US3224348A

US3224348A - Vibrating screed

Info

Publication number: US3224348A
Application number: US193468A
Authority: US
Inventors: Hamilton J Maginniss
Original assignee: Individual
Current assignee: Individual
Priority date: 1962-05-09
Filing date: 1962-05-09
Publication date: 1965-12-21
Anticipated expiration: 1982-12-21
Also published as: CH396068A; GB997867A; DE1658507B1; NL132201C; BE632104A; FR1368787A; NL292535A; DE1261152B

Description

Dec. 21, 1965 H. J. MAGINIINISS VIBRATING SCREED 5 Sheets-Sheet 1 Filed May 9, 1962 INVENTOR.

HAMILTON J. MAGINNISS ATTORNEYS Dec. 21, 1965 H. J. MAGINNISS VIBRATING SGREED 5 Sheets-Sheet 5 Filed May 9, 1962 INVENTOR.

HAMILTON J. MAGINNISS fiwfifl w ATTORNEYS FIG.6

Dec. 21, 1965 H. J. MAGINQISS 3,224,348

VIBRATING SCREED Filed May 9, 1962 5 Sheets-Sheet 4 42 44 42 J l A 4/ 43 I I 72 7 I I 76 FIG.8

INVENTOR. HAMILTON J. MAGINNISS BYWMCDW ATTORNEYS 1965 H. J. MAGININISS 3,224,348

VIBRATING SCREED Filed May 9, 1962 5 Sheets-Sheet 5 no I INVENTOR. HAMILTON J. MA GINNISS ATTORNEYS United States Patent 3,2243% VIBRATING SREED Hamilton J. Maginniss, 563 Russell Road, Mansfield, ()hio Filed May 9, 1962, Ser. No. 193,468 9 Claims. (Cl. 9448) The present invention relates to apparatus for consolidating and finishing concrete. More particularly, the present invention relates to a vibrating screed. Specifically, the present invention relates to a self-propelled vibrating screed having screed boards which can be raised and lowered as the screed is being propelled.

Screeds are particularly suitable in the construction of roads and highways, airport runways, floors, bridge decks or any other slab-like concrete structure. In the construction of such structures, the concrete is brought to the site and spread on the sub-grade, sub-base or receiving surface in any of a variety of ways. The concrete must then be struck to the proper thickness, preferably compacted, and then finished so that the surface presents the desired texture and smoothness.

Certain prior power operated screeds merely mechanized the manual strike-off board which rode on the forms and was oscillated back and forth transversely to the direction the screed was traveling. This type screed presents two major drawbacks: The oscillation of the screed board imparts severe lateral forces against the side forms; and, unless the concrete is extremely wet, the screed board will engage and drive the aggregate ahead of the board leaving gouge marks on the surface of the concrete.

Other prior power operated oscillating screeds are carried on frames supported on side rails, and the oscillation of the screed exerts lateral pressures on the side rails.

To obviate these difliculties the vibratory screed was developed. The prior art vibratory screeds have relatively wide contact area with the cement and vibrate with alow frequency and high amplitude. As a result 'the surface of the concrete is patted smooth. This too requires that the concrete be extremely wet and results in causing the aggregate to work the surface, both weakening the concrete and causing it to spall when subjected to wide temperature variations. Moreover, when such screeds ride directly upon the form the vibrations drive the forms into the ground.

It is therefore an object of the present invention to provide a vibrating screed which will strike off and finish low slump concrete which produces strong slabs.

It is a further object of the present invention to provide a vibrating screed that will impart deep penetrations of vibrations to the concrete in order to thoroughly densify it and yet will not vibrate the forms or separate the aggregate.

It is a still further object of the present invention to provide a self-propelled vibrating screed in which the screed board can be raised and lowered while the screed is moving backward and forward.

It is a still further object of the present invention to provide a self-propelled vibrating screed in which the screed boards can be skewed with respect to the direction the screed is traveling during movement of the screed and without manual adjustment.

It is a still further object of the present invention to provide a vibrating screed employing tandem screed boards the forward of which will serve as a strike-off and consolidating screed and the latter of which serves as a finishing screed.

It is a still further object of the present invention to provide a screed which is adaptable to finish slabs of various widths, slabs which incorporate an integral curb therewith and slabs which are to constitute a sub-base for an asphalt surface and which therefore have manholes or scuppers extending above the surface of the slab.

Another object is toprovide a vibrating screed which can be manipulated by the operator to prevent surging of the concrete behind the screed as it starts to move forwardly.

It is a still further object of the present invention to provide a screed which is light in weight and which can be readily assembled and disassembled for ease of transportation.

These and other objects which will become apparent from the following specification are accomplished by means hereinafter described and claimed.

One preferred embodiment of the present invention is shown by way of example in the accompanying drawings and described in detail without attempting to show all of the various modifications in which the invention might be embodied; the invention being measured by the appended claims and not by the details of the specification.

In the drawings:

FIG. 1 is a top plan view of a screed according to the present invention;

FIG. 2 is an elevation taken substantially on line 2-2 of FIG. 1;

FIG. 3 is an enlarged end elevation taken substantially on line 3-3 of FIG. 1;

FIG. 4 is an enlarged cross section taken line 4-4 of FIG. 1;

FIG. 5 is a view similar to FIG. 3 showning the articulation of the screed to raise and lower the screed boards;

FIG. 6 is a top elevation of a screed dolly taken substantially 011 line 6-6 of FIG. 4;

FIG. 7 is an enlarged cross section depicting the screed board mounting assembly taken substantially on line 7-7 of FIG. 4;

FIG. 8 is an enlarged cross section of the articulating hinge connection between the tandem members of the screed dolly taken substantially on line 88 of FIG. 4;

FIG. 9 is an enlarged cross section depicting the screed board grip plates substantially on line 99 of FIG. 7;

FIG. 10 is a partial frontal elevation of one end of a modified screed board;

FIG. 11 is a partial frontal elevation of a modified overlapping screed board; and,

FIG. 12 is a top plan view taken substantially on line 1212 of FIG. 11.

In general a vibrating screed according to the present invention comprises two dollies which support at least one screed board therebetween. Each of the dollies is comprised of two tandem frame portions. The two portions are joined by a hinge means, and a power means articulates the two frame portions about the hinge means. Each of the two tandem frame portions is adapted to support a screed board which is provided with a vibrating means. Mounting means between the screed board and the respective frame portion is adapted to isolate the frame from the vibration of the screed board.

Articulation of the tandem frame portions raises and lowers the screed boards but retains at least one wheel on each of the tandem frame portions in contact with the surface on which they roll. By applying a controlled driving means to at least one of the wheels that retains rolling contact with the surface on which the dolly travels, and maintaining an independence between the driving means, the articulating power means and the vibrating means for the screed boards, the screed boards can be raised or lowered while the screed is moving forward or backward and while the vibrators are on or 01?. These controlled movements at varible speeds substantally on permit tailoring the operation of the screed to a particular job and offer extreme flexibility of operation for an infinite variety of unique applications.

Referring to the drawings, a screed according to the present invention, indicated generally by the numeral 10, is self-propelled by two spaced apart, identical dollies 11 and 12 which are braced and interconnected by an adjustably attached transverse bracing beam 13. A catwalk plank 14, which is preferably in multiple sections for partial removal, as more fully hereinafter described, may be removably mounted to the uppermost side of the bracing beam 13 by suitable clip-like fastening means 15 which embrace the sides of the box-like bracing beam 13.

Supported between dollies 11 and 12 are two screed boards, or beams, 16 and 17, the front screed board being designated by the numeral 16 and the rear screed board by the numeral 17. The front screed board 16 is the strike-01f screed and may be vibrated by two standard, eccentric vibrators 1S and 19 spaced at suitable intervals, although a single vibrator may be used if desired. The rear screed board 17 is the finishing screed and is preferably vibrated by a single vibrator 20, similar to vibrators 18 and 19. Both the number of vibrators used on each board and the number of screed boards vare determined by the texture desired on the finished surface and the slump characteristic of the concrete being screeded and the width of the concrete slab on which the machine is operated. It has been found that the preferred embodiment will screed an extremely low slump concrete to a smooth finish if the

vibrators

18, 19 and 20 are of a low amplitude-high frequency variety; i.e., vibrators that have a variable vibrating rate on the order of 3000 to 8000 v.p.m.

As best shown in FIG. 3, the dolly 11 of the two identical dollies is comprised generally of two

tandem members

21 and 22 articulately joined together. The member 21 which is generally the forward of the two members is constructed in the shape of an inverted V, with two

tines

23 and 24. The lower end of each

tine

23 and 24 is bifurcated to receive a wheel 25 mounted on an axle 26 journaled in the bifurcated end of the respective tine. The forward of the two Wheels is designated 25A for a purpose later to become apparent.

Connected to and extending forwardly from each

tine

23 and 24 is a scraper 28 which precedes the

wheels

25 and 25A to remove any dirt, concrete or other foreign material which may have been inadvertently deposited upon the rail 29.

Member 22 which is generally the trailing of the two members is constructed in the shape of a dog leg with one end 30 pivotally hinged to tine 23 of the V shaped member 20. The other end 31 is bifurcated to receive a wheel 32 mounted on axle 33 journaled in the bifurcated end 31 similarly to axles 26 carrying

wheels

25 and 25A. Wheel 23 may also be preceded by a scraper 34 attached to the inclined portion 35 of dog leg member 22 for cleaning rail 29.

The rail 29 may be a broad or narrow form, an adjacent concrete slab, or a pipe set either on the adjacent finished concrete or in screed chairs mounted on the falsework. For adaptation to this latter type rail the

wheels

25, 25A and 32 should be provided with an annular groove 36 in the peripheral edge thereof.

The end 30 or dog leg member 22 has an angularly inclined face 38 for engaging the rearward face 39 of tine 23 when all three wheels, 25, 25A and 32 are riding on rail 29. The end 30 is also provided with spaced apart hinge

plates

40 and 41 adapted to straddle one or more wing plates 42 extending rearwardly from the rearward face 39 of the tine 23. The

hinge plates

40 and 41 and the wing plates 42 have registered bores to receive a hinge pin 43. If desired, a sleeve 44, also bored to receive pin 43, may be secured between wing plates 42, as best shown in FIG. 8. Articulation of the two

members

21 and 22 is accomplished by pivoting the members on their

respective wheels

25A and 32 and about the hinge pin 43, as shown in FIG. 5 and described in greater detail hereinafter.

An expansible and contractible power means is connected between the

members

21 and 22 to selectively control the direction and rate of articulation. Specifically, a hydraulic cylinder 45 is pivotally attached to the V shaped member 21, as by a stub shaft 46 extending outwardly from the base, or intersection, 48 of

tines

23 and 24. A piston rod 49 provided with a standard piston on one end, not shown, for controlled reciprocation within the cylinder 45 is pivotally attached at the other end to the horizontal portion 50 of the dog leg member 22, as by the stub shaft 51 extending outwardly from portion 50.

The

screed boards

16 and 17 are mounted in a suspension system adapted to isolate the dollies from the vibrations of the screed boards. It has been found that by fabricating the screed boards of laminated longitudinal wooden sections, a tougher board results and one with a more uniform density for transmitting the vibrations with more equal facility along the lengths of the board. Each

screed board

16 and 17 is provided with a channel foot plate 53 suitably secured thereto. The foot plate 53 increases the life of the screed board by preventing the abrasion of the concrete from acting directly upon the wooden screed board. If desired, the channel foot plate 53 may be replaced by a Wide channel up to 12" wide, to plane the concrete surface.

A similar channel cap plate 54 is secured along the top of the screed board. The cap plate 54 has

legs

55 and 56 engaging the sides of the screed board, as better shown in the FIG. 9 representation of the top of rear screed board 17.

Each end of the screed boards is gripped for mounting to the respective dollies 11 and 12 by a pair of opposed

grip plates

58 and 59. Each grip plate is preferably a right angular section having a downwardly oriented leg 60 and a horizontally disposed leg 61. Each downwardly oriented leg 60 extends along one side of the screed board and is provided with a carrying ledge 62 which extends inwardly in opposed relation to the carrying ledge on the other grip plate of the pair. The carrying ledges 62 form a trackway along which the

legs

55 and 56 of top cap plate 54 can be selectively slidably engaged.

The upper portion of the downwardly directed legs 60 of each pair of

grip plates

58 and 59 is bored to receive a tightening means, such as one or more bolts 63, as the horizontally disposed legs 61 are positioned in sliding juxtaposition. A nut 64 is tightened on each bolt 63 to secure the grip plates on to the screed board.

As best shown in FIGS. 3 and 7, the vibration isolating suspension system suspends the screed boards through an upstanding bolt 65 secured to the horizontal leg 61 of grip plate 58 and extending through a slot 66 in the horizontal leg 61 of grip plate 59. The dimension and orientation of slot 66 permits the legs 61 of

grip plates

58 and 59 to slide without interruption in order to grip and release the screed board as the nut 64 is tightened or loosened.

Opposed nuts

68 and 69 are threaded on the upstanding portion of bolts 65 and are partially tightened against the opposite side of a floating plate 70 to permit the plate 70 to slide. The bolts 65 extend through transverse slots 70A in the floating plates 70, thus allowing the screed boards to skew relative to the forward and rearward travel thereof. At each end of the floating plate 70 are one or more downwardly extending keepers 71. The keepers 71 engage the inner diameter of a helical compression spring 72 at the top thereof. The bottom of each helical compression spring 72 rests on a foot plate. As shown in FIG. 3, the foot plates 73 extend between the face members of

tines

23 and 24; the foot plate 74 is attached to cross the under side of

hinge plates

40 and 41; and, the foot plate 75 extends downwardly from the horizontal portion 50 of dog leg member 22. Each

foot plate

73, 74 and 75 has one or more upwardly directed keepers 76 for engaging the inner diameter of each spring 72 at the bottom thereof.

Thetransverse bracing means 13 which extends between dollies 11 and 12 may be attached to each dolly on the upper side of the horizontal portion 50 of dog leg member 22. As shown, a U-shaped retaining plate 78 embraces the box beam 13 at each dolly. The

legs

79 and 80 of the U-shaped retaining plate 78 are of lesser length than the corresponding sides of the box beam 13 and terminate in outwardly directed flanges 81 and 82 which are bored to receive fastening bolts 83. The top plate 84 of the horizontal portion 50 of dog leg member 22 has registered bores and may either be tapped or have a nut 85 welded thereto to provide a means for tightening bolt 83. The beam 13 thus imparts rigid lateral stability to the screed between the dollies 11 and 12 and yet is adjustable to permit adaptation of the screed to various lateral dimensions between the dollies. When the distance between the dollies is lessened one or more sections of the catwalk 14 may be removed, as required.

An engine-generator unit 86 may also be mounted on the horizontal portion 50 of the dog leg member 22. The engine-generator unit 86 is preferably demountably attached to the dog leg member to permit easy removal of the engine-generator unit from the dolly in order to lessen the weight of the screed in situations where operation of the screed would be facilitated thereby.

Together with the demountable aspects, the engine-generator unit 86 is preferably spring mounted to prevent the natural vibrations of the engine from being transmitted to the dolly. The spring suspension of the engine may be comprised to helical springs 88 interpositioned between the engine-generator unit 86 and the horizontal portion 50 of the dog leg member 22 of dolly 11. The springs 88 are maintained in the desired position by keepers 89 directed downwardly from the base of the engine-generator 86 and engaging the inner diameter of the top of the respective springs 88, and keepers 90 directed upwardly from the horizontal portion 50 and engaging the inner diameter of the bottom of the respective springs 88.

The electrical current generated by the engine-generator unit 86 is used to operate the

vibrators

18, 19 and 20, the pump motors 89 and'the driving motors 90.

The pump motors 39, as best shown in FIG. 6, are mounted on the V-shaped member 21 of each dolly and drive a hydraulic pump 91. The fluid from a reservoir, not shown, is pumped through flow control valves 92 into conduits 93 and then to the cylinder 45 of the expansible and contractible power means. A control cable 94 leads from the flow valves 92 to a remote control station, not shown, where an operator may selectively control the flow, as hereinafter more fully described. Although a pump 91 is shown on each dolly, if desired, one pump may feed the cylinders 45 on both dollies.

A driving motor 90 is also mounted on the V-shaped member 21 of each dolly and is connected through a gear reducer 95 to a driving sprocket 96. As best shown in FIG. 4, the driven sprockets 98 are nonrotatably mounted on each axle 26, and are operably interconnected to the driving sprocket 96 by a chain drive 99 which is also reeved around an idler sprocket 97 to prevent the chain drive from interfering with the screed board 16. It has been found more desirable to drive both

wheels

25 and 25A on the V-shaped member 21, although it is well within the scope of the present invention to drive only wheel 25A or to drive Wheel 32 or any combination thereof.

The laminated

wooden screed boards

16 and 17 may be provided with a straight or cambered bottom edge. Even with a straight bottom edge, some parabolic crown can be imparted to the concrete surface being finished by the use of wedges or the like inserted at spaced intervals along the screed board bet-ween the board and the channel 6 foot plates 53. For providing a crown on the finished slab, each screed board can also be constructed of two sections joined in an overlapping arrangement, as shown in FIGS. 11 and 12.

For example, the screed board 16 may be constructed of

sections

16A and 16B. Section 16B is bored, as at 101, to receive a bolt 102 which slidably engages a slot 103 in section 16A. A spacer 104, similarly bored, is interposed between

section

16A and 16B to allow for the thickness of the adjacent leg portions of the

channel foot plates

53A and 53B. The spacer 104 also assures a solidity of joinder when the nut 105 is tightened on to bolt 102.

The section 16B isprovided with a series of bores 106 spaced along concentric arcs about the center of bore 101, and section 16A is provide with several bores 107 on each side of the slot 103. Bores 107 are drilled to align with the bores 106 as the two

sections

16A and 16B are inclined at various selected angles with respect to each other and as the two sections are moved longitudinally of each other at'selected intervals.

Thus, the nut can be loosened to permit the sections to rotate about bolt 102 or to permit section16A to slide longitudinally. When the desired longitudinal adjustment and inclination of the sections is eifected,bolts 108 are inserted through bores 107 in section 16A and the aligned bores 106 in section 16B. Nuts 109 are tightened on bolts 108 and nut 105 is tightened on bolt 102 to lock the sections together.

Moreover, the screed board can be shaped as shown in FIG. 10, to finish an integral curbing 110 with a road surface 11 or an outrigger section can be attached to the end of a screed board.

Further, the pipe rail 29 may be positioned as shown in phantom at 29' and the screed board notched around the rail as indicated at 29A. This is possible because there is no lateral movement with the vibrating screed board. In addition, if the concrete road surface being finished is to comprise the base for an asphalt road surface and there are scuppers or manholes protruding above the surface, the screed board 16, as shown in FIG. 10, may be provided with flap gates 118 connected to the board 16 by hinges 119. A latch bolt 120 or other suitable means is used to maintain the gate in closed position until its swinging operation is desired.

An outrigger section can also be used to undersling the screed board when it is necessary to have the dollies ride above the level of the slab being finished, as, for example, when the rails 29 are placed above the curb rebars.

Operation In addition to the remote control of the hydraulic pump motors 89, as hereinbefore mentioned, the motors 90 of the driving means for the

wheels

25 and 25A of the two dollies 11 and 12 are also provided with a remote control. Motors 90 should be of a variety capable of operating at variable speeds and also capable of reversal.

Remote control of the

vibrators

18, 19 and 20 and the engine-generator unit 36, as well, affords the most desirable operation of the screed. Independent vertical adjustment of the screeds allows the forward of the two screed boards to be operated as a strike-01f and the rearrnost to function as a finishing screed.

In FIG. 3, the screed is represented in the down or finishing position. By controlling the frequency of vibration of the

screed boards

16 and 17 by their

respective vibrators

18, 19 and 20, and the rate of forward travel of the screed by motors 90, concrete of various consistencies can be readily finished, and surging of the concrete under the screeds is prevented. As pointed out previously, the number of screed boards used is also an adjustable variable.

Should it be necessary to refinish a section to correct irregularities, the operator can actuate the cylinder 45 and piston rod 49 of the expansible and contractible power means, which lies above the hinge means 43, to articulate the

tandem members

21 and 22 so as to raise the

screed boards

16 and 17, as depicted in FIG. 5. At the same time, the direction the screed is moving can be reversed, via motors 90, and the screed backed up with reference to the slab being finished.

Then, by controlled operation of the driving motors 90 and the retraction of piston rod 4-9 into cylinder 45, the screed can be moved forwardly coincident with the return articulation of the screed to the finished position depicted in FIG. 3. The articulation of the dollies thus occurs on

wheels

25A and 32 and about the hinge 43 which lies between the wheels (25A and 32) and the cylinder 45. This coordination of forward movement of the dollies and their articulation prevents surging of the concrete at the point the screed boards contact the concrete, because the screed can be moved gradually downwardly and forwardly into the concrete so that there is no appreciable build up behind the screed boards. With the high frequency vibration available it is possible to vibrate the concrete in place both beneath and immediately in front of the screed boards.

To maintain the screed boards in a substantially vertical disposition, adjustable bumpers 125 may be provided for each screed board. The bumpers preferably comprise a cylindrical sleeve 126; one end of one is attached to the inclined portion 35 of dog leg member 22 for screed board 17 and one end of another is attached to the tine 23 of the V-shaped member 21 for screed board 16. The interior of the sleeves 126 are threaded to receive a threaded screw post 127 on the outer end of which is a bumper head 128. A lock nut 129 threaded on screw post 127 can be tightened against cylinder sleeve 126 to firmly secure the position of bumper head 128.

The unique suspension and gripping arrangement for attaching the screed boards to the dollies permits the screed to be skewed, as may be desired when finishing super-elevated curves or rhomboid sections. When screeding slabs with widths of from 12 to 32 feet some minor skewing may be accomplished merely by operating the motor 90 on one dolly momentarily faster than the motor 90 on the other dolly. This moves the first mentioned dolly slightly ahead of the other and the slight differential of length of screed board required can be accommodated by the slots 70A in floating plates 70.

At the same time, the tightening bolts 83 holding the retaining plates 78 in engagement with beam 13, should be slightly loosened to permit the beam to similarly accommodate the differential distance between the dollies as the screed is skewed. This latter adjustment together with loosening nuts 64 on bolts 63 also permits the distance between the dollies to be readily adjusted when finishing slabs of different widths.

The adjustment of

nuts

68 and 69 on the upstanding bolt 65 is also used to adjustably raise or lower the screed board with respect to the dollies when they are in the finishing position of FIG. 3, for the purpose of properly positioning the screed boards relative to the concrete surface.

It should be apparent that a screed constructed in accordance with the concepts herein disclosed accomplishes the objects of the invention.

What is claimed is:

1. A screed machine comprising, spaced apart, parallel dollies, tandem screed boards extending transversely between said dollies, vibrating means mounted on each of said screed boards for individually vibrating each of said screed boards, vibration absorbing supporting means connecting said screed boards independently to said dollies, said supporting means being adjustable individually to control the vertical disposition of each of said screed boards with respect to said dollies, said supporting means having a floating means for permitting the limited lateral movement of said screed boards with respect to at least one of said dollies occasioned when said screed boards are skewed and vibrated, each of said dollies having two tandem frame portions, a hinge means interconnecting said tandem frame portions, and power means mounted on said dollies for articulating said tandem frame portions about said hinge means simultaneously to raise and lower said screed boards.

2. A screed machine comprising, spaced apart, substantially parallel dollies, a pair of screed boards extending substantially transversely between said dollies, means for pivotally and slidably connecting said screed boards to said dollies, means mounted on each of said screed boards to vibrate said screed boards, each of said dollies having two tandem frame portions, each tandem frame portion having wheel means, driving means mounted on said dollies and operatively connected to said wheel means for selectively and individually propelling said dollies forwardly or rearwardly, a hinge means interconnecting said tandem frame portions, a power means connected between said tandem frame portions and operative to articulate said tandem frame portions on said wheel means and about said hinge means to raise and lower said screed boards.

3. A screed machine comprising, spaced apart, substantially parallel dollies, a pair of screed boards extend ing substantially transversely between said dollies, means for pivotally and slidably connecting said screed boards to said dollies, means for individually controlling the vertical disposition of each said screed board with respect to said dollies, means mounted on each of said screed boards to vibrate said screed boards, shock absorbing means between said screed boards and said dollies to isolate the dollies from the vibrations of said screed boards, each of said dollies having two tandem frame portions, each tandem frame portion having wheel means, driving means mounted on said dollies and operatively connected to said wheel means for selectively and individually propelling said dollies forwardly or rearwardly, a hinge means interconnecting said tandem frame portions, a power means connected between said tandem frame portions and operative to articulate said tandem frame portions on said wheel means and about said hinge means simultaneously to raise and lower said screed boards.

4. A screed machine comprising, spaced apart, parallel, dollies supported on wheel means, each of said dollies having two tandem frame portions, two parallel screed boards extending between said dollies, the corresponding frame portion on each of said dollies supporting a screed board therebetween, means mounted on at least one of said screed boards for vibrating that screed board, floating means connected between each of said screed boards and each of said dollies to permit the limited lateral movement of the screed boards relative to the dollies occasioned by vibration of the screed boards, a hinge means interconnecting said frame portions above said wheel means, power means connected between said tandem frame portions above said hinge means to articulate said tandem frame portions on said wheel means and about said hinge means to raise and lower said screed boards simultaneously, and means connected between said screed boards and said dollies to adjust the height of said screed boards independently.

5. A screed machine comprising, spaced apart dollies, each of said dollies having two tandem frame portions, two parallel screed boards extending between said dollies, the corresponding frame portion on each of said dollies supporting a screed board therebetween, means mounted on at least one of said screed boards for vibrating that screed board, shock absorbing means between said screed boards and said dollies to isolate the dollies from the vibrations of said screed boards, wheel means on the under side of said tandem frame portions, driving means mounted on said dollies and operatively connected to the wheel means on each said dolly, floating means connected between each of said screed boards and each of said dollies to permit limited lateral movement of the screed boards relative to the dollies occasioned by vibration of the screed boards, a hinge means interconnecting said frame portions above said wheel means, power means connected between said tandem frame portions above said hinge means to articulate said tandem frame portions on said wheel means and about said hinge means simultaneously to raise and lower said screed boards.

6. A screed machine comprising, spaced apart dollies, each said dolly having two tandem frame portions, one said frame portion being an inverted V-shaped member having two downwardly directed tines, the other said frame portion being a dog leg member, hinge means for attaching one end of said dog leg member to said inverted V-shaped member, wheel means on the tines of said V-shaped member and on the other end of said dog leg member, two screed boards extending substantially transversely between said dollies, two clamping means for each of said screed boards for gripping said screed boards at selected positions along the length thereof, a floating plate pivotally connected to each said clamping means and movable with respect thereto along the axis of the screed board connected thereto, spring means suspending each of said floating plates from one of said frame members, the two floating plates attached to the clamping means on each of said screed boards being supported by the corresponding frame member on the spaced apart dollies, means mounted on each of said screed boards for individually vibrating said screed boards, independent power means connected between said tandem frame portions operative to articulate said tandem members and about said hinge means to raise and lower said screed boards, and power means mounted on said dollies for selectively propelling each dolly independently of the other.

7. A screed machine comprising, spaced apart, parallel, individual dollies, a transverse beam extending between said dollies, connecting means for fastening said transverse beam to each of said dollies, said connecting means adapted to loosely fasten said transverse beam to said dollies in a horizontal plane and simultaneously assure lateral stability of said dollies, tandem screed boards extending transversely between said dollies, vibrating means mounted on each of said screed boards for individually vibrating each of said screed boards, supporting means individually connecting said screed boards to said dollies, said supporting means being adjustable individually to control the vertical disposition of the said screed boards with respect to said dollies, power means mounted on said dollies for selectively propelling each dolly independently of the other and at selective speeds to permit controlled skewing of the screed boards while the machine is in operation, said supporting means having a resilient floating means to permit limited lateral movement of said screed boards with respect to at least one of said dollies when said screed boards are vibrated and skewed.

8. A screed machine comprising, spaced apart, parallel, individual dollies, a transverse beam extending between said dollies, connecting means for fastening said transverse beam to each of said dollies, said connecting means adapted to loosely fasten said transverse beam to said dollies in a horizontal plane and simultaneously assure the lateral stability of said dollies, tandem screed boards extending transversely between said dollies, vibrating means mounted on each of said screed boards for individually vibrating each of said screed boards, supporting means connecting said screed boards to said dollies, said supporting means being adjustable individually to control the vertical disposition of said screed boards with respect to said dollies, first power means mounted on said dollies to raise and lower said screed boards, and second power means mounted on said dollies for selectively propelling each of said dollies independently of the other and at selective speeds to permit controlled skewing of the screed boards while the machine is in operation, and said supporting means having a resilient floating means to permit limited lateral movement of said screed boards with respect to said dollies when said screed boards are vibrated and skewed.

9. A screed machine comprising, spaced apart, parallel, individual dollies, a transverse beam extending between said dollies, connecting means for fastening said transverse beam to each of said dollies, said connecting means adapted to loosely fasten said transverse beam to said dollies in a horizontal plane and simultaneously assure the lateral stability of said dollies, tandem screed boards extending transversely between said dollies, vibrating means mounted on each of said screed boards for individually vibrating each of said screed boards, grip means securely holding each of said screed boards in proximity to each of said dollies, a floating plate attached to each said grip means and movable with respect thereto along the axis of said screed boards, resilient means connecting each floating plate to its respective dolly, means for individually adjusting the vertical disposition of each of said screed boards with respect to said dollies, and power means mounted on said dollies for selectively propelling each dolly independently of the other to permit controlled skewing of the screed boards while the machine is in operation, the movement of each said floating plate along the axis of the screed board with which it is associated permitting limited lateral movement of said screed boards with respect to said dollies when said screed boards are vibrated and skewed.

References Cited by the Examiner UNITED STATES PATENTS 413,846 10/1889 Chambers 94-45 1,306,353 6/1919 Reynolds 94-45 1,334,483 3/1920 Brooks et a1. 94-45 1,479,949 1/ 1924 Ashmore 94-45 1,524,728 2/1925 Busch 94-45 2,094,910 10/1937 Baily 94-48 2,110,413 3/1938 Baily 94-48 2,542,979 2/1951 Barnes 9448 2,584,459 2/1952 Jackson 94-48 2,605,682 8/1952 Sarosdy 94-45 2,693,136 11/1954 Barnes 9448 3,008,388 11/1961 Nave 94-48 3,015,259 1/1962 Apel et al 94-46 3,110,234 11/1963 Oster 94-45 3,118,353 1/1964 Neil 9445 CHARLES E. OCONNELL, Primary Examiner. JACOB L. NACKENOFF, Examiner.

Claims

9. A SCREED MACHINE COMPRISING, SPACED APART, PARALLEL, INDIVIDUAL DOLLIES, A TRANSVERSE BEAM EXTENDING BETWEEN SAID DOLLIES, CONNECTING MEANS FOR FASTENING SAID TRANSVERSE BEAM TO EACH OF SAID DOLLIES, SAID CONNECTING MEANS ADAPTED TO LOOSELY FASTEN SAID TRANSVERSE BEAM TOP SAID DOLLIES IN A HORIZONTAL PLANE AND SIMULTANEOUSLY ASSURE THE LATERAL STABILITY OF SAID DOLLIES, TANDEM SCREED BOARDS EXTENDING TRANSVERSELY BETWEEN SAID DOLLIES, VIBRATING MEANS MOUNTED ON EACH OF SAID SCREED BOARDS FOR INDIVIDUALLY VIBRATING EACH OF SAID SCREED BOARDS, GRIP MEANS SECURELY HOLDING EACH OF SAID SCREED BOARDS IN PROXIMITY TO EACH OF SAID DOLLIES, A FLOATING PLATE ATTACHED TO EACH SAID GRIP MEANS AND MOVABLE WITH RESPECT THERETO ALONG THE AXIS OF SAID SCREED BOARDS, RESILIENT MEANS CONNECTING EACH FLOATING PLATE TO ITS RESPECTIVE DOLLY, MEANS FOR INDI-