Patent Application
20060018715
The present invention relates generally to raking or striking-off devices for striking-off uncured concrete at floors and surfaces.
One common practice for the placement of concrete during the construction of slab-on-grade concrete surfaces and floors is to discharge concrete directly from concrete delivery trucks via a chute onto a subgrade upon which the slab will be formed. In some cases, such as where the truck has a front discharge chute, only the truck driver is required to perform the task of controlling the concrete chute from the driver's seat. However, considerable manual labor is required to spread the concrete to a reasonably uniform depth for subsequent strike-off or screeding. Automated laser system responsive screeding machines, such as a Laser Screed machine manufactured by Somero Enterprises of Houghton, Mich., USA (and/or such as the types described in U.S. Pat. Nos. 4,655,633; 4,930,935; 6,129,481; 6,152,647; 6,183,160; 6,588,976; and/or 6,623,208, which are hereby incorporated herein by reference), reduce the manual labor of screeding concrete substantially over large areas. However, in many instances where such a screeding machine cannot be used, the concrete still must be spread out or struck-off in a somewhat uniform fashion by manual effort which is very labor intensive and costly.
Therefore, there is a need in the art for an improved striking-off or raking apparatus and/or method that requires less manual labor and thus overcomes the shortcomings of the prior art.
The present invention provides a power rake or plow apparatus for striking-off uncured concrete that is moved and/or controlled by an operator walking behind the apparatus as the apparatus is moved over and along and through the uncured concrete. The apparatus includes a wheeled base unit and a plow assembly that is adjustably mounted to the wheeled base unit and adjustable to strike-off the concrete at a desired level or grade. The plow assembly may be adjustable in response to a laser plane reference system. The plow assembly may include a vibrating member to vibrate, compact and smooth the concrete at the desired grade as established by the plow or grade setting device.
According to an aspect of the present invention, a wheeled concrete working device that is movable over a surface of uncured concrete (that has been placed on a subgrade surface) and operable to establish a desired grade of the uncured concrete surface includes a wheeled support, a plow assembly and a controller. The wheeled support includes a frame portion and a pair of wheels rotatably mounted at the frame portion. The wheeled support is selectively movable in a forward direction and a rearward direction. The plow assembly is mounted to the frame portion and includes at least one plow member for engaging the concrete when the wheeled support is moved in the rearward direction. The device is operable in response to a signal from a laser receiver mounted at the plow assembly to adjust an elevation of the plow member to establish a desired grade of the concrete when the wheeled support is moved in the rearward direction. The controller automatically controls the elevation of the plow member in response to a direction signal indicative of the direction of travel of the wheeled support and controls the elevation of the plow member irrespective of the signal from the laser receiver when the direction signal is indicative of the wheeled support at least one of stopping and moving in the forward direction.
According to another aspect of the present invention, a wheeled concrete working device that is movable over a surface of uncured concrete and operable to establish a desired grade of the uncured concrete surface includes a wheeled support, a plow assembly and a user input. The wheeled support is selectively movable in a forward direction and a rearward direction. The wheeled support comprises a forward frame portion supported by at least one front wheel and a rearward frame portion pivotally attached to the forward frame portion and supported by at least one rear wheel. The plow assembly is mounted to the forward frame portion and includes at least one plow member for engaging and establishing the desired grade of the concrete when the wheeled support is moved in the rearward direction. The device is operable in response to a signal from a laser receiver mounted at the plow assembly to adjust an elevation of the plow member to establish the desired grade of the concrete when the wheeled support is moved in the rearward direction. The user input is adjustable by an operator of the wheeled concrete working device to adjust a down pressure of the plow assembly at the concrete when the wheeled support is moved in the rearward direction.
According to another aspect of the present invention, a wheeled concrete working or processing device or machine may include a bump detecting device that is operable to detect a surface irregularity of the subgrade upon which the wheels travel and at a location rearward or ahead of either of the wheels and in the rearward direction of travel of the wheeled support. The controller may be operable to reduce the rearward speed of the wheeled support in response to a detection of a surface irregularity by the bump detecting device. The controller may control the frame portion and/or the plow assembly to substantially maintain the plow assembly at a desired orientation when at least one of the wheels engages the detected surface irregularity. The controller may be operable to increase the rearward speed of the wheeled support after the wheels have passed the detected surface irregularity. The wheeled support may comprise a four-wheeled support having a forward frame portion supported by a pair of front wheels and a rearward frame portion pivotally attached to the forward frame portion and supported by a pair of rear wheels, with the plow assembly being mounted to the forward frame portion. The bump detecting device may comprise a rear level sensor located at the rear frame portion. The rear level sensor may detect a tilt of the rear frame portion about a longitudinal axis of the rear frame portion, where the detected tilt is indicative of one of the rear wheels engaging a surface irregularity.
According to yet another aspect of the present invention, a wheeled strike-off device is movable over a surface of uncured concrete or subgrade materials and is operable to establish a desired grade of the uncured concrete surface or subgrade surface. The wheeled strike-off device includes a wheeled support and a plow assembly. The wheeled support has a frame portion and a pair of first wheels rotatably mounted at or near a first end of the frame portion, and a second wheel rotatably mounted at or near a second end of the frame portion. The second wheel is pivotable about a generally vertical pivot axis to assist in steering the strike-off device as it is moved over the surface. The plow assembly is adjustably mounted to the frame portion and is vertically adjustable relative to the frame portion via an actuator. The plow assembly includes at least one plow member for engaging the uncured concrete or subgrade materials and establishing the desired grade.
The actuator may be automatically adjustable in response to a laser leveling system. The plow assembly may include a first plow member facing in a first direction and a second plow member facing in a second direction, with the first direction being generally opposite to the second direction. The first plow may establish the desired grade when the wheeled support is moved in the first direction and the second plow may establish the desired grade when the wheeled support is moved in the second direction. Optionally, the plow assembly may be adjustable relative to the wheeled support about a longitudinal axis of the wheeled support.
The first wheels may be independently rotatably driven to move and steer the strike-off device over and through the uncured concrete surface. The second wheel may be rotatably driven to move the strike-off device. The wheeled support may include a handle portion that extends from the second end of the wheeled support and that is connected to the second wheel, such that pivotal movement of the handle portion imparts a corresponding pivotal movement of the second wheel to steer the wheeled support.
According to another aspect of the present invention, a method of establishing a desired grade of an uncured concrete surface or subgrade surface includes providing a wheeled strike-off device having a wheeled support and a plow assembly. The wheeled support has a frame portion, a pair of first wheels rotatably mounted at or near a first end of the frame portion, and a second wheel rotatably mounted at or near a second end of the frame portion. The plow assembly is adjustably mounted to the frame portion and is vertically adjustable relative to the frame portion via an actuator. The plow assembly includes at least one plow member for engaging and establishing the desired grade. The strike-off device is moved over a surface of uncured concrete or subgrade materials. The plow assembly is adjusted relative to the wheeled support to establish the desired grade as the strike-off device is moved over the surface. The second wheel is pivoted about a generally vertical pivot axis to assist in steering the strike-off device as it is moved over the surface.
According to another aspect of the present invention, a screeding device that is manually movable over a surface of uncured concrete placed between opposite forms, and that is operable to level and smooth the uncured concrete surface to a level set by the forms, includes a wheeled unit, a plow and a concrete surface working member, such as a vibrating member or the like. The wheeled unit has a frame portion and at least one wheel rotatably mounted to the frame portion. The plow is mounted to a rear portion of the frame portion and includes a spacing element for spacing the plow at a desired level above the forms. The concrete surface working member is attached to the plow and positioned rearward of the plow. The concrete surface working member is at least partially supportable on the forms, and works the uncured concrete to a finished condition at a level generally defined by the forms and below the level of the plow.
The spacing element may comprise a pair of spacing elements, with each of the spacing elements being positioned along a lower edge of the plow at or near an end of the plow. Each of the spacing elements may include a curved lower lip that substantially encompasses the lower edge of the plow.
Optionally, a powered, laser controlled, four wheel, articulated, strike-off plow, and raking machine or four wheel power rake may be implemented to screed a concrete surface. In one form, the machine is intended for striking-off and leveling uncured concrete and loose subgrade materials. A plow head assembly is attached to the front of the machine for leveling materials whereby a laser leveling system is included to provide automated leveling and power raking of materials to a desired grade elevation.
A further aspect of the present invention beyond power raking is a machine that can be readily adapted for other uses by a concrete construction contractor with appropriate and optional sets of accessories and attachments. The plow head assembly may be quickly and/or readily detached from the front of the machine and another assembly installed. For example, the machine can be adapted to become a sprayer with a boom containing spray nozzles, a pressurized fluid pumping system, and a reservoir of fluid material, in order to apply sprayed-on coatings and sealers to a freshly cured concrete surface. Optionally, for example, the machine can be adapted to become an automated, laser system responsive screeding machine with a screed head attachment to provide a drive-through-the concrete, laser-guided, concrete strike-off, screeding and finishing machine. Optionally, for example, the machine can be adapted to become a hose handler to drag and otherwise move concrete pumping supply hose at construction sites where concrete is being pumped from a pumping unit to a location where concrete placing operations are taking place. Optionally, for example, the machine can be adapted for use as a powered sweeper having a cylindrical rotating brush attachment where the rotating axis of the brush is roughly parallel to the surface being swept.
Each of these adaptable uses provides the concrete construction contractor with a machine having a high level of machine utility and utilization. Thus, the present invention provides a significant increase in productivity, ease of effort, and profitability to the concrete construction industry.
Therefore, the present invention provides a strike-off device and method that provides a desired and accurate strike-off or raking of an uncured concrete surface or of subgrade materials. The device or apparatus or machine may be moved in either direction to strike-off or establish the desired grade or level of the uncured concrete or subgrade material. The plow is automatically adjusted to maintain the desired grade or level in response to a laser reference system, so that the uncured concrete or subgrade materials are struck-off at the appropriate level over the targeted area. The wheels of the machine may be independently operable or controlled to move the machine over and through the uncured concrete or subgrade materials and to turn or steer the machine as it is moved over and through the uncured concrete or subgrade materials. The rear wheel may be steered via a handlebar or the like to further enhance the steering and controlling of the machine as it is moved over and through the uncured concrete or subgrade materials. The present invention thus provides a strike-off or raking device or apparatus or machine that substantially reduces the manual labor required to strike-off the uncured concrete or subgrade materials, since an operator need only walk behind the apparatus (or in front of the apparatus, depending on the direction of travel of the apparatus) and control and/or steer the apparatus to establish the desired grade.
The present invention also provides a sidewalk screeding machine that is operable to establish an initial grade of uncured concrete that is slightly above the desired final grade and then to screed the uncured concrete at the initial grade and compact and vibrate the uncured concrete to the final grade, without the use of laser leveling or grade setting systems or the like. The plow functions to cut or establish an initial grade or level of the uncured concrete that is above the level or grade at which the concrete surface working member or vibrating member will work and/or vibrate and/or screed the concrete. The plow thus leaves a small amount of excess concrete for the vibrating member to compact and screed so that the vibrating member provides an enhanced surface of the concrete slab.
These and other objects, advantages, purposes and features of the present invention will become apparent upon review of the following specification in conjunction with the drawings.
Referring now specifically to the drawings and the illustrative embodiments depicted therein, a power rake or powered plow or strike-off or raking apparatus or machine 10 is operable to rake or plow or otherwise establish the grade of uncured concrete or subgrade materials as the machine is moved over and through the uncured concrete or subgrade materials. Strike-off apparatus 10 includes a wheeled base unit 12 and a plow head or assembly 14 adjustably mounted to base unit 12 and adjustable relative thereto via an adjustment mechanism or linkage 16. Plow assembly 14 includes a strike-off member or plow, such as a forward facing plow 18a and a rearward facing plow 18b, for engaging and striking-off the uncured concrete or subgrade materials at the desired grade. The level or grade of plows 18a, 18b may be adjusted relative to base unit 12 in response to a signal from a laser receiver 20 of a laser plane generating system, as discussed below. The wheeled base unit 12 may be driven and steered by an operator walking behind the apparatus, as also discussed below.
Wheeled base unit 12 includes a frame 22 supported by a pair of rubber-tired wheels 24 at one end and a single rubber-tired wheel 26 at the other end. The wheels may be rotatably driven via respective hydraulic motors or the like to provide driving of the apparatus over and through the uncured concrete or subgrade materials. The wheel 26 may be turned relative to the frame 22 to steer the apparatus, such as via a handlebar 28 or the like at the wheel 26. In the illustrated embodiment, the handlebar 28 may support a control panel 29 for an operator to actuate to control the various valves and motors of the strike-off apparatus as the operator walks behind the strike-off apparatus.
The strike-off apparatus 10 thus is a walk-behind machine with rubber-tired wheels, two in the front and one in the rear. Power for driving the hydraulic motors may be provided via any known power source or power means, such as via a gasoline powered internal combustion engine or the like (although other power means, such as electric motors, diesel engines or the like may be implemented without affecting the scope of the present invention). The base unit 12 may include the mechanical frame and components, a supply of hydraulic fluid or oil in a reservoir, a hydraulic pump, control valves, hydraulic pressure lines, and an electrical system including a battery and charging system.
The plow head assembly 14 consists of a forward facing plow 18a and a rearward facing plow 18b so that the strike-off apparatus may be operable in either direction. The plow head assembly 14 is able to either push or pull loose material, such as freshly poured concrete or subgrade materials, such as sand, dirt or gravel or the like, as the plow head is moved over and through the material via driving of the wheel motors of the wheeled support unit.
The plow assembly 14 is attached to the front of the machine through a mechanical linkage or lift mechanism 16 and a hydraulic actuator 30. In the illustrated embodiment, the plow head or plow assembly 14 is supported by the linkage or mechanism 16, which includes a lift arm 32 and an upper tie-rod or head support link 34, and the hydraulic actuator or cylinder 30, which form a vertically movable mechanical linkage. Extension and retraction of actuator 30 causes the plow assembly 14 to lower and raise, respectively, relative to wheeled support 12 via pivotal movement of lift arm 32 and upper link 34 simultaneously relative to the rear end of wheeled support 12. The movement of the linkages 16 relative to wheeled support 12 and to the plow assembly provides generally vertical reciprocal movement of the plow assembly relative to the wheeled support, such that the plow assembly and plows 18a, 18b may remain in generally the same orientation as the plow assembly is raised or lowered relative to wheeled support 12.
The height or elevation of the plows 18a, 18b may be controlled by an automated laser control system having a laser receiver 20 attached to the plow by a mast 36. The mast 36 that supports the laser receiver 20 is located at a generally middle region of the plow. As can be seen in
The laser receiver 20 may be adjusted to a desired height above the plows 18a, 18b via adjustment collars 36a on mast 36 that may allow for extension or retraction of mast 36, which may be a telescoping rod or mast or the like. A laser transmitter (not shown) provides a laser reference plane for the machine. The actuator 30 thus may be automatically adjusted or extended/retracted and controlled in response to a laser reference plane system, preferably using laser beacon receivers and a laser reference plane generator that establishes a laser reference plane at the worksite, such as the types described in U.S. Pat. Nos. 4,655,633 and/or 4,930,935, which are hereby incorporated herein by reference. For example, a standard laser control system provided by Trimble Navigation comprising the GCR Laser Control System package may be adapted to the machine to actively control the elevation of the plow head. The laser system may control a hydraulic valve which in turn controls the position of the hydraulic actuator 30 at the plow in response to the position or level of the laser reference plane at the laser receiver while the machine is in operation.
During operation, an operator stands nearest the single rear wheel 26 and controls and steers the machine at the handlebar 28 and control panel 29. The front wheels 24 are driven, such as via respective hydraulic drive motors 35a, 35b (
In a preferred embodiment, two hydraulic flow control valves 40a, 40b are connected to the respective front wheel drive motors 35a, 35b and are actuated by turning of the handlebars, such as by mechanical cables (not shown) or small chains or members or the like attached to the steering column or shaft or the like. The hydraulic valves help control the steering of the machine and may be actuated by the turning of the handlebars. For example, when the handlebar is turned one way, one of these valves will close by an amount that is determined by how far the handlebar is turned in that direction (either left or right). As the respective hydraulic valve closes, it reduces the flow of hydraulic oil delivered to the respective drive motor at the inside of the turn. This creates a differential flow to the drive motors and causes one of the front wheels to rotate more than the other, which in turn causes the machine to turn more easily either left or right under power.
In addition to providing propulsion power to drive the machine and provide powered steering, the front wheel axle assembly may also have the ability to oscillate or tilt the machine and plow head side-to-side with respect to the horizontal. For example, the front wheels may be attached to a single axle member or subframe 38 (
The tilting of the framework and plow assembly relative to the axle or subframe allows the machine and operator to adjust and maintain a generally horizontal position of the plow head and plows with respect to the desired grade when the wheels of the base unit encounter variations in the subgrade that may cause the machine to tip or tilt either left or right. Thus, the operator may manually control the machine speed, steering of the machine, forward and reverse direction of travel, and side-to-side or horizontal leveling position of the plow, while the elevation of the plow head may be automatically controlled by the laser control system. The controls for these functions may be provided at the control panel 29 at the handlebars 28, where they are readily accessible by the operator walking behind the strike-off machine 10.
Optionally, it is envisioned that the strike-off apparatus or machine of the present invention may alternately include an auger (or other means for moving or striking-off or raking the uncured concrete or subgrade materials) positioned at the forward or rearward portion of the plow assembly, whereby the auger may be operable to cut or establish the grade height of the concrete or subgrade as the strike-off apparatus is moved along and through the uncured concrete or subgrade materials. Such an embodiment may or may not include a strike-off plow at either or both ends. The auger may replace the function of this component entirely or, optionally, the auger may supplement engagement and strike-off of the concrete or subgrade materials, without affecting the scope of the present invention.
The strike-off apparatus of the present invention thus may be suitable to facilitate and improve the accuracy of rough raking of uncured concrete and subgrade materials. The strike-off apparatus may reduce labor and increase productivity and may be quite versatile for use on many types of construction jobs. The strike-off apparatus of the present invention is especially well suited to the small to mid-size company contractor who may already use various types of screeding devices, such as, for example, the Somero Copperhead Laser Screed machine and/or Copperhead XD Laser Screed machine, which are commercially available from Somero Enterprises of Houghton, Mich., and which are described in U.S. patent application Ser. No. 10/728,620, filed Dec. 5, 2003; Ser. No. 10/266,305, filed Oct. 2, 2002; and Ser. No. 10/902,528, filed Jul. 29, 2004, which are hereby incorporated herein by reference, or various types of hand-held vibratory screeds, and/or even simple wooden “2×4” hand-held screeds or the like. The strike-off apparatus of the present invention is preferably small and light enough in weight such that it can be used on elevated decks in addition to on grade sites, thus supplementing the concrete placement work of concrete delivery trucks, pumps, and buggies and the like.
The strike-off apparatus of the present invention will also help the contractor with subgrade work by having the ability to grade and smooth loose earth working materials such as dirt, sand, and gravel and/or the like. The height of the plow is automatically maintained at the correct elevation by the laser control system. This makes the present invention highly suitable for the powered leveling of dirt, sand, or gravel in relatively small areas before concrete is poured or before precast paving stones or “pavers” are installed to create a finished driveway or sidewalk, for example. Accurate grading of the subgrade improves concrete yield by reducing the chance of low spots in the subgrade and any resulting thicker sections of concrete. High spots in the subgrade are also minimized, which reduces the chances for thin sections in the finished concrete where reduced strength and cracking may occur. Precast paving stones and pavers can also be installed on a more accurately prepared subgrade. This can reduce the likelihood of high or low areas when these materials are installed to create a sidewalk, driveway, or patio, for example.
The strike-off apparatus may be used primarily by the small to mid-sized concrete contractors who typically install concrete slabs or paved areas in size from about 2,000 to 20,000 square feet. This includes the “hand-rod” concrete contractors up to and including those who may already be using screeding machines, such as, for example, the Somero Copperhead and Copperhead XD line of Laser Screed products, which are commercially available from Somero Enterprises of Houghton, Mich., and which are described in U.S. patent application Ser. No. 10/728,620, filed Dec. 5, 2003; Ser. No. 10/266,305, filed Oct. 2, 2002; and Ser. No. 10/902,528, filed Jul. 29, 2004, which are hereby incorporated herein by reference. The lightweight raking device or strike-off device or apparatus or machine of the present invention is particularly suited for use at both over ground sites as well as on elevated deck surfaces, and may be implemented at other uncured concrete surfaces, such as interior floors, exterior slabs, roadways, ramps, parking areas or the like.
Optionally, and with reference to
Plow 118 of screeding attachment 114 may comprise any known plowing device or strike-off member, and may include a curved material engaging surface for plowing and carrying or moving the excess uncured concrete along the concrete area as the screeding device is moved along the forms. Plow 118 and screeding attachment 114 may be mounted to the wheeled base unit 112 via connection of a mounting frame 137 to the adjustment mechanism 16 of the wheeled base unit 12.
The mounting frame 137 of screeding attachment 114 includes a pair of cross members 137a that extend from a generally horizontal beam or member 137c along the rear of plow 118 and that extend upward and toward a center junction of the cross members 137a. A bracket or attachment plate 137b is positioned at the center junction of the cross members 137a for connecting an upper tie-rod or head support link 34 of the adjustment mechanism 16, while a pair of generally vertical members 137d extend between the cross members 137a and the generally horizontal member 137c for connection to the end of the lift arm 132 of adjustment mechanism 16. The cross members 137a, horizontal member 137c and vertical members 137d support the plow 118 and provide enhanced rigidity to the plow when the screeding attachment 114 is mounted to the adjustment mechanism 16 and the wheeled base unit 12.
Vibrating member 119 of screeding attachment is attached to the frame 137 of plow 118 and behind or at the rear of the plow 118, such as via a pair of mounting members or attachment members or links 146. Vibrating member 119 may comprise any known type of vibrating member, such as a vibrating member of the types described in U.S. patent application Ser. No. 10/728,620, filed Dec. 5, 2003; Ser. No. 10/266,305, filed Oct. 2, 2002; and Ser. No. 10/902,528, filed Jul. 29, 2004 (Attorney Docket SOM01 P-326), which are hereby incorporated herein by reference. Vibrating member 119 includes a generally flat member with a generally planar, flat and smooth lower surface for engaging and working the uncured concrete surface. In the illustrated embodiment, vibrating member 119 extends along a longitudinal axis and includes a lower, generally flat planar portion 119a and a pair of generally vertical walls or rails 119b extending therealong to strengthen or stiffen the planar portion and limit or substantially preclude deflection of the member. Although shown and described as having a vibrating beam, the screeding device and/or screed head may alternately include any other type of concrete surface working device or member, such as a roller, a flat or contoured plate or the like, which engages and works the uncured concrete surface to flatten and/or smooth the concrete surface as the screeding device is moved over and along the uncured concrete.
Vibration of the vibrator member 119 is accomplished by a powered vibrator device or motor 148, which is powered by power source (not shown), such as a gasoline powered drive motor or engine, or a battery powered drive motor, or the like. As is known in the art, the vibrator device 148 includes a pair of eccentric weight shafts or members that are rotatably driven to cause vibration of the vibrating member 119 as the vibrating member is moved along and over the uncured concrete surface.
Optionally, and with reference to
The operator thus may walk ahead of the wheeled unit as the wheeled unit is driven or moved in the rearward direction and over and through the uncured concrete (with the wheels rolling along and over the subgrade surface beneath the poured/placed concrete) and the screeding attachment is pulled or dragged behind the wheeled unit to establish the grade of the concrete and vibrate and compact and screed the concrete, as discussed below. When a screeding pass is completed, the operator may push down on the handle bars 128 to raise the screeding device or attachment 114 above the concrete surface and to move the machine to another location. Optionally, the wheeled unit 112 may include a kick stand or support leg 113 at a rearward end (opposite to the screed head assembly or device) of the unit to support the rearward end of the unit when the screeding device is not being used. In the illustrated embodiment, the support leg 113 may be pivotally mounted at or near the rearward end of the wheeled unit and may be pivoted between a raised position (as shown in
The adjustment mechanism or linkage 116 of wheeled unit 112 may be similar to linkage 16, discussed above, and may include a lift arm 132, an upper tie-rod or head support link 134, and a hydraulic actuator or cylinder 130. Extension and retraction of actuator 130 causes the screeding attachment 114 to lower and raise, respectively, relative to wheeled unit 112 via pivotal movement of lift arm 132 and upper link 134 simultaneously relative to the rear end of wheeled unit 112. The movement of the linkages 116 relative to wheeled unit 112 and to the screeding attachment 114 provides generally vertical reciprocal movement of the screeding attachment relative to the wheeled unit, such that the plow 118 and vibrating member 119 may remain in generally the same orientation as the screeding attachment is raised or lowered relative to wheeled unit 112.
In the illustrated embodiment, the upper tie-rod 134 attaches to the bracket 137b at the center junction of the cross members 137a of the mounting frame 137, and may be adjusted to adjust the attack angle of the screeding device via pivoting the screeding device about the attachment pins at the end of the lift arm 132. As can be seen with reference to
During operation, the wheeled unit 112 may be moved rearwardly over and through the uncured concrete, such as between a pair of forms or sidewalls 150 that contain the uncured concrete and define the sides or edges of the concrete slab, such as forms that may be placed along opposite sides of a sidewalk or the like during pouring and curing of the concrete sidewalk. As shown in
The spacer member 152 may be attached or secured to the plow via fasteners or the like extending through apertures 152a (
The vibrating member 119 is dragged or pulled behind the plow 118 while the wheeled unit 112 is moved forwardly over and through the uncured concrete via the attachment links 146 connecting or attaching the vibrating member to the plow. Each attachment link 146 may be connected between a bracket 137e of frame 137 of plow 118 and a bracket 154 at each side of vibrating member 119. The brackets 137e, 154 may comprise generally U-shaped brackets that receive a respective end of the link 146 therein. In the illustrated embodiment, and as shown in
Optionally, the attachment link 146 may be secured relative to the vibrating member to retain the vibrating member at a desired attack angle as the vibrating member is dragged or pulled along the forms. The attachment link may be pivoted about the pin through the apertures 154a and 146b to adjust the attack angle of the vibrating member until one of the multiple apertures or openings 146c generally aligns with a corresponding one of multiple apertures 154b (
During operation of the sidewalk screeding machine, the wheeled unit is moved or driven rearwardly and over and through the uncured concrete and between the forms to move the screeding attachment along the forms and over the uncured concrete placed between the forms. The plow functions to cut and establish the concrete grade to a level above the level of the forms, while the vibrating member is dragged behind the plow and rests on and moves along the upper surfaces of the forms. Because the attachment links are pivotally attached to the rear of the plow, the vibrating member may freely float relative to the plow and thus may rest on the forms so that the vibrating member is generally at the elevation of the forms and at a level slightly below the level of the concrete grade established by the plow 118.
As shown in
Referring now to
In the illustrated embodiment, the plow head assembly 214 is attached to the front frame portion of the machine through a mechanical linkage 216 and a hydraulic actuator, such as in a similar manner as described above. The height or elevation of the plow blade 218 is controlled by an automated laser control system having a single laser receiver 220 attached to the plow by a vertical mast 236. A laser transmitter (not shown) stationed away from the machine provides or generates a laser reference plane for the machine's automated laser control system.
As shown in
Desirably, each of the four wheels may be driven by hydraulic motors providing a four-wheel drive propulsion system. Hydraulically released brakes may be used on preferably two or more of the four wheels. The wheels and tires may be optionally selected for particular site conditions. For example, narrow wheels and tires 224, 226 (
The plow head assembly 214 is supported by a lift arm 232, upper tie-rod or head support link 234, and a hydraulic actuator or cylinder 230 forming a vertically movable mechanical linkage, such as described above. The plow head assembly consists of a forward plow 218a and a rearward plow 218b. A laser receiver 220 is attached to a mast 236 located in the middle of the plow 218. The plow head is able to either push or pull loose material such as freshly poured concrete, sand, dirt, or gravel. A standard laser control system, such as a laser control system provided by Trimble Navigation and comprising the GCR Laser Control System package (or other suitable laser control system or the like), is adapted to the machine to actively control the elevation of the plow head. The laser control system controls a hydraulic valve which in turn controls the position of the hydraulic actuator at the plow with respect to the laser reference plane while the machine is in operation.
In addition to providing propulsion power to drive the machine and provide powered steering, the front wheels 224 and axle assembly or subframe 225 of front frame portion 212a may also have the ability to oscillate or tilt the machine and plow head side to side with respect to the horizontal. In the illustrated embodiment, the front wheels are attached to a single axle member or axle assembly or subframe 225, while the frame portion 212a is pivotally mounted to the axle assembly 225 and is pivotable about a generally horizontal axis that is generally parallel to the ground and that extends generally parallel to the direction of travel of the machine as it moves during operation. Side-to-side tilting or oscillation of the machine (such as the front frame portion 212a and plow head) relative to the axle assembly and wheels may be controlled by an actuator or hydraulic cylinder 238 (or other actuating device) with a first end of the cylinder or actuator attached to the frame portion 212a of the machine and a second or opposite end attached to the axle or subframe 225. In such an application, the hydraulic actuator may comprise a double-rod cylinder having a single piston, whereby the amount of hydraulic oil required for a given displacement in either direction may be substantially the same. The operator thus may manually control the amount of tilt of the machine and plow head by a control switch or lever or input at the user controls or handlebars. This allows the machine and operator to adjust and maintain a generally horizontal position of the plow head with respect to the desired grade due as the machine (such as one or both tires of the front portion of the machine) encounters variations in the subgrade that may cause the machine to tip or tilt toward either side.
Optionally, the horizontal leveling of the plow may be automatically controlled by the input signal of a left-right horizontal level sensor or cross slope level sensor mounted to or at the forward frame portion of the machine. During most machine operating mode conditions, the operator may manually control the machine speed, steering of the machine, and the forward and reverse direction of travel, while the side-to-side or horizontal leveling position of the plow head is controlled by the left-right leveling sensor and actuator. The elevation of the plow head may be automatically controlled by an input signal from the laser receiver of the laser control system, as discussed above.
A further aspect of the machine's control system includes an “auto rake” or “auto raise” controller or control system or other control means that is operable to automatically raise the plow head assembly (including the plow blade) at the end of a material leveling or raking or grade establishing pass. For example, as the machine is being driven in the “reverse” travel direction through uncured concrete, the plow is engaged in striking-off and/or leveling of the excess uncured concrete material to the desired grade. In this mode of operation, the height of the plow head is automatically controlled to the desired elevation by height correction signals from the laser receiver (as the laser receiver receives or detects the laser signal or plane transmitted by the laser plane transmitter or generator).
As shown in
At the end of a material raking or leveling pass, the operator may stop the machine and may then select the “forward” travel direction position of the propulsion direction control. Stopping the machine and/or election of the “forward” travel position of the propulsion direction control may automatically provide a signal (from the direction switch or direction indicating device or wheel encoder or the like) to the controller, whereby the controller may actuate or control the lift actuator or cylinder (such as to a hydraulic raise valve of the plow lift cylinder) to raise the plow blade out of and away from the uncured concrete material in response to the signal. During this part of the operation, any “lower” signal from the laser receiver (as the laser receiver is also raised and thus is raised above the laser reference plane) is temporarily blocked (or the laser receiver is deactivated or its signal is otherwise effectively ignored by the controller) to prevent the plow from being automatically lowered toward the correct grade height. Once the plow and laser receiver are raised so that the laser receiver is out of the sensing range of the laser receiver, blocking of the corrections signal from the laser receiver is no longer necessary.
At the fully raised position, the plow head may be brought to a point where the plow lift arm or lifting mechanism engages a limit switch, which may limit further raising of the plow head. At this position, the plow remains at rest in the raised position (and may be secured or retained in the raised position) as the machine is driven through the uncured concrete by the operator in the forward direction. During this step of the process, the plow is not engaged in striking-off and leveling the material. At the end of the forward travel pass, the machine's travel may again be stopped by the operator. The operator may again select the “reverse” position of the propulsion control and may also select a switch to once again lower the plow head for engagement with the concrete (optionally, the plow head may be automatically lowered in response to selection of the reverse position or movement of the machine in the reverse direction or in response to the stopping of the wheeled device after traveling in the forward direction). As the plow is brought toward the desired grade, the laser control system again assumes control and establishes and maintains the cutting edge of the plow at the correct elevation while the operator drives the machine in the reverse travel direction. This semi-automated “auto rake” or “auto raise” process is repeated as many times as is necessary to accomplish the desired strike-off and levelness of the concrete prior to the finish screeding operations. The “auto rake” or “auto raise” system thus provides the operator with an option for reducing the number of necessary control inputs while operating the machine. This can help reduce operator fatigue and increase overall machine productivity.
A further aspect of the machine's control system may be referred to as an “auto drag” function. The “auto drag” function is provided by an adjustable user input or relief valve input 246 (
For example, when an excessive amount of loose subgrade material or uncured concrete is encountered at the plow while driving the machine in the reverse travel direction, the operator may elect to reduce the downward force of the plow by adjusting the “auto drag” setting. By reducing the “auto drag” setting, the plow will tend to rise up and disengage a portion of material whenever it encounters an excessive load of material to be moved. Thus, the load on the machine is reduced to a level that will more closely match the machine's tractive effort and the available engine horsepower under the given conditions. It is then possible to maximize the machine's productivity without actually stalling the hydraulic motors that drive the propulsion wheels, or cause the wheels themselves to spin from a loss of traction at high levels of tractive effort. Therefore, the “auto drag” feature provides the operator with the ability to readily adjust the degree of engagement of the material with the plow and promote the highest available level of productivity of the machine. Optionally, the down pressure of the plow may be automatically adjusted or reduced by a control or controller or control system of the machine in response to a detection of slippage of the wheels/tires at the subgrade or other input (such as a resistance measurement of the resistance against rearward movement of the plow against material that has accumulated at the plow or the like) that may be indicative of excess material at the plow that limits the rearward progress of the concrete working or processing machine or device.
Referring now to
In the illustrated embodiment, the head assembly 314 comprises a screed head assembly, having a plow member 318 and a vibrating member 319. Optionally, and as shown in
As shown in
In the illustrated embodiment, the rear frame portion 312b may pivot about its longitudinal axis 350 relative to a mounting or connecting arm or member 352 that pivotally mounts to front frame portion 312a and that pivots relative to front frame portion 312a about the generally vertical pivot axis 331a of the wheeled support 312. For example, the rear frame portion may rotatably receive a generally cylindrical connecting arm within a generally cylindrical receiving member, where the connecting arm may rotate or pivot within the receiving member to allow for pivoting or tilting of the rear frame portion relative to the connecting arm and the front frame portion. The rear frame portion 312b thus may pivot about two axes relative to the front frame portion. Optionally, the rear frame portion may pivotally attach to the front frame portion via other pivotal means, such as a ball and socket type arrangement or universal joint or a flexible connecting member or the like, in order to provide the desired degree of freedom between the front and rear frame portions.
As can be seen in
As shown in
The control system of the concrete screeding or working device may be operable to detect a bump or surface irregularity on or at the subgrade surface as it is encountered by the rear wheels (such as via a bump detecting device or system or the like) and may reduce or decrease the speed of the machine (by reducing or controlling an output of a drive system 364 of the machine) in anticipation of the front wheels encountering the bump, so that the control 358 and actuator 338 may more readily adapt to and accommodate the surface irregularity when the front wheels subsequently encounter the surface irregularity at the reduced rate of travel. In the illustrated embodiment, the bump detecting system comprises a rear level sensor or tilt sensor or cross slope level sensor 362, which is operable to detect a side-to-side tilt or pivotal movement of the rear frame portion 312b about its longitudinal axis 350, such as in a similar manner as the front level sensor 356. As shown in
The control 358 may also receive an input signal from a speed or distance or travel indicating device or indicator 368 (which may comprise a wheel encoder, a wheel speed sensor, a distance sensor and/or a timing device and/or the like). The control 358 thus may determine when the front wheels 324 have passed over the detected bump or surface irregularity (such as by calculating the distance traveled based on the speed of travel and/or determining when the distance traveled since the bump detection is at least equal to the distance between the front and rear wheels or axles, or by other suitable distance or time or speed detecting or determining means). After the control determines that the front wheels have passed the detected bump, the control may increase the speed of travel of the machine to resume the previous speed of travel before the bump was detected.
The control system of the present invention thus provides an enhanced plowing or screeding device and method that allows for faster passes over the concrete surface. This is because the machine may travel at a greater speed when the wheels are traveling over a substantially smooth subgrade surface, but the speed of the machine is automatically reduced when surface irregularities are encountered, thereby providing enhanced responsiveness to the tilt control at the front frame portion or screed head assembly. Thus, the operator may set the speed of the machine to a desired level for smooth subgrades, and the control system will automatically adjust the speed to an appropriate speed level when bumps or other surface irregularities are encountered by the machine. It is envisioned that the control system may adjust or vary the degree of reduction in speed depending on the size or height of the bump that is detected or encountered by the rear wheel or wheels of the machine.
Optionally, and particularly for plowing or raking or screeding machines of the present invention with two-wheeled supports or bases or units (such two-wheeled devices as of the types described in U.S. Pat. Nos. 4,655,633; 4,930,935; 6,129,481; 6,152,647; 6,183,160; 6,588,976; and/or 6,623,208; and/or U.S. pat. application Ser. No. 10/728,620, filed Dec. 5, 2003; Ser. No. 10/266,305, filed Oct. 2, 2002; and/or Ser. No. 10/902,528, filed Jul. 29, 2004 (Attorney Docket SOM01 P-326), which are hereby incorporated herein by reference), the bump detecting device or system may comprise a movable sensing device, such as a wheel or roller or the like, that may be positioned generally ahead of each wheel of the wheeled support (in the rearward direction of travel) to encounter and detect any bump or subgrade surface irregularity before the respective wheel encounters the bump or surface irregularity. For example, a wheel or roller may be mounted on an arm that extends rearward and downward from the wheeled support, whereby a detected upward movement of the arm (such as upward pivotal movement of the arm) is indicative of the wheel or roller encountering a bump at the subgrade surface.
Therefore, when one or both of the front wheels encounter the detected bump or surface irregularity, the machine travel speed is reduced to a reduced level so that the control and tilt actuator 338 may more readily substantially maintain the screed head in the level or desired orientation as the front wheels 324 and axle assembly 325 twist or pivot as the front wheels encounter and roll over the bump. The sensed event at the rear wheels is thus used to automatically slow (anticipate) the travel speed of the machine such that screeding can continue at a reduced machine travel speed during the controller-calculated duration of the bump event. The front frame cross slope control system helps keep the boom and screed head substantially level in the cross slope direction, and the temporary slowing of the machine's travel speed helps keep the control system responses within the capabilities of the respective components. Then, when the machine has cleared the bump event after a controller-calculated amount of travel distance (such as sensed by wheel encoders or the like), the machine can resume its previous travel speed. If no further bump (rear frame cross slope) signals are generated and the subgrade remains substantially smooth or even, the screeding machine can continue screeding at the faster travel speed. Although shown and described as detecting a side-to-side tilt of the rear frame portion and slowing the machine down in anticipation of a similar side-to-side tilt of the front frame portion and screed head, the machine of the present invention may also detect a change in pitch of the rear frame portion (such as may happen when both wheels encounter the same bump or surface irregularity) and the machine may slow down in anticipation of similar encounter by the wheels/tires of the front frame portion (in order to provide a pitch adjustment of the screed head assembly while the machine is traveling at a reduced rate).
Optionally, and as shown in
In the illustrated embodiment, screed head assembly 314′ is pivotally mounted to front frame portion 312a via an upper arm linkage 334 and a lower arm linkage 332, and may be raised and lowered relative to the front frame portion 312a via a lift cylinder or actuator 330′. During the screeding operation, the screed head is allowed to float upon the concrete surface at the vibrating member by substantially free pivoting movement at the upper and lower lift arm linkages and through selected free movement or free floating of the lift-arm cylinder. With this design, the front cross slope or tilt sensor may be located on the vibrating member resting upon the surface of the concrete, whereby the plow actuators may be responsive to the tilt sensor to substantially maintain the screed head assembly in the desired orientation, while both the front axle and the rear frame portion of the machine are free to oscillate over uneven subgrade surfaces through their respective longitudinal pivot axes.
Optionally, the upper link 334 of the lift arm linkage may be an adjustable length linkage, and may include a linear actuator, such as an electric linear actuator or the like. The linear actuator may comprise a substantially rigid member, and may be automatically adjusted to change its length according to a signal from a pitch level sensor 372 on the screed head frame 370. The pitch level sensor 372 may sense the pitch or fore-aft tilt of the screed head assembly as the screed head assembly may tilt when the wheels of the wheeled unit encounter bumps or inclines in the subgrade. Such an adjustable lift arm linkage and pitch sensor arrangement may enable the pitch of the screed head to be controlled so as to remain substantially constant as the wheels of the machine encounter bumps or inclines in the subgrade. As described above, the rear frame portion may include a pitch detecting sensor and the control may slow the rate of travel of the machine when a sufficient or threshold pitch change is detected, in anticipation of the front wheels/tires and the screed head assembly encountering a similar pitch change.
Depending on the design weight of the screed head and the conditions of the concrete, it may be desirable to either add or subtract “weight” at the screed head. Thus, the normally free floating lift cylinder 330′ may optionally and selectively act as a “constant force” actuator as selected by the operator, whereby the operator may cause the actuator or cylinder to extend or retract or become substantially rigid or locked. Such an application may allow the operator to increase or decrease a down pressure of the screed head assembly onto the concrete surface so as to adjust the desired amount of force the vibrating/floating member exerts upon the surface of the concrete. Optionally, the machine may include variably adjustable torsional springs or other biasing elements or springs or the like at the pivot between the lower lift arm and the front frame portion. Such an arrangement may counteract the weight of the screed head through the range of movement of the screed head, such as in a similar manner as the torsional springs used on overhead garage doors counteract the weight of the door through its range of movement.
The machine may also include the bump anticipation and speed control system described above, where the actuator 338 may maintain the front frame portion 312a in a substantially level or desired orientation as the front wheels encounter and roll over a bump (and at a reduced speed due to the prior detection of the bump by the bump detection device or sensor at the rear frame portion). Optionally, however, the front level sensor or cross slope or tilt sensor 356 may be removed in this embodiment, since a tilt sensor may be provided at the screed head assembly.
Optionally, and with reference to
Also, the wheeled support 412 may be substantially similar to the wheeled support 312, discussed above, such that a detailed discussion of the wheeled supports will not be repeated herein. However, a front portion 412a of wheeled support 412 includes a front frame portion 413a, which is pivotally mounted to the axle assembly 425 and pivotable relative to the axle assembly via actuator 438 (such as described above), and includes a pivotable support arm or support frame 413b that is pivotally attached to front frame portion 413a and pivotable about a generally horizontal axis 413c. The screed head assembly 414 is mounted to a forward portion 413d of pivotable support frame 413b via the linkages 432, 434 and actuator 430 (such as in a similar manner as screed head assembly 314′ is mounted to front frame portion 312a as described above).
As can be seen in
The forward end portion 413d of the pivotable support frame 413b may be adjustably connected to the forward end of the front frame portion 413a via an adjustable actuator 474 or the like. During operation of the concrete working device or machine, the actuator 474 between the support frame and the front portion of the front frame portion is allowed to freely extend and retract. However, the small actuator 474 may be selectively locked in a fixed position to allow the lift cylinder or actuator 430 to raise or lift the screed head out of the concrete. When the actuator 474 is in its free float mode, the screed head assembly is supported by the vibrating member on the concrete; such as described in U.S. patent application Ser. No. 10/728,620, filed Dec. 5, 2003; Ser. No. 10/266,305, filed Oct. 2, 2002; and Ser. No. 10/902,528, filed Jul. 29, 2004 (Attorney Docket SOM01 P-326), which are hereby incorporated herein by reference.
It is further envisioned that the actuator 474 may also function as a constant-force actuator to help control the desired amount of either down pressure or up pressure at the vibrating member as it is partially supported on the surface of the concrete. A pressure sensor or load cell (not shown) may be mounted between the vibrator and the frame of the screed head, and may sense the amount of vertical force the vibrator is exerting on the concrete surface. An output signal form the pressure sensor or load cell may be directed to a controller to adjust the output force of the constant-force actuator to provide a desired down-pressure at the concrete surface.
Optionally, the forward end portion 413d of support frame 413b may be pivotally attached to the generally horizontal portion 413e of support frame 413b and thus may be pivotable about a generally vertical pivot axis at the forward end of the horizontal portion 413e of support frame 413b. Such a pivotal arrangement allows pivotal movement of the screed head assembly about the vertical pivot axis and relative to the wheeled support to reduce or alleviate sideward movement of the screed head assembly when the articulating wheeled support is articulated or steered to one side or the other. Optionally, an actuator (not shown) or the like may be provided to selectively allow the support frame to be locked or to float about the generally vertical pivot axis. The actuator may be actuatable to control or adjust the position or orientation of the support frame about the pivot axis and in the sidewardly direction relative to the wheeled support.
Although shown and described as being driven over a subgrade surface and being operable to plow or establish a desired grade of the concrete and/or to vibrate or screed the uncured concrete, aspects of the wheeled working or processing devices or machines of the present invention may be suitable for plowing or screeding other materials as well, such as subgrade materials (such as dirt, sand, gravel or the like) or other uncured materials placed or poured on subgrade surfaces (such as other types of concrete, cement, asphalt or the like), without affecting the scope of the present invention.
The present invention thus may provide a concrete working or processing device or machine that includes a plow assembly for striking off concrete and/or a screed head assembly for screeding or smoothing and compacting the concrete. The plow head or screed head assembly may be mounted to a two-wheeled or three-wheeled or four-wheeled unit or base and may be adjustable relative to the wheeled unit in response to a laser receiver to establish and/or screed the concrete at the desired grade. Optionally, the plow or screed head assembly may be mounted at the wheeled unit and may substantially freely float relative to the wheeled unit, whereby the grade is established via a grade setting device or plow of the plow/screed head assembly in response to actuators and laser receivers at the plow/screed head assembly. The machine may include a control system that is operable to automatically raise the plow/screed head assembly after a pass and may hold the plow/screed head assembly at the raised position while the machine is moved to the beginning of another pass along and through the concrete. The machine may include a control system that includes a down-pressure control that controls or increases/reduces the down pressure applied by the plow/screed head assembly at the concrete surface, so that the plow/screed head assembly may rise over excessive concrete that may accumulate at the plow as the plow/screed head assembly is moved over the concrete surface. The machine may include a control system that may detect a bump or surface irregularity at the subgrade and that may automatically adjust the speed of the wheeled unit in response to the detection of the bump or uneven terrain by one of the wheels of the wheeled unit, so that the machine may reduce the speed over uneven terrain to allow for enhanced grading or screeding of the concrete in those areas by providing additional time for the machine to adjust and maintain the plow/screed head assembly in a generally horizontal orientation.
Therefore, the present invention may serve to produce a desired and rough but substantially accurate strike-off of a concrete surface in order to facilitate and complement concrete placing and screeding operations that may follow, as well as generally smooth and accurately level loose and spreadable materials for subgrade preparation found within the construction industry. A further advantage of this machine is that the machine operator can stand and ride upon the machine with his feet out of the concrete and/or loose materials. This improves ease of use of the machine and personal safety during the use of the machine. For example, the operator is not as likely to catch his feet in loose materials such as uncured concrete or trip upon objects obscured by loose and flowable materials. Additionally, higher machine travel speeds are possible and a commanding view of the work area are provided with the operator in a stand-and-ride-on design. This provides a significant increase in productivity of the machine over walk-behind versions. Additionally, the machine of the present invention provides a high level of utilization to the owner operator within the concrete construction industry in that it can optionally be adapted for use as a concrete coatings sprayer, a laser responsive screeding machine, a concrete pumping hose handler, and a surface sweeper. The machine may be suitable for other applications as well, without affecting the scope of the present invention.
The present invention may also provide an apparatus and method for achieving a desired and accurate strike-off of an uncured concrete surface in order to facilitate and compliment concrete placing and screeding operations that may follow, as well as generally smooth and accurately level loose and spreadable materials for subgrade preparation found within the construction industry. The apparatus or machine may be moved in either direction to strike-off or establish the desired grade or level of the uncured concrete or subgrade material. The plow is automatically adjusted to maintain the desired grade or level in response to a laser reference system, so that the uncured concrete or subgrade materials are struck-off at the appropriate level over the targeted area. The wheels of the machine may be independently operable or controlled to move the machine over and through the uncured concrete or subgrade materials and to turn or steer the machine as it is moved over and through the uncured concrete or subgrade materials. The rear wheel may be steered via a handlebar or the like to further enhance the steering and controlling of the machine as it is moved over and through the uncured concrete or subgrade materials. Optionally, the wheeled base unit may comprise an articulatable frame with front and rear wheels. One frame portion may support a plow head or screed head or other attachment or head assembly or the like, while the other frame portion may provide an operator control station with a platform on which the operator may stand during the plowing or striking off or screeding or other concrete processing operation.
The present invention may also provide a sidewalk screeding machine that is operable to establish an initial grade that is slightly above the final grade and then to screed the uncured concrete at the initial grade and compact and vibrate the uncured, concrete to the final grade, without the use of laser leveling or grade setting systems or the like. The plow rides on forms and the lower edge of the plow is spaced above the level of the forms by the spacer members or elements such that the plow cuts and establishes a grade that is above the level of the forms. The planar portion or surface of the vibrating member rests on and moves along the forms behind the plow such that the planar surface vibrates and compacts and screeds and smoothes the excess concrete to the level set by the forms. The plow thus functions to cut or establish an initial grade or level of the uncured concrete that is above the level or grade at which the vibrating member will vibrate and screed the concrete. The plow thus leaves a small amount of excess concrete for the vibrating member to compact and screed so that the vibrating member provides an enhanced surface of the concrete slab.
Changes and modifications in the specifically described embodiments may be carried out without departing from the principles of the present invention, which is intended to be limited only by the scope of the appended claims, as interpreted according to the principles of patent law.
The present application claims benefit of U.S. provisional applications, Ser. No. 60/521,950, filed Jul. 26, 2004; Ser. No. 60/619,672, filed Oct. 18, 2004; and Ser. No. 60/666,672, filed Mar. 30, 2005, which are all hereby incorporated herein by reference in their entireties.
| Number | Date | Country | |
|---|---|---|---|
| 60521950 | Jul 2004 | US | |
| 60619672 | Oct 2004 | US | |
| 60666672 | Mar 2005 | US |
