Excavating – Scoop or excavating and transporting container – Supported on vehicle between longitudinally spaced ground...
Reexamination Certificate
1999-08-18
2001-08-21
Will, Thomas B. (Department: 3671)
Excavating
Scoop or excavating and transporting container
Supported on vehicle between longitudinally spaced ground...
C037S412000, C172S783000
Reexamination Certificate
active
06276077
ABSTRACT:
TECHNICAL FIELD OF THE INVENTION
The present invention relates to road working heavy equipment and, more particularly, to an improved wheel tractor scraper used for removing dirt to prepare a roadway for paving or for other surface preparation.
BACKGROUND OF THE INVENTION
Wheel tractor scrapers are used to remove dirt for preparing a roadway for paving or for other road surface preparation. Such wheel tractor scrapers, as the Caterpillar® model 631E, are typically driven in the direction of the roadway and remove dirt to an appropriate depth, according to survey stakes positioned alongside the proposed roadway. The dirt is simultaneously removed as the ground below is leveled for providing an acceptably flat and smooth roadway. All standard highways and roads are desirably crowned in a parabolic shape, high in the middle and low along the edges of the roadway, primarily to facilitate drainage and also, to a lesser degree, to increase strength through the upwardly curved arch shape and to enhance safety by slanting each side of the roadway in opposite directions so that vehicles will have a tendency, although mostly imperceivable, to move away from the center. When a vehicle is not properly guided by an inattentive operator, it will drift to the side and away from oncoming traffic.
In order to provide the desirable parabolic crown or arch shape to the roadway, an existing wheel tractor scraper can be used to the surface only to the highest desired depth at the center of the road. Another piece of equipment, such as a road grader, must then be used to blade the dirt away from the edges on both sides of center. Graded dirt may also accumulate and may need to be removed from the roadway using one or two other pieces of equipment, such as the tractor wheel scraper or a front-end loader and a dump truck.
Prior U.S. Pat. No. 3,561,538 discloses an earth-moving machine with depth and cross-slope control. This machine provides for depth control using a pair of hydraulically operated rams that operate in parallel, i.e., both rams acting simultaneously up or down at the front of the main member so that the height of the blade is adjusted. The cross-slope is adjusted with a single hydraulically-operated ram operating against pivotable brackets which support one rear wheel by raising and lowering one of the rear wheels; the cross-grade is said to be adjustable. This prior device requires a specially constructed rear axle bracket and brace support that presents certain inherent suspension difficulty and reduced load-carrying capacity and has not been a widely accepted machine design.
Other prior tractor scrapers with material collection bowls, such as in U.S. Pat. No. 3,905,136 and U.S. Pat. No. 3,486,254 and U.S. Pat. No. 3,984,927 consistently describe tilting the front of the bowl downwardly or upwardly to adjust the depth of cut only with parallel actuation of hydraulic cylinders and rams or hydraulic actuators. In each of these prior devices, the front blade is tilted downward or upward, thereby adjusting the depth of the cut but not adjusting the cross-grade cutting angle.
SUMMARY OF THE INVENTION
The present invention provides a single vehicle that can remove dirt from a roadway while forming a desirable crown shape therealong. The invention basically comprises a structure of a vehicle, such as a wheel tractor scraper, including a tractor and driver cab, a bucket with a frontward-directed scraper blade mounted on a pair of wheels and turnably connected by a draft frame to the tractor behind the drivers cab. Front hydraulic cylinders and rams are mounted, one each at opposite sides of the draft frame toward the front of the bucket and above the scraper blade. The hydraulic cylinders and rams are selectively actuatable from the driver cab. To form a crown, the hydraulic cylinders are uniquely constructed and controlled to be selectively actuatable, both to control the depth of cut and control the cross-grade angle of the scraper blade. To control depth of cut, both cylinders ad rams operate in parallel. To control the cross-blade angle, the cylinders and rams operate in relative opposite directions. The cylinder on one side lifts the front of the scraper blade and the cylinder on the opposite side of center pushes the scraper blade downward. Thus, one front corner of the scraper is lower than the other front corner and the edge of the roadway can be made lower than the middle. With the cross-angle established, both cylinders and rams can be actuated in parallel or in the same direction to adjust the depth of cut while maintaining the cross-angle or the “stagger.” The actuation maintaining the different extension of each ram is sometimes referred to as staggered actuation. The hydraulic cylinders and rams are dual actuation cylinders so that the blade may be adjustably maintained at the appropriate depth and cross-angle with respect to the roadway, to form a roadway with a single machine at a desired cross-grade. The cross-grade angle can be adjustably controlled, depending on whether one of the other edges of the roadway is being formed or whether a portion closer to the center of the parabolic curve shape or at the top of the roadway crown is being formed.
The tiltable bucket, wheel tractor scraper, according to the present invention, can therefore be used to form appropriate angles for a parabolic crown, up at center of the roadway, down at the side edges and at other angles therebetween. The inventive tiltable bucket, tractor wheel scraper alleviates the need for a separate piece of heavy equipment, such as a road grader. The inventive tiltable bucket, wheel tractor scraper is not only capable of removing dirt to an adjustable depth with a blade parallel to the wheels carrying the bucket, as with prior wheel tractor scrapers, but can also scrape and remove dirt to a simultaneously adjustable depth and adjustable cross-grade angle along any portion of the roadway crown or along either of the sloped edges of roadways.
In an alternative embodiment, in order to accomplish the cross-grade tiltability of the bucket blade, the entire bucket may be attached to the rear axle between the rear wheels using two adjustably inflatable nitrogen cylinders. Prior proposals for hydraulic adjustment of one of the rear wheels did not accommodate cushioned suspension as with the inventive dual nitrogen cylinder aspect of this embodiment of the invention. Prior devices might have used nitrogen cylinders for shock absorbing. The separately adjustable nitrogen cylinders attached according to this embodiment of the invention may be inflated or deflated in parallel to change the angle of forward tilt of the blade. The nitrogen cylinders may be selectively inflated and deflated with opposite, direct actuation to adjust the cross-grade or with staggered actuation to adjust both forward tilt and cross-grade tilt simultaneously. Thus, the entire bucket, including the blade, may be pivoted at its connection to the center beam and relative to the rear axle. The depth of cut could be controlled by standard dual parallel action front cylinders and rams.
In another embodiment, the actuation of two front hydraulic cylinders and rams act in coordination with two rear nitrogen cylinders to allow the scraper blade and the entire scraper blade bucket to more easily tilted about either a front-to-back imaginary control axis or an imaginary transverse axis to obtain any desired blade of angle and depth relative to the roadway. Preferably, the rear nitrogen cylinders and the front hydraulic cylinders and rams are controlled simultaneously by the operator using a simplified two-axis tilt controller arrangement that actuates both hydraulic and nitrogen cylinders to accomplish the desired blade attack angle, depth of cut and crown-forming, cross-grade scraping angle.
The invention further contemplates a kit for modification of existing wheel tractor scrapers, with either the front hydraulic cylinders and rams and controls, the rear nitrogen cylinders and controls, or the combination of hydraulic cylinders and rams and the rear
Haynes and Boone L.L.P.
JHC Holding Company
Mammen Nathan
Montgomery John W.
Will Thomas B.
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