Screeding apparatus includes an elongated support and a strike board extending from a carriage on the elongated support, the support moved by drive structure along spaced side forms. The carriage and strike board are moved relative to the elongated support to engage, move and compact wet concrete within a cavity between said side forms during formation of a concrete slab.

TECHNICAL FIELD

This invention relates to a screeding apparatus for engaging, moving and compacting wet concrete during formation of a concrete slab.

BACKGROUND OF THE INVENTION

Screeding of concrete to form slabs is a well known process. For small slabs, screeding is often accomplished by manual tools. Screeding machines exist for screeding larger slabs. The standard approach when using screeding machines is to have one or more workers employ shovels to perform the back breaking work of pregrading poured concrete for the screed. This approach is relatively expensive and inefficient.

The known prior art does not teach or suggest the screeding apparatus disclosed and claimed herein.

DISCLOSURE OF INVENTION

With the apparatus of the present invention, screeding of a concrete slab can readily and efficiently be accomplished without employing personnel utilizing shovels to do the back breaking work of pregrading poured concrete for the screed. In fact, the apparatus of this invention lends itself to operation by a single individual. Slabs are completed in an expeditious manner and the screeding machine has relatively low construction and maintenance costs as compared to other screeding apparatus employed when forming a screeding large slabs.

The screeding apparatus is for engaging, moving and compacting wet concrete during formation of a concrete slab in a space defined by spaced side forms.

The apparatus includes a double-ended, elongated support extending across the space and between the spaced side forms.

Support transport structure is incorporated in the screeding apparatus for transporting the elongated support in a predetermined direction along the spaced side forms. A carriage is mounted on the elongated support for movement along the elongated support in a direction transverse to the predetermined direction.

A strike board depends from the carriage for engaging wet concrete in the space.

Carriage mover structure is employed for moving the carriage and the strike board transverse to the predetermined direction along the elongated support to selectively position the carriage and the strike board in selected alternative positions over the space whereby the strike board is engageable with wet concrete of different width segments of the concrete slab between the spaced side forms.

The strike board is associated with structure which moves the strike board up or down relative to the carriage and vibrator structure for vibrating the strike board.

The strike board vibrates, compacts and strikes poured concrete to a desired height within the space and moves excess concrete to the front or rear of the pour without employing workers using shovels to pregrade concrete for the screed.

MODES FOR CARRYING OUT THE INVENTION

Referring now toFIGS. 1-8of the drawings, a first embodiment of apparatus constructed in accordance with the teachings of the present invention includes a double-ended, elongated support in the form of an open framework or truss10. The framework extends across and above a cavity defined by spaced side forms12. Rollers14mounted at opposed ends of the elongated support are positioned on the spaced side forms.

The rollers14comprise components of support transport structure for transporting the framework10in a predetermined direction (corresponding to the direction of the side forms) along the spaced side forms. Hydraulic capstan winches16are located at the ends of the framework10. Cables18extend along the lengths of the side forms, the ends thereof being held in place by stakes20or in some other manner. The cables18are wrapped about the rotating drums of the hydraulic capstan winches. Rotation of the winches will serve to move the framework either forward or rearward along the side forms. This operation is controlled by an operator at a station including a seat22located at one end of the framework through suitable controls.

A carriage30is mounted on the framework for movement along the framework in a direction transverse to the direction of travel of the framework. Bearings (not shown) are preferably employed between the carriage and the framework to facilitate such movement.

Carriage mover structure is provided for moving the carriage along the framework. In the arrangement illustrated, this is accomplished through use of a third hydraulic capstan winch32(FIG. 6) operated independently from winches16by the operator. A cable34extends the length of the framework and is attached at the framework ends. Cable34is wrapped about the rotating drum of the hydraulic capstan winch32so that the carriage can be moved to any desired location along the framework.

A strike board40depends from carriage30, the strike board40in the illustrated embodiment of the invention being in the form of a rectangular-shaped frame.

Strike board moving structure is operatively associated with the carriage and the strike board for selectively moving the strike board up or down relative to the carriage.FIG. 7illustrates the strike board in its elevated or up position andFIG. 8shows the strike board40in its lowered or down position.

Mechanical linkage and a prime mover in the form of a hydraulic cylinder42(FIG. 6) is employed to raise and lower the strike board. The movable piston arm of the hydraulic cylinder42is connected to a T-shaped cross-member44of the mechanical linkage. Pivotally connected at the ends of cross-member44are link members46, the link members46also being pivotally connected to carriage30at the lower ends thereof.

Extension of the hydraulic cylinder42by the operator at station or seat22will cause the cross-member44to move from the position ofFIG. 7to the position ofFIG. 8and consequent rotation of link members46to their illustrated positions inFIG. 8. Movement of links48,50of the mechanical linkage results in the desired movement of the strike board. Retraction of the hydraulic cylinder by the operator will cause the strike board to move upwardly. Slotted guides52provide support and stability for the cross-member44.

In addition, the slotted guides are employed to positively control how deep the strike board enters into the space or cavity defined by spaced side forms12. The guides are adjustably connected at their proximal ends to threaded rods54pivotally connected at the other ends thereof to carriage30. Each rod has two sections connected by a turnbuckle nut58threadedly positioning the two sections to change the total effective lengths of the combined slotted guides and rods. When the outer ends of the vertical portion56of the T-shaped cross-member engage the guides52at the outer ends of the slots thereof, further downward movement of the strike board is prevented.

Vibrator structure is operatively connected to the strike board40to vibrate the strike board. The vibrator structure includes a hydraulic drive motor60mounted on the carriage30and operated by the operator. A drive belt62(FIGS. 4 and 5) is driven by drive motor60, the other end of the drive belt being looped about a gear64. Operation of the drive motor60will cause rotation of the gear64and the shaft66to which it is attached. The shaft66extends the length of the strike board and is rotatably journaled with respect thereto. One or more weights68are eccentrically and fixedly mounted on the shaft66. When the drive motor rotates shaft66and the eccentrically attached weight or weights, the strike board will vibrate. Control of the drive motor is accomplished by the operator at station22.

With the arrangement described above, the single operator employs the drive winches, the up and down strike board function and vibrator function to compact and scrape excess concrete in the cavity between the side forms in low areas in the slab being poured. The operator would not normally process the full width of the slab, but instead process width segments of the slab, moving the carriage and strike board to selected alternative positions over the space whereby the strike board is engageable with wet concrete of different width segments of the concrete slab between the spaced side forms. This structure and operation compact and scrape excess concrete to low areas in the slab being poured. The operator can move the apparatus at will either forward and backward along the side forms to work the concrete in the cavity defined by the side forms in any manner desired to accomplish his objectives.

For example, the truss of the apparatus may be up to 80 feet or more in length, depending upon the width of the slab. The strike board may be 12 feet long for example, and the operator will utilize the apparatus to consecutively process different width segments as determined by the size of the pour, moving the carriage down the truss to process another 12 feet along the length of the pour until the partial slab width is complete. Then the apparatus will be moved down the slab length and the process started again.

Another advantage resides in the ability of the operator to move the carriage along the truss to avoid engaging structural elements, for example posts, pipes, etc., in the space between the side forms with the strike board as the truss moves along the side forms.

FIGS. 9-13describe an alternate embodiment of the apparatus which is similar in many respects to the embodiment ofFIGS. 1-8described above. Like structural components are designated by like reference numerals.

This alternate embodiment incorporates a different form of drive system. Rather than utilizing a capstan/cable drive, this embodiment supports the framework10not only on rollers14but also on two pairs of ground engaging ground wheels80, one pair disposed at each end of the framework. The wheels of each pair of wheels are driven by a belt82which in turn is driven by a hydraulic motor84(seeFIG. 11).

Each pair of wheels and associated drive motor are supported on a rigid T-shaped structural element81which is affixed to the movable piston arm of hydraulic jack88(FIG. 11) disposed in a vertical housing attached to the framework.

The hydraulic jacks are employed to selectively move the framework10toward or away from the drive wheels80to vary the weight carried by the drive wheels and the rollers. The objective of this arrangement is to cause the wheels to carry the great majority of the weight of the framework, carriage and other structure, such as the strike board, associated therewith. A relatively small percentage of the weight is borne by the rollers14. Extra heavy duty side forms don't have to be used and the tires of the wheels are kept in contact with the ground at a specific amount of pressure for traction.

FIG. 10is a schematic illustration of a jack88in association with a representative arrangement for controlling pressure to the jack. The arrangement includes a hydraulic pump90and pressure tank92connected to an up/down selector valve94. A pressure reducing valve96is interposed between hydraulic lines98,100leading to the jack cylinder and up/down selector valve94. Operatively associated with the pressure reducing valve are a pressure setting control knob102and a pressure gauge104.