US2187080A

US2187080A - Road building machine

Info

Publication number: US2187080A
Application number: US50934A
Authority: US
Inventors: John N Heltzel
Original assignee: Individual
Current assignee: Individual
Priority date: 1935-11-21
Filing date: 1935-11-21
Publication date: 1940-01-16
Anticipated expiration: 1957-01-16

Description

ROAD BUILDING MACHINE Filed Nov. 21; 1935 5 Sheets-Sheet 1 t I 41 I awe/WM;

"7 J. N- HELTZE} Jane 16, 1940. J. N. HELTZEL ROAD BUILDING MACHINE Filed Nov. 21, 1935 5 Sheets-Sheet 3 2E gwucwlo J. N. HELTZ BL Fl 1;. 5. z

Jan, 16, 1940.

J. N. HELTZEL ROAD BUILDING MACHINE Filed Nov. 21, 1935 5 Sheets-Sheet 4 awe/whom:

J- NHBLTZ 16, 1940. I J, TZ 2,187,080

" ROAD BUILDING MACHINE Filed Nov. 21, 19:55 S'Sheets-Sheet 5 oi JNHBLTZg Patented Jan. 16, 1940 UNITED STATES PATET OFFiCE 6 Claims.

The present invention relates to improvements in road building machines and is a continuation.

in part of my prior application for Road making machines, Serial No. 475,492 filed August 15, 1930.

An object of the present invention is to provide an improved method and device for producing curb formations at the edges of a concrete road adjacent the side forms.

Another object of the invention is to produce a raised central portion in the road in and about the zone of the joint to reinforce and strengthen the material at the sides of the joint and the road slabs whereby to avoid spalling off of the lastic material.

A further object of the invention is to provide an improved form of screed and method of hanging or suspending the same whereby the screed, in addition to operating in its normal transversely reciprocating manner, may be given a rocking motion on its suspension whereby to compact the concrete in a novel way.

It is a still further object of the invention to produce an improved screed or finishing implement capable of forming lip curbs.

A still further object of the invention is to pro-v duce an improved screed or finishing implement for the purpose of preventing honey-combing of the concrete at the sides of the road-adjacent the side forms by compacting the concrete downwardly to fill up such voids as would otherwise be rearward movements of the implement and also upon lateral reciprocating movements of such implement; to provide guards for the sides of the machine to prevent the loose aggregate from spilling over the side forms; to provide detachable devices at either of the sides and/or in the center of the screed for producing compacting effects upon the concrete at the sides and center portions of the slabs.

With the foregoing andother objects in view, the invention will be more fully described hereinafter, and will be more particularly pointed out in the claims appended hereto.

In the drawings, wherein like symbols refer to like or corresponding parts throughout the several view,

Figure 1 is a perspective viewof a road building machine constructed in accordance with the present invention.

Figure; 2 is a fragmentary perspective view, with parts broken away andv parts shown in section, and illustrating the central arched construction of the screed.

Figure 3 is also a fragmentary perspective view showing the finished form of slab.

Figure i is also a perspective view with parts of the roadway and side forms shown in section, illustrating a modified form of road building machine.

Figure 5 is a similar View showing a modified form of screed-and guard plate.

Figure 5-A is a cross-section taken on the line I ii-A -5 --A of Figure 5.

Figure 6 is also a perspective View with portions of theroadway shown in section and the side forms broken away, illustrating the same "form of screed with guard plates at the front and rear of the same.

Figure '7 is a similar View showing a modified form of screed in which the compacting devices are detachable.

Figure 8 is a similar View showing the com-- pacting member in place.

Figure 9 is a perspective View of a. part of the compacting member separated from the screed, and

Figure 10 is a perspective view of a finishing machine having the novel features of this invention applied thereto.

Referring more particularly to Figures 1, 2 and 3 of the drawings which correspond to Figures 6, '7 and 8 of my-prior co-pending application Serial No. 475,492, platforms in are shown with reinforcing mesh ll thereon. The platforms 3-0 are linked, as by'the chains or other connections ll, to the subgrader or other machineby which the same are drawn along. The mesh 45 may be laid on the platforms it and, as the pouring-of the concrete progresses, the platform or platforms 40 are drawn from under the mesh.

After the concrete'has been poured and the mesh reinforcing installed, the screed member 42 follows, which screeds off the concrete.

The screed is shown more particularly in Figure 2 and is composed of divided base plates t3 and 44 having the side angleircns 45 and it, between which are arranged the braces til. The. base plates #3 and 44 are separated and indented, as indicated at 48; and the angle bars are arched upwardly at a central point between the two base plates, as indicated at 19. At 5!) is shown the screeding bar which encounters the concrete, this bar resting upon the base plates #33 and it and against the vertical web of angle irons 46.

The recessed and arched screed will supply a surplus of material in the center of the road along the joint blade 39. In both Figures 1 and 2 I the raised central portion of the concrete is indicated at 5|, this raised portion being formed as the screed passes over the concrete.

The screed member 42 follows progressively back of the pouring. This screed member will preferably be a mechanically-operated screed having an eccentric, as hereinafter described, for reciprocating the screed transversely of the roadway.

The screed has the arched portion 48 as heretofore referred to. This arched portion may be completely closed on the bottom face so as to prevent arry material from projecting through the screed, or it may be provided with the opening 48 which will permit surplus mortar to project through the screed to be deposited in the rear of the screed, as indicated at 5!. The screed has adjusting screws to vary the arched portion 9. There is an offset a: at either or both ends of the screed to produce a header or curb r-l along the edge of the road.

In Figure 2, I have shown more "fully the opening in the screed, together with the arched mem bers. The rear member 55 of the screed may be raised slightly more than the front member It will be understood that the front member will depress the stone or coarse aggregate below the surface and the finer material will accumulate in the open space ill. As the screed moves forward, the finer material will project in the rear of the screed, as shown at E5.

The open space 48 may be provided with sides or braces ll t retain the surplus material within the space 48. The joint forming member or joint material 39 is shown in place after the joint installing operation has been completed. This elevated joint 5i will eliminate the low joints which have been experienced from time to time where the plain or regular surface type of screeds have been used. The recess in the screed may be Varied by adding filler plates M secured by bolts or suitable fastening means 49 In Figure 3, I have shown a slab of concrete molded as it would appear in complete form. The raised portion of the slab '52 along the longitudinal joint is indicated at El. It will be understood that this raised screed member may be used in connection with any type of longitudinal joint forming a raised portion to guide traffic and prevent surface water entering the joint.

It is desirable in many instances to form a curb or header, such as indicated at w-! in Figure i, sometimes at both sides of the road, and in other cases only on one side of the road. This curb is sometimes called a lip curb.

The object of forming the curb by the screed member 22 is to provide means whereby the concrete contained in the curb or header is built integrally with the base portion of the roadway. This is accomplished by offsetting the lower face of the screed as indicated at It will be understood that the screed is reciprocated transversely in the conventional way well known in the art. After the concrete header or curb has been formed by the reciprocating screed, suitable temporary forms may be positioned to support the concrete curb until the concrete has hardened sufficiently; thereafter, the forms may be removed. The forms referred to are of a type well known in the art.

It will be understood that the screed 42 reciprocates transversely in the conventional manner and is pushed forward progressively with the movement of the conventional finishing machine to which my improved screed may be attached.

Referring more particularly to Figure i, there is shown a method of forming what is generally termed lip" curbing, as indicated at Xl-A by the use of the laterally-reciprocated screed member I. This screed may be carried forwardly and backwardly by the conventional finishing machine. This screed is provided with depressed portions ii at opposite sides of the raised center. The screed rests on the side forms 2 and is arched upwardly, as indicated at 3 to the contour of the lip curb |A. The distance between the arched or upwardly curved ends 3 of the screed is less than the distance between the lip curbs at opposite sides of the road to give the screed an opportunity to reciprocate laterally across the road without destroying the lip curbing and to better compact the same.

Also the arched central portion M: of the screed is struck on a greater radius of curvature than the resultant raised central portion 5! of the roadway, the reciprocating action of the screed compacting the material at opposite sides of the joint.

Either mechanical or electrical vibrating devices l may be provided on the screed to vibrate the screed as the screed is reciprocated and pushed forward to strike off the concrete level with the tops of the forms 2 and simultaneously build up the lip curbing.

The machine is arranged for forward and backward screeding. The screed member may rest on the side forms 2 for back screeding, and I" to simultaneously form the lip curb with the backward movement of the machine in the same way as it would in the forward movement of such machine.

A longitudinal joint cutting blade 5 may be positioned under the screed as shown more particularly in my prior Patent No. 1,982,337, granted. November 27, 1934. The joint cutting blade is provided with slots '1 to permit up and down movement of the blade when the screed is raised out of position by the lifting chains or other suitable devices 8. Such lifting members 8 are provided on each side of the screed and are carried up to the frame of the machine, being wrapped or Wound around the pipe member or shaft 9, which is secured to the frame of the machine in the conventional manner.

By rotating the pipe member or shaft 9, the screed may be raised and lowered with respect to the surface of the roadway. It has been found to be very practical to raise the screed approximately six inches above the side forms when making the first strike oil of the concrete, and while the screed is thus elevated to reciprocate the same by use of the arm it] and eccentric H or other means, such eccentric being operated by a suitable power unit carried by the machine.

The vibrators 4 may also be operated to vibrate the screed during the operation of the initial strike-off of the material.

It is very important at this stage of the operation to understand that, when the screed is suspended on the chains 8 and reciprocated laterally by the eccentric H, the screed will swing on an are having a radius with pivot point at 9.

Such screed motion will produce a tainping action on the concrete, and in this way the screed will serve as a tamping member, as well as a screeding member.

Iii]

By operating the screed in the various manners above described there will result a maximum amount of compaction to the concrete. Therefore, a very dry concrete may be used.

Modern specifications require transverse con traction joint. Such a joint is indicated at It. A transverse joint may be produced by the blade member l3 positioned adjacent the front of the screed. The lower edge of the blade is out to the contour of the lip curb. The blade is is supported and movable up and down, by the screw members M or other devices, the same being manipulated by the hand wheels 55.

It will be understood that, when cutting the transverse joints 12, the forward movement of the machine is stopped and the ends of the screed rest on the side forms 2. The screed may be reciprocated laterally and also vibrated by the vibrators 4 as the blade I3 is moved downwardly into the concrete by the hand wheels it: and screw members 44. It may be desirable in some cases not to reciprocate the screed when cutting the transverse joints. Instead, the joint may be produced by moving the blade 63 down into the concrete progressively while the screed is vibrated by the vibrators 4.

In practice it has been found that forms are not required for supporting the lip curb, as indicated at XIA, because of the fact that the curb is of a rather flat construction. However, when curbs are produced with a vertical face. as indicated in Figure 1, it is necessary insuch cases to support the face of the curb by suitable form members which are positioned back of the screed after the curb material has been formed or moved up into position.

Referringmore particularly to Figure this figure illustrates a modification of screed construction wherein a reciprocating screed is provided with a fiat base portion it. Such flat portion rests on top of the side forms 2 on both sides of the roadway. The bottom portion it constitutes a wide surface and may be arched to conform to the required crown of the roadway; thus, the bottom portion it of the screed may perform the function of producing the finished surface of the concrete.

It has been found in practice in building concrete roads that honeycombing or voiding has not been overcome by the conventional design of screeds heretofore used. It has been necessary, therefore, for workmen to spade the concrete along the side fonms; however regardless of the spading of the concrete along the side forms, this voiding or honeycombing along the inside face of the forms has never been overcome, but it has compelled engineers to provide a thickened edge adjacent the side forms. I have overcome the necessity of hand spading along the edge of the forms by providing upwardly-flared walls I6A at the forward portion of the screed, and similar upwardly-flared walls iii- B at the rear edge portion of the screed. These upwardlyfiared walls terminate inwardly from the ends of the screed at points designated generally at l6C, which may be approximately six to twelve inches inside of the side forms. When the screed is moved forward against the accumulation or body of loose concrete, the upturned wall lB-A will form a. raised portion along the side forms; in other words, an excess amount of concrete will be positioned along the side forms. The volume of this material will be controlled by the height of the flare i6.-A. As the screed moves forward, and is reciprocatedthe bottom surfacing portion US of the screed forces this excess material downwardly level with the top treads of the side forms 2. The walls lfi-A and Iii-B flare or incline not only in a forward and rearward direction but also transversely of the roadway downwardly to the terminal points l6-C whereby these shoulders or transversely inclined or rounded end parts itC thrust the excess material laterally toward the side forms and in a downward direction as indicated by the arrow in Figure 5. This has the eifect to pack the concrete against the vertical face 2A of the side form 2.

. The flared or inclined walls ltA and lt-l3 are not carried continuously. across the front or rear faces of the screed, and these walls may or may not be integral with the screed. Separate wall structures are shown in connection with subsequent figures of the drawings.

The screed i6 is reciprocated transversely of the roadway and is powered for backward and forward screeding, for instance in the manner shown and described in my co-p-ending application Serial No. 369,475 filed October 25, 1932. Owing to this backward and forward movement, the front and rear parts of the screed carry the flaring or inclined walls.

In the forward motion of the screed, the front flared walls l6-A virtually forms a raised curb. This curb portion is then forced down and compacted by the flat surfacing portion it of the screed. On the rear movement of the screed the opposed flared wall Iii-B has a similar effect.

After the necessary material has been forced down against the side forms, perhaps there may not be any surplus coarse aggregate with which to contend. When this stage of the operation is reached. the surface of the concrete is then considered to be completely finished, and all of the coarse aggregate that could possibly be forced down along the side form-s has already been projected in position, so that, in effect, an armoured edge along the roadway is produced by the compaction of an excessive volume of coarse aggregate longitudinally along the zone of the side forms.

To prevent the coarse aggregate from rolling over the side forms, one or more baffle plates or guards I! are provided. Such baffle plate may be supported by members it secured to the carriage of the machine. Slots l9 in the members 18 admit of the vertical adjustment of the baffle plate; while slots 25! which intersect the. vertical slots 19 are useful to allow the baffle plate I! a longitudinal play within the limits of the horizontally elongated slots 21!. Bolts or other fastenings 6 pass through the intersecting slots to bind the baffle plates 9? to the supports H3 in the adjusted position. The two adjustments permit the baffle plate to be moved toward and. from the rear vertical face 2! of the screed and also allow the lower edge of the bafiie plate I! to be lifted and lowered with respect to the top tread of the side form 2.

Referring more particularly to Figure 5---A, this figure is a cross-section taken on the line 5A5A in Figure 5. The section looks in the direction of the arrow and shows the other end portion of the screed with the flared end wall sections.

Referring more particularly tov Figure 6, this figure shows more comprehensively the screed and the guard plates of Figures 5 and 5--A. The front vertical face of the screed is indicated at 2|, and the rear vertical face by a like number.

The flared walls lG-A and lt-B are shown at v both ends of the screed. These walls function during both the forward and rear passes of the screed. The excess concrete to be thrust down against the inside faces of the side forms is indicated at 22. In this case two baffle plates I? are provided. One baffle plate is arranged forwardly of the screed at the side of the roadway, and a second baflle plate follows the screed in substantial alinement with the front bafile. One or more baille plates may also be mounted at the right hand end of the screed. The bafile plates may be arranged with their lower edges very close to the treads of the side forms, in which case they will prevent any excess material flowing over the top of the side forms. However, the openings immediately under the flared walls will permit excess moisture or water to drain off of the surface of the roadway over the tops of the forms and between the bafile plate N. This is desirable because excess mortar, moisture or water are apt to produce a scaling effect on the surface of the roadway. Therefore, to prevent this scaling of the surface of the roadway provision is made to drain this excess water or moisture from the surface to the roadway by permitting the water to drain under the flared walls l6-A and l6B.

The screed is reciprocated by the arm l driven by the eccentric l l, which is driven from any suitable source of power preferably installed upon the carriage or bridge. This carriage or bridge may be of a conventional type. A vibrator 4 is shown in this instance as being mounted centrally of the screed. One or more vibrators may be mounted at desired positions along the length of the screed. Such vibrator may be either mechanically or electrically operated for the purpose of vibrating the screed as the screed reciprocates transversely and moves either forwardly or rearwardly over the roadway.

Now the segregation of concrete is corrected by the forward and backward movement of the screed. In Figure 6 a transverse windrow 23 of coarse material is shown. This material has been carried backwardly in the direction of the arrows by the screed during its backward movement and while being reciprocated in contact with the road material. This backward screeding eliminates the necessity of workmen shoveling the required material back to a rearward point which has been the common practice. Backward screeding also serves to thrust the coarse aggregate in a back direction, as well as in a forward direction, and will also thrust the excess material against the side forms during the backward movement, as well as during the forward movement. This forward and backward screeding method has been described in my prior application above referred to Serial No. 369,475. Before the final forward pass of the finishing machine is made. the machine will be backed up to a point as indicated at X-Z in Figure 6, and the screed lowered in position whereby, when the screed moves forward it will reciprocate on the surface of the roadway and pick up the excess material from the windrow 23, carrying such excess material forwardly. The operation is repeated progressively throughout the length of the roadway. The finished roadway is indicated at 24 in Figure 8 and includes the installation of the joints l2.

In cases when an armored surface is desired throughout the entire surface of the road, to provide a harder wearing surface a sufficient quantity of coarse stone or aggregatepreferably dry-may be added by spreading a layer of such coarse stone or aggregate over the surface of the roadway after the concrete has received its initial screeding. Such layer of stone or coarse aggregate may be quite uniformly spread by workmen with shovels.

After this layer of coarse aggregate or stone has been spread over the surface of the roadway, the machine is then moved over the roadway with the screed reciprocating and simultaneously vibrated progressively as the machine moves over the roadway.

The thrust member IE will engage the stone or coarse aggregate, which has been spread substantially uniformly over the surface of the green concrete and, consequently, thrust down into the plastic concretethereby absorbing the surplus moisture and causing the mortar to be thrust around the stone or coarse aggregate and thereby thoroughly coating the coarse material by the combination screeding and vibrating process and attracting sufficient mortar to the surface to completely cover the stone or coarse aggregate and provide a smooth surface finish with the course of stone reposing very close to the top surface of the finished slab to provide a dense or armored surface devoid of surplus mortarthereby preventing the scaling or peeling off of the top surface of the concrete. The armored surface produced by this method will prolong the life of the roadway by minimizing the abrasion action of the traffic on the surface of the road because of the fact that the top layer of stone serves as an armored surface, which will greatly prolong the life of the road.

Referring more particularly to Figure 7, there is herein shown a modified form of the screed involving the use of removable flared wall members which may be attached to the front or to the rear walls, or both, of the screed. These removable wall members are for packing the material along the side forms 2. Furthermore a central packing member may be aflixed to the central part of the screed at the front or at the rear, or both, for the purpose of packing the road material along the center joint.

The object of this device is to prevent the formation of voids or honeycombing as indicated at 26 along the side forms. This honeycombing or voiding is particularly to be noted when the side forms have deformed vertical faces as shown at A. The flared wall member at the left end of the screed has been removed. The wall of the screed is provided with horizontally elongated openings 29 adapted to mate with vertically elongated slots 28 to receive bolts or other fastening means for securing the wall member 21 to the screed. The wall member is designated generally at 21 and is formed with a vertical web or flange 30 and a horizontal web or flange 3|. The slots 28 are produced in the vertical web 30, which vertical web is adapted to be placed against either the front or rear wall of the screed.

The removable member 2'1 carries a baffle plate HA to prevent the coarse material from being projected over the top of the side form. Such member l'l--A is positioned so as to perform the function of preventing the stone or coarse aggregate from rolling over the side forms; however, the small arched portion |'lB will permit surplus water to drain off over the side forms. This arched portion HB will be of such dimensions as to prevent the coarse stone from moving therethrough.

The horizontal flange 3| is formed with a flared or inclined wall I6E having end wall sections IB-F which incline not only rearwardly as does 7 the wall section l5-E but also flare downwardly until the same merge with the horizontal flange 3|. The wall section i6-E thrusts thematerial downwardly and the end wall sections l6-F tend to converge the material to the central wall section ld- E whereby the material is compacted downwardly progressively as the screed is moved forward. The end wall section l6F, owing to their transverse inclination, will also force the material downwardly as the screed is reciprocated by the eccentric H and arm ID. This compacting of the concrete downwardly causes the same to fill out against the side forms thus preventing the formation of voids and honeycombing.

On the opposite end of the screed there is shown a modified form of removable wall member, which is not provided with a baifie plate but which contains the inclined wall sections Iii-E and l6F. The outer wall section l6F is omitted and this device is so mounted that it bridges over the tread of the side form 2.

In the central portion of the screed is a central detachable member 32 which is in most respects similar to the left endmember in that it is adjustably secured in substantially the same manner and is formed with the central inclined wall iii-E and the two inclined end wall sections l5-F made in the lower horizontal flange. This member is not provided with any side baflie plate. The central member is positioned in the center of the screed whereby the wall section l8-E will pack the material on one side of a division plate D, which is sometimes used in road construction. Inorder to prevent honeycombing, this plate if deformed, requires an excessive amount of hand spading. It will be understood that by the use of the attachment 32 such member 32 will thrust coarse material down along the plate D and compact it to prevent honeycombing along the plate throughout the length of the roadway. It may be desirable to attach thrust members ifi to the screed so as to more thoroughly compact the concrete through the entire width of the road.

The edges of the roadway, as well as the middle. are considered the two Weakest points in modern roads. Therefore it is important that the efficiency of the road at these points he increased to the maximum. In order to tie the road slabs together, dowel bars as indicated at B, are used at spaced intervals longitudinally of the road. Associated with the dowel bars are load transfer plates L. These plates have anchor elements M which project back into the slab to hold these plates securely in position. Therefore, the dowel bar B will bear against the shear plates L through which the bars pass and will transfer the load from one slab to the other and will prevent the concrete from shattering due to excessive loading.

Referring now to Figure 8 this figure shows at the left hand end of the screed a device similar to that shown at the right hand end in Figure 6.

The recessed portion beneath the inclined walls lE-E and l6 F actually forms a curb O, representing comparatively loose, coarse material, which is progressively compacted by the shoulder or wall Hi -E and. by the shoulder or wall section i'F. This curb O is thrust down along the side forms and compacted substantially by the entire weight of the screed and finished with the bottom face it of the screed.

Rigid requirements for high strength concrete now being demanded call for further radical improvements in vibrating apparatus. Therefore, in addition to surface vibration as described herein, I propose to attach to the finishing machine an internal vibrated apparatus, which will vibrate the concrete internally prior to the screeding operation, as well as immediately after the preliminary screeding of the concrete. The strength of concrete is greatly depreciated because of the air pockets or minute bubbles as they might be called being trapped in the plastic mass.

In order to dispose of these minute air pockets in the plastic concrete, I provide an internal means of vibration, which may be attached to the conventional finishing machine, of which 35 is the frame of said machine; 36 represents the screed of the finishing machine, which may be of the conventional type or of the improved type illustrated in this application. The screed rests on the side forms 37 and is reciprocated in the conventional manner.

The internal vibrating apparatus comprises frame members 248, which are pivoted to the finishing machine at 3 3. The frame is provided with wheels 33, which operate on the side forms 37!. These wheels 33 are provided with rubber tires so as to prevent the vibrations being carried to the side forms.

There is a vertical housing '52 at each side .of the frame. The transverse frames 53 are supported by the housings. The frames '53 are cushioned by the spring members 5d. The transverse shaft 55 is supported by the transverse frames 53. There are a series of rotary members 56 supported by the shaft in a rotating position. These members 56 are provided with a series of prongs "5?, which are secured to the rotary members 56, which are preferably made of tubular sections. These members to rotate by gravity progressively by the forward movement of the machine by projecting these pins down into the plastic concrete to the desired depth. Their contact within the plastic concrete will produce the desired rotary movement of these vibrating elements in and out of the plastic concrete progressively as the machine moves forward.

The shaft 55 and the members 56 are supported immediate of the housings 52 by a series of die frames or brackets 58, which are secured to the transverse members 53 and project down and engage the rotating members 56.

When operating the machine, the concrete is placed on the subgrade of the road and is struck off to the desired height above the side forms by the strike-off member 553, which is arranged to be adjusted up and down to and from the concrete by the hand wheels fill and the screw members 6!.

As the machine moves forward, the concrete is struck off to the desired height and the pins or elements 5? are moved down into the plastic concrete to desired depth and progressively as the machine moves forward vibrations are produced on the beam members 53 by the mechanical vibrators 62, which are actuated by the universal shaft 553, power being transmitted from a suitable power unit positioned on the finishing machine, or if desired, these vibrators may be operated electrically.

It will be understood that a large number of vibrating elements 5? penetrate the plastic concrete and are vibrated progressively as the machine moves forward and these elements pierce the plastic concrete, and as the shaft rotates, the elements are withdrawn from the plastic concrete progressively as the machine moves forward. Therefore, substantially all of the air pockets are punctured so the air may be released from the mass of material.

The vibrating elements 51 are pointed at their ends so as to prevent the possibility of depressing any of the coarse aggregate. It is very important that the coarse aggregate remains closely to the top surface of the concrete. Therefore, these vibrating elements are pointed to prevent any possibility of thrusting any of the coarse aggregate downwardly.

Immediately back of the internal vibrating element is positioned a screed member 36, which reciprocates progressively as the machine moves forward so that the compaction of the concrete by the screed is materially assisted because of the internal vibration of the concrete immediately forwardly of the screed.

In order to induce maximum compaction and assist in the surfacing of very dry concrete, a sufficient number of vibrating elements 64 are supported on the vibrated frame 53 with the spring members 65 to facilitate the required vibration on the screed by the mechanical method.

It will be understood that electrical vibrators may be used in lieu of the mechanical vibrators as illustrated.

It will be understood that the vibrators may remain in position when screeding forwardly or backwardly. Therefore, the concrete may be treated by vibration both forwardly or backwardly as may be desired.

It is important to note that in the construction of concrete roads, involving the use of reinforcing mesh as indicated at 66, the bottom course of concrete 6! is first positioned and struck off to the proper elevation by the strikeoif plate 59 and during the forward movement of the machine-while the bottom course is being struck off, the vibrating elements are moved down into the plastic concrete by the hand wheels 68 and the threaded screws 69 or by some other suitable means.

After the bottom course has been struck off and vibrated, the mesh 66 is then laid and the top course of concrete I is placed and struck off to the proper elevation by the strike-off plate 59. The machine is then moved forward with the vibrating elements moved down into the plastic concrete. The vibrating elements will vibrate the concrete mass internally.

The vibrating elements 57 will more or less contact the reinforcing 66 so that the vibrators will cause vibrations to be carried throughout the reinforcing, as well as throughout the mass of concrete.

It is understood that the strike-off member 59 may also be used for cutting and installing transverse contraction joints if desired.

A longitudinal joint H may be produced by suitable joint cutting element 13. This element may consist of a substantially flat bar as shown, which is secured to the frame 53, and is arranged for up and down adjustment by the screw and hand wheel 8|A. The member 13 may be moved down so as to contact the reinforcing steel 66 so that the member 13 will vibrate the steel reinforcing.

I have found that by placing a plurality of bars 13 to the frame 53 it has been found practical to vibrate concrete when used in connection with grids. I have found by this method very uniform vibrations can be supplied to grids and very stiff concrete can be effectively vibrated into the grids for bridge decks, railroad crossings and the like.

When using this apparatus in connection with the installation of grids, the vibrating elements 51 are moved down into the pockets of the steel grids, thereby vibrating the concrete internally and providing means for ejecting the air. When the grids are simultaneously vibrated by the plurality of bar members 73, it has been found that concrete having no slump whatever is effectively compacted and voiding is entirely eliminated.

It will be understood that this joint cutter is simultaneously vibrated because of its contact with the frame 53.

It is obvious that various changes and modifications may be made in the details of construction and design of the above specifically described embodiment of this invention without departing from the spirit thereof, such changes and modifications being restricted only by the scope of the following claims.

What is claimed is:

1. In a road building machine, a screed, means to reciprocate the screed, said screed having upwardly-arched central and end bottom portions, a transverse joint forming blade carried to move and reciprocate with the screed and having upwardly-arched central and end bottom edge portions, and means to move the blade up and down with respect to the screed.

2. In a road building machine, a reciprocating surfacing member, means for moving said surfacing member backwards or forwards, and walls carried by the forward and rear portions of the member, said walls being at the end portion of the member only and being flared upwardly in opposite directions from the base of the member, the walls also flaring toward the central part of the member and toward the plane of the working surface of said member.

3. In a road building machine, a forwardly movable and laterally reciprocating surfacing member having inclined longitudinal walls at the end portions only extending over the treads of the side forms and for a short distance inwardly of such side forms and a shield member following the surfacing member and adjustably supported with respect to the rear portion of said surfacing member and to the treads of the side forms.

4. In a road building machine, a surfacing member, means to move the member backwards and forwards, means to reciprocate the member laterally, said member having forward and rear inclined walls at the end portions only thereof for straddling the side forms and extending inwardly for a distance therefrom, said walls being flared forwardly and laterally, shields carried forwardly and rearwardly in close relation to the end portion of said surfacing member, and means to adjust said shields with relation to the treads of the side forms and the adjacent end portions of the surfacing member.

5. In a road building machine, a screed, means to reciprocate the screed, said screed having upwardly-arched end bottom portions, a transverse joint forming blade carried to move and reciprocate with the screed and having upwardlyarched end bottom edge portions, and means to move the blade up and down with respect to the screed.

6. In a road building machine, a screed having an upwardly-arched end bottom portion to form a curb along the edge of the roadway simultaneously with the formation and surfacing of the plastic material of the roadway, a transverse joint forming blade also having an upwardly-arched end bottom portion, means for adjustably supporting said blade from said screed,

means for reciprocating the screed and blade transversely of the roadway, and vibrating means on the screed above the upwardly-arched end bottom portion for vibrating the screed and the cutter simultaneously with the screed from a point above the curb.

JOHN N. HELTZEL.