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CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not Applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not Applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not Applicable. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention relates generally to concrete screeding apparatus for placing, consolidating and finishing plastic concrete. In particular, the present invention relates to an inverted triangular truss modular screed with an outrigger support. Relevant art may be found in U.S. Class, subclasses 101, 114, 115, as well as others. 
     2. Description of the Known Art 
     As will be appreciated by those skilled in the art, wet or plastic concrete must be worked before it sets and forms a hardened slab. Working plastic concrete generally involves consolidating the plastic concrete to evenly distribute water and aggregates throughout the resulting monolith and, subsequently, leveling and finishing the consolidated plastic concrete to appropriately contour the top layer of the plastic concrete. 
     Consolidating plastic concrete is often performed by vibrating the plastic concrete to evenly distribute water and aggregate materials throughout the monolith of concrete. The vibrations also fracture air pockets trapped inside the monolith and permit the air to escape therefrom. Other pockets of materials, such as sand and gravel or the like, are also shattered so that their components may be more evenly distributed throughout the monolith. 
     Several tools have been previously proposed for working plastic concrete. These tools include screeds, trowels (both manual and self-propelled), and other tools such as floating pans and the like. Of the former, screeds with strike-offs are commonly employed during initial plastic concrete consolidation while the other types are typically used to finish the top surface of the concrete to a desired smoothness. 
     Form riding screeds are typically at least ten feet in length and ride upon the forms bounding the concrete monolith. These form-riding screeding apparatus are usually pulled along the form by a series of cables or the like and generally employ remote power to vibrate the smoothing blade. Examples of conventional form-riding screeds are shown in U.S. Pat. Nos. 3,299,786 and 3,541,931. 
     Screeds may generally be grouped according to the number of operators needed to operate them, support mechanisms necessary for their proper operation, structural shapes, or other meaningful characteristics. It is not uncommon for a screed to meet the criteria for several groups. Screeds with strike-offs are normally employed in “wet” plastic concrete to initially level and consolidate the monolith because the wet plastic concrete typically will not support heavy weights. (“Wet” plastic concrete generally has a slump of between three and ten inches.) 
     Exemplary multiple operator screeds are shown in U.S. Pat. Nos. 3,110,234, 3,299,786, 3,541,931 and 3,593,627. These devices generally strike-off, vibrate and level plastic concrete in a single pass. They may employ remote power and are typically drawn through plastic concrete by multiple operators. However, they are large and unwieldy and they often require excessive site preparation and cannot be moved quickly about the pour. These devices also suffer from other handicaps associated with maintenance and the like. The configuration of their truss system is such that the vibratory mechanism and strike off blades are essentially an integral part of the screed. As a result of this configuration, the vibrations shake the entire unit, which makes continuous adjustment of alignment characteristics during the screeding operation a matter of course. The concrete leveling blades need to be changed to provide for different finish textures and the like. The strike-off blades occasionally need to be changed to accommodate different plastic concrete mixes. As will be appreciated by those skilled in the art, changing blades on existing screeds requires considerable time. 
     U.S. Pat. No. 3,110,234 to Oster shows a concrete screeding machine with a rectangular cross-sectional truss beam. The device employs oppositely moving screeds (rather than vibrating screeds) to eliminate side thrust. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally. 
     U.S. Pat. No. 3,299,786 to Godbersen shows a bridge deck finisher that utilizes a rectangular cross-section truss beam. The apparatus uses spring urging toward the concrete to provide resiliency. The apparatus does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally. 
     U.S. Pat. No. 3,541,931 to Godbersen shows a concrete finishing mechanism having an adjustable rotating drum. While this device is of only marginal relevance, it too employs a rectangular cross-section truss beam. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally. 
     U.S. Pat. No. 3,593,627 to Rowe et al. shows a concrete finishing machine movable longitudinally of a road and having a pair of oppositely reciprocating finishing members movable transversely back and forth across the road. The device utilizes a rectangular cross-section truss beam to support the finishing members. The device employs elongated adjustment rods to enable the device to accommodate crowns on roads. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally. 
     U S. Pat. No. 5,533,831 to Allen shows an obstacle bypass system for concrete finishing tools. The device utilizes a rectangular cross-section to support the finishing members. The device employs pivoting members to enable the device to retract to bypass obstacles. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally. 
     U.S. Pat. No. 5,988,939 to Allen et al. shows a universal bridge deck vibrating system that utilizes a translating carriage atop a conventional rectangular cross-sectioned beam screed. The device does not utilize supporting outriggers to prevent sagging or to maintain a selected alignment pitch nor does it utilize an inverted triangle truss to support concrete-finishing elements centrally. 
     Thus, there exists a need in the art for a vibratory screed that may be easily transported about a pour site as well as from pour site to pour site, with minimal preparation time required before use to consolidate and level plastic concrete. The screed width needs to be easily adjustable to accommodate a large range of spans. The working or finishing tools, such as strike-off blades and leveling bars, need to be easily removable to accommodate various concrete mixes that might be spread and the desired texture of the finished concrete monolith. A particularly advantageous apparatus would use a dependable vibratory dispersion system that dampens vibration transmission to the truss system while preventing undesirable down time for camber or pitch adjustments to promote efficient concrete consolidation and leveling. 
     A need also exists for an improved multiple operator vibratory concrete screeding apparatus that has vibration dampening between the vibratory mechanisms and the trussed beam, has easily changeable strike-off and leveling blades, and has easily adjustable alignment mechanisms, especially for pitch camber alignment. 
     SUMMARY OF THE INVENTION 
     In accordance with one exemplary embodiment of the present invention, a screed with a trussed main beam having a cross-section in the geometrical shape of an equilateral triangle is used for finishing concrete. This beam is oriented such that the equilateral triangle is turned upside down or inverted with the wide base at top and the bottom pointed toward the concrete being worked upon below the screed. The inverted triangular truss beam gives sufficient space to mount working tools, such as a leading scraper or strike-off or leveling blade as well as a trailing smoothing tool or bar more closely within or substantially within the peripheral edges of the screed beam rather than being placed a substantial distance in front or behind the main screed beam. In this position, the tools or blades are stabilized by the weight of the beam and do not unduly torsion the supporting truss system. This reduction in torsion is primarily due to reduction in the lever multiplier effect for locations forward or behind the screed beam. 
     The screed has several primary members including carriage assemblies, a concrete spanning beam from which tools are suspended and uprising outriggers. The screed is adapted to be used to work plastic concrete to produce a desirably formed monolith in a single pass. The screed rides on forms bounding the plastic concrete on spaced apart, wheeled end carriage assemblies. The main trussed beam extends between the carriage assemblies and it is thus supported over the plastic concrete to be worked. 
     In use, the carriage assemblies ride on the forms bounding a concrete pour site while the beam passes over the concrete therebetween. Any tools suspended by the beam can thus work on the concrete passing beneath the beam in a conventional fashion to produce a desirably finished concrete monolith. 
     Usually only one concrete finishing tool is mounted before and one aft of the main trussed beam. As a result of the particular geometry of the inverted triangle truss beam, there is sufficient space on the quick connector to mount additional concrete finishing tools if desirable. 
     The main beam has spaced apart ends, each of which include a terminal steel plate that has the same dimensions as the trussed beam and which mate with corresponding coupling points on each carriage. At each beam end, an outrigger assembly is captivated between the beam end and the carriage assembly. 
     Each outrigger includes a front and rear stanchion. Each stanchion rises above the plane of formed by the truss base. A front and rear adjustment bar extends inwardly from the front and rear stanchion to a point proximate the beam midpoint where they are anchored to the beam. The front and rear adjustment bars may be selectively lengthened or shortened to change the pitch or alignment of the screed to vary the angle of attack for the suspended tools or the resultant shape of the concrete monolith produced by the screed. 
     The terminal beam plates and the other primary members have triangular slots adapted to receive short alignment members that facilitate coupling abutting members. Thus, the primary members may be transported in an unassembled state and quickly assembled at a job site. 
     In one exemplary embodiment in accordance with the present invention, the main trussed beam includes several sections of modular design. The sections or modules can include only the main beam or they can include concrete finishing tools. The latter is preferential since at a minimum each main trussed beam module will have a leading working tool such as a scraper or strike-off blade and a finishing tool such as a vibrator or a vibrator bar attached. Individual modules can range from 2.5 feet to 10 feet in width. As a result of the different sizes, combinations of modules can be assembled in any configuration to meet the width requirement of the job at hand. The ends of the modules are shaped for quickly attaching one to another in their central trussed beam geometry. The modules are coupled together with bolts through holes in their respective steel end plates. 
     The ends of each main beam module have reinforcing steel bands located next to the steel end plate. Longer modules can have these reinforcing bands spaced along them. In addition to providing extra strength, these bands can serve as attachment locations both in front of as well as behind the main trussed beam for “quick connecting” concrete finishing tools. This “quick connection” utilizes a common geometrical configuration for attaching concrete finishing tools to the main inverted triangle trussed beam which results in a system that makes attaching various concrete finishing tools to the inverted triangle trussed beam simplistic. In one exemplary embodiment, the common geometrical configuration is a bracket that has a cross section in the shape of an equilateral triangle whose dimensions are determined by the distance in front of or behind the main beam it is desired for the concrete finishing tool to operate as well as their mounting height. 
     In addition, the leveling blade as well as the vibratory bar may each be attached with only one bolt at each reinforcing band of a main beam module. Anti-vibration components can be included as desired at the points of attachment of vibratory bars to the “quick connector” framework as well as where the “quick connector” attaches to the main trussed beam. Vibration control is further enhanced by isolating the source of the vibration by having small vibrators mounted on the vibratory bar for each module. 
     During setup, the inverted triangle trussed beam screed is aligned and adjusted to give the desired surface crown. Even with the dampened vibrations acting on the screed, the vibrations are such that the screed can be shaken out of alignment. Thus, continual alignment adjustments may need to be made during operation. Since the screed has outriggers, the pitch or alignment of the screed can be adjusted outside of or exteriorly from the pour site. Thus, the operator is not required to walk through the plastic concrete to make these adjustments. This is preferential since walking through the plastic concrete is to be avoided as it disturbs the concrete by leaving depressions and imperfections in the concrete or it slows the process by stopping the forward movement of the screed. The outriggers also support the center of the screed from the outer edges of the screed, which is especially important for longer spans. 
     Thus, a principal object of the present invention to provide a concrete leveling and finishing apparatus that enhances and improves concrete leveling and finishing operations. 
     A basic object of the present invention is to provide a concrete finishing apparatus for which a selected pitch may be easily implemented and maintained. 
     Another basic object of the present invention is to provide a concrete finishing device that minimizes torsion stresses by positioning leading and trailing tools centrally. 
     Another object of the present invention is to provide substantial weight reduction in a concrete screeding apparatus without a reduction in its strength. 
     Yet another object of the present invention is to provide a method of adjusting the pitch of a screed without requiring operators to enter poured plastic concrete. 
     Another object of the present invention is to provide a method of quickly changing the leveling blades and smoothing bars of a concrete finishing apparatus. 
     Yet another object of the present invention is to provide a means for dampening vibrations upon a concrete finishing apparatus. 
     A further object of the present invention is to provide a means to accommodate various span widths by using module units of various lengths that can be assembled in any order or combination. 
     An object of the present invention is to provide a concrete finishing apparatus that can be assembled and disassembled rapidly to facilitate transport among job sites. 
     These and other objects and advantages of the present invention, along with features of novelty appurtenant thereto, will appear or become apparent in the course of the descriptive sections. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     In the following drawings, which form a part of the specification and which are to be construed in conjunction therewith, and in which like reference numerals have been employed throughout wherever possible to indicate like parts in the various views: 
     FIG. 1 is an environmental view taken generally from the front showing one exemplary embodiment of an inverted truss screed with outrigger support in accordance with the present invention with portions omitted or shown in section for clarity; 
     FIG. 2 is an environmental view taken generally oppositely from FIG. 1 with portions omitted or shown in section for clarity thereof; 
     FIG. 3 is an end elevational view with portions omitted or shown in section for clarity thereof, 
     FIG. 4 is a partially exploded perspective view of the outrigger support, carriage assembly and a portion of the beam for the screed with portions omitted or shown in section for clarity thereof, 
     FIG. 5 is an enlarged front elevational view of one section of the screed with portions omitted or shown in section for clarity; 
     FIG. 6 is a top plan view thereof; 
     FIG. 7 is side elevational view thereof; 
     FIG. 8 is side elevational view thereof showing a moved position; 
     FIG. 9 is a front elevational view of a portion of the screed with portions omitted or shown in section for clarity; and, 
     FIG. 10 is a front elevational view similar to FIG. 9 showing a moved position. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     One exemplary embodiment of the inverted truss screed in accordance with the present invention is generally designated by reference numeral  20  in FIGS. 1-10. The screed  20  will be normally used at construction sites  23  where wet or “plastic” concrete  24  is being used to build roads, bridge decks, commercial building floors, and the like. The plastic concrete  24  is typically bounded by rigid forms  27  that define a pour area containing the plastic concrete  24  which is worked by screed  20  to form a finished concrete monolith  30 . The top of the finished monolith  32  is commonly at the same level as the top of the forms  27 . The forms  27  may also be used to support and guide the concrete screed  20  with attached finishing tools. Thus, the forms  27  support the riding concrete screed  20  permitting the screed  20  to span the concrete pour area  29  as it sits or rides atop the forms  27 . 
     The concrete monolith  30  is made by first placing the containing and dimension defining forms  27 . Then, fresh plastic concrete  24  is poured into the area  29  bounded by the forms  27 . Any excess plastic concrete  24  is then removed before the consolidating or packing the plastic concrete  24  and finishing the surface of the plastic concrete. The next step is to work the plastic concrete  24  to remove air pockets or bubbles that may exist within plastic concrete  24 . Finally, the packed and finished plastic concrete  28  cures into a solid monolith  30 . 
     It needs to be stressed that the procedure just described is time critical in that as soon as water is added to the dry concrete mix the cement in the mix begins to react chemically and the plastic concrete  24  mix will only remain plastic and formable for a given time period before it hardens or “sets”. The plastic concrete  24  only has the proper consistency for certain forming operations during shorter periods of the overall “setting” time. 
     On large commercial jobs such as one exemplified by FIG. 1, the forgoing steps are arranged to occur as a spatial sequence whose steps parallel the time sequence outlined herein. The concrete forming process begins at a first end  33  of the pour site and proceeds laterally in the direction indicated by the arrow identified by reference numeral  35  toward the other end  37 . FIG. 1 shows the concrete pouring, consolidating and finishing processes after they have progressed sufficiently to yield a newly finished concrete monolith  32 . Thus, the screed  20  traverses the forms  27  moving in the direction of arrow  35  over the freshly poured plastic concrete  24  while pushing excess plastic concrete  26  forward and packing or consolidating and smoothing or finishing all of the plastic concrete passing beneath the screed  20 . Of course, other operations could be performed simultaneously as well with appropriate tooling for screed  20 . 
     In operation, the screed  20  must be supported while it is propelled forward across the unfinished plastic concrete  24 . The screed  20  can ride on forms  27  or it can ride on finished, hardened concrete adjacent to the current pour that act as forms  28 . This is an important mode of operation as it allows for the removal of forms  27  and the insertion of material for planned jointing of several concrete monoliths to accommodate the natural expanding and contracting of concrete monoliths thus preventing random cracking. 
     The screed  20  is propelled across the unfinished plastic concrete  24  either by self-propulsion or by retracting cables located at each end  21 ,  22  of the screed  20 . The cables can be retracted manually or with other power sources such as hydraulically or electric motors or the like. 
     During a concrete pouring operation, plastic concrete  24  is deposited in front of the screed sufficiently fast to have a zone of slight excess  26  immediately in front of the screed  20 . A crew of workers is spaced along the front of the screed  20 . Their job is to ensure that this slight excess of plastic concrete  26  is continually maintained. This slight excess of plastic concrete  26  is maintained by manually moving plastic concrete  24  toward the screed  20  to create the excess  26  or dragging the plastic concrete  24  away from the screed  20  to reduce the excess  26  sufficiently to avoid problems associated with too large of an excess  26 . 
     Screed operators or tenders normally are stationed at each end  21 ,  22  of the screed  20 . The operators regulate the screed&#39;s forward movement. The operators also check and usually adjust the overall screed  20  pitch and/or alignment. The adjustment of the screed  20  for shaping the desired crown in the finished monolith  30  is a critical factor since an error in the finished monolith&#39;s crown is expensive and time-consuming to rectify. 
     The inverted truss concrete screed  20  has a central beam  40  extending between the ends  21 ,  22 . The beam  40  includes at least one elongated modular section  42  and possibly several modular sections that are coupled together to form screed  20 . Each module  42  supports concrete working and finishing tools as will be more fully discussed hereinafter. 
     Two outrigger systems  80 ,  100  stabilize the main truss beam  70  and facilitate adjustments to screed pitch and alignment for producing the desired crown on the finished concrete monolith  32 . At the screed ends  21 ,  22  carriage assemblies  50 ,  60  support the truss screed  20  on forms  27 . Optional attachments include auxiliary generators, hydraulic motors, and the like, which can be affixed to the end carriage units  50 ,  60  as needed. 
     The end carriages  50 ,  60  each include a body  52 ,  62  that directly supports the inverted truss screed  20  to support, stabilize and guide the screed  20  during operation. Each rear arm  56 ,  66  is longer than each fore arm  54 ,  64  to compensate for the pressure to tilt the screed  20  backward. The guide bars  55 ,  65  keep the load bearing wheels  58 ,  68  centered on forms  28  or other narrow supporting media. The wheels  58 ,  68  are exchangeable so that their properties best meet the requirements needed to be transported over the available support forms  27 , i.e. rails, pipes, hardened flat concrete and the like. Each rear arm  56 ,  66  is arched above the vibratory packing and smoothing bar  150  so that the bar  150  can extend over form  27  allowing concrete to be finished to the very edge and utilizing the form  27  to establish the level of the finished concrete. Each front arm  54 ,  64  is short so that the leveling blade  140  can extend past the form  27  in front of any screed  20  parts. Not having any obstacles in front of the leveling blade  140  facilitates moving the plastic concrete  24  to maintain the proper excess immediately in front of the leveling blade  140 . 
     The inverted truss screed  20  has a common geometric cross-sectional shape as well as dimension for connections between all abutting elements for facilitating component assembly. These coupling elements  70  are preferably internal to the perimeter of the main beam  40 . 
     Each coupling  70  uses a common cross-sectional shape with that shape being an equilateral triangle defined in a terminal plate  75 . Four holes  76  to receive coupling bolts are located centrally in each plate  75 . Holes  78  with triangular peripheries are located proximate each of two adjacent sides in each plate  75  and can be advantageously ⅜ inch from each side. The inside dimensions of these triangular holes  78  can be the same as the inside dimensions obtained by welding three ⅛ inch thick by 1.5 inch wide steel plates in the cross-sectional form of an equilateral triangle although other dimensions will work acceptably. A short alignment tube  79  with a triangular cross section fits inside these holes  78  during assembly of components to serve as positioning guides to facilitate rapid assembly. 
     Each inverted truss beam section  42  has a plurality of equilateral triangles incorporated in its structure. Firstly, the main beam  40  has a cross section in the shape of an equilateral triangle. The frame  42  of the main beam  40  includes a ¼ inch steel plate for the coupling elements  70  at each end of each section  42 . Each section&#39;s ends are connected with three triangular shaped framing members  43 . These triangular framing members  43  are constructed by welding three ⅛ inch thick by 1.5 inch wide steel plates of the desired length together to form reinforcing strut  44  with a cross-sectional equilateral triangle shape. The ends of the framing members  43  form triangular shaped holes in the coupling element  70  and are welded so that the end of the framing member  43  and the surface of a respective coupling  70  are flush on the outside. 
     A web of triangles  45  function as a truss. The truss may be advantageously constructed from ⅜ inch steel rod along the sides of each section  42 . These steel rods  45  are welded to the framing members  43  whenever they meet thus creating stiffing triangles located along the side (i.e. the truss). Attachments made via welding are the round steel rods  45  to the framing members  43 , the round steel rods  45  to each other, and the framing member  43  to each end coupling  70 . 
     The screed  20  is disassembled for moving by unbolting the coupling bolts placed in the holes  76  located at the end of each section  42  and the other screed components. The screed  20  sections  42  have a plurality of lengths ranging from 2.5 to 10 feet. There is also a quick connector for the vibrator  156  to facilitate fast assembly and disassembly. 
     The screed  20  is assembled by inserting the short metal guides  79  into holes  79  and pushing adjoining sections  42  and/or other screed components including the carriage assemblies  50 ,  60  and outrigger  80 ,  100  together. In this manner the bolting holes are quickly aligned and held in place for the subsequent bolt insertion. The outriggers  80 ,  100  are aligned similarly to facilitate quick assembly at the job site. 
     The concrete finishing tools  140 ,  150  are attached to the main beam  40  with braces  142 ,  152  that also serve as “quick connectors.” An exemplary embodiment of the configuration of scraper blade  144 , main beam  40 , and smoothing bar  154  is shown in FIG.  1 . The braces  142 ,  1 , 52  are attached to the main beam  40  at the reinforcing bands  44 . 
     In one exemplary embodiment with a plurality of sections  42  comprising beam  40 , a plurality of vibrator bars  154  for packing and smoothing the plastic concrete  24  are arranged in offset, overlapping rows. That is, the vibrator bars  154  in one row lap those in the other row. This overlap prevents surface imperfections such as ridges and seams. Individual vibrator units  156  are located in the center and on top of each vibrator bar  154 . The vibrator unit  156  is composed of a waterproof electric motor that drives an offset cam to originate the vibrations. 
     While screed  20  moves forward, the vibrators  156  vigorously vibrate to cause the smoothing bar  154  to vibrate to pack and smooth the plastic concrete  24  resulting in a packed and smoothed concrete monolith  30 . While the vibrations are necessary to pack and smooth the plastic concrete  24 , their effect on the screed  20  is to shake it out of alignment. To minimize the deleterious effect of the vibrations on the screed  20 , vibration dampeners can be installed between smoothing bar  154  and braces  152  as well as between braces  152  and beam  40 . However, provision must still be made for periodic alignment of screed  20  to maintain a desirable alignment and pitch. 
     An enlarged view of one of the outriggers  80  is shown in FIG.  4 . The outrigger  80  has base bars  81 ,  82  which form support as well as connectors for spacing bar  83  and vertical stanchions  84 ,  85 . The tops of the vertical stanchions  84 ,  85  are connected to a spacing bar  86  that also serves as the attachment point for connecting bars  87 ,  88 . These components together form a front and rear triangle joined by spacing bars  83 ,  86  and stabilizer plate  89 . Stabilizer plate  89  is an extension of the triangular shaped mounting plate  70  and extends ⅓ the distance up the vertical stanchions  84 ,  85  to provide sufficient space for attaching the stanchions  84 ,  85  to its edges. Spacing bar  86  extends laterally past the vertical stanchions  84 ,  85  to provide for attaching connecting rods  91 ,  92  that are attached to bar-clamp  90 . The outrigger arms  91 ,  92  are usually made with steel rods that bolt onto the top crossbar  93  of the bar-clamp  90 . 
     The outrigger assembly  80  is attached toward the screed&#39;s middle using bar clamp  90 . The upper crossbar  93  is placed atop the two upper main beam  40  frame members  43  with the lower crossbar  94  placed below these frame members  43 . The clamp placement is also chosen so that a reinforcing strut  44  is adjacent to a clamp  90  and prevents the clamp  90  from sliding toward the ends  21  or  22 . Upper and lower cross bars  93 ,  94  are clamped to the framing members  43  with bolts on either side of each framing members  43 . The exact attachment location relative to the outrigger assembly  80  is dependent on the overall width of the assembled screed  20  and is generally greater than ⅓ but less than ½ the length of the assembled main beam. 
     The second outrigger  100  is similar to outrigger  80  but it is located oppositely on screed  20 . Outrigger  100  has base bars  101 ,  102  which form support as well as connectors for spacing bar  103  and vertical stanchions  104 ,  105 . The tops of the vertical stanchions  104 ,  105  are connected to a spacing bar  106  that also serves as the attachment point for connecting bars  107 ,  108 . These components together form a front and rear triangle joined by spacing bars  103 ,  106  and stabilizer plate  109 . Stabilizer plate  109  is an extension of the triangular shaped mounting plate  70  and extends ⅓ the distance up the vertical stanchions  104 ,  105  to provide sufficient space for attaching the stanchions  104 ,  105  to its edges. Spacing bar  106  extends laterally past the vertical stanchions  104 ,  105  to provide for attaching connecting rods  111 ,  112  that are attached to bar-clamp  110 . The outrigger arms  111 ,  112  are usually made with steel rods that bolt onto the top crossbar  113  of the bar-clamp  110 . 
     The outrigger assembly  100  is attached toward the screed&#39;s middle using bar clamp. The upper crossbar  113  is placed atop the two upper main beam  40  frame members  43  with the lower crossbar  114  placed below these frame members  43 . The clamp placement is also chosen so that a reinforcing strut  244  is adjacent to a clamp  110  and prevents the clamp  110  from sliding toward the ends  21  or  22 . Upper and lower cross bars  113 ,  114  are clamped to the framing members  43  with bolts on either side of each framing members  243  The exact attachment location relative to the outrigger assembly  100  is dependent on the overall width of the assembled screed  20  and is generally greater than ⅓ but less than ½ the length of the assembled main beam. 
     The outriggers  80 ,  100  both sit atop the inverted triangular trussed beam  40 . The support bars  81 ,  82 ,  101 ,  102  are aligned with the two upper frame members  43  of the beam  40 . The triangular attachment coupling plates  75  are attached to the terminus of the main beam  40  using bolts that pass through the matching bolt holes in the outrigger attachment plates  75  and in the main screed beam  40  coupling plates  75 . 
     Each of the arms  91  and  111  is shortened or lengthened by use of adjuster  96  and  116 , this adjustment results in a lifting or lowering action (See FIGS.  7 - 10 ), respectively, at the point of attachment to the bar clamps  90 ,  110 . Similarly a lifting or lowering action is obtained at the point of connection of arm  92  and  112  by using adjuster  97  and  117 . In one exemplary embodiment, adjusters  96 ,  97 ,  116  and  117  are threaded bolts although other conventional devices could be used for adjustment as well. 
     Although when adjusting the front or back there is some resultant force on the other side of the screed beam  40 , sufficient slack exists for limited independent front-side or rear-side adjustment. This is important as torsion on the main screed beam  40 , arising from imbalances in the manner of operation of the fore and aft concrete finishing tools  140 ,  150 , often times makes it necessary to raise or lower either the front or rear to maintain proper adjustment of the overall screed main beam  40  (as can be seen in FIGS.  7 - 8 ). 
     At the opposite end of the screed  20 , arm  91  and  11  is shortened or lengthened by use of adjuster  96 ,  116 , this adjustment results in a lifting or lowering action, respectively, at the point of attachment to the bar clamp  90 ,  110 . Similarly a lifting or lowering action is obtained at the point of connection of arm  92  and  112  by using adjuster  97  and  117 . 
     Thus it is possible with the outriggers  80 ,  100  to adjust each end to affect the screed&#39;s pitch by lifting at their respective screed attachments proximate the middle of the screed  20  (FIGS. 9-10) as well as the front and back of the screed independently to affect the screed&#39;s alignment (FIGS.  7 - 8 ). The placement of the adjusting mechanisms  96 ,  97 ,  116  and  117  is such that an operator standing at either end  21 ,  22  of the screed  20  can adjust the screed from his monitoring position. 
     From the foregoing, it will be seen that this invention is one well adapted to obtain all the ends and objects herein set forth, together with other advantages which are inherent to the structure. 
     It will be understood that certain features and subcombinations are of utility and may be employed without reference to other features and subcombinations. This is contemplated by and is within the scope of the claims. 
     As many possible embodiments may be made of the invention without departing from the scope thereof, it is to be understood that all matter herein set forth or shown in the accompanying drawings is to be interpreted as illustrative and not in a limiting sense.

Summary:
A screed with a trussed beam having a cross-section in the geometrical shape of an equilateral triangle used to support tools for working plastic concrete. The beam is supported between spaced apart, wheeled carriages riding forms bounding the plastic concrete. The beam is oriented such that the cross-sectional triangle is inverted with the wide base at the screed top and the apex at the bottom. The inverted triangular truss beam has sufficient space to suspend working tools substantially within the peripheral edges of the beam. The screed uses upstanding integral outriggers so that the pitch at the center of the screed can be adjusted exteriorly to the pour site.