Earth working – Towed scraper with ground support wheels
Reexamination Certificate
2000-08-22
2001-12-11
Novosad, Christopher J. (Department: 3671)
Earth working
Towed scraper with ground support wheels
C172S197000, C172S199000
Reexamination Certificate
active
06328115
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates generally to the field of mobile equipment used to move or remove dirt and to level ground surfaces over relatively large areas, and more particularly to such equipment which are wheeled constructions pulled behind motorized vehicles, such being commonly referred to as dirt scrapers, box blades, box scrapers, pull-behind scrapers, levelers or the like. More particularly, the invention relates to such equipment which are provided with stabilizer means to reduce negative effects caused by uneven terrain, these negative effects known by such terms as bounce, walking or rocking, where the stabilizer means is damped to reduce vertical motion.
Dirt scrapers are used to remove large quantities of dirt in a relatively rapid manner and/or to level large areas of ground with relatively high precision. The scrapers are wheeled apparatuses having a large laterally extending scraping or cutting blade which shaves off raised areas of ground, the loose or removed dirt being retained within a box structure comprising lateral wings and a curved back panel. Loose dirt is deposited into depressions as the box is pulled along, such that the combination of dirt removal from the raised areas and the dirt deposition into the depressed areas produces a level surface. It is most important that the cutting blade be maintained in a horizontal position to insure a level scrape, but unevenness in the terrain and the speed of the operation combine to produce negative effects known as bouncing, walking or rocking, where the sides of the box and therefore the blade move up and down simultaneously or in alternating fashion, such that the blade alternately cuts too low and then not low enough to produce a level surface. Because of this bounce effect, scraping is usually performed at a very slow pace until a sufficient amount of dirt is accumulated in the box to preclude the problem—the weight or mass of the accumulated dirt tending to negate or diminish the bounce effect. When leveling large areas, maintaining this extremely slow pace is time-consuming and costly in terms of man-hour expenses, so it is highly desirable to correct the bounce effect problem in a manner which allows the box scraper to be pulled at a much higher speed during the leveling operation.
Prior attempts to address this problem include mounting fixed skid shoes or skid plates to the box, the tongue or the wheel suspensions of the scrapers, the skid shoes or plates providing additional contact points with the surface, but this adaption has been shown to reduce the negative effects only slightly. An improved approach has been to provide the skid shoes with damping means, such as springs or shock absorbing pistons, but the configuration and location of the shoes has not been optimized. Examples of such apparatuses are shown in U.S. Pat. No. 5,307,570 to Brown, U.S. Pat. No. 5,072,531 to Pronovost et al., U.S. Pat. No. 4,389,800 to Goby, U.S. Pat. No. 4,125,950 to Mashford, and U.S. Pat. No. 1,968,412 to Lull. The prior art typically teaches the use of skid shoes of relatively small surface area, with the skid shoes located to the rear of the cutting blade.
It is an object of this invention to provide a stabilizing means for dirt scrapers which alleviates the problem of bounce, by providing a pair of stabilizing rails of relatively large surface contact area, where the rails are mounted in a pivoting manner, laterally external to the side wings of the box, such that the rails extend along the base of the wings. The stabilizing rails are provided with damping means, such as shock absorbing pistons, to reduce shocks encountered during the leveling operation, thereby limiting or eliminating the negative bounce effects, enabling the scraper to be pulled at a much higher speed than normally available. Upward travel limiting means are also provided such that the amount of upward movement of the stabilizer rails can be controlled in order to maintain the lower surface of the rails at a desired height relative to the cutting blade. Furthermore, the stabilizing rails act to maintain the loose dirt within the box by precluding lateral movement of the removed dirt out from under the wings when they are slightly off the ground surface, thus preventing the formation of wind rows—a pair of raised ridges of loose dirt laid down on either side of the box portion of the scraper paralleling the direction of travel. These and other objects not expressed at this time are to be accomplished as described below.
SUMMARY OF THE INVENTION
The invention comprises in general an improvement to a dirt scraper apparatus used for leveling or removing dirt from large areas, such as the type comprising a dirt-controlling box with a curved mold board or back member, a pair of lateral wing members and a cutting blade suspended below the mold board, where the box is mounted in a cantilevered fashion between a set of rearwardly positioned wheels and a tongue and hitch combination for securing the apparatus to a motorized towing vehicle, such as a tractor. Height adjusting means, typically a hydraulically controlled piston, alters the position of the box relative to the ground between a passive, non-working position with the blade fully raised and an active, working position with the blade lowered, such that when the apparatus is pulled across terrain, any dirt encountered by the blade will be scraped from the surface and pushed along within the box.
The improvement is the provision of stabilizing means which comprise a pair of laterally disposed, relatively elongated, stabilizer rails or bars mounted externally to the wings of the apparatus. The rails are relatively wide laterally and have a preferably planar lower surface with a relatively large surface area in comparison to the width and surface area of the bottom edges of the wings. The stabilizer rails are connected to the wings in a pivoting manner, preferably with the pivot positioned toward the front of the apparatus, such that the stabilizer rails are able to move in the vertical direction independently of the wings. The stabilizer rails are mounted onto the wings such that the lower surfaces of the stabilizer bars are able to extend beneath the bottom edges of the wings and beneath the blade. Damping means, preferably a piston connected near the rear of each stabilizer rail, absorb shocks, dampen upward movement and allow the lower surfaces of the rails to float across the uneven ground surface as the apparatus is pulled forward. A retention member, such as a chain, limits travel of the stabilizer rails in the downward direction.
Preferably the stabilizer means are also provided with upward travel limiting means, such that the rails are prevented from upward movement relative to the wings past a predetermined point. Most preferably the limiting means is adjustable, such as a threaded bolt mounted into a flange on each of the wings, so that the amount of allowable upward travel can be changed as desired, effectively adjusting the cutting edge depth.
The stabilizer rails serve several functions, the primary of which is to restrict, limit or preclude rocking or bounce of the box of the apparatus, thereby allowing the apparatus to be pulled across the ground at a faster pace, since the rails remain in contact with the ground and the damping means limits the negative effects of asymmetric terrain and the inherent spring or bounce of the tires. Secondarily, the rails prevent lateral loss of removed dirt when the bottom edges of the wings are not in contact with the ground surface, since the lower surfaces of the rails extend beneath the bottom edges of the wings to remain in contact with the ground. Further, in conjunction with the upward travel limiting means, the stabilizer rails can be used to maintain the blade a minimum distance above the ground in a more controlled manner than can be achieved by using the height adjusting means of the dirt scraper apparatus itself, since the upward travel limit of the rails relative to the wings can be preset.
REFERENCES:
patent: 196
Novosad Christopher J.
Saitta Thomas C.
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