ROAD MAINTENANCE METHOD AND VEHICLE

Abstract

The cutting blades and smoothing blades of a road maintenance vehicle are adjustable in position with respect to the wheels to avoid extremes in changes in the depth of a cut by a blade or the height of the blades caused by wheels of the vehicle dropping into low places in a road. By including a selected number of wheels mounted to the same stiff frame, the wheels riding on the highest part of the road will lift the rigid frame and other wheels rather than the wheels riding on the lowest part of the road determining the depth of the cut of the cutting blades. The height of the blades with respect to the wheels can then be adjusted so that they never cut too deep and overly stress the blades but do cut the highest elevations of the road and move the loose dirt and gravel into the lower parts of the road. A first frame is supported by wheels and a second frame is movably mounted to the first frame.

Description

BACKGROUND OF THE INVENTION

This invention relates to road maintenance and more particularly to methods and equipment for smoothing the surface of roads.

One type of road maintenance equipment for smoothing the surface of roads includes a vehicle that is pulled by a tractor or truck and includes one or more cutting or shearing or buster blades that break elevated portions of the road into loose gravel and dirt and one or more striker or smoothing blades to spread the loose gravel and dirt over the road. One prior art road maintainer of this type has a centrally located V-shaped cutting or shearing blade and two side cutting blades that cut the road material and deliver it to a centrally located striker or smoothing blade that spreads the material across the road. This prior art road maintainer is disclosed in U.S. Pat. No. 5,071,284.

This prior art road maintainer has several disadvantages, such as for example: (1) the resistance to cutting is at times undesirable in magnitude; (2) the height of the cutting and smoothing blades above the road is controlled by only two wheels near the end of the road maintainer and thus subject to wide variations as wheels alternately contact the lowest parts of the road and the highest parts of the road; (3) the scrapped and cut material is not distributed with sufficient evenness over the road; and (4) the height of the cutting and smoothing blades is not easily adjustable.

SUMMARY OF THE INVENTION

Accordingly, it is an object of the invention to provide a novel method and apparatus for maintaining roads.

It is a further object of the invention to provide a novel method and apparatus for controlling the magnitude of stress on the blades of a road maintenance vehicle.

It is a still further object of the invention to reduce the variations in the elevation of the blades of the maintenance apparatus during the road surface smoothing operation.

It is a still further object of the invention to control the height of the blades above the road by any of a plurality of different wheels on the road.

It is a still further object of the invention to provide a method and apparatus for cutting free material from high spots on a road and distributing it evenly.

It is a still further object of the invention to provide a method and apparatus for distributing the cut or scrapped material from a road over a wider area of the road.

It is a still further object of the invention to provide a method and apparatus by which the operator of road maintenance equipment can adjust the height of the blades.

In accordance with the above and further objects of the invention, a road maintenance vehicle is constructed to be towed by a tractor or a truck to smooth the surface of a road. For this purpose, a plurality of blades with selected length and angle are provided to cut into or burst or scrape the high points on the surface of the road and move the cuttings or scrapings through a plurality of paths towards the rear of the vehicle. The vehicle includes an angular blade designed to receive the cuttings or scrapings from a number of paths and channel some of it to the center of the road for the proper crown while filling in low spots by material being moved towards the rear most blade.

The vehicle has a plurality of wheels so that as it is towed, the height of the blades is controlled by the wheel that is riding over the highest point rather than by the wheel that is in the lowest depression to cause the blades to follow the road more evenly. The height of the blades with respect to the wheels can be adjusted by any suitable mechanism such as hydraulic cylinders under the control of an operator prior to a leveling operation and can be locked in place.

From the above description it can be understood that the road maintenance vehicle and method of this invention has several advantages such as: (1) the stress imposed on cutting blades is kept within manageable limits by controlling the angle of the blade and the depth of the cut for specific length blades and using multiple blades; (2) the depth of cuts is maintained reasonable in spite of low portions in the road that cause the wheels to drop to a low depth by including a sufficient number of wheels so that the height of the cutting blades is controlled by the wheel riding on a relatively high portion of the road; (3) a plurality of cutting blades is used to distribute the loosed road material more evenly; and (4) the height of the cutting and smoothing blades can be easily adjusted.

BRIEF DESCRIPTION OF THE DRAWINGS

An above noted feature of the invention will be better understood from the following detailed description when considered in connection with the following drawings, in which:

FIG. 1 is a flow diagram of a process for maintaining road surfaces;

FIG. 2 is a fragmentary simplified side view of a truck pulling a road maintenance device in accordance with an embodiment of the invention;

FIG. 3 is a simplified partly schematic plan view of a tractor or other vehicle pulling a road maintenance vehicle in accordance with an embodiment of the invention;

FIG. 4 is a perspective view of a road maintenance vehicle in accordance with an embodiment of the invention; and

FIG. 5 is a perspective view from another direction of the road maintenance vehicle of FIG. 4.

DETAILED DESCRIPTION

In FIG. 1 there is shown a flow diagram 10 of a process for using the road maintenance vehicle of this invention comprising the step 12 of determining relevant road surface condition, the step 14 of adjusting the cutting and smoothing blades, the step 16 of pulling the road maintenance vehicle at a fast relevant surface speed for the relevant road surface conditions and the tep 18 of pulling the road maintenance vehicle at a slow relevant speed. The step 14 of adjusting the blades for the relevant road surface conditions includes the step 24 of adjusting the height of the cutting blades within the blade-height wheel-averaging arrangement to keep the stress on the cutting blades within tolerances, the step 26 of adjusting the height of the smoothing blade to build a crown and smooth out ruts and holes, and the step 28 of adjusting the angle of the cutting blades to correspond to the length of the blades, road surface conditions, number of blades and height of the blades with respect to the wheels of the vehicle to form a crown.

In this specification, the term “blade-height wheel-averaging arrangement” means the selection and positioning of the wheels of the road maintenance vehicle to avoid extremes in changes in the depth of a cut by a blade or the height of the blades caused by wheels of the vehicle dropping into low places in a road. By including a selected number of wheels mounted to the same stiff frame, the wheels riding on the highest part of the road will lift the rigid frame and other wheels rather than the wheels riding on the lowest part of the road determining the depth of the cut of the cutting blades. The height of the blades with respect to the wheels can then be adjusted so that they never cut too deep and overly stress the blades but do cut the highest elevations of the road and move the loose dirt and gravel into the lower parts of the road. The term “cutting blade” in this specification includes scarring blades or bursting blades or any blades constructed and located to break up hardened material on the road such as raised gravel or dirt mounds into loose material that can be moved into lower spots. The term “smoothing blade” shall mean a blade that moves and distributes loose material to fill in ruts and build a crown on the road.

The cutting blades are arranged in a cutting-blade distribution arrangement. In this specification, the words “cutting-blade distribution arrangement” means an arrangement of a plurality of cutting blades to avoid excessive stress on any one blade while cutting and spreading the cut dirt and gravel over the entire path of the maintenance vehicle with an effective evenness. In this specification, the term “effective evenness” means the distribution of loose dirt and gravel in a manner that provides material to fill in holes and depressions evenly rather than having more loose material than needed along one line in the road such as the center of the road as in the case with cutting plates that have a central opening with V-shaped blade portions extending outwardly and forwardly to channel material to the center of the road or V-shaped blade portions with a point facing forwardly to move loose dirt and gravel to the sides. In this specification, the word “forwardly” means the direction that the road maintenance vehicle is being pulled.

The speed at which the road maintenance vehicle is pulled depends on the relevant road surface conditions. In this specification the terms “relevant road surface condition” includes considerations such as how much moisture is in the road or how dry the road is, sometimes referred to as soft or stiff road surfaces and the size of any ruts and holes, if any. The words “slow relevant road surfaces” means the relevant road conditions are considered slow relevant road conditions when the road surface is dry and stiff and/or the ruts and holes are deep, such as more than three inches deep. Under slow relevant road conditions, the maintenance vehicle is pulled at a speed of between 10 and 15 mph with an average speed less than 15 mph. This speed is referred to in this specification as “slow relative speed”. On the other hand, “fast relevant road surface conditions” means the surface conditions that exist when the road surface is moist and soft and the ruts and holes are shallow such as no more than 2 or 3 inches. The road maintenance vehicle can be pulled at speeds up to 20 mph and average over 15 mph under fast relevant road surface conditions. This speed is sometimes referred to herein as “fast relative speed”.

In FIG. 2, there is shown a fragmentary schematic side view of a road maintenance operation 30 being performed by a truck or other heavy vehicle 32 driven by an operator 34 pulling a road maintenance vehicle 36 in accordance with the invention. The heavy vehicle 32 will pull the road maintenance vehicle 36 at a speed in accordance with the relevant road surface conditions. In this specification, the term “relevant road surface conditions” shall mean how much moisture is in the road or how dry the road is, sometimes referred to as soft or stiff road surfaces and the size of ruts and holes if any. The road maintenance vehicle 36 includes a plurality of wheels, three of which are shown at 38A, 38B and 38C in FIG. 2 on one side of the road maintenance vehicle. Other corresponding wheels are shown on the other side.

The number of wheels is chosen in accordance with typical road conditions for which the vehicle is designed. It is intended to prevent a blade from dropping low because a wheel is in a low spot to put too much stress on the blade and damage it or cause excessive wear or an excessively deep cut. Instead, there are sufficient wheels so that one of them will always be on a high spot. The frame of the vehicle 36 to which the wheels are mounted is stiff so that the highest wheel will determine the elevation of the vehicle. As will be described hereinafter, the blades are adjustable with respect to the wheels so that the blade height may also be adjusted in accordance with the relevant road surface conditions.

In FIG. 3, there is shown a simplified plan view of the road maintenance equipment of FIG. 2 in operation showing the vehicle 32, which may be a truck or tractor, pulling the road maintenance vehicle 36. As shown in this view, the road maintenance vehicle 36 includes a hitch 42, a main carriage or frame 44, and a movable blade carriage or frame 46. The main carriage 44 has mounted to it the axles for the wheels 38A-38C and 40A-40C so that it rises and falls in accordance with the wheels 38A-38C and 40A-40C as the road maintenance vehicle 36 is pulled down the road. To form a complete blade-height wheel-averaging arrangement, however, the movable blade frame 46 must be mounted and controlled by a hydraulic cylinder 48 (FIG. 4) under the control of the operator 34 (FIG. 2) to position the movable blade frame 46 with respect to the rigid main frame 44 at a proper elevation for the cutting blades 50A-50D and thus to avoid undue stress.

The width of the blade-height wheel-averaging arrangement is normally approximately 8 feet and is intended to cover a lane of a road. The cutting blades 50A-50D are adjustable in angle to move loose gravel and dirt to their out edges. Thus, the blades 50A and 50B as the vehicle is being pulled, move material to the outside or the edge of the roadway and the blades 50C and 50D are angled to move material towards the center of the roadway or the outside of the lane. A smoothing blade 52 is also positionable to form an angle and move the loose material to the center or crown of the road. The movable blade carriage 46 itself is adjustable in position by the hydraulic cylinder 48 to position all of the blades and complete the blade-height, wheel-averaging arrangements for smoothing out of the road.

In FIG. 4, there is shown a fragmentary perspective view of the maintenance vehicle 34 more clearly showing the hydraulic cylinder 48 and movable blade frame 46 connected by hydraulic lines 54. As more clearly shown in this view, the movable frame 46 may move up and down to position the blades appropriately. In FIG. 5, there is shown another perspective view of the road maintenance vehicle 36 showing the cutting blade 50D mounted to the movable frame 46 (FIGS. 3 and 4) by a support 56D attached to it and attached to the movable frame 46 so that its angle may be changed by movement with respect to the movable frame 46 and thus change the angle of the cutting blade 50D. Similarly, the smoothing blade 52 (FIG. 3) is supported and its angle may be changed.

From the above description, it can be understood that, the road maintenance vehicle of this invention has several advantages, such as: (1) the stress imposed on cutting blades is kept within manageable limits by controlling the angle of the blade and the depth of the cut for specific length blades and using multiple blades; (2) the depth of cuts is maintained reasonable in spite of low portions in the road that cause the wheels to drop to a low depth by including a sufficient number of wheels so that the height of the cutting blades is controlled by the wheel riding on a relatively high portion of the road; (3) a plurality of cutting blades is used to distribute the loosed road material more evenly; and (4) the height of the cutting and smoothing blades can be easily adjusted.

While a preferred embodiment of the invention has been described in some detail, it is to be understood that within the scope of the appended claims, many modifications and variations of the invention are possible. Accordingly, it is to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described.

Claims

1. A road maintenance vehicle, comprising: a first frame supported by a plurality of wheels;a second frame movably mounted to said first frame, whereby the second frame may be adjusted with respect to said plurality of wheels;a plurality of cutting blades;at least one smoothing blade;said plurality of cutting blades and said at least one smoothing blade being mounted to said second frame whereby said plurality of cutting blades and said at least one smoothing blade may be adjusted in position with respect to said plurality of wheels;said first frame, said second frame, said plurality of cutting blades, said at least one smoothing blade and said plurality of wheels being arranged in a blade-height wheel-averaging arrangement.

2. A road maintenance vehicle in accordance with claim 1 wherein the plurality of cutting blades are moveably connected to the second frame wherein they may be adjusted to a cutting-blade distribution arrangement.

3. A method of maintaining a road with a road maintenance vehicle that includes a first frame supported by wheels, a second frame movably mounted to the first frame and movably supporting blades, comprising the steps of: determining relevant road surface condition;adjusting the movably supporting blades, said first frame and said second frame into a blade-height wheel-averaging arrangement; andpulling the road maintenance vehicle along the road at a fast relevant speed and a slow relevant speed in accordance with the relevant road surface condition.