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TECHNICAL FIELD 
       [0001]    The present invention relates generally to land-leveling scrapers and apparatus for modifying the earth&#39;s surface by removing soil from the earth&#39;s surface at one location and moving the soil to a new location. More specifically, the present invention relates to earth moving apparatus, such as scrapers, that include skidplates or skid shoes which engage the ground surface to stabilize the earth moving apparatus and lessen the tendency of the cutting blade to dig unevenly without substantially affecting the desired grade. 
       BACKGROUND 
       [0002]    Scrapers and other earth moving apparatus of the general type to which the present invention relates are known. Representative examples of earth moving scrapers include, without limitation, those scrapers disclosed in U.S. Pat. Nos. 4,383,380, 4,388,769, 4,398,363, 4,553,608, 6,347,670, and 6,845,824 to Miskin, each of which is incorporated by reference in its entirety. A typical scraper includes a frame having a front end, two opposing sides and at least two wheels connected to the opposing sides. A bucket for holding soil removed from the earth is connected to the frame. The bucket may include a floor, two opposing side walls, an open front and an open top. A blade is located adjacent the front edge of the floor of the bucket for cutting the earth to a predetermined depth as the earth moving apparatus is moved forward over the earth&#39;s surface. The soil cut from the earth by the blade is collected in the bucket. 
         [0003]    Soil may be removed from the bucket of the scrapers in different ways. For instance, moving back scrapers, sweep scrapers, open bottom dump scrapers and dump scrapers are known. For instance, an ejector scraper has a moving wall or ejector assembly which pushes the soil out of the bucket. An example of an ejector scraper is disclosed in U.S. Pat. No. 6,041,528 assigned to Harvey Mfg. Corp., which is incorporated by reference in its entirety herein. An example of a sweep scraper is an elevating type scraper that discharges soil collected in the bucket by moving members, or slats, across of the floor of the bucket. An exemplary sweep scraper is disclosed in U.S. Pat. No. 3,934,360 assigned to Westinghouse Air Brake Company, which is incorporated by reference in its entirety herein. In an open bottom dump scraper, the bucket of the scraper is tilted to dump the soil out of an open end of the bucket. Examples of pull-type, bottom dump scrapers include construction scrapers disclosed in U.S. Pat. Nos. 4,383,380, 4,388,769, 4,398,363, 4,553,608 and 6,347,670 to Miskin, discussed previously herein. Other scrapers, such as “open bottom” scrapers may lack a bucket and simply include a frame or an elongated pole having an earth moving blade attached thereto which is used to cut and level soil. 
         [0004]    A pull-type scraper or earth moving apparatus may have an elongated tongue attached to a frame. The tongue may be connected to a tractor that tows the scraper or the earth moving apparatus. The tongue may be connected to a tractor with a hitch or may include a so-called rigid, gooseneck that pivots and is attached to the tractor. Alternatively, the scraper may include a front set of “dolly” wheels or may be attached to a separate dolly that attaches to a tractor. Other scrapers or other earth moving apparatuses are self-propelled. 
         [0005]    When the scraper or earth moving apparatus is moved forward over the surface of the earth and the blade is lowered, the blade cuts the soil and delivers the soil to the bucket. The soil travels over the upper surface of the blade and into the bucket. Scrapers may thus be used to accomplish ground leveling or grading. Similarly, ejecting soil from the bucket of a scraper ahead of the blade may be used to “fill in” low spots to achieve even leveling. During the process of ground leveling, the elevation of the cutting blade with respect to the ground surface may be adjusted by the operator raising or lowering the blade or the wheels of the scraper. Some scrapers implement laser surveying systems to achieve precise leveling of the ground surface. 
         [0006]    While performing land leveling operations scrapers have been known to bounce, undulate from side-to-side, waddle and duck walk. These undesirable motions are particularly severe when scrapers travel at higher speeds. This can cause the cutting blade to dig unevenly into the ground surface, require additional leveling work to obtain a satisfactory ground surface, and accelerate wear and tear on the scraper components from additional vibration and cyclical loading, especially when the scraper is used for “skimming” (making shallow cuts or spreading thin amounts of unloaded soil). 
         [0007]    Different solutions have been proposed to prevent or minimize these undesirable motions. U.S. Pat. No. 4,389,800 discloses a land leveling scraper which includes a skid shoe system where the bottom surface of the skid shoes are intended to accommodate and follow irregularities in the ground surface being leveled, and the skid shoes are urged against the ground surface with a force proportional to the load on the bucket of the scraper. Such force is to be applied by a hydraulic cylinder. However, this type of skid shoe system is an integral part of the land leveling scraper as opposed to an easily installed after-market addition. Moreover, this system operates on the same hydraulics which lower and raise the bucket and thus is not independently adjustable by the operator to allow custom settings for different earth removal applications, such as digging a sump as opposed to obtaining precise leveling of the ground surface. Finally, because this system is connected to other dirt bucket hydraulics, blade and bucket reaction times are slower and the system can be difficult to maintain. 
         [0008]    Another attempted solution has been to add additional axles and wheels to the back of the scraper. However, this solution is expensive, requires additional maintenance, and may prevent running scrapers in tandem as the additional axles and wheels interfere with installing the towing mechanism required for connecting additional scrapers. 
         [0009]    U.S. Pat. No. 5,307,570 discloses the attachment of skid shoes to dirt buckets by spring-loaded legs. However, adjustment of the load-bearing capacity of the skid shoes requires changing of the coil compression spring. Even if the proper spring is available, the spring-loaded legs must be dismantled for installation of different springs. Additionally, such skid shoes are not easily retractable, and are thus almost always active. This leads to additional wear on the shoe and increases fuel consumption. 
         [0010]    U.S. Pat. No. 6,289,614 attempted to address these shortcomings by attaching an after-market skid shoe to a pivot on the bottom of a scraper dirt bucket and using a hydraulic cylinder to extend a rear end of the shoe to the ground. Using an independent hydraulic system increases the maintenance required on the scraper and the pivoted skid shoe design limits the area of the skid shoe that could be in contact with the ground. Attempts to contact more of the shoe to the ground would either attempt to force the shoe further into the ground or exert a lift force on the scraper. The result is that the shoe is rigidly locked when the hydraulics are centered, and the shoes dig trenches, and wear out rapidly. 
         [0011]    Thus, apparatus, systems and methods that provide skid shoes that make for greater or more effective contact with the ground to reduce bounce, which are easier to use or maintain, or capable of independent control would be an improvement in the art. 
       SUMMARY 
       [0012]    The present invention provides apparatus, systems and methods for the stabilization of an earth-moving apparatus, such as an earth-moving scraper. A skidplate is attached to the earth-mover by one or more inflatable airbags, such as a pneumatic suspension air-spring, which may be inflated to lower the skidplate into contact with the ground surface. The skidplate (or a skid shoe attached thereto) remains held firmly on the ground regardless of minor adjustments to the blade height, due to the “springiness” of the air bag). The skidplate can be retracted when use is not desired, by deflation of the air bags. Such a skidplate assembly may be offered as a separate unit for after-market installation on an earth-moving vehicle. 
         [0013]    Systems in accordance with the present invention may also include one or more motion sensors and a control unit, which may be a computer. Using such a system, the bounce or “duckwalk” motion may be detected before it is visible to the operator. The control unit may cause the airbags to inflate as needed to stabilize the earth-moving apparatus, then deflate to minimize wear on the skidplate. 
     
    
     
       DESCRIPTION OF THE DRAWINGS 
         [0014]    It will be appreciated by those of ordinary skill in the art that the elements depicted in the various drawings are for exemplary purposes only. The nature of the present invention, including the best mode, as well as other embodiments of the present invention, may be more clearly understood by reference to the following detailed description of the invention, to the appended claims, and to the several drawings. 
           [0015]      FIG. 1  is side view of one illustrative embodiment of an earth moving scraper including a stabilization control system in accordance with the present invention. 
           [0016]      FIG. 2  is a top perspective view of an illustrative embodiment of another skidplate assembly in accordance with the present invention. 
           [0017]      FIG. 3  is a schematic view of a stabilization system including at least one sensor and a control unit, in accordance with the present invention. 
       
    
    
     DETAILED DESCRIPTION 
       [0018]    The present invention relates to systems and methods for stabilizing an earth-moving machine during a cutting or scraping operation. It will be appreciated by those skilled in the art that the embodiments herein described, while illustrating certain embodiments, are not intended to so limit the invention or the scope of the appended claims. Those skilled in the art will also understand that various combinations or modifications of the embodiments presented herein can be made without departing from the scope of the invention. All such alternate embodiments are within the scope of the present invention. Similarly, while the drawings depict illustrative embodiments of devices and components in accordance with the present invention and illustrate the principles upon which the depicted device or component is based, they are only illustrative and any modification of the invented features presented herein are to be considered within the scope of this invention. 
         [0019]    Turning to  FIG. 1 , in one illustrative embodiment, the earth-moving machine may be an earth-moving scraper  10 . Representative examples of earth moving apparatus which may be used in conjunction with the stabilization systems of the present invention include, without limitation, the scrapers disclosed in U.S. Pat. Nos. 4,383,380, 4,388,769, 4,398,363, 4,553,608 and 6,347,670 to Miskin. It will be apparent that the stabilization systems of the present invention may be configured to be operatively connected to any pull-type scraper, self-propelled scraper, moving back scraper that includes a moving wall or ejector assembly in the bucket that pushes the soil out of the bucket, sweep scraper that includes at least one moving section of the floor of the bucket that transfers the soil out of the bucket, open bottom scraper or dump scraper that includes a bucket configured to tilt and dump the soil out of the bucket in addition to the disclosed in the Miskin patents. 
         [0020]    As illustrated in drawing  FIG. 1 , the earth moving apparatus  10  includes a cutting blade  14 , a bucket  16 , an apron  18 , a tongue  20  and ground engaging wheels,  22 . The cutting blade  14  may be attached to a frame of the scraper  10  and be generally disposed laterally between the opposing sides of the scraper  10 . In other embodiments, the blade  14  may be attached to the bucket  16  and it will be apparent that the blade  14  may be adjoined to the earth moving apparatus  10  in any manner known by those of ordinary skill in the art. 
         [0021]    As depicted at  100  in  FIG. 1 , a skidplate, generally indicated at  100 , may be attached to the underside of the earth moving apparatus. In the depicted embodiment, skidplate  100  is attached to a front loading, bucket tilting scraper, behind blade  14  and under the bucket  16  (when bucket  16  is in the lowered position). As depicted, skidplate  100  may be used to directly contact the ground surface G, although it will be appreciated that one or more skid shoes may be attached to the lower surface of the skidplate, such that the frictional wear is absorbed by the skid shoes. 
         [0022]    As best depicted in  FIG. 2 , the skidplate  100  may be a single plate that has a width similar to space between the left and right members of the scraper frame. It will be appreciated that the skidplate may be of any desired width, and that one or more narrower skidplates, each separately attached to the scraper, as discussed further herein, may be used. 
         [0023]    In the depicted embodiment, the skidplate has an elongated planar midsection  102 , which may be used to contact the ground G, and an upturned leading edge  104 . The upturned leading edge  104  may act similar to the upturned edge of a ski, assisting in the movement of the skidplate  100  over the ground G by reducing the tendency of the edge to catch and dig into the ground G surface. 
         [0024]    An embodiment similar to that depicted in  FIGS. 1 and 2 , where a generally ski-shaped skidplate  100  is used, such that the entire planar midsection of the body  102  may be used to contact the ground, resulting in maximization of the contact therebetween and the resulting reduction of bounce. However, it will be appreciated that embodiments, where the front or leading edge of the skidplate  100  is pivotally attached to the scraper body are contemplated and may be used within the cope of the present invention. 
         [0025]    The skidplate  100  is attached to the scraper or other earth moving apparatus by one or more inflatable airbags  106 . Inflatable airbag  106  may be an airspring, such as a reversible sleeve or a double convoluted airspring. Airsprings are airbags designed for used as springs in automotive, train, tractor-trailer, and other vehicular suspension systems. As depicted, typically, airsprings include a bellows attached to one or more plates. Physical connections may be made to the plates or the pistons of the airbags through connection bolts disposed therein. Currently, air springs are available in reversible sleeve (piston) and single, double or triple convoluted conformations, any of which may be used with embodiments of the present invention. Suitable airsprings are available from FIRESTONE and other suspension component manufacturers. These may be used in the present invention as well. 
         [0026]    It will be appreciated that where each airbag  106  is an airspring, each may be considered a pneumatic spring configured as a column of gas (air) confined within a container. The pressure of the confined gas, and not the structure of the container, acts as the force medium of the spring. A wide variety of sizes and configurations of airsprings are available, including sleeve-type airsprings, bellows-type airsprings, convoluted-type airsprings, rolling lobe airsprings, etc. Such airsprings commonly are used in both vehicular and industrial applications. Airsprings, regardless of their size and configuration, share many common elements. In general, an airspring includes a flexible, sleeve-like member made of fabric-reinforced rubber that defines the sidewall of an inflatable container. Each end of the flexible member is closed by an enclosure element, such as a bead plate which is attached to the flexible member by crimping. The uppermost enclosure element typically also includes air supply components and mounting elements (e.g., studs, blind nuts, brackets, pins, etc.) to couple the airspring to the vehicle structure. The lowermost enclosure element also typically includes mounting elements to couple the airspring to the vehicle axle. Examples of airsprings are set forth and discussed in U.S. Pat. No. 6,957,806, the disclosure of which is incorporated by reference herein. 
         [0027]    One end of pneumatic airbag  106  is secured to the skidplate  100 , at a portion of planar midsection  102 , typically towards the rear portion thereof. The other end of the pneumatic airbag  106  is attached to the earth moving apparatus  100 . It may be attached directly to the scraper frame or to a suitable mounting plate or fitting attached thereto. In some embodiments a protective structure may be formed to encase airbag  106 . For example, concentric metal rings  108  and  110  may be attached to the skidplate  100  and the scraper frame or the airbag mounting plate. Rings  108  and  110  may be slidably disposed over the other. As airbag  106  is inflated and deflated, rings  108  and  110  may slidably move with respect to one another, protecting the airbag  106  through continuous encasement. In such embodiments, the rings  108  and  110  may have channels or stops that interact with each other to provide a uniform pathway for the movement of skidplate  100  and to prevent over inflation of the airbag  106 . 
         [0028]    It will be appreciated that any number of airbags  100  may be used to attach a single wide skidplate  100  to the earth-moving apparatus  10 . For example, a single airbag  106  may be useful for some embodiments, while two or more airbags, which may be evenly space across the lateral surface of the skidplate  100 , may be used in other embodiments, as may be desired (and as shown in  FIG. 2 ). For embodiments where multiple skidplates  100  are used, each may be separately attached to the scraper  10  by one or more individual airbags  106  attached thereto. 
         [0029]    Attached to each airbag  106  is a fitting  120  to which an air hose  122  and a valve  124  may be functionally attached. There structures may be used to inflate the airbag  106 . In some embodiments, a pressure gauge P may be attached to the line, allowing the pressure in the airbag  106  and air hose  122  to be monitored. Valve  124  may include an exhaust, or a separate exhaust may be included for deflation of the bag. 
         [0030]    The air hose  122  is attached to a gas source  130 , such as an air compressor or a tank holding compressed air. Where the earth-moving implement  10  is configured for attachment to a prime mover, the air compressor may be located on the prime mover. Connection to the air compressor may be made through airlines also providing air to air brakes on the earth moving apparatus  10  (which may be through a system including a compressed air reservoir tank). Where the earth moving apparatus  10  is a self-propelled implement, an air compressor located thereon and powered by an onboard engine may provide the gas to the airbag  106 . 
         [0031]    It will be appreciated that a skidplate assembly, including one or more skidplates  100 , one or more pneumatic airbags  106 , and any attachment or inflation components may be made available as an assembly for installation (such as aftermarket installation) on pre-existing earth-moving vehicles. 
         [0032]      FIG. 3  depicts a schematic of a control system for utilizing a pneumatically activated skidplate system in accordance with the present invention. While reference is made to numerals in  FIGS. 1 and 2  for clarity, it will be appreciated that other embodiments of pneumatically operated skidplate systems in accordance with the present invention are contemplated and considered within the scope of the present invention. 
         [0033]    One or more sensors  200  may be disposed on the earth moving vehicle. These sensors may be motion sensors, such as electronic vibration sensors. In one illustrative embodiment, at least two vibration sensors may be used located opposite one another on the left and right sides of the earth mover  10 . Such sensors may provide output in the form of electrical signal that may be digitally read by a computer to determine the frequency or amplitude of vibrations. During use, a control unit  202 , such as an onboard computer system, monitors the vibrations reported by the sensor(s)  200 . When the vibrations reported by the sensor are above a predetermined level, the control unit actuates the valve or valves  124  to inflate the airbag  106 , moving the skidplate into a lowered position contacting the ground surface. 
         [0034]    In this way, the occurrence of bounce can be reduced for the earth mover  10 . The control unit  202  may be adjusted so that the level of vibration reported by the sensor  200  which causes the control unit  202  to actuate the airbags  106  at the onset of bounce or prior to the onset of bounce. It will be appreciated that the control system  202  may be further configured to deflate the airbags  106 , upon the sensors reporting the drop of the monitored vibrations below another predetermined level, which may be done by actuating the valves  124  to exhaust gas from the airbags. Alternatively, the control unit  202  may report the actuation of the skidplate to the operator of the earth mover  10  and require the operator to deflate the airbags or discontinue use. It will be appreciated that the control unit may inflate and deflate the airbags to “cycle” or repeatedly contact the skidplate to the ground then retract it therefrom, in order to reduce bounce while minimizing wear on the skidplate and drag on the earth-moving vehicle. 
         [0035]    Other sensors  200  may include hydraulic pressure sensors which monitor the hydraulic pressure in the hydraulic system of the earth mover  10 . For example, two hydraulic pressure sensors  200  may be located opposite one another on the left and right sides of the earth mover  10  and monitor differences in hydraulic pressure at the opposite sides of the earth mover  10 . Pressure spikes across the hydraulic system that are generally in opposition to one another could indicate the onset of bounce. The control system  202  may respond by inflating the airbags to deploy the skidplate. 
         [0036]    While this invention has been described in certain illustrative embodiments, the present invention can be further modified within the spirit and scope of this disclosure. This application is therefore intended to cover any variations, uses, or adaptations of the invention using its general principles. Further, this application is intended to cover such departures from the present disclosure as come within known or customary practice in the art to which this invention pertains and which fall within the limits of the appended claims.

Summary:
Apparatus, systems and methods for the stabilization of an earth-moving apparatus, such as an earth-moving scraper. A skidplate is attached to the earth-mover by one or more inflatable airbags, such as a pneumatic suspension air-spring, which may be inflated to lower the skidplate into contact with the ground surface. The skidplate (or a skid shoe attached thereto) remains held firmly on the ground regardless of minor adjustments to the blade height, due to the “springiness” of the air bag. The skidplate can be retracted when use is not desired, by deflation of the air bags. One or more motion sensors and a control unit may be included, allowing bounce to be detected before it is visible to the operator. The control unit may cause the airbags to inflate as needed to stabilize the earth-moving apparatus.