US2255343A - Apparatus for making concrete pavements - Google Patents

Description

R'. W. BAILY APPARATUS FOR MAKING CONCRETE PAVEMENTS Sept. 9, 1941.-

F'iled Feb. 7, 1951 INVENTOR APPARATUS "FOR. MAKING CONCRETE PAVEMENTS Robert W. Baily, Philadelphia, Pa.

Application February 7, 1931, Serial No. 514,124

6 Claims.

My invention relates to improvements in apparatus for making concrete pavement.

It is one object of this invention to provide a novel apparatus for striking off the surface of concrete or other material during the making of a roadway or similar structure. I provide a screed member in front of which the unformed mass of concrete is deposited and by which this mass is leveled and rapidly and intensively vibrated to cause the concrete to become more dense and fluent and also to cause the elimination of air. and water entrapped in the concrete. It is the particular object of this invention to concentrate all or the greater part of the described vibration to the unformed-concrete in front of the screed member.' This I preferably accomplish by attaching the vibrating mechanism to the back of the screed member. Another object is to maintain the screed member at a predetermined level above the sub-grade line so that the surface of the concrete will have a uniform finish. It is also an object of this invention to provide a screen by which the described vibration may be transmitted vertically to the concrete after it has been struck off, some of the vibration being transmitted -horizontally to the unformed concrete through a screed member having a vertical face which may be tilted to a slight degree either forwardly or backwardly. Other objects appear hereinafter.

Referring to the accompanying drawing, Fig. 1 is a perspective view partly in section and partly broken away showing my invention in connection with both unformed concrete inj'froi t of the screed member and a completed slab below the same. Fig. 2 is a detail section of the screed member on the line 22 on 1- carrying the vibrating mechanism in connection with an attachment at the upper side for leveling the unformed concrete. Fig. 3 is'a plan view of Fig. 2 with parts i, 3, l8 and I9 omitted. Fig. 4 is a view on a reduced "scale of Fig. 2 rotated to the right 90. Fig. 5 is a detail like Fig. 2' with the top screed member omitted and the righthand screed member tilted slightly to the right. Fig. 6 is a view like Fig. 5 but having the screed member tilted to the left of the position shown in Fig. 2.

Referring to the drawing, I designates a screed member extending from one side of the roadway to the other and having its ends resting upon the side forms 2 .which form mold members for the sides of the concrete roadway. The screed memher is preferably made of steel and is shown to be a channel member having its ends closed by plates 3 through which bolts 4 are passed. for securing the ends of the screed member to the" members 5 having horizontal portions 6 riding on top of the forms 2. The screed member is shown' with its front or right hand face vertical, but it may be inclined forwardly or rearwardly of its vertical position by removing the bolts 4 and passing them through other pairs of holes 4' in the members 5. The .members 5 are provided with handles 1 by which the screed can be moved along the roadway and on the side forms 2, but

these handles merely indicate the presence of some means for moving the screed rather than the indication of any particular means for moving it.

The rear face of the screed member I carries two pairs of housings 0 extending rearwardly at right angles theerfrom. A horizontal shaft 9 is mounted in these housings and is driven by the band wheel I 0 secured to the shaft. This band wheel may be driven by any suitable prime mover supported and having travel in any suitable manner, as on the side forms 2. Each pair of hous- .ings has a crank l0 secured to the shaft, each lying in front of the screed sothat it may be levedge of the screed member I.

eled and formed into a slab such as l5 which has already been made by the forward movement of the screed which struck off the concrete so as to produce the upper even surface N5 of the slab.

As the screed member advances, the shaft 9 is driven rapidly, preferably 2,500 revolutions or more per minute though good results may be obtalned at 2,000 revolutions per minute. This very rapid vibration of the screed is transmitted to the unformed mass of'concrete H which is converted from a rather stifl. mass to a practically fluent and dense mass, freed of substantially all of its air and excess water. Some vibration will be transmitted from the up and down movements of the crank to the slab l5 through the platform member l9 extending rearwardly from the lower member l9 has its ends welded or otherwise secured to the\end members 5 of the screed. Such vertical vibration tends to eliminate any air or water which may remain in the slab. I find that vided with wings H which extend out over the The platform I side forms 2 to scrape any concrete from the side forms upon the mass of concrete I4.

As shown in Figs. 2 and 4 the screed member I may have bolted or otherwise secured thereto the auxiliary screed member I8 at right angles to the screed member I and at the upper edge thereof, the screed member I8 extending out over the housings 8 at the rear of the screed member I when the latter is vertical. The platform member I9 cooperates with the screed member I in striking off the concrete of the road slab and also functions to impart surface vibration to the concrete below it. The members I9 and I may be bolted to the end members so that the platform I 9 forming one ,of the screed members is horizontal and the member I is vertical. The forward edge of the platform I9 and the lower edge of the member I afford a transitional cylindrical surface as shown in Figure 2. The member I may be adjusted by changing the bolts 4 to different holes for prying to cause the screed member I to incline rearwardly as, for instance, as illustrated in Figure 2, or to cause it toincline forward from lower edge as shown in Figure 5 where both members I9 and I are bolted to the end members 5. They may be adjusted byproper arrangement of the fastening bolts until the member I is in horizontal position as illustrated in Figure 4 and the member I8 is in vertical position so that the member I becomes the leveling screed cooperating with the member I8 for striking off the concrete. When the parts are in the position shown in Figure 2 the more powerful vibrations are directed forwardly. When they are in the position shown in Figure 4 the more always maintains its platform in contact with the upper surface of the slab, this being an improvement over vibrators which project themselves along .the roadway by small leaps or jumps. This application embodies a modified form of the features shown in my application Serial Number 428,747, filed February 15, 1930 and restricted to methods which the apparatus of the including a front member adjustable to various powerful vibrations are directeddownwardly so far as the effect on the concrete is concerned.

Fig. 5 shows the screed member I tilted forwardly. It is tilted this way preferably when the unformed concrete mass I4 is rather harsh or stiff. The screed member I is shown in Fig. 6 tilted rearwardly. It is preferably given this position when the concrete mass I4 is rather soft or plastic.

This invention avoids the necessity of using perforated or slotted platforms orthe like on the finished grade line for the purpose of letting entrapped air and excess water escape. There is very little or no air and excess water in the slab as the screed member passes over the slab because all or practically all of the entrapped air and excess water is vibrated out while the concrete is in engagement with the forward face of the screed member I. It is to be noted that the apparatus described is in no sense a tamping apparatus. It is also to be noted that the screed angles relative to a pavement slab, and vibrator mechanism carried by said front member.

2. In apparatus of the kind described, a vibrating apparatus having a main and an auxiliary elongated parallel contacting. screed members forming a front face and trowel member respectively, arranged to lie crosswise of a roadway slab being constructed, for movement along the roadway, means mounted on the front face member for vibrating the apparatus to impart to unformed concrete deposited in front thereof,

rapid and intense vibrations, and for imparting the major intensity of the vibrations to the concrete in front of the apparatus and the minor intensity of the vibrations being imparted to the concrete below the member.

3. A screed having a base plate and an upwardly extending front plate, a. transverse drive shaft 'mounted on one face of said front plate, of!- center weights connected at spaced intervals to said drive shaft, and means for rotating the drive shaft whereby vibrations are imparted to the screed.

4. A screed having a base plate and an upwardly extending front plate, and vibrators mounted on one face of the front plate.

5. A screed having a base plate and an upwardly extending front plate, and vibrators mounted on one face of the front plate, and an adjustable connection between the front plate and the base plate whereby the angle between the two may be selectively adjusted.

6. A screed having a. base plate equipped with end plates,'a front plate extending upwardly from the base plate and adjustably connected to the end plates, and vibrators mounted on one face of the front plate.

ROBERT W. BAILY.

Images