Apparatus and method for subgrade preparation

Abstract

A subgrade preparation apparatus is operable to level, accurately grade and compact a subgrade surface for receiving a preformed concrete slab on the subgrade, in order to repair a concrete surface. The subgrade preparation apparatus includes a base unit, an extendable boom extending from the base unit, and a screed head assembly vertically adjustable on the extendable boom. The base unit is positionable on the concrete surface being repaired. The screed head assembly is vertically adjustable to be lowered into a cut out area defining the subgrade. Preferably, the screed head assembly includes a plow, auger and/or vibrator for grading, leveling and/or compacting the subgrade surface, and is further operable to grade, level, compact and/or smooth the subgrade surface close to the edges or walls of the cut out area.

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:  
     
         1 . A subgrade preparation apparatus for leveling, grading and compacting a subgrade surface for receiving a preformed concrete slab on the subgrade to repair a concrete surface above the subgrade surface, said subgrade preparation apparatus comprising: 
 a base unit positionable on the concrete surface being repaired;    an extendable boom extending from said base unit; and    a screed head assembly adjustably mounted on said extendable boom, said screed head assembly being vertically adjustable relative to said extendable boom to be lowered into a cut out area of the concrete surface defining the subgrade surface, said screed head assembly including a framework, a plow and at least one of a means for moving material toward at least one side of said screed head assembly and a vibrator mounted to said framework for grading, leveling and/or compacting the subgrade surface, said plow having an outer end, said outer end of said plow defining an outermost portion of said screed head assembly such that said screed head assembly is operable to grade, level, compact and/or smooth the subgrade surface close to the walls of the cut out area.    
     
     
         2 . The subgrade preparation apparatus of  claim 1 , wherein said plow comprises a main plow and at least one plow wing extending laterally outwardly from said main plow, said outer end of said plow comprising an outer end of said plow wing.  
     
     
         3 . The subgrade preparation apparatus of  claim 2 , wherein said at least one plow wing is pivotably mounted at said main plow.  
     
     
         4 . The subgrade preparation apparatus of  claim 1 , wherein said means for moving material toward at least one side of said screed head assembly comprises an auger having a longitudinal rotatable portion rotatably mounted to said screed head assembly.  
     
     
         5 . The subgrade preparation apparatus of  claim 4 , wherein said auger of said screed head assembly includes at least one outer end of said rotatable portion and a drive motor for rotatably driving said rotatable portion, said drive motor being positioned inward of said at least one outer end of said rotatable portion.  
     
     
         6 . The subgrade preparation apparatus of  claim 5 , wherein said drive motor is interconnected to said at least one outer end of said rotatable portion via a drive chain, said drive chain being operable to rotate said rotatable portion in response to said drive motor.  
     
     
         7 . The subgrade preparation apparatus of  claim 4 , wherein said auger is movably mounted to said framework and is movable outward from said framework to provide access to at least one of said plow and said auger of said screed head assembly.  
     
     
         8 . The subgrade preparation apparatus of  claim 7 , wherein said rotatable portion of said auger is rotatably mounted to a swing arm, which is pivotally mounted to said framework, said swing arm being pivotable to move said auger outward from said framework.  
     
     
         9 . The subgrade preparation apparatus of  claim 8 , wherein said swing arm is adjustable to adjust a level of said rotatable portion of said auger relative to said screed head assembly.  
     
     
         10 . The subgrade preparation apparatus of  claim 8 , wherein said plow is pivotally mounted to said framework of said screed head assembly and is pivotable to provide access to at least one of said plow and said auger of said screed head assembly.  
     
     
         11 . The subgrade preparation apparatus of  claim 1 , wherein said plow is pivotally mounted to said framework of said screed head assembly and is pivotable to provide access to at least one of said plow and said auger of said screed head assembly.  
     
     
         12 . The subgrade preparation apparatus of  claim 11 , wherein said means for moving material is pivotally mounted to said framework and is pivotable outward from said framework to provide access to said at least one of said plow and said means for moving material of said screed head assembly.  
     
     
         13 . The subgrade preparation apparatus of  claim 12 , wherein said means for moving material comprises an auger.  
     
     
         14 . The subgrade preparation apparatus of  claim 1  including an elevation device which is operable to lower and raise said screed head assembly relative to said extendable boom and said base unit.  
     
     
         15 . The subgrade preparation apparatus of  claim 14 , wherein said elevation device further includes a tilt limiting device which is operable to limit or substantially preclude excessive vertical movement of one side of said screed head assembly relative to the other side of said screed head assembly.  
     
     
         16 . The subgrade preparation apparatus of  claim 14 , wherein said elevation device comprises a pair of actuators mounted to said extendable boom and connected to said screed head assembly toward opposite ends of said screed head assembly, said actuators being extendable and retractable to vertically adjust respective sides of said screed head assembly.  
     
     
         17 . The subgrade preparation apparatus of  claim 16 , wherein said tilt limiting device is operable to deactuate at least one of said actuators in response to a level sensor to limit excessive extension or retraction of said at least one of said actuators relative to the other of said actuators.  
     
     
         18 . The subgrade preparation apparatus of  claim 14 , wherein said elevation device comprises a pair of hydraulic cylinders having a cylinder and a piston rod extendable and retractable relative to said cylinder.  
     
     
         19 . The subgrade preparation apparatus of  claim 18 , wherein said cylinders of said elevation device are mounted to said extendable boom and said screed head assembly is mounted to a lower end of said piston rods.  
     
     
         20 . The subgrade preparation apparatus of  claim 14 , wherein said elevation device is operable in response to a laser reference plane and laser receivers mounted to a portion of said elevation device.  
     
     
         21 . The subgrade preparation apparatus of  claim 14 , wherein said elevation device is operable in response to a three dimensional profiler system mounted to a portion of said elevation device.  
     
     
         22 . The subgrade preparation apparatus of  claim 1  including a second plow mounted to a rearward side of said vibrator.  
     
     
         23 . A method for leveling, grading and/or compacting a subgrade surface for receiving a preformed concrete slab on the subgrade to repair a concrete surface above the subgrade surface, said method comprising: 
 providing a subgrade preparation apparatus comprising a base unit positionable on the concrete surface being repaired and a screed head assembly having a plow which defines at least one end, said screed head assembly having no major projections extending laterally outwardly from said at least one end of said plow;    vertically moving said screed head assembly relative to said extendable boom into a cut out area of the concrete surface defining the subgrade;    generally horizontally moving said screed head assembly along the subgrade; and    grading, leveling and/or compacting the subgrade surface close to the walls of the cut out area with at least one of said plow, a means for moving material to one side of said screed head assembly and a vibrator of said screed head assembly.    
     
     
         24 . The method of  claim 23 , wherein generally horizontally moving comprises generally horizontally moving said screed head assembly via an extendable boom extending from said base unit.  
     
     
         25 . The method of  claim 23  including providing a screed head assembly having a plow, wherein said plow comprises a main plow and at least one plow wing extending laterally outward from said main plow, and outer end of said at least one plow wing defining said at least one end of said plow.  
     
     
         26 . The method of  claim 23 , wherein said means for moving material to one side of said screed assembly comprises an auger.  
     
     
         27 . The method of  claim 26  including rotatably driving said auger of said screed head assembly with a drive motor positioned inward of one of opposite outer ends of said auger.  
     
     
         28 . The method of  claim 27 , wherein rotatably driving said auger includes rotatably driving said auger with a drive motor and drive chain connected between said drive motor and said one of opposite outer ends of said auger.  
     
     
         29 . The method of  claim 26  including pivoting said auger relative to and away from a framework of said screed head assembly to provide access to said at least one of said plow and said auger of said screed head assembly.  
     
     
         30 . The method of  claim 23  including pivoting said plow relative to and away from a framework of said screed head assembly to provide access to at least one of said plow and said means for moving material of said screed head assembly.  
     
     
         31 . The method of  claim 30  including pivoting said means for moving material relative to and away from said framework to provide access to said at least one of said plow and said means for moving material of said screed head assembly.  
     
     
         32 . The method of  claim 23  including limiting excessive vertical movement of one side of said screed head assembly relative to the other side of said screed head assembly.  
     
     
         33 . The method of  claim 32 , wherein limiting excessive vertical movement includes limiting excessive extension or retraction of at least one of a pair of spaced apart actuators positioned toward opposite sides of said screed head assembly.  
     
     
         34 . The method of  claim 33 , wherein vertically moving said screed head assembly includes vertically moving said screed head assembly in response to a laser reference plane and laser receivers mounted to a portion of said pair of actuators.  
     
     
         35 . The method of  claim 33 , wherein vertically moving said screed head assembly includes vertically moving said screed head assembly in response to a three dimensional profiler system mounted to a portion of said pair of actuators.  
     
     
         36 . A subgrade preparation apparatus for leveling, grading and/or compacting a subgrade surface for receiving a preformed concrete slab on the subgrade to repair a concrete surface above the subgrade surface, said subgrade preparation apparatus comprising: 
 a base unit positionable on a concrete surface being repaired;    an extendable boom extending from said base unit; and    a screed head assembly adjustably mounted on said extendable boom, said screed head assembly being vertically adjustable relative to said extendable boom to be lowered into a cut out area of the concrete surface, the cut out area defining a subgrade surface below the concrete surface, said screed head assembly including a framework and at least one of a plow, a means for moving material toward at least one side of said screed head assembly and a vibrator mounted to said framework for grading, leveling and compacting the subgrade surface;    a pair of spaced apart actuators mounted on said extendable boom and connected to said screed head assembly at spaced positions on said screed head assembly, said actuators being operable to extend and retract to vertically move said screed head assembly relative to said extendable boom and said base unit; and    a tilt limiting device which is operable to detect a degree of tilt of said screed head assembly and to deactuate at least one of said pair of actuators in response to a threshold degree of tilt of said screed head assembly.    
     
     
         37 . The subgrade preparation apparatus of  claim 36 , wherein said screed head assembly comprises a plow and at least one of a means for moving material toward at least one side of said screed head assembly and a vibrator.  
     
     
         38 . The subgrade preparation apparatus of  claim 37 , wherein said plow includes an outer end which defines an outermost portion of said screed head assembly such that said screed head assembly is operable to grade, level, compact and/or smooth the subgrade surface close to at least one wall of the subgrade surface.  
     
     
         39 . The subgrade preparation apparatus of  claim 38 , wherein said plow comprises a main plow and at least one plow wing extending laterally outwardly from said main plow, said outer end of said plow comprising an outer end of said plow wing.  
     
     
         40 . The subgrade preparation apparatus of  claim 36 , wherein said screed head assembly defines at least one side surface which has no major projections extending laterally outward therefrom such that said screed head assembly is operable to grade, level, compact and smooth the subgrade surface close to the walls of the cut out area.  
     
     
         41 . The subgrade preparation apparatus of  claim 36 , wherein said pair of actuators comprises a pair of hydraulic cylinders having a cylinder and a piston rod extendable and retractable relative to said cylinder.  
     
     
         42 . The subgrade preparation apparatus of  claim 41 , wherein said cylinders are mounted to said extendable boom and said screed head assembly is mounted to a lower end of said piston rods.  
     
     
         43 . The subgrade preparation apparatus of  claim 36 , wherein said screed head assembly includes at least one plow wing extending laterally outward from said at least one side surface for engaging the subgrade surface along the walls of the cut out area.  
     
     
         44 . The subgrade preparation apparatus of  claim 43 , wherein said at least one plow wing is pivotably mounted to said at least one side surface of said screed head assembly.  
     
     
         45 . The subgrade preparation apparatus of  claim 36 , wherein said means for moving material toward at least one side of said screed head assembly comprises an auger having a longitudinal rotatable portion rotatably mounted to said screed head assembly.  
     
     
         46 . The subgrade preparation apparatus of  claim 45 , wherein said auger of said screed head assembly includes outer ends and a drive motor for driving said auger, said drive motor being positioned inward of one of said outer ends of said auger.  
     
     
         47 . The subgrade preparation apparatus of  claim 46 , wherein said drive motor is interconnected to said one of said outer ends of said auger via a drive chain, said drive chain being operable to rotate said auger in response to said drive motor.  
     
     
         48 . The subgrade preparation apparatus of  claim 45 , wherein said auger is pivotally mounted to said framework and is pivotable outward and away from said framework to provide access to at least one of said plow and said auger of said screed head assembly.  
     
     
         49 . The subgrade preparation apparatus of  claim 48 , wherein said auger is rotatably mounted to a swing arm, which is pivotally mounted to said framework, said swing arm being pivotable to move said auger outward and away from said framework.  
     
     
         50 . The subgrade preparation apparatus of  claim 36 , wherein said plow is pivotally mounted to said framework of said screed head assembly and is pivotable to provide access to at least one of said plow and said means for moving material of said screed head assembly.  
     
     
         51 . The subgrade preparation apparatus of  claim 50 , wherein said means for moving material is pivotally mounted to said framework and is pivotable outward and away from said framework to provide access to said at least one of said plow and said means for moving material of said screed head assembly.  
     
     
         52 . The subgrade preparation apparatus of  claim 51 , wherein said means for moving material comprises an auger.  
     
     
         53 . The subgrade preparation apparatus of  claim 36  including a second plow mounted to a rearward side of said vibrator.  
     
     
         54 . A subgrade preparation apparatus for leveling, grading and compacting a subgrade surface for receiving a preformed concrete slab on the subgrade to repair a concrete surface above the subgrade surface, said subgrade preparation apparatus comprising: 
 a base unit positionable on the concrete surface being repaired;    an extendable boom extending from said base unit; and    a screed head assembly adjustably mounted on said extendable boom, said screed head assembly being vertically adjustable relative to said extendable boom, said screed head assembly including a framework, an auger device for moving material toward at least one side of said screed head assembly and at least one of a plow and a vibrator mounted to said framework for grading, leveling and/or compacting the subgrade surface, said auger device including a rotatable portion rotatably mounted to and extending laterally across said framework and a drive motor for rotatably driving said rotatable portion, said rotatable portion having at least one outer end, said drive motor being positioned at least partially laterally inboard of said at least one outer end of said rotatable portion such that said screed head assembly is operable to grade, level, compact and/or smooth the subgrade surface close to at least one wall at least partially surrounding the subgrade surface.    
     
     
         55 . The subgrade preparation apparatus of  claim 54 , wherein said drive motor is interconnected to said at least one outer end of said rotatable portion of said auger device via a drive chain, said drive chain being operable to rotate said rotatable portion of said auger device in response to said drive motor.  
     
     
         56 . The subgrade preparation apparatus of  claim 54 , wherein said auger device is movably mounted to said framework and is movable outward from said framework to provide access to said auger device of said screed head assembly.  
     
     
         57 . The subgrade preparation apparatus of  claim 56 , wherein said rotatable portion of said auger device is rotatably mounted to a swing arm, said swing arm being pivotally mounted to said framework, said swing arm being pivotable to move said auger device outward from said framework.  
     
     
         58 . The subgrade preparation apparatus of  claim 57 , wherein said swing arm is adjustable to adjust a level of said rotatable portion relative to said screed head assembly.  
     
     
         59 . The subgrade preparation apparatus of  claim 57 , wherein said screed head assembly includes a plow, said plow being pivotally mounted to said framework and being pivotable to provide access to at least one of said plow and said auger device.  
     
     
         60 . The subgrade preparation apparatus of  claim 54 , wherein said screed head assembly includes a plow.  
     
     
         61 . The subgrade preparation apparatus of  claim 60 , wherein said plow is pivotally mounted to said framework and is pivotable to provide access to at least one of said plow and said auger device.  
     
     
         62 . The subgrade preparation apparatus of  claim 60 , wherein said plow includes an outer end, said outer end of said plow defining an outermost portion of said screed head assembly such that said screed head assembly is operable to grade, level, compact and/or smooth the subgrade surface close to the at least one wall.  
     
     
         63 . The subgrade preparation apparatus of  claim 62 , wherein said plow comprises a main plow and at least one plow wing extending laterally outwardly from said main plow, said outer end of said plow comprising an outer end of said plow wing.  
     
     
         64 . The subgrade preparation apparatus of  claim 63 , wherein said at least one plow wing is pivotably mounted at said main plow.  
     
     
         65 . The subgrade preparation apparatus of  claim 54 , wherein said screed head assembly is vertically adjustable relative to said extendable boom to be lowerable into a cut out area of the concrete surface defining the subgrade surface, the cut out area defining the at least one wall.