US1522138A - Machine and method for compacting and surfacing concrete and similar pavements - Google Patents

Description

ND SURFACTNG ORD Jan, 6, 1925.

MACHINE AND METHOD FOR COMPACTLNG A CONCRET'E AND SIMILAR PAVEMENTS Flled June 6, 1923 6 Sheets-Sheet 1 l Filed June 6, 1923 CONCRETE AND SIMILAR PAVEMENTS MACHINE 4AND METHOD FOR COMPACTlNG AND SURFAGTNG lan. 6, 1925.

jan. 5, 1925 1,522,138

MACHINE AND METHOD FOR COMPACTlNG AND SURFACTNG` i W. ORD

CONCRETE AND SIMILAR PAVEMENTS Filed June 6, 1923 6 Sheets-Sheet 5 IMM. r2.7

MACHINE AND METHOD FOR COMPAGTlNG AND SURFACTNG Jan.

W. ORD

CONCRETE AND SIMILAR PAVEMENTS Filed June e, 1923 6 Sheets-Sheet 4 6 Sheets-Sheet 5 W. ORD

CONCRETE AND SIMILAR PAVEMENTS Filed June 6, 1923 61l ioj`'l MACHINE AND METHOD FOR COMPACTlNG AND SURFACTNG Jan. 6, `1925.

Jan. 6

W. ORD

MACHINE AND METHOD FOR COMPVACTLNG( AND SURFACTNG CONCRETE AND SIMILAR PAVEMENTS Filed June 6, 1925 6 Sheets-Sheet 6 NGN Patented Jan. 6, 192.5.

PATENT OFFICE.

WILLIAM om), or CHICAGO, ILLINoIs.

MACHINE AND METHOD FOR COMPACTING- AND SURFACING- CONCRETE AND SIMILAR PAVEMENTS.

Application led .Time 6,

To ZZ lwhoml t may concer/n.'

Be it known that I, WILLIAM ORD, a citizen of the United States, and a resident of Chicago, Illinois, have invented certain new and useful Improvements in Machines and Methods for Compacting and Surfacing Concrete and Similar Pavements, of which the following is a specification.

This invention relates to methods and machines for compacting and surfacing concrete and similar pavements, including highways, fioors, etc., Whichomay be flat or plane or may be concave or convex, as desired. The term pavements, as used herein includes every type of Work for which machines of the general class to which the invention relates, are or may be adapted.

As the machine embodying'my "invention is particularly designed to carry out the method of my invention in its adaptation to the compacting and surfacing of concrete highways, both method and machine Will be herein described with reference t0 this class of Work, Without, however, in anyway limiting the scope of uses of the machine, either in the particular embodiment illustrated and described herein, or iinsruch modified form as may be necessary or'desirable to adapt it to other kinds of structures.

The objects of the invention are fully set -l'orth in the following specification and will be more fully understood by reference therelo, but for convenience, the principal objects thereof are briefly stated to be as follows,viz

In the construction of concrete highways the concrete is discharged in batches, usually, from concrete mixing machines and varies considerably in character in many respects, being sometimes so-called dry and sometimes Wet, and varyingfin kind and grade of limestone, slag and other materials used. In all cases there are apt to be air pockets and Water pockets in the mass. Consequently, after the concrete is discharged upon the sub-surface or foundation, it is spread upon it to a greater depth than is required, (this being done to some extent by operation of the bucket of the mixer, in some instances, and by workmen) and yis then Worked down and compacted, and, in settling, the air bubbles and free or excess 1923. Serial No. 643,618.

`water rise .to the surface. `voids and bulges result which are required to be eliminated.

The highways include grades so-that the compactmg and surfacing machine is required to be adaptable not only to the conc,dltions presented by the concrete on levels, but also to those vastly different conditions presented inwerking up-grade and down* grade respectively, these conditions vary'- lng in degree according to the fluidity of the concrete and steepness of the grade.4

My invention has for its object to provide a machine of the character indicated which is readily adjustable inall necessary particulars to adapt it to all and severally the conditions presented by the particular v vkind and condition of the concrete used, as

well as to all of the conditions further resulting from up-grade and down-grade Working.

The compacting of the concrete is, in the case of my invention, expressed in terms of method effected by a kneading action produced on the mass by means of pressure combined with motion as will be hereinafter fully1 pointed out, the provision of means affording the application of these forces constituting the most essential object and feature of the machine. This object of the invention is comprehensive and includes first'as, in the normal course or speed of travel of the machine, to provide van interval of rest for the concrete between the sucv cessive operations during which air may find its Way to the surface, holes or other defectsI disclosed and remedied before the final finishing is done by a single passage of the machine over the pavement.

The most essential object of the invention is to provide means whereby a mass of surplus concrete is accumulated and maintained in front of the machine to therebymaintain a hydrostatic pressure on the portion of the concrete leveled or struck off andretained inthe roadbed immediately behind the surplus mass and subjected to the kneading action referred to.

A further essential objectof the invention is to provide kneading and linishing elements on the machine which may be reciprocated transversely of the pavement, either during travel of the machine forward and wheels of the latter to pass over obstructions or uneven joints in the side rails without disturbing the operation of said elements or putting any additional strain or load on the when working on up or down grades,

actuating motor and the parts connecting the latter with said elements, and wherein said connecting parts last referred to will permit of some free play and variation in position of the said elements relatively to the frame or carriage Without increasing strains, stresses or load on the motor and said connecting parts.

A further very important object of the invention is to provide means whereby the compacting and finishing elements of the machine may be easily, quickly and accurately adjusted for highways of Varying crowns and for other purposes hereinafter particularly set forth; may be rendered perfectly flat, and may be adapted for concave roadways, such as alleys or passageways, this adjustment being of particularly great valu an also, when working on certain kinds of concrete on levels and grades, the particular advantages resulting-from theseand other adjustments being'hereinafter more fully set forth. The foregoing object includesthat of providing said adjustable means which are at all times so rigid Qr inflexible when in o-pe-ration as to wholly eliminate spring or vibration thereof vertically to cause the formation of transverse grooves in the pavenient surface-the absolute iniiexibility of said means, after adjustment thereof, being quite as important as ease and latitude of adjustment. j

Further objects of the invention will be 4apparent fro-m the following specification. A suitable embodiment of the machine 1nits adaptation to concrete highways is illustrated in the accompanying drawings in which: y

Fig. 1 is a perspective'view of a machii'ie constructed in `accordance with the invention, seen from the rear thereof.

Fig. 2 is a fragmentary rear elevation of the same, partly in section, illustrative of certain details of construction.

Fig. 3 is a top plan View of the machine.

Figs. 4 and 5 are fragmentary front elevations of the machine, Fig. 5 being a continuation of Fig. 4.

Fig. 6 is a side elevation of the machine.

Fig. 7 is a vertical section on the line 7-7 of Fig. 3.

Fig. 8 is a fragmentarytop plan view of the machine, illustrative of the gearing einployed.

Fig. 9 is a fragmentary section on the line 9 9 of Fig. 6. Y Fig. 10 is a section on the line 10-.10 of Fig. 6.

Fig. 11 is a section on the line 11-11 of Fig. 4.

Fig. 12 is a section on the line 12--12 of Fig. l1.

Fig. 13 is a diagrammatic longitudinal section of a pavement and parts of the machine illustrative of the operation of the latter.

Referring first to Figs. G and 7, it will be noted that the frame of the machine, preferably built of structural steel, includes the pairs of parallel side- rails 1 and 2, supported upon the trucks 3 and 4 of the flanged wheels 5 and 6 adapted to travel on the sideforms 7 of the road bed and constituting the side walls of the form between which the concrete is received and held.

The side-rails or beams 1 carry the several cross-beams 8 and 9 and other -frame inembe-rs upon which the motor 10 and the gearing and control devices, hereinafter particularly described, are mounted.

The trucks 4 are rigidly mounted on the said side rails and the wheels 6 thereof are idle, said trucks-being disposed at the eX- treme rear ends of said side rails. The trucks 3 are pivotally engaged with the side rails by means of stud-shafts 11 and each thereof is provided with a pair of said wheels 5, the latter being rigid with drivesprockets 12, the pivotal engagement of said trucks with the side-rails assuring contact of both wheels with the :rails 7 at all times regardless of unevenness at joints in the latter or from other causes. i

The details of construction o-f the framing and details of gearing constitute no part of the invention as the same may be changed and varied as desired and are, generally, selective. Hence, detailed description thereof is omitted.

rlihe gearing includes a motor-driven shaft 13 and such clutches and other elements as are necessary to effect rotation of said shaft 13 to cause the machine totravel relatively slowly'forward and at a higher speed in the reverse'direction' and to effect starting and stopping thereof at will. Sprocket chains 14, trained over the sprockets 12 and over a lill lit)

lill) sprocket-pinion on shaft 13, serve to effeet rotation of the wheels 5.

In rounding curves, for example, or yin, event that, because 'of differences in resistance. to travel of opposite sides of the machine, it is sometimes necessary to cause one side of the machine to travel withrelation to the other. This is accomplished by making the vshaft 13 of three sections normally v coupled to, rotate in unison by means of suitable clutches 16 and .17, each including a part slidably -mounted on the shaft and are the brackets 19 and 20. v.Associated with the beams 8 and 9 and the brackets 19 and 20 and the side rails 1 and 2, respectively,

and suitably carried thereby, are the bearing for vertical shafts 21, 22, 23 and 24 each of which carries an idle-roll 25, said rolls f constituting guides .between which reciprocable elements `26, which, for convenience, I term screeds, move. Each of said screeds comprises an I-beam 27 (constituting an inflexible element) to which there is securedv a channel-bar (to which the reference numeral 26 is applied), the plane faces of said channel-bars being adapted to bear upon and knead the concrete deposited upon the road-bed to compact the same and strike offmsurplusage as is hereinafter particularly described. The disposition of the beams or screeds respectively in front o f and behind the traction or driving wheels of the carriage insures proper spacing of saidbeams, and causes the front beam to keep the rails free of obstructions over which the traction wheels might otherwise have to pass.

Said channel-bars v26 are flexible and are flexed so that the plane faces thereof are rendered arcuate to correspond substantially with the' curvature or crown to be imparted to the road surface as hereinafter more particularly explained. They are secured to the I-beams 27, and their curvature v adjusted, by the means illustrated in detail in Fig. 1l, comprising yokes 28 provided between their ends with T-shaped recesses of dimensions corresponding substantially with the cross-sectional dimensions of the upper fianges of the I-beams. These areslipped upon and moved longitudinally of said I-be'ams to such respective ositions as may be desired. In the ends of t e yokes ,28 are openings through which the threaded end portions of inverted T-bolts 29 pass freely, the head ends 3() of said bolts 29 engaging in openings in castings31 suitably mounted on the flanges of the channel-bars 'i 26. Nuts 32 and 33 on each bolt 29 are disposed, respectively, above and below the cross-heads and serve in lan obvious manner, to permit the said bolts to be vertically adjusted'to flex the channel-'bars to any desired curvature. I

The said screeds 26 are connected 'by means ofchains 34 (Fig. 7) with .inverted T-levers 35 pivotally mounted, at substantially the meeting points of the several arms thereof, upon the side-rails. Theupwardly y extending arms of the levers 35 are con, nected vby means of the J-shaped links 36 Xwth hand levers 37 of which there. are two,

having a common pivotal axis on the studshaft 38,. The curved end s of the links 36 connect with the levers 37, between the ends of the latter 'and straddle the stud-shaft 38 when said-levers 37 are thrown over tothe position shown in Fig. 7 to maintain the screedsl in elevated position. When said levers 37 are so disposed thel axes ofthe pivotal connections between the same and the links 36 are disposed slightly below the plane intersecting the axes of the stud-shaft 38 and the pivotal connections of thelinks 36 with the levers 35 so that the weight of I the screeds tends to'throw the free ends of said levers 37 down.v The latter rest upon the side rails so that/a further downward swing is prevented.

The chains (Figs. 4 to 9 inclusive) 34 con# neet with one each of the lateral larms of said lever 35 and the other lateral arms of the latter are connected witlrvertically reciprocable links 39 which connect with bell-crank levers 40 pivotally secured at their elbows to the frame. Similar bell-crank levers 41 are associated with the levers 42 at the other side of the machine and are coupled with the bell-crank levers 40`by means of' the rods 43.

Thus, obviously, the rocking movements of. the levers 35 arecommunicated to the levers 42 to simultaneously raise and lower the screeds throughout their length. The rods When lowered, the screeds 26 are adapted to rest on the rails 7 and the' chains 34 are then suflciently slack to permit free reciprocation of the screeds. Bolted to the flanges of the channel-bars 26, at the .ends of the latter, are vertically slotted castings or shoes 44 of a very hard metal, such as manganese steel. These are. normally positioned so that their lower wearing faces project very minutely below the plane faces of the channel bars so as to nprotect those portions of the lattermwhich normally wouldpride upon the rails 7, from wear. v Q

Reci Arocation of the screedsis effected by the motor actuated crank-shaft 45 having radially adjustable crank-pins 46 for vary-I fore referred to.

ing the strokes of the screeds. They will also permit the strokes of the respective screeds to be varied relatively to each other, this being sometimes desirable. Preferably, though not essentially, the cranks of the shaft are relatively diametrically opposed so as to move the respective screeds simultaneously 1n opposite dlrections to thereby effect more or less of a counterbalancing of the tendency to impart lateral the use of short connecting rods 47 and 49 and also eliminates the downward push and upward pull on the screeds that practice has shown to result from a 'direct connection between the crank-pins and the screeds. Ball and socket or similar universal joints 50 are used to connect the pitmen 49 with the rockers 48 and the screeds so as to permit of some lateral play of the screeds and not interfere with the canting thereof hereinbe- The gearing between the motor and operating mechanism includes a pinion 51 on the motor shaft which meshes with gear 52 on jack-shaft 53. Rotatably mounted on the latter are three spur- pinions 54, 55 and 56. Pinion 54 is adapted, through gear- train 57, 58 and 59 to rotate the shaft 60 at low speed in one direction, while pinion 55, meshing with spur-gear 6l on said shaft, is adapted to' rotate it more rapidly in the other direction. Shaft `60 is geared to the middle portion or section of the shaft 13 for roating the latter slowly to effect forward travel of the machine and more rapidly reversely. Companion clutches 62 and 6?, keyed to shaft 53 and reciprocable to effect engagement with clutch elements associated with `the pinions 54 and 55, are manually thrown from a neutral position to actuating relation to either of said pinions by means of the manually operable lever 64.

A clutch 65 similarly associated with pinion 56 and manually operable by means of the lever 66, controls the rotation of the stud-shaft 67 geared to pinion 56 and'also geared, by means of bevel-pinion 68 and 69, to the crank-shaft 45. Y

Housings 70 and 71 are preferably provided to cover the motor and gearing. The motor is, preferably, of theinternal combustion ltype with its appurtenances.

The machine frame includes a platform 7 3 `for the operator, which affords a convenient bridge across fresh-laid concrete.

The simplicity of the structure will be appreciated from the foregoing specification and its operation with respect to its action on the plastic concrete will be more fully understood from the following As distinguishedv from machines of the `the strike-off beams referred to in point of weight and area o f surface acting on the concrete and in that, while in operative position, it is wholly unsupported by the carriage. The front screed or strike-off beam 26 carries an apron 74 adjustably bolted to the front flange of the channel beam and projecting far above the top of the lf-beam 27.

This apron permits of and promotes the accumulation of a relatively high level of concrete in front of the strike-off beam which is very advantageous in that it bears upon the lower or road strata of the concrete with a decidedly compacting pressure which tends to displace the concrete directly underneath and even slightly rearwards of the front screed, in an upward direction tending to lift said screed. By making the o weight of the latter sufiicient to resist this lifting tendency, the compactness of the bed is not only maintained, but by the increase in frictional' contact bet-Ween the surface of this mass and the plane face of the screed resulting from the said displacing hydostatic pressure, the aforesaid kneading operation takes place which would not result from the use of a thin or narrow strike-off element nor from one incapable of resisting the lift of the concrete underneath the l same. The mass of aggregate accumulated in front of the strike-ofi' screed is not only heavy but also sticky and presents great resistance to movement by the screed. In Fig. 13, T have diagramniatically indicated the general direction and area of the pressure on the part of the mass disposed below the screed which, by its weight, exerts a counterpressure in the direction vof the indicated dotted lines of force so that said screed may be said to exert a strong compacting pressure forward and downward upon the part of the mass disposed below it. It is quite immaterial whether this pressure is expressed in terms of displacement tending to throw that portion of the mass up or in terms of downward and forward pressure exerted by the screed. Tn either event there is pressure and counter-pressure which, coupled with the movement of the screed, effects the linea-ding and compacting action referred to.

My invention in this regard is founded upon the conception and discovery of this lifting pressure of the concrete and includes broadly the particular means disclosed for I taking advantage thereof and such equivadirections and this lateral pressure exerted o onthe portion of the mass directly underneath the first screed in the direction opposite to that in which the machine is traveling, will crowdthe said concrete back against the mass behind said screed and the resistance to this'pressure causes the squeezing out and upward surge of cement mortar (frequently including pieces of coarse aggregate) and the aforesaid lifting force on the bottom of said screed, such lateral pressure being also efficient in forcing air andv free or surplus water to the surface. This hydrostatic pressure exerted upon the base portion of the mass in advance of the surplus level must obviously be eective to l squeeze .out air and water and practicehas demonstrated that this is true. The ad- Avantages resulting therefrom are immediately obvious to those skilled in the art.

The requisite width of the surface acting on the concrete required to attain'the results above mentioned has avery definite relation to the characteristics of the aggregate and the depth thereof below the screed surface. If the latter is unusually great and the aggregat is of the extreme wet type, the

width of surface of strike-olf screed required to produce the best results will be greater than if the mass 1is ofthe so-called The conditions aforesaid become umore .marked in working up-grade and `it is,

' grades, respectively.

therefore, preferable to ,employ Width and weight of screed sufficient, to meet the ex' tremes most apt to be encountered.

y In this connection the adjustment of curv# ature of the plane face of the strike-oliI screed is of particularly great importance as affording a ready means for meeting the different conditions encountered in working on level stretches, up-grades and down- Assuming the aggregate to be of the average consistency commonly employed, theback or.` lifting pressure referred to will be vgreatest on up-v grade work and possibly entirely lacking on ,steep down-grades.- l/Vhen working on the y latter, therefore, it is advisable to allow for an initially higher crown than the ultimate specified'in order tos provide asurplusage .0f material to'vsettle and to be compacted by the second screed, the curvature of which should accordustrictly at all times with the specified curvature ofthe road. nHence, by decreasing the radius o-f curvature of the front screed during down-grade operations, the higher crown would be presented for settling and further compacting action bythe second screed.

During up-grade work, on the contrary, the radius of curvature of the front screed should be .increased so as to strike olf below the normal crown level because the backpressure of the mass in front of said screed will force enough concrete up behind the front screed to compensate. Obviously, the extent to which curvatures is thus varied will be determnedby the `several conditions presented, viz: the steepness of the grade, fluidity of the concrete, etc.` Y

From the foregoing and from the drawsol ings it will be obvious that a variation in curvature of the bottom of a screed will vary the means strike-off level as there will be a hardly appreciable change adjacent the siderails and the .maximum will occur in the middle ofthe pavement. It will also be apparent that' in working up steep grades the normal tendency of the plastic yconcrete to flow downhill will obviate the necessity of utilizing excess,I` material in front of the for- Ward screed for eecting surge of surface mortar behind the same and that it may even be necessary to lower the mean strike-oli' level of the front screed tao prevent excess surge in the absence of thev excess advance mass.

In practice, I have found that in work on levels the concrete bulges up slightly behind the strike-oh' screed and .that thereafter air bubbles come to the surface and in spots there are slight voids and in others, slight bulges in the surface. A more or less gradual settling now takes place resulting 'largely inbrin ing water to the surface. A sec- 'ond working over of the surface is absolu'telyv necessary to effect filling of the, voids and depression of the bulges but this second 4 i working should be accomp-lishedafter the lapse of a very brief time interval serving mainly to relieve the lconcrete from pressure 1 to permit release of air and water.

It is thereforean essential and important feature of my invention to separate the.

screeds from each other so as to automatically provide a suitabletime interval between treatments of the \surface and thls separation or spalce is primarily provided by interposing themain. supporting and driving truck between the screeds. Preferably,

however, this4 space-is expressed or deter- 1 mined by time intervals in terms of speed of travel. The average speed of travel of the machine approximates live feet per minute. If then the screeds are disposed four feet apart, atimeinterval approximating %(,ths

over the pavement a. second time with a sin gle y`machine as has been heretofore most commonly practiced, and which, under some conditions, l have found to be necessary and advisable in the use of the machine of my invention. Regarded in a broad light, my machine constitutes the equivalent of two separate and independent machines, as will be obvious. This is particularly evidenced by the fact that either of the two screeds may be raised free of the pavement without discontinuing its reciprocation, leaving only one beam active. Furthermore the travel of the carriage may be discontinued while one or both screeds continue to work on the pavement, this being very desirable in some instances as, for example, in working the concrete in proximity to expansion or work joints in the pavement.

lt will also be obvious that, especially when working on grades, where the plastic concrete mass tends to flow down-hill and thus forms ridges, it is advantageous to reverse the travel of the machine to rework the pavement, using either one or both screeds,l as desired. Such operations may be repeated until the concrete has set to the point at which fluency is entirely lacking or has been reduced to the degree necessary to resist movement or flow.

From the foregoingit will be. apparentoft element, has' been particularly avoided-.-

The hydrostatic pressure of such a surplus mass as a mea-ns for effecting compaction has not heretofore beeirrecognized and the machines referred to have been built too iiimsily to overcome the resistance to forward travel offered by such a mass. l'llhe importance of this surplus mass as a compacting force, has, apparently, never been' recognized prior to my invention inasmuch as it has never, so far as l am informed, been utilized.

This importance will perhaps be appreciated more fully when regarded in the light of a function not heretofore mentioned, namely that of surfacing a freshlaid pavement with trap-rock, granite or similar very hard surfacing material to take the place of the cement mortar to a large extentfthe latter being rather quickly worn and chipped away by traliic. 'lhis traprock or granite or similar surfacing in the shape of the crushed material of perhaps one-inch mesh, approximately, may be easily applied after the machine has passed over a section of pavement, and before the latter has set, by first raising the screeds and moving the machine `back to the desired point approximately from which the surfacing is to start. The screeds are then lowered and the crushed rock dumped upon the pavement in front of the machine to a height lapproximating two-thirds the height of the apron. The screeds are then reciprocated and the machine moved forward. 'lhe weight or head of pressure exerted by'the mass of rock will obviously effect embedding of the lowest or bottom stratum thereof into the still plastic surface mortar and the front or strike-off screed will again perform its function of striking off the surplusage and forcing the partially embedded pieces into the surface mortar which is caused tosurge up and largely cover said pieces. lfhe rear screed will again effect the finishing.

There this class of pavement is to be laid it will obviously be necessary, in the primary operation of the machine, to strike off to a slightly lower level or crown than is intended for the finished pavement in order to allow for the additional surfacing material. rlhe adjustment of curvature of both screeds may be required and the canting of one or both during the nal operation may be desirable. Both screeds may be equipped with aprons for this surfacing operation and thelatter performed during rcverse travel of the machine, thus causing the rear screed to function as the strike-off element. y

ln this connection, it will also be apparent that the support of the screeds on the siderails of the-form, whereby the side edges of the pavement are rendered alwv ys flush with the crowns of the siderails, is also very advantageous in that the supporting wheels may pass over stones or obstruc tions on the rails without in the silghtest degree interfering with the functioning of the screeds in every way.

Thus, it will be seen, that besides permit ting and promoting accumulation of a high level of aggregate and surfacing material for their pressure exerting purposesin front of the active strike-oftl beam, my machine eliminates the hand-labor ordinarily required to prevent such accumulation.

The operation of thescreeds independently of the travel of the carriage is also very important in that the carriage may be stopped at any point in the pavement where, as for example in up or down-grade work, the flow of the aggregate has produced ya ridge required to be worked down by reciprocating one ofthe screeds over it. At header boards this same mode of treatment mayibe adopted and excess mortar worked back over the pavement or alternately forward and back to insure the same compactness and finish directly back of the headerboard as is accorded to the balance of the pavement.

As distinguished from tamping, .the lat;

eral reciprocation .of the screds. over the pavement is of great importance 1n the resulting differencein the finished pavement.

- The skin friction imparted by the screeds tends only 'to oscillate the surface coarse parts of then aggregate to crowd the same into place just as the horizontal reciprocation of a container full of candy, cookies, gravel or other material will effect compacting thereof to occupy vless space. It does not, as in tamping, clause the coarse pieces -of rock or other material to be projected down to a lower level and a correspondingly deeper layer of cement mort-ar to be brought to the surface to be quickly worn and chipped away. It is commonly known that the greater the amount of coarse component of the aggregate at the surface, the

more dura-ble will be the pavement surface.

Tamping, on the contrary, requires that the tamping element shall be projected about one-half to five-eighths of an inch below the normal surface of the pavement whereby the cement mortar coating, brought to lthe surface byo displacement, acquires a .substantially corresponding (and possibly somewhat greater) depth which diminishes gradually toward the side edges of the pavement where the tamping is decreasingly effective with corresponding lack, probably, of equal compactness or density of the aggregate.

The accumulation of a relatively high head of aggregate in front ofthe strike-off screed -being the primary compacting force exerted on the portion retained in the form and acting in all directions late ally of the area of accumulation, insures m lre uniform compactness and density throughout the width of the pavement without corresponding dierencesV in depth of surface mortar,y such as resultsl from the tamping operation referred to. p

Reciprocation of the screeds will tend also l to effect a verticalfiexing thereof which, in

l theI absence of sufiic-ient rigidity, will' become so pronounced as toproduce lateral ridges or slight corrugations in the pavement surface.- A. construction of screeds whereby a degree of infiexibility or rigidity sufficient to obviate such more or less vibratory flexion, also constitutes an important feature of the invention.

A further important feature or function of the screed adjusting means provided is that for purposes of regulating the amount of excess accumulating behind the strike-off screed, the lower face thereof need not be adjusted'in curvature throughout to retain it accurately arcuate but only the end portions of the channel bars raised or lowered with respect to the middle portion. Ordinarily the extent of' adjustment does not exceed a quarter-inch. j

It is vobviously necessaryv that the strikeofl" and kneading beams shall be of a length equal to the distance between the side-rails plus the maximum reciprocat-ory stroke of said beams. Thus,I if the distance between side rails of the, form is sixteen feet', and the maximum stroke of the beams is one-foot, f

port of both ends by the rails.. at all times.

It sometimes occurs that obstructions are disposed so near to the side rails (as for example, less than one foot therefrom) asto prevent the full stroke of the beams in passig. Adjustment of the stroke by the means illustrated and described, or by any equivalent thereof,v.will permit operations on the pavement by the machine where otherwise hand labor would have to be resorted to.

I claim as my invention:

1. The method of compacting and surfacing concrete pavements which consists in depositing in a conventional pavement form, an excess mass kof concrete, manipulating a predetermined gradually advancing lateral area of .said concrete by laterally reclprocating and advancmg over said form.

2. The methodof compacting and surfacl .ing concrete pavement which consists in depositing in a conventional forman excess of concrete, manipulating a gradually advancing lateral area lof said concrete while maintaining al high level mass of excess concrete immediately forward of said area for exerting hydrostatic pressure -on the concrete within .said area, and effecting said manipulation by reciprocating laterally and gradually advancing a screed covering said area and of sufficient weight to resist said hydrostatic pressure and counteract surfacedistortion thereby within said area.

3. rfhe method of compacting and surfacing concrete pavements, which consists inn depositing in a conventional pavement ferm an excess of concrete, manipulating a predetermined gradually advancing lateral area of said material to advance the excess concrete, maintaining excess material immediately in advance of said area for exerting within the latter, during manipulation, appreciable hydrostatic pressure, exerting on said area a pressure sufficient to counteract surface distortions within the same resulting from said hydrostatic pressure of said excess mass, and after an appreciable time interval and while the manipulated pavement area is still plastic, again similarly manipulating a predetermined gradually advancing area thereof, said manipulations being in substantially the plane of the ultimate pavementrsurface.

4. The method of compacting and surfacing concrete pavements which consists in subjecting the same to successive surface manipulations, the second manipulation following the first after an appreciable time interval and both manipulations consisting in reciprocating heavy screeds laterally of and gradually advancingu the same along a conventional pavement form while supported on the side rails of the latter, maintaining an excess of concrete immediately in front of the first screed for exerting appreciable hydrostatic pressure on the concrete underneath the same to thereby effect compaction of the latter and a surge of mortar behind the same for manipulation by the second screed, the weight of said screeds counteracting surface distortion of the pavement by said hydrostatic pressure.

5. Vlfn a machine of the kind specified including a vehicle, la laterally reciprocable beam associated therewith having a high front wall and a smooth, flat bottom yface contiguous to said wall, said beam adapted to be wholly supported on the side rails of a conventional pavement form and to accommodate a deep mass of surplus concrete immediately proximate to said front wall for exerting appreciable hydrostatic pressure on the concrete covered by said beam, the latter being of such weight as to counteract said hydrostatic pressure and prevent surface distortion of the surface undergoing manipulation thereby, and a motor on said vehicle for effecting travel thereof and reciprocation of said beam.

6. In a machine of the kind specified including a vehicle, a laterally reciprocable beam associated therewith having a high front wall and a smooth, fiat bottom face -manipulated pavement surface, and a motor on said vehicle for effecting travel thereof and reciprocation of said beam.

7. ln a machine of the kind specified including a vehicle, a laterally reciprocable beam associated therewith having a highfront wall and a smooth, flat bottom face contiguous to said wall, said beam adapted to be `wholly supported on the side rails of a conventional pavement form and to accommodate a deep mass of surplus concrete immediately proximate to said front wall for exerting appreciable hydrostatic pressure on the concrete covered by said beam, the latter being of such weight as to counteract said hydrostatic pressure and prevent surface distortion of the surface undergoing manipulation thereby, a motor on said vehicle for propelling the latter and reciprocating said beam, and manual controls for causing said motor to reciprocate the beam independently of travel of the vehicle and vice versa.

8. ln a machine of the `kind specified including a vehicle, a laterally reciprocable beam associated therewith having a high front wall and a smooth, fiat bottom face contiguous to said wall, said beam adapted to be wholly supported on the side rails of a conventional pavement form and to accommodate a deep mass of surplus concrete immediately proximate to said front wall for exerting appreciable hydrostatic pressure on the concrete covered4 by said beam, the latter being of such weight as to counteract said hydrostatic pressure and prevent surface distortion of the surface undergoing manipulation thereby, a second similarly supported and reciprocable beam associated with said vehicle and so spaced from said first named beam as to provide an appreciable time interval between successive manipulations of the pavement by said beams, and a motor on said vehicle for propelling the sa1ne\and reciprocating said beams.

9. lfn a machine of the kind specified iucluding a vehicle provided with guides at opposite sides, a laterally reciprocable beamy mounted in said guides and having a high front wall and a substantiallysmooth fiat bottom face contiguous to said wall, said beam freely vertically movable in said guides and adapted to be entirely supported on the side rails of a conventional pavement form,

the high front wall accommodating the lill) lli of exerting appreciable hydrostatic pressure on the concrete beneath said beam, the latterb-eing of sufficient weight to resist said hydrostatic pressure and counteract surface distortion of the area covered by said beam ando being also of suflicient width to cover substantially the Zone of influence of said hydrostatic pressure rearwardly of said front wall, and a motor on said vehicle for propelling the same and reciprocating said beam.

10. A machine of the kind specified including a vehicle frame, a traction truck dis-f posed between the ends thereof, laterally reciprocable surfacing beams associated with said carriage in front and rearwardly of said truck, respectively, and adapted to be normally supported entirely upon the side rails of a conventional pavement form for guidance thereby, and a motor on said frame operatively and controllably associated with said truck for propellingthe vehicle and with said beams for reciprocating the latter.

11. A machine of the kind specified including a vehicle frame, a traction truck disposedbetween the ends thereof and pivotally connected with said frame, laterally reciprocable surfacing beams associated with said vehicle in front and rearwardly of said truck, respectively, and adapted to be normally supported entirely upon the side rails of a conventional pavement form for guidance thereby, and a motor on said frame' operatively and controllably associated with said truck for propelling the vehicle and with said beams for reciprocating the latter simultaneously in respectively opposite directions.

12. A machine of the kind specified including a vehicle frame, a traction truck disposed between the ends thereof, laterally reciprocable surfacing beams associated with said vehicle in front and rearwardly of said y truck, respectively, and adapted to be normally supported entirely upon the side rails of a conventional pavement form for guid ance thereby, idle supporting wheels at the rear end of saidframe behind said rear beam., and a motor on said frame operatively and controllably associated with said truck for propelling the vehicle and with said beams for reciprocating'the latter.

13. A machine of the kind specified including a vehicle frame, a traction truck disposed between the ends thereof, laterally reciprocablesurfacing vbeams associated with said carriage in front and rearwardly of said truck, respectively, and adapted to be normally supported entirely upon the side rails of a conventional pavement form for guidance thereby, the forward beam having ahigh front wall for accommodating a deep mass of surplus concrete immediately in front thereof for exerting appreciable hydrostatic pressure on the concret-e beneath said beam, the latter being ofl such weight and width as to counteract surface distortion of the pavement -rearwardly of said front wall by said hydrostatic pressure, and a motor on said frame operatively and controllably associated with said truck for propelling the vehicle and with said beams for reciprocating the latter.

14. In a machine of the kind specified, including a vehicle, two relatively widely spaced laterally reciprocable beams associated with said vehicle and adapted to be normally entirely supported at their end portions by the side rails of a conventional pavement form and guided as to path of reciprocation by the latter, said beams having smooth, flat lower faces, means for adjusting the normal contour of the latter to thereby permit their respective paths of reciprocation to be varied for the purpose of effecting control by the front beam of the amount of surface material presented for manipulation .by the second beam, said front beam having a high front wall for accommodating immediately in advance thereof a high level mass of surplus concrete for eX- erting appreciable hydrostatic pressure on the concrete beneath said beam for compacting the latter and effecting surge of mortar to the pavement surface behind the same for manipulation as aforesaid, and a motor on said vehicle for propelling the latterand reciprocating said beams.

- 15. In a machine of the kind specified, including a vehicle, two relatively widely spaced laterally reciprocable beams associated with said vehicle and adapted to be normally entirely supported at their end portions by the side rails of a conventional pavement form and guided as to path of reciprocation by the latter, said beams having smooth, Hat lower faces, said front beam having a high front wall for accommodating immediately in advance thereof a high level mass of surplus concrete for exerting appreciable hydrostatic pressure on the concrete beneath said beam for compacting the latter and effecting surge of mortar to the pavement surface behind the same for manipulation by the rear beam, the lower face of said front beam adjustable in contour for varying its path of reciprocation for control carriage supported between its en s on traction-wheels adapted to be propelled to ef-y fect travel of the carriage on the side-rails o f a conventional pavement form, transverse guides forwardly and rearwardly of said traction wheels, laterally reciprocable beams mounted in said guides, manually operable means associated with said carriage and said beams for causing the latter to be supported wholly upon the former out of operative relation to the pavement or wholly upon the side rails, a motor on said carriage, manually controllable means for operatively as-J sociating said motor with the traction-wheels on either or both`sides of the carriage at will, and similar means for operatively associating said motor with said beams for reciprocating the latter while the carriage travels or is at rest.

17. A machine of the kind specified inl cluding a vehicle, a pair of spaced, laterally reciprocable surfacing beams associated therewith and adapted to be normally wholly supported upon the side rails ofa conventional pavement form for guidance thereby, the rear beam having a smooth flat lower face corresponding in contour with the ultimate pavement and the front beam having a similar lower face adjustable in contour for varying the mean level of its plane of action relatively to the rear beam to thereby control the depth of surface material presented for manipulation by the second beam.

18. A machine of the kind specified including a vehicle, a pair of spaced, laterally reciprocable surfacing beams associated therewith and adapted to be normally wholly supported upon the side rails of a conventional pavement fo-rm for guidance thereby, the rear beam having a smooth flat lower face corresponding in contour with the ultimate pavement and the front beam having a similar lower face adjustable in contour and having a high front wall for accommodating a mass of surplus concrete immediately forward thereof for exertingv appreciable hydrostatic pressure on the concrete beneath said beam and effecting surge of mortar to the pavement surface rearwardly ofv said beam, the weight of said beam sufficient to counteract surface distortion of the pavement by said pressure and the adjustment of curvature of the lower face of said beam effecting variation oglthe mean level of its plane of action relatively to the rear beam to thereby control the depth of surface material presented for manipulation by the second. beam.

19. In a machine of the kind specified, a carriage adapted to travel on the side-rails of the form, a transverse guide in said carriage, a surfacing beam mounted in said guide for forced travel with said carriage without movement relatively to the latter longitudinally ofthe form while wholly unsupported by the carriage, a motor on said carriage for reciprocating said beam whilei Meanies said carriage travels or is at rest, said beam adapted to rest at its' end portions upon said side-rails for guidance solely thereby to effect reciprocation thereof in a pathv determined by the portions of the lower face of said beam contacting with said side-rails during said reciprocation, tand means included in the association of said beam with said motor for obviating lifting and depressing force on said beam during reciprocation of the latter. i

20. In a machine of the kind specified, a carriage, a motor thereon, a reciprocable surfacing beam, a transverse guide in said carriage for said beam, thelatter adapted to be wholly supported by the side-rails of the form on which the carriage is adapted to travel, connection between said motor and said beam for effecting reciprocationof the latter inthe course or direction determined by contact of the lower face of said beam with said side-rails, said connection including means permitting the length of stroke of reciprocation of said beam to beA varied and to obviate lifting or depressing or flexing strains on said beam during reciprocation thereof.

21. In a machine `of the kind specified, a carriage, a motor thereon, a reciprocable surfacing beam, a transverse guide in said carriage for said beam, the latter adapted to be wholly supported by the side-rails of the form on which the carriage is adapted to travel, connection between said motor and said beam for effecting reciprocation of the latter in the course or direction determined by contact of the lower face of said beam with said side-rails, said connection including a rotating crank, a rocking element on the carriage connected with said crank, and a connecting rod associating said rocking element'with said beam, said connecting rod arranged to reciprocate in a substantially horizontal planeV to thereby obviate lifting and depressing and other flexing stress on said beam.

22. A machine of the kind specified including a carriage, a motor carried thereby a surfacing element associated therewith and adapted to be normally supported wholly upon the pavement, manually controlled gearing between motor and said carria e for effecting travel of the latter forwar and reversely, manually controlled gearing between the motor and said element for effecting reciprocation of the latter relatively to said carriage in the plane of the lower face of said element and wholly independently of the travel of said carriage, the connection between said motor and said element includinga rocking element pivotally mounted on the carriage, a crank, a connecting-rod associating the latter with the rocking element, and a connecting rod associating said rockng element with said surfacing element.

lll@

23. A machine of the kind specified includin a carriage, a motor carried thereby, a sur acing element associated therewith and adapted to be normally supported wholly upon the pavement, manually. controlled gearing between said motor and said carriage for effecting travel of the latter forward and reversely, manually controlled gearing between the motor and said element for effecting reciprocation of the latter relatively to said carriage wholly independently of the travel of said carriage, means for canting said element, the connection between said motor and said element including a rocking element pivotally' mounted on the carriage, a crank, a connecting-rod associating the latter with the rocking element, and a connecting rod associating said rocking element with said surfacing element, said last-named connecting rod having uni-l versal joint connections with said rocking element and said surfacing element for permitting ranting of the latter.

24. In a machine of the kind specified, a surfacing beam comprising a rigid member and a flexible member, the latter being channel shaped having upwardly extending flanges and horizontal web and the former consisting of an I-beam having a. vertically disposed web, said channel and I-beam coacting to impart rigidity to' said surfacing beam in both vertical and horizontal planes, a plurality of yokes slidably engaged with opposed top flanges of said I-beam, and adjusting bolts operatively associated with said yokes and said channel-bar for adjusting the latter to any desired contour longitudinally.

25. In a machine of the kind specified, a

surfacing member comprising an I-beam and a channel-bar, the latte-r having upwardly extending flanges and the former a vertical web, the lower flanges of the I-beam is normally subjected, and adjusting means connecting said channel-bar and said I-beam for imparting to the former any desired contour.`

26. In a machine of the kind specified, a surfacing member adapted for support upon the side rails of a form, a carriage adapted to travel on said side-rails and having a guide to receive saidsurfacing member and permit vertical and transverse movements of the latter relatively to thecarriage, a manually operable lever pivotally mounted'on the carriage, a pair of bell-crank levers pivotally mounted on the carria e, flexible means connecting said bell-cran levers with the end-portions of said surfacing member, and connection between said last named bellcrank levers and said first-named lever for causing all of said levers to swing in unison to thereby lift or lower said surfacing member, and a stop for limiting the pivotal lifting movement of said first-named lever to thereby bring and hold the point of connection thereof with said other levers in a posi.- tion relatively to its pivot to cause the Weight of the surfacing member to hold said rst-named lever engaged with said sto Ipn testimony whereof, I have hereunto set my hand.

WILLIAM ORD.

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