US2373828A - Method of and apparatus for the construction of roads - Google Patents

Description

vApril 17,1945. E. L. HARRINGTON I I 2,373,828

I METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS Filed March 19, 1940 7 l0 ShQetS-She9t l April l945.- HARRINGTON 2,373,828

METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS Filed March 19, 1940 10 Sheets-Sheet 2 ILI:

lNVENT OR April '17, 1945. E. HARRIINGTON v METHOD OF AND APPARATUS FOR THE CONSTRUCTIONOF ROADS 1940 10 shee cs-sheet 5 Filed March 19 v r L 13$ v 5' m hm Sm Q IN V E N TO R fowaro Lf/al'r/hgfan m m M M Q N I l l I l l l ill T: 1 .1 NM E w W mm. l||llfliiwullll a RN R1: fi H l HHuul un INHHHHHMMHHUHN WMW hWW I i f Li r Cr a w. %N 5 3 o n J F w m a w RN m m. RM.- Q.

April 17, 1945. v E. HARRINGTON A 2,373,828

METHOD OF AND APPARATUS FOR IfHE CONSTRUCTION 0F ROADS Filed March 19, 1940 10 SheetsShet 4 INVENTOR April 1945. v E. LAHARRINGTON I 2,373,828

METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS Filed March 19, 1940 A 10 Sheets-Sheet 5 IINVENTOR I [dn amL/rarringfm v M M E. L. HARRINGTON 2,373,828

METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS April 17, 1945.

' Filed March 19, 1940 10 Sheets-Sheet 6 April 1945- I E. L. HARiTINGTON 2,373,828

METHOD OF AND APPARATUS FOR THE CONSTRUCTION ROADS Filed March 19, 1940 1o Sheets-Sheet '1 c: )I 20 :1; flgll o o I 12 INVENTOR Ap 1945- E. HARRINGTON I 2,373,828

METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS Filed March 19, 1940 10 Sheets-Sheet INVENTOR April 17, 1945. 'E. HARRINGTON 2,373,828

METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS Filed March 19, 1940' 10 Sheets-She et 9 Y April 17, 1945- E. HARRI'IVNGTON METHOD OF. 'AND APPARATUS FOR THE CONSTRUCTION OF ROADS Filed March 19, 1940 10 Sheets-Sheet 10 M 15w A 2 NW N w% v/ mm MA it Q A \H W, a a g. 5 (a: 3% NE llll NQ E Patented Apr. 17, 1945 METHOD OF AND APPARATUS FOR THE CONSTRUCTION OF ROADS Edward L. Harrington, Pittsburgh, Pa., assignor to Blaw-Knox Company, Pittsburgh, Pa., a corporation of New Jersey Application March 19, 1940, Serial No. 324,755

, 11 Claims.

This invention pertains to the art of paving and is for a method and apparatus. for the spreading of concrete in the laying of roads or like paving operations.

The present practice in the building of concrete roads is to place form rails along each side of the lane to be paved after the grading has been completed. Sometimes the lane is the full width of the road to be constructed, but more frequently the road is constructed of parallel lanes 8 to 12 feet wide. Concrete is dumped between these rails, spread by any suitable means, and the surplus pushed forward by some kind of a strike-off so as to leave an approximately level but unfinished surface a few inches below the desired top surface. On this surface steel reinforcing rods or mesh are placed, and concrete then placed above, spread, and the surplus again pushed forward, usually by a finishing machine which at the same time smooths and irons the surface as closely as possible to the final requirement.

Hitherto it has been customary for preliminary spreading of the concrete to be done by apparatus on the concrete mixer itself; but recently, especially on large paving operations requiring the placing of a large yardage and employing more than one mixer, especially where the work is conducted in a narrow lane, the practice has grown customary for the mixer to dum the concrete more or less indiscriminately between the road rails, taking care only to provide a sufficient quantity and to avoid too large a surplus. leaving the spreading as well as the pushing forward of the surplus to be accomplished by other means.

Accordingly, lateral spreading is done by hand or special Spreaders. and the striking off and moving forward of the surplus so as to leave the concrete approximately level for the steel reinforcement by strike-oil members pushed by various means. The so eeds of the finishing machines, which usually oscillate transversely of the road, push forward the surplus concrete for the final finishing process only; and as would be anticipated, the amount of this surplus concrete varies greatly both from point to point longitudinally along the road but also from point to point transversely of the road, when in contact with the screed. Because the material has some fluidity, it will rise back of the screed to some extent. depending on the height of the surplus material in front of the screed. Variations in the distribution of surplus material in front of the screed accordingly produces some corresponding variation in the surface back of the screed, these variations being manifested as transverse and longitudinal waves in the surface.

According to the present invention I provide an apparatus for spreading the concrete transversely over the distance between the rails, I also provide a method and apparatus whereby a pile of surplus concrete is moved back and forth across the surface of the road between the rails as the apparatus is advanced thus spreading and leveling the concrete. I prefer that this means for moving the concrete back'and forth also work the pile of material forwardly in the direction of the movement of the apparatus as it is carried back and forth. Moreover, I prefer to provide a method and apparatus wherein a scraping or leveling operation in a forward direction follows the first transverse scraping of material, there being a screed or other transverse strike-off means back of the transversely moving scraper to further spread and even off the surface of the concrete, the back and forth scraping operation, however, being effected in such a manner as to prevent the building up of any undesirable surplus of concrete in front of the screed or strikeoif whereby only a surplus of concrete is maintained in front of the screed sufficient for the most effective operation of the screed. By thus maintaining a controlled surplus in front of the screed, resistance to forward movement of the screed is substantially uniform, and since the depth of surplus material in front of the screed or strike-off is controlled and kept substantially constant along the length of the paving and 7 crosswise of the screed, waves in the surface back of the screed due to variations in the distribution of material in front of the screed are substantially completely avoided.

According to a. preferred embodiment of my invention there is provided a supporting frame mounted on wheels for movement along the form rails at each side of the roadway being built. This supporting frame is provided with a transverse runway along which a transversely movable carrier or trolley may b reciprocated. A scraping means depends from the carrier or trolley and means is provided for raising and lowering the scraping means so as to determine the thickness of the bed of concrete being laid. Power driven means is provided for moving the trolley back and forth along its runway, and

mechanism is provided whereby as the trolley approaches each limit of its travel, the position of the scraping means with respect to the pile of material being scraped is shifted so that the scraping means will be moved at the limit of movement of the trolley from a position where it is facing toward an outside rail of the road to a position where it is facing toward the middle of the road.

Mounted on the supporting frame back of the trolley is a vertically adjustable screed which is preferably provided with a vibrator, the sc eed being parallel to the runway along which the trolley movesand being positioned a predetermined distance back of the path of travel of the scraper so that the transversely movable scraper determines the toe of the pile of surplus material in front of the screed- A power plant is mounted on the supporting frame'and there are connections for transmitting power from the power plant to the trolley. There are also connections for driving the carriage along the rails operated from the same power plant whereby the back and forth movement of the trolley is corre-.

lated to the travel of the frame along the road bed. Another driving connectlon transmits power from the power plant to the vibrating screed.

My invention may be more fully imderstood by reference to the accompanying drawings in which Figure 1 shows a top plan view embodying my invention;

Figure 2 is a side elevation of the machine shown inFigure 1;

Figure 3-is a rear end view of the machine shown with the screed being broken away to show the scraper which is located in advance of it;

Figure 4 is a detail view showing a part of the of a machine asvasas mechsnism,shown in Figure 15 in which one of-thespresderbladesisdowmand l lgure l'l-isasimilarsectionin whichthe oppositescrsperbladeisshowninelevated osition.

Referringflmttoliguresltollinclusive,the machhiecomprlsesairamedesignatedgenerally aslformedofstructuralmetalmembers. Itis with two front, wheels 3. one at each sideofthemschineandtworearwheelsl,'one ateachsideofthemachine. Thesewheelsare flangedtorollalong atrackpmvidedbythe formsAateachsideofthepavement.

Extendingacrossthefullwidthofthe frame are two spaced-apart channel members 5 and 6 Y which form a runway for a carrier or trolley deschain drive through which the trolley or carrier for the scraper is reciprocated;

Figure 5 is a transverse section through the trolley and that portion of the machine which provides the runway for the trolley, the view being in substantially the plane of line V-V of Figure l;

Figure 6 is a horizontal section in the plane oflineVI-VIofFigure 5;

Figure 7 is a fragmentary view showing a front elevation of a portion of the frame of the ma,- chine with the trolley and scraper;

Figure 8 is a detail view of the scraper itself, the view being a side elevation of the scraping blade;

Figure 9 is a schematic view showing various portions -of the scraper in relation to the travel of the trolley, the view being a top plan view;

Figure 10 is a diagrammatic view showing the swinging movement of the scraper from one position to the other, the view being also a plan view;

Figure 11 is a transverse vertical section through that portion of the machine which supports and braces the screed and through the screed itself; V

Figure 12 is a front elevation showing a modifled form of scraper in which the scraper has two blades instead of one;

Figure 13 is a transverse section through th mechanism shown inFigure 12, the view bein substantially in the plane of line XIII-XIII of Figure 12;

Figure '14 is a side elevation of a machine embodying the construction shown in Figures 12 and 13;

Figure 15 is a front View showing another form of spreader or scraper;

Figure 16 is a section through one side of the ignated generally as I. There is an open space (seeFigure 1) Ibetweenthetwochannelsi and 8 providing a clearance for the trolley and the parts which are carried thereon.

Extending crosswise of the machine to the rear of the channel 6 is a structural member II, and byreferencetoFigure 11 itwillbeseenthatth-z structural member II is provided with an upright supporting frame ii. The upright supporting structure ll, formed of the several spacedapart uprights, is provided at intervals across the widthof the machine with bearings 12 for a rock shaft ii. The rock shaft I3 is provided with arms i4. Depending from the arms ll are adjustable links l5, and the lower ends of the links I! are connected through vibration dampening connections at Ii to a box-like screed i'l within which is a vibrating mechanism iii. The general construction of the screed and of the vibrating mechanism may be similar to that disclosed in the copending application of William M. Venable. Serial No. 291,711 filed August 24; 1939. Connected to one of the arms I4 is an upwardly extending link i! the upper end of which is threaded and which passes through a nut 20 carried on the support II and which has an operating crank 2| thereon, the arrangement being such that when the crank 2| is turned, the nut 28 will move the link I! up and down thereby rock- 'ing the arm II and the shaft I! to correspondingly raise and lower the screed. An indicator 22 moving alon a calibrated scale 23 shows the height of the screed. For permitting the vertical adjustment of the screed while resisting the thrust to which the screed is subjected in the forward travel of the machine, adjustable parallel links 2| pivotally secured to brackets at the back of the screed are provided, the rear ends of these links being pivotally attached to suitable structural members 25 rigidly carried on the frame.

The vibrating member It includes a powerdriven shaft 2 with eccentric elements thereon (not shown) so that when the shaft is rotated at high speed, the screed as a whole will be vibrated. The vibration dampening connections I! serve to prevent this vibration from being transmitted, at least to any substantial intensity, to the frame 0f the machine, and it should also be stated that 21 .(see Figures 1, 2 and 3). At is a transmission through which power from the engine is provided for moving the trolley back and forth along its runway, for driving the wheels 3 and 4, and for vibrating the screed. This drive which forms no part of my invention per se transmits power to two shafts 2 5 and best shown in Figure 3. Shaft I0 drives a sprocket wheel II to drive a chain 32 (see Figure 2) which chain passes around sprocket wheels for driving the wheels I and 4 on one side of the machine. Shaft 2! drives a similar sprocket wheel 3| which in turn drives a chain 32 for driving the other two wheels 3 and 4 at the other side of the machine. The wheels on one side of the machine are preferably geared to the source of power separately from the wheels on the other side of the machine in order that one side of the machine may be driven faster than the other in going around a ciu've. \The power plant also drives a pulley I! (see Figure 3) which drives belts 34 for transmitting power to the shaft 25 of the vibrator in the screed. This power transmitting mechanism to the vibrator constitutes no part of the present invention and is more fully shown and described in the said copending application of William M. Venabl and is merely referred to here for the purpose of fully understanding the general construction of the machine.

In the construction of the machine illustrated in Figures 1 to 11 inclusive, the power plant serves to further drive a shaft 35 (see Figure 1) having a sprocket 31 thereon (see Figure 4) which sprocket drives a second sprocket 35 through a chain 39. The sprocket 38 is keyed to a disk 40 through a shear pin 4| (see Figure 1) so as to drive a short shaft 42 having a sprocket wheel 43 at its forward end. A trolley-operating chain 44 passes around the sprocket wheel 43. Adjacent the opposite end of the runway for the trolley there is a sprocket wheel 45 around which the chain 44 passes, the sprocket wheel 45 being carried on an adjustable bracket 46 (see Figures 1 and 4) through which a proper tension on the chain 44 can be maintained.

The chain 44 is provided for moving the trolley 1 back and forth, and the transversely movable scraper for spreading the concrete is suspended from this trolley. The scraper may take a number of different forms and may be operated in a number of difierent ways. The particular scraper and drive for the trolley shown in the form of the machine illustrated in Figures 1 to 11 is fully shown and described in'the copending application of Charles A. Long, Serial No. 353,860 filed August 23, 1940.

The trolley 1 comprises a suitably constructed frame 50. It is provided on its forward side with two spaced-apart rollers 5! which extend into the channel 5 and which roll along the inside of this channel as a trackway. The frame 55 is also provided with two flanged upper rollers 52 which travel along the top of the channel member 5. The frame is likewise provided with two flanged rollers 53 positioned below the rollers 52 and which bear against the underside of the channel 5. This general construction is best shown in Figure 5 and by this arrangement the trolley may move back and forth along its runway but is restrained from vertical movement in the runway.

The trolley is provided with a vertical sleeve 54 at the center thereof. A post 55 passes through this sleeve. To the lower end of this post is secured a scraping blade 55. The top of the post 55 is threaded and there are two large hand wheels or nuts 51 and 58 through which the threaded upper end of the post 55 is screwed. The hand wheel 51 is provided for raising and lowering the post 55 to raise and lower the scraper 55, and the hand wheel 58 is provided as a lock nut for the hand wheel 51. To change the elevation of the scraper 55 the hand wheel 58 is first turned to back it away from the hand wheel 51 after which the hand wheel 51 is turned to raise or lower the post 55. When the scraper is at the desired elevation, the hand wheel 58 is tightened down against the hand wheel 51. This arrangement allows the scraper to be adjusted vertically to any given elevation within the range provided for and leaves the post 55 free to rotate so that the position of the scraper may be changed.

For moving the trolley back and forth the chain 44 is provided with a special link which carries a transverse pin 50 which may be clearly seen in Figures 5, 6 and 9. Supported on the frame of the trolley is a vertically slotted guide 6| into which one end of the pin projects, and opposite the guide BI is a slotted upper guide 52 and a slotted lower guide 63, the guides 52 and 53 being directly opposite the guide 5| and being in alinement with each other. The other end of the pin 80 is adapted to extend into one or the other of these guides 52 and 53. The arrangement is such that one end of the pin 50 is always in the guideway 5| and the other end of the pin 60 is either in the' guide 52 or 53 except at the time that the link carrying the pin 60 is passing around one of the sprockets 43 and 45. When the pin is moving along the upper reach of the chain, it moves the trolley in one direction. As it passes around one of the sprockets 43 or 45, its movement is principally in a vertical direction and when it is in the lower reach of the chain, the trolley is of course moved in the reverse direction. The mechanism described provides a sim ple arrangement whereby the trolley may be moved back and forth along its runway while the chain 44 is driven continuously in one direction. In order to guide the pin 60 when it is passing around the sprocket and is between the upper and lower guides 82 and 53, the frame of the machine is provided as shown in Figures 1 and 9 with fixed guides 450, the purpose of which is to prevent the pin from twisting or pulling out of line.

In the operation of the scraper illustrated, the scraper is dragged back and forth by the back and forth movement of the trolley. As it nears each limit of its travel it is swung in such a manner as to pass from one side of the pile which it is pushing to the other side of the pile so that when the movement of the trolley is reversed, the mass of material being pushed by the scraper will be carried along in the reverse direction. Preferably, as shown in Figure 9, the scraping blade 56 is at an angle to the direction of travel of the trolley so that it not only carries the material sideways but tends to shove it forwardly. The scraper is in a predetermined spaced relation to the screed so that the inner end of the scraper determines the toe of the material which may pile up in front of the scraper, which in turn limits the height of the pile of such material. This is illustrated in Figure 11 wherein B is the layer of concrete and S is the surplus in front of the screed.

For reversing the position of the scraper the post 55 is provided with a horizontally projecting arm 84 which is perpendicular to the plane of the face of the scraper. The forward end of this arm is provided with a roller 88 best shown in Figures 5 and 6. Secured to the underside of the frame of the machine forwardly of the runway and spaced inwardly from each end of the runway are fixed abutments or striking plates 88A and 663. These may be formed simply from pieces of angle iron welded to the underside of the frame of the machine with one leg of the angle projecting downwardly. These striking plates are so positioned as to be engaged by the roller 65 on the end of the arm 84 as the trolley.

Figure 9. The trolley will continue to move toward the right but as the abutment cannot move further in this direction, the further movement of the trolley will cause the arm 64 to transmit a rotating motion to the post 85 causing the inner edge of the scraper to move away from the screed. At one position in its movement the scraper will be parallel with the screed as shown in the dotted line position X in Figure 10. Further movement of the trolley toward the right as viewed in Figure 9 causes this rotary motion of the post 88 to be continued untilthe position of the scraper has been reversed and the parts are in the position shown at X The stop or striking plate "A is so positioned that the reversing movement of the scraper will be completed at the time that the trolley is at the furthest limit of its movement toward the right as viewed in Figure 9 at which time the transverse pin 60 on the chain will be passing through the fixed chain guide it. The movement of the trolley will then reverse and the scraper will be dragged toward the left until the roller 65 engages the striking plate 888, and as the travel of the trolley continues toward the left, the blade will be again reversed to the position shown at X.

It will be observed that the trolley is moving as the position of the scraper is changing so that the scraper in swinging into the position shown at X in Figure 10 and then swinging to the reversed position, travels from one side of the pile which is being pushed by the scraper to the other. The length of travel of the trolley and the position of the striking plates 68A and 68B is such that the scraper will swing out close to the rails A thus assuring of the spreading of the material even close to the rails, especially as the scraper will sweep some of the pile of material close to the rail around with it.

In order to hold the scraper from changing its position except adjacent the limits of travel of the trolley, a latch mechanism is provided. In

the embodiment of the invention illustrated there are two similar latch elements 88, one being at the biasing force of the spring 88 until the shoulder 880 of the latch snaps over the arm. One or the other of these latches holds the am to prevent the scraper from being turned. on the underside of the frame adjacent the striking plates 88A and 68B are cams I8. Secured to the underside of the frame of the machine adjacent the striking plates 88A and 88B are cams 18A and "B respectively. Each of the operating extensions 88b of the latches 88 is provided with a roller 88d for cooperation with one of these cams. As best shown in Figure 7, when the roller 88d of the left-handlatch rides under the cam "A, the latching terminal 880 of the latch will be raised out of engagement with the arm .88.. This will occur at just the moment when the roller 88 on the end of the arm 88 is striking the abutment 68A. This releases the latch to permit the scraper to turn. When the scraper is nearing the opposite limit of its turning movement, the arm 84 will engage under the other latch, which in Figure '7 would be the right-hand latch, and the scraper would thus be locked until the right-hand latch engaged its releasing cam 18B. Stops a (see Figure 6) prevent the arm 84 from swinging beyond the latching position.

As hereinbefore stated, the specific mechanism for operating the trolley and for turning the scraper i the invention of Charles A. Long and is described in the copending application filed by him, it being contemplated in my invention that any type of scraper may be moved back and forth through any suitable mechanism so long as the scraper is manipulated in such a way as to pass from one side of the pile to the other adjacent the limits of travel of the trolley.

Another example of a scraping mechanism which may be used in my invention is illustrated in Figures 12, 1'3 and 14. In the modification shown in Figures 12, 13 and 14, I5 designates a trolley which is movable back and forth along a runway 18 provided on the frame of the machine. Carried on the underside of the trolley 15 is a shaft 11. Hung from the shaft TI is an archshaped frame 18 having scrapers I8 along the two edges thereof. Secured to each end of the shaft I1 is a segment-shaped member 88 having a gear rack 8| on its periphery. Supported on the trolley is a transverse shaft 82 having a pinion 88 at each end thereof, the pinions 83 engaging the racks 8| on the members 80. By rotating the shaft 82 in one direction or the other, the shaft 11 may be rotated through a limited arc to tilt one or the other of the two scraping blades 19 down into scraping position. In the specific arrangement shown, the shaft 82 is operated by .means of a sprocket 85 secured to the center of the shaft 82. A sprocket chain 86 is guided around the top of the sprocket wheel 88, the return reach of the chain passing through the carriage clear of the sprocket. The chain 88 is guided over sprockets 81 adjacent each end of the runway and one of the sprockets 81 may be driven in the manner previously described except that with this arrangement the chain is driven in a reverse direction instead of continuously in one direction. The reversing movement of the driving sprocket 81 may be accomplished mechanically or manually'a will be readily unde stood by those skilled in the art. The trolley I8 is provided with stops 88 positioned to be engaged by the terminal portions of the arch-shaped scraper 18, as is clearly shown in Figure 12.

In the arrangement shown in Figure 12, it may be assumed that the chain 88 is traveling in the direction of the arrow. At this time the righthand scraper is elevated against its stop II and the left-hand scraper is in scraping osition. When the trolley reaches the limit of its travel, the direction of the chain is reversed. The reversing movement of the chain will first cause the sprocket 85 to be rotated to rotatethe pinions 83 and thereby transmit a rotary motion to the shaft 11 in a clockwise direction. This will cause the right-hand" scraper as viewed in Figure 12 to swing down and the left-hand scraper to swing up. When the left-hand scraper I9 has come up against the left-hand stop 88, the shaft 82 provided with an adjustable stop III to limit the downward travel thereof so that after a blade has lowered to a predetermined extent, it will be stopped.

Parallel sprocket chains I02 are employed which are driven in unison and which are reversible. The chain at each side of the carriage is guided over guide sprockets and then over the cannot rotate further and the chain 86 will then be effective for moving the trolley in the reverse direction. When the direction of travel of the chain is again reversed, the shaft 82 will be rotated in the opposite direction and the scraper returned to the position shown in Figure 12. A

limited relative movement between the trolley and the reversible driving chain 86 is thus utilized for shifting the position of the scraper.

The arrangement shown in Figure 12 has an advantage over that previously described in that should it be necessary, the position of the scraper can be shifted not only at the ends of the travel of the trolley, but at any intermediate point in the travel of the trolley.

It will be noted that with the arrangement shown in Figures 12, 13 and 14, when the lefthand scraper 19 swings upwardly and the righthand scraper 1'8 swings downwardly, the righthand scraper will come into position against the opposite side of the pile. In order to prevent any spilling over of the material with this type of scraper, a retaining plate 89 is provided at each side of the frame of the machine to extend from a point adjacent the form rail A to the underside of the frame.

For adjusting the scraper vertically I may raise and lower the runway for the trolley. This mechanism for raising and lowering the runway is shown in Figures 12 and 14 wherein there are threaded posts 16a at the end of the frame forming the runway which passes through nuts secured to the frame and the lower ends of which are mounted in bearings on the main frame 2 of the machine. TWo posts are intergeared as illustrated so that by turning a crank 18b secured to the top of one of the posts, both of the threaded posts may be turned at the same time for raising or lowering the frame members which provide the runway.

My invention contemplates, therefore, that vertical adjustment of the scraper may be made either by adjusting the scraper vertically with respect to the trolley or by raising and lowering,

a. portion of the machine, as for example,-the runway on which the trolley is carried.

In the modification shown in Figure 15, 9| designates the runway for the trolley 92. This trolley is provided with a shaft 93 having a sprocket 94 at each end thereof. There are two scrapers 95 and 96 eachwith an upwardly extending portion 95a and 96a respectively thereon. Each of these upwardly extending portions carries a, rack 91. Guide rollers are provided at 98 and'99. The shaft 93 is provided with a pair of pinions Hill which engages the rack 91 on both extensions. The arrangement is such that when the sprockets 94 are rotated in one direction, one of the blades is lowered and one of them is raised, and when the direction of rotation of the sprockets 94 is reversed, the position of the blades is correspondingly reversed. Each of the blades is main sprocket 94. When the chain is moved in one direction the sprockets 94 are operated until the stop H on the descending blade contacts a part of the trolley when the sprocket cannot rotate further, and further operation of the chain serves to move the trolley along its runway. When the direction of the chains is reversed, the sprockets are turned in the opposite direction to reverse the blades, and after the sprockets have turned to reverse the blades, the pull of the chain is again utilized to move the trolley. In this modification as in the modification shown in Figures l2, l3 and 14 there is a relative movement between the chain and the trolley which is utilized for shifting the blades.

While the blades in the two modifications described are illustrated as being parallel with the direction of travel of the machine, that is, transverse to the direction of movement of the trolley, it will be apparent that in these modifications the bladesmay also be set at opposite oblique angles so as to push the material forward as well as sideways.

In using the machine, the scraper and the screed are set at the desired elevation, the latter preferably slightly lower than the former. The

' screed is generally tilted crosswise of its length to a very slight angle so that the leading edge is slightly higher than the trailing edge to more effectively iron or smooth out the material, the difference in elevation between the two edges being of the order of about A; of an inch and the adjustable links 24 enable the adjustment to the proper angle to be established and maintained. Concrete is dumped between the forms for perhaps twenty or thirty feet in advance of the machine and ample concrete is provided to assure of the desired depth of concrete being spread. It is contemplated that there will al ways he an excess of material for the machine to spread in order to assure of all voids being completely filled. The machine is then driven forward at a slow speed and as it is driven forward, the trolley is simultaneously driven back and forth to move the scraper transversely of the roadway. The forward speed of the machine is so correlated to the operation of the trolley that the scraper will make overlapping passes or swaths crosswise of the road as it travels back and forth. At any time the operator may stop the forward movement of the carriage and continue to operate the scraper, or he can move the carriage without the scraper operating, the transmission including various clutches forming no part of this invention for securing such selective operation. As the scraper or spreader moves back and forth it accumulates a pile of material at the places where the concrete is piled up and spreads it into the valleys or recesses, completely filling in the space between the two forms to the desired depth. At each limit of travel of the trolley the spreader pulls away from one side of the pile that has accumulated and passes around or over the pile so that as the trolley is moved along in the opposite direction, the pile of material is pushed along in the opposite direction,

some slight shifting of the material in the pile taking place if the scraper or spreader is of the vertically pivoted blade type as the blade sweeps around tospread close to the side rails. This pushing of the material back and forth not only prevents the material from being left in heaps at the side of the pavement, but it produces a spreading action not unlike a troweling action which serves to compact the material. Because the scraper is a predetermined distance in front of the screed it will remove surplus material that would otherwise pile up in front of the screed. At the same time it does not prevent a slight excess from accumulating at the front of the screed as some excess is desirable. In the process of paving, the screed is moved along as the material is worked back and forth, and a. substantially controlled amount of surplus material is maintained in front of the screed uniformly across its width. As previously stated, this is important because in a paving operation the material rises to a slight extent to the rear of the screed r strike-off, and this varies according to the surplus in front of the strike-oil. By maintaining a controlled volume of material in front of the strike-off and keeping it distributed uniformly across the front ,of the strike-off, the material back of the strike-off raises more uniformly, eliminating those transverse or longitudinal waves or ripples that result where the amount of material in front of the strike-oil is continually varying.

Usually in the laying of a roadway an initial layer of concrete will be put down to within perhaps 2" of the top of the forms after which reinforcing may be laid and then a finishing layer of concrete put down on the reinforcing. By reason of the vertical adjustment of the scraper and the screed of the machine described, it is possible for the one machine to perform both operations or it is possible for a contractor to use two similar machines one following the other. Where one machine is used to do both operations, the scraper and the screed may be lifted clear of the paved surface when the machine is traveling backward to the point where it begins to spread the second layer.

An important advantage of the present invention is in the provision of a spreader which works the material back and forth transversely of the roadway. Another important advantage is that by making the spreader or scraper blade oblique to the direction of travel of the trolley, the material may be simultaneously worked sideways and forwardly. Still another advantage is that the scraper will spread the material clear up to the side rails but will not leave the material in heaps adjacent the side rails. It should be noted that while the carriage moves a distance less than the full distance between the rails, the scraper in any case reaches beyond the limits of travel of the carriage to the rails due to the relative movement which occurs between the carriage and the scraping means. It is by this overreaching movement that the pile of material can be pushed across the full width of the area to be paved and then engaged from the opposite side and moved in the reverse direction. By combining the transversely moving scraper with a screed, particularly a vibrating screed, it is possible to prevent the uneven piling of material in front of the screed and at the same time assure of there always being a sufiicient excess for the best results to be secured. The invention thus considerably facilitates the laying of roads and the carrying out of similar paving operations.

While I have illustrated and described certain embodiments of my invention, it will be understood that this is by way of illustration and that various changes and modifications may be made in the machine within the contemplation of my invention and under the scope of the following claims.

I claim:

1. A spreader for concrete paving operations comprising a mobile supporting frame, a spreader mounted on the frame for movement back and forth across the frame transverse to the direction in which the frame is moved, means for raising and lowering the elevation of the spreader, means for driving the spreader, and means for imparting an overreaching movement to the spreader relative to said driving means adjacent each limit of its back and forth travel to transpose the position of the spreader from one side of the pile of material being spread to the opposite side.

2. A spreader for concrete paving operations comprising a. wheeled supporting frame, the wheels of which are adapted for travel along rails at each side of the pavement to be constructed, a spreader member supported on the frame and movable back and forth in a rectilinear direction between the rails, means for driving the spreader, and means for imparting an effective overreaching movement to the spreader adjacent each limit of its travel.

3. A spreader for concrete paving operations comprising a mobile supporting frame, a spreader carried on the frame and movable back and forth across the frame, means for driving the spreader back and forth, and automatic means for shifting the spreader relatively to the material being pushed by the spreader to extend the effective sweep of the spreader at the limits of its travel beyond the range of the actual back and forth movements thereof.

4. A spreader for concrete paving operations comprising a mobile supporting frame, a carriage on the frame and movable back and forth across the frame, means for moving the carriage back and forth, spreading means carried by the carriage and means for shifting the spreader means relatively to the carriage from one operating position to another operating position more remote from the center of the road adjacent each limit of travel of the carriage.

5. A spreader for concrete paving operations comprising a mobile supporting frame, a carrier on the frame movable back and forth across the frame, means for driving said carrier back and forth, spreading means depending from said porting frame, a trolley on said frame movable back and forth across the width thereof, scraper means pivotally carried on the trolley, and means for turning the scraper means about its pivotal axis to substantially reverse the position of the scraper means end-for-end adjacent the limits of travel of the trolley.

back and forth across the width thereof, scraper means pivotally carried on the trolley, means for driving the trolley back and forth, and means for moving the scraper means about its pivot adjacent the limits of travel of the trolley and before the trolley reaches the limit of its travel.

8. A paving machine of the class described. comprising a wheeled frame having a strike-off member extending transversely across it, a spreader movable transversely back and forth in front of the strike-off at a spaced distance therefrom but sumciently close thereto to engage excess surplus material that accumulates in front of the strike-off, said spreader being set oblique advance of the opposite end,means for'driving the spreader and means for reversing the angular position of the spreader with its change in direc tion of travel. '9. A road paving machine comprising a momaterial in front of the strike-o8 and redistribute it in the space to be paved forwardly of the strike-off.

10. A road paving machine comprising a mobile truck adapted to travel on forms at each side of the area to be paved, a transverse runway on the truck, a carrier movable along the runway, a support depending from the carrier, a

paddle-like spreader on the support set edgewise to the surface to be paved, means for moving the carrier back and forth whereby the spreader is caused to effect a preliminary distribution of the to its direction of travel with the end of the spreader closest the strike-off being normally in paving materialwhich may be irregularly heaped in the space between the side forms, said spreader being movable relatively to the carrier in a manner such as to overreach the travel occasioned by the back and forth movement of the carrier, and means for imparting such relative movement to the spreader adjacent the limits of bile truck adapted to travel on forms at each paddle-like spreader on the support set edgewise to the surface to be paved, means for moving the carrier back and forth whereby the spreader is caused to effect a preliminary distribution of the paving material which may be irregularly heaped in the space between the side forms, and transtravel of the carrier to thereby project the spreaderbeyond the pile of material being pushed by it and engage it from the opposite direction.

11. In a concrete paving machine having a supporting frame spanning a strip to be paved and movable along said strip, a carriage mounted on said frame for movement transversely of said strip, mechanism carried by said carriage and adaptedto push a deep pile of concrete in a direction having a component in the direction of movement of said carriage, said mechanism being shiftably mounted in said carriage to selectively engage said pile from either side of said pile,

' means for moving said carriage to-and-fro across verse strike-off means on the truck rearwardlyof the spreader for effecting a furtherand complementary paving operation, said spreader be.- ing arranged with reference to the strike-off in such manner. as to also carry away excess surplus said frame, and means for shifting said mechanism to engage the opposite side of said pile when said carriage is adjacent the limits of its travel.

EDWARD L. HARRINGTON.

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