riding surface for modern traffic. Well made asphalt concrete can undergo greater distortion in service without going to pieces than any other generally used riding surface.

One of the most valuable features of asphaltic concrete is the facility with which it can be reheated and remolded to its original smoothness. This very property also allows defects to form in the riding surface. The common failures of asphalt concrete pavement known to the highway maintenance engineer can be classified in five general classifications: 1) corrugations, or ripple; (2) expansion humps; (3) potholes; (4) longitudinal cracks; (5) transverse cracks.

According to the invention, any asphalt concrete pavement may be quickly and permanently reconditioned by combining, in proper relationship to each other, three operations: heating, levelling and compaction.

Heat is directed to the pavement by oil burners so regulated that a nonxidizing flame is maintained.

This flame pattern bathes the riding surface and flows through a heavy grid roller, which subdivides the flame into a multiplicity of different paths channeled against the top of the pavement to be heated. During this process the heated grid roller absorbs short wave radiant heat from the flame and in turn radiates this stored radiant energy at lower frequencies into the black surface of the asphaltic concrete pavement. A fire chamber encloses the flame, and its heavy refractory lining also absorbs radiation and sensible heat from the flame and emits the absorbed energy at longer wave lengths.

The flanges of the roller massage the softening surface on which they ride into longitudinal grooves. in so doing they deliver heat by direct conduction to the material in contact with them, as well as mechanically dispersing the heat already in the material by the mixing and kneading action.

Heated compaction rollers in front and behind the fire chamber move with it longitudinally along the pavement and flatten out the striations made by the grid roller. This adds another increment of heat and of mixing and leaves a fiat surface for the fire chamber and grid roller to work on in the next pass.

In operation, this entire heating, massaging and compacting procedure is carried on repeatedly, in a forward and backward operational motion so that the intense heat is only in contact with a given area of the asphaltic pavement for a short period of time. The combination of direct flame contact, radiant heat, conducted heat from the grid roller, and conducted heat from the compaction rollers, makes up all the heating of a thin top layer of the asphaltic concrete aggregate. This heated layer, in turn, transfers heat by conduction, slowly but continuously, down to the lower layers of the pavement. In this manner I am able to heat the asphaltic pavement mat through and through without at any time raising the surface temperature beyond a normal safe limit of approximately 300 P. which is the ideal working temperature selected by asphaltic concrete experts throughout the country.

The levelling of the surface of the asphaltic concrete pavement is accomplished by a shaving action similar assassa Patented lif ers. 4, 1962;

to that of a large smoothing plane in the hands of an experienced carpenter. A small amount of material is bladed off the high spots in each successive pass or stroke, of the machine. Since both the high spots and the low spots of the pavement are heated, hot material bladed from the high spots is deposited in the low spots of the riding surface. Since they are combined while they are both hot, a vulcanizing eflect takes place which fills in the depressions with excess material shaved from the hump, and gets as good a bonding throughout the mass as in a new construction. Tln's material is also constantly compacted by the repeated passes of the machine. Fnrther levelling action is accomplished by use of a second, levelling blade which is longitudinally spaced from the shaving blade. In this manner a mass of hot mix asphalt is piled up by the shaving blade. It is shoved forward and deposits itself by gravity in the depressions and valleys of the worn pavement. When the machine reverses itself, the second blade comes into action and moves any excess material above the shaving level in a backward motion to spread a layer approximately /4" thick over the surface of the road area being worked. This kneading of the loose hot mix serves to recoat the granules with asphalt cement and produces a satisfactory paving material.

Heating, levelling and compaction operations are carried on almost simultaneously on each pass, with a short interval before the next pass to let the temperature gradients level out a little by conduction.

In the accompanying drawings:

FIGURE 1 is a plan view of a complete unit according to the invention;

FIGURE 2 is a perspective of the forward portion or" the machine, with some of the rear parts omitted for clearness;

FEGURE 3 is a fragmentary perspective of the heating chamber and grooving roller and parts receiving heat therefrom, substantially in the direction of the arrow 3-3 in FIGURE 1;

FIGURE 4 is a side elevation of the complete unit; and

FIGURES 5 to 13, inclusive, are diagrams indicating successive stages of the process of reforming a defective road surface.

In the embodiment selected to illustrate apparatus ac cording to the invention, the unit has a frame comprising side channels it) braced at suitable intervals by cross pieces, such as the front cross piece 12 and rear cross piece shown in dotted lines in FIGURE 4 at 14. At the front end of the frame, standards 15 extend downwardly to carry the ends of a transverse axle 17 carrying front wheels 16 each freely and independently rotatable on the front axle. At the rear end the weight is carried by a central roller 18 journaled in downwardly extending arms 2%) at the ends of a transverse cross piece 22. The cross piece 22 has a central pivot at 24 extending upwardly. Steering is by rotating the cross piece 22 and rear roller 18 about the axis of the pivot 24 Main Heat Supply The fire chamber 26 is defined at the rear end and along both sides by a refractory housing having a flat top 28 and side walls 34 extending down close to the pavement level and protected against abrasion by metal shoes 30. There is no transverse wall in front.

At the rear, five flame guns 32 deliver fuel into inlet ports 34 to fill the entire chamber substantially full of incandescent flame, at least as far forward as the grooving roller 36. This roller turns as an idler on a shaft 32% and carries a series of discs 40, 24" in diameter and spaced at 3 intervals axially. The discs are 1" thick, which leaves a 2" space between them. The hub on which the speassa discs are mounted is about 8" in diameter. Thus, when the discs do not sink in, there is a flame passage 2" wide and 8" high between each pair of discs, but usually the discs ride about 1" below the surface level, with the material between them extruded up 1. This still leaves a passage 2 by 7" for the products of combustion, and gives the top 1" of road mat a thorough kneading on each pass. As the material gets softer, the depth of the kneading action increases.

The ends of the shaft 33 float in guide blocks 42 (see FIGURE 4), which slide up and down freely in guides 44. The grooving assembly weighs about two tons and it will follow the contour of the pavement, except for pot holes or other depressions so small in transverse dimension that other portions of the roller bear on the pavement beside the depression enough to carry the weight.

By the time the products of combustion have flowed forward between the discs n}, they have lost enough heat so that incandescence is ended or about to end. But the remainder of the heat in the gases continues forward and impinges against a central stop comprising the breast 46 and floor 43 of a storage bin having side walls 5% in which storing bin it is convenient for the workmen operating the equipment to deposit excess material that is picked up here and there. This maintains a supply of hot fresh mix which can be shovelled out into local pot holes that have been leached away to such an extent that the material at the pot hole is insufficient.

The heat is checked from going out under the floor 48 by a downwardly turned baffle '52 which lies between the compaction rollers 16. There remains an upward exit for the hot gases at each side. The curved ducts 54 have their side and rear walls of stationary sheet material and their front walls are the turning surfaces of the compaction rollers 16. They are continued in short stacks 55, to get just a little suction and deliver the products of combustion almost entirely through the stacks, without sticking in much air from below.

The compaction roller 13 is also heated to approximately the same temperature as the front rollers 16 by means of a separate set of flame throwers at 56 which fill the housing 58 with flame that bathes the rising surface of the compaction roller 18. The heating capacity required at this point is a minor fraction of that required for the main heating chamber. The compaction roller 18 is provided with a pivoted scraper at at} and the compaction rollers 16 are each provided with two scrapers at 62, so that small particles adhering to the hot surface of the roller will be dislodged during travel in either direction.

Blading The shaving blade 64 is adjustably mounted on depending arms 66 at the ends of carrying beams 68 having their rear ends 74? pivoted on the axle for the compaction rollers 16. A flexible tension member '72, indicated as a chain, is carried by a vertical rod 7 5 adjustable in its vertical position by the hand Wheel 75. The parts are illustrated in FIG. 4 in shaving position. When not in use, the arms 68 and blade 64 may be picked up by a hydraulic hoist at 78.

The same arms 68 carry depending standards $0 that support a pivoted blade 82, which is prevented from turning further counter-clockwise, as seen in FIGURE 4, than the full line position, by suitable means such as a contact 84 engaging the outside of the fire chamber. Because the blade is pivoted, it can swing up to the dotted line position when movement is to the right as seen in FIGURE 4, so that any irregularities will pass under it without being disturbed. But the blade 64 will accumulate a pile of shaved off material and when movement is reversed the blade 82 will come back to the full line position, which is normally about A higher than the blade 6 Therefore, it will strike off the pile left by the blade s4 and spread it out continuously until the pile is exhausted.

It is also necessary to lift the heating chamber away from the road surface when moving from place to place. The heating chamber is also carried on a pair of shorter arms 86, pivoted on the same transverse axis as the arms as, see FIGURE 4, are connected by a rear cross channel 89 to a central hydraulic hoist 88 that can lift the remote end of the chamber much higher than it is necessary to lift the arms 68. This lifting has to go far enough to elevate the shoes 3d at their front ends reasonably clear of the pavement and the angular displacement required is two or three times as great. A definite stop means limits the downward movement of the heating chamber, but this does not need to be readjusted from time to time by the operator during the processing of the road. Therefore, in the embodiment disclosed, when the piston in the hoist 83 reaches the bottom of its stroke, the chamber is held up by simple tension in the structure of the hoist itself.

The power plant 9i (see FIGURE 4) is centrally located partly under the drivers seat 92, and delivers power through a conventional transmission Wt to a propeller shaft 96, which extends to the difierential 98. The transverse drive shafts Tilt) drive the front wheels 16 through conventional sprocket chains 102 (see FIGURE 1). The space occupied by these sprocket chains is substantially protected from the products of combustion by extensions The, covering the rear end of that space where the products of combustion on their way to the stacks 55 might tend to flow forward and subject the sprockets to undesirable heating. The space occupied by the sprockets 102 is further protected from access of the products of combustion by housings 163, which are closed at the top and extend down far enough to form a pocket, with its open lower end protected by the barriers 1M.

Conventional power plant and steering control means is located centrally at the top of a control column 106. Accurate adjustment of the blading frame, with precise control of the level of the blade 64 at each side of the area being treated is secured by having the adjustment means 76 in duplicate on both sides. The pivotal connection to the stationary front axle only needs to be a little loose, to allow the frame to cant to either side enough to secure precise and fine control of the transverse slope of the blade.

Suitable storage means may be provided beside the power plant, as indicated at 108 in FIGURE 1, for fuel supply for the power plant. The fuel for the flame throwers 32 and 56 is of much lower volatility and it is convenient to store it in two much larger containers 110 and 112, located on either side of the propeller shaft 96, and centrally above the heating chamber 26. This is desirable in order to let a little warmth from the heating chamber rise and keep the low grade heating oil in these heating chambers comfortably warmed for good combustion, especially when the weather is cold. At the same time, the wide space above the chamber and below the tanks avoids any risk of setting fire to the fuel. The refractory lining assures low operating temperatures for ::he outer steel shell, with correspondingly low heat osses.

Referring now to FIGURES 5 to 13, inclusive, I have indicated, in a more or less idealized, diagrammatic form, the successive stages of operation in a typical levelling procedure. In FIGURE 5, the washboard surface to be corrected includes the large hump 114 and the deep depression 115 just in front of it, which will frequently be one of a series of closely similar humps and depressions.

On the first pass, the blades 64 and 82 are lifted clear and perform no function at all, but the passage of the flame generates a heated surface layer, indicated at 116, which will cover the entire surface. Depending on the degree of irregularity, the operator may pass over two or three times to increase the thickness of the heated layer 116.

Eventually, on a forward pass, he will lower the knife 64 and blade off the top of the hump as indicated at 118 in FIGURE 6. The material thus displaced will slide more or less down the slope of the hump and come to rest in an excrescence at 120. The next passage of the rolling discs 40 will massage not only the heated layer 116 but the protuberance 120 and spread it out more or less. I have indicated at 122, the degree of spreading that will usually be secured by a single passage of the discs 40.

Similarly, on the next pass in a forward direction, the blade 64 will slice a little deeper and strike a lower plateau at 124%, generating a larger protuberance 126 which will be spread out approximately along dotted lines 128.

In FIGURE 8, after the third blading, the plateau has moved down to 139 and the protuberance at 132 is getting quite bulky. The heated layer 116 is considerably thicker on the sides of the hump but relatively thin across the top of the hump where the removal of the material by the blade is working down toward the true road level at 133.

After the fourth blading, the plateau will be down to some such level as 134, and the protuberance at 136 will still be very conspicuous but it will begin to spread, as indicated at 138, down to and across the bottom of the depression I15. After the fifth pass, the plateau will be at 1'40 and the protuberance starts to become a filling 142 which will extend past the bottom of the former hollow 11S and be spread farther up the opposite side at 144 if the rollers can get down there. In a typical washboard road the rollers can usually get down, and the contour at 144- will result, but if the depression 115 is very small in transverse dimension, such spreading will not be effective until the condition of FIGURES l1 and 12 is reached.

In FIGURE 11, after the sixth blading, the plateau is at 146, and the fill 148 has been subjected to displacement by blading, more than half way across the original depression 1115, leaving a small cavity indicated at 156 in dotted lines. This contour will be changed to the full contour line 152 by the next passage of the discs 40 and this contour will be closely approximated even if the cavity was so short that the discs did not get down into the bottom of it at the outset.

After the seventh, and penultimate, blading, the plateau at I54 is almost down to road level 133, and extends continuously across the former hump and almost all the way across the former depression 3115, leaving a small dimple 156, which will be almost obliterated by the next passage of the rollers 46. The final condition of the hump is, naturally, directly at the original road surface 134, and the final condition of the cavity 115 is indicated in FIGURES 5 and I3. If the original cavity was so short that the rollers could not get down into it at the start, the dotted lines at 153, indicating the approximate planes of union of the successive deposits that have been made, may be inclined as deeply as in FIGURE 13, or a little more so. But if the cavity extended transversely to a length equal to or greater than that of the disc roller, these lines will be much nearer horizontal, as indicated at 16h in FIGURE 5. In either case, there is a perfect vulcanized weld along the plane of every dotted line indicated.

In the drawings, for the sake of clearness, the height of the hump and the depth of the depression have been exaggerated, with respect to the condition that will usual ly be encountered. A true sine curve, such as that in FIGURE 5, will not be encountered very often, and when it occurs it will be of greater length compared to its height.

The composition of matter resulting from the heating 6 of the formed from the material of the old road have been analysed and found to be well within the compositions and tolerances of the specifications that were used when the roads were first laid.

In a typical operation, the controls 76 are adjusted with precision to the known pitch, or camber, of the area to be processed. Then the blades 64 and 82 are lifted high with the hydraulic hoists 7 S.

The rollers 16 and I8, the chamber 26 and grid rollers it being all preheated to, or nearly to, working temperature, the unit is rolled back and forth over a predetermined area. The length of the strip to be processed at one time for best results is a matter of judgement, being relatively long in warm weather, and much shorter when cold weather gives a faster cooling rate during the time intervals between the heating increments.

Until the top surface begins to soften, the grid rollers 49 will roll over the area without forming any notice able grooves, and it normally takes from about three to twelve or more passes to get the pavement. warm enough to yield under the grid roller.

As soon as grooves appear in the pavement, the hoists 78 are operated to drop the blades 64 and 82 to their predetermined setting. On the next forward pass, the operator keeps his hand on the control level for the hoists 73. The machine will not have enough traction to pull the blade 64 for a full slice, and as each hump is about to stall the forward movement, a little lift with the hoists eases the unit over the hump. On each successive blading pass the amount of easing required becomes progressively less until the machine goes through without faltering and the job is done.

The operator now lifts the blades high and moves on to another area. It is often desirable to get a slightly more compact top skin than Was produced up to this point, but that cannot be done While the softness is deep. After a half hour or so, the unit can come back, and, with the heat supply reduced to let the rollers cool to about 180 F., a few trips develops the finished product. It will be apparent that no other equipment is needed to go to work on an area that needs reconditioning and/ or repairing, and to leave it a short time later with nothing left to be done.

The final result is to bring the pavement back to its existing average level, rather than to shave it down to the level of the bottoms of the depressions.

Others may readily adapt the invention for use under various conditions of service by employing one or more of the novel features disclosed, or equivalents thereof. It will be obvious that if the consistency of the material worked on does not happen to accord well with the normay weight of the discs 40 and shaft 38, a compression spring 162 riding above the block 42 could easily be employed to increase the downward pressure of the rollers and provide a varying load on the discs, which would be increased on the higher portions of the road surface, and reduced in the depressions. In one successful unit for general work, the discs at and their axle weigh a little less than two tons, and springs 162 having a loading factor at each end of about 400 pounds per inch, set to begin compression when the rollers are already riding one inch above the plane of the rollers 16 and 18, give the right amount of extra pressure on the humps. There is a limit to the force that can be exerted in this way, at the point where the pressure of rollers 1.6 on the road becomes insuficient to give traction.

It has been established that the initial heating is preferably employed to bring the surface temperature up to 275 F. to 325 F., by actual measurement. This is the common temperature for new mix from a hot mix plant.

The machine travels over the ground at speeds from 40 to feet per minute, and the length of the heating chamber is such that each period of intense heat lasts from 5 to 8 seconds, depending on operating conditions.

aoeasea In cold weather, the surface can stand a longer heating period until it gets fairly hot, and the surface temperatures given above are in a range well below the flash point of the asphalt.

As at present advised, with respect to the apparent scope of my invention, I desire to claim the following subject matter.

1. Equipment for restoring the uniform top surface and the structural strength of asphaltic concrete pavement which has been distorted by traffic, substantially entirely from the material already in said pavement, comprising, in combination: a chassis frame; front and rear end roller supporting means at opposite ends of said frame for supporting said frame above a road bed; a heating hood between said supporting roller means, adapted to define a flame chamber in combination with the road surface below it; means for filling said chamber with live, nonoxidizing flame; power means for moving said frame in either direction along the road to limit the duration of flame application on any portion of the road surface below a predetermined safe maximum; and an intermediate distorting roller between said supporting rollers, adapted to ride on the road surface and rotate on a transverse axis parallel to the road surface and affect the contour of the road surface by downward pressure thereon; said intermediate roller having an irregular road-engaging surface adapted to press a plastic underlying road surface into an irregular configuration.

2. Equipment according to claim 1 in which the road engaging surface of said roller is a surface of revolution having circumferential grooves and is also heated and positioned to act on road surface freshly softened by the flame in said chamber.

3. Equipment according to claim 2 in which said intermediate roller is mounted in said chamber near the rear end thereof, and receives its heat supply direct from the flame enveloping it.

4. Equipment according to claim 2 in combination with a pushing blade mounted to the rear of said flame chamber; said blade lying in a vertical transverse plane;

operator-controlled means for raising and lowering said pusher blade; said blade, when lowered, being adapted to push plastic material above the level of said blade forward into the next adjacent area of lower level.

5. Equipment according to claim 4 in combination with a spreader blade pivoted on a transverse horizontal axis spaced in front of said pusher blade and behind said flame chamber; pivot means permitting said spreader blade to swing back during forward movement to clear material passing under it; and stop means preventing said spreader blade from moving forward during backward movement; whereby said spreader blade, when movement is reversed from forward to backward, automatically engages undistributed material lying against the front of said pusher blade, and spreads it out again.

6. Equipment according to claim 5 in which said spreader blade is mounted with its active edge about inch higher than the active edge of said pusher blade.

7. Equipment according to claim 1 in combination with heating means associated With each end roller and controlled by the operator for keeping said front and rear end rollers heated to any desired temperature up to at least about 325 degrees Fahrenheit.

References Cited in the file of this patent UNITED STATES PATENTS 197,713 Abbott Dec. 4, 1877 524,939 Dennison Aug. 21, 1894 1,886,748 Schutte Nov. 8, 1932 1,952,452 Monroe Mar. 27, 1934 2,241,299 Finley May 6, 1941 2,705,906 Fizzell Apr. 12, 1955 2,753,772 Harrison July 10, 1956 2,875,675 Searight Mar. 3, 1959 2,937,580 Spalding et a1. May 24, 1960 2,937,581 Havelin et al May 24, 1960 FOREIGN PATENTS 694,027 Great Britain July 15, 1953 757,229 Great Britain Sept. 19, 1956

Images