Grade Trimming Apparatus

Abstract

A mobile supporting unit for a surfacing apparatus such as a transverse rotary trimmer for excavating and trimming a pavement base to grade along a sidewalk, curb or roadway. The mobile supporting unit comprises a longitudinally open rigid framework carried by transversely spaced track assemblies. The rigid frame is pivotally connected to each track assembly about a common transverse axis and is further mounted for pivotal movement about a longitudinal center axis between the track assemblies. Power suspension means is provided to selectively modify the orientation of the frame and surfacing apparatus relative to the track assemblies for maintaining a preselected grade and cross leveling attitude during surface operations along a longitudinal path.

Description

BACKGROUND OF THE INVENTION

This disclosure is concerned with a surfacing apparatus in the form of a transverse rotary trimmer designed specifically for high production sidewalk and curb preparation in cities and suburbs. The apparatus lends itself to automatic control from a single preset string line. It is capable of operating on straight runs, curves and culdesacs.

Prior development of similar surfacing equipment has been centered primarily on roadway machines for large production use along straight runs. The present apparatus is directed toward small scale use as well as high production, and provides a versatile mobile structure that can be readily adapted to the needs of a sidewalk contractor. The mobile supporting unit is carried by ground engaging track assemblies and does not require the laying of tracks or other supports. The structure operates within its own working width, and the ground engaging tracks follow the surfacing apparatus and ride upon the prepared graded surface.

SUMMARY OF THE INVENTION

The invention is concerned with the mobile supporting unit for a transverse surfacing apparatus directed across a continuous longitudinal path. The supporting unit includes a rigid frame that is longitudinally open to accept conveyors or other devices auxiliary to the surfacing apparatus. The rigid frame is supported by transversely spaced ground engaging means. The mounting apparatus connecting the rigid frame and the ground engaging means permits pivotal movement of the rigid frame about a transverse axis common to the ground engaging means at each of its respective sides. Suspension means (in the form of hydraulic cylinders) are provided between the rigid frame and ground engaging means for selectively locating the rigid frame about this transverse axis. In addition, pivotal adjustment of the rigid frame is provided about a longitudinal axis centrally located between the ground engaging means.

It is one object of this invention to provide an economical mobile supporting unit for transverse surfacing equipment such as a rotary trimmer. By making use of a rigid frame that is movably adjustable with respect to ground engaging drive units, the surfacing apparatus can be mounted to the rigid frame and both the frame and surfacing apparatus can be controlled automatically as an integral unit by one set of controls. This requires a minimum number of moving elements for grade and transverse attitude adjustment.

Another object of the invention is to provide a mobile supporting unit that integrally carries the surfacing apparatus and all devices auxiliary to it. By mounting the rotary trimmer across the movable frame and also mounting the receiving conveyors for excess soil on the same frame, no special provision need be made in this structure to accommodate movement of the trimmer with respect to the conveyors, since all will move as a unit relative to the supporting track assemblies.

Another object of the invention is to provide an apparatus capable of practical operational production with a minimum manual labor effort.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation view of a rotary trimmer embodying the present invention;

FIG. 2 is an enlarged side elevation view of the frame, trimming head and track assemblies;

FIG. 3 is a rear view of the apparatus shown in FIG. 2;

FIG. 4 is an enlarged top view of the apparatus shown in FIG. 1;

FIG. 5 is a front view of the trimming head;

FIG. 6 is a fragmentary sectional view through the trimming head as seen along line 6--6 in FIG. 5;

FIG. 7 is a schematic transverse elevation showing the stabilizer assembly for the track units;

FIG. 8 is an enlarged fragmentary sectional view taken along line 8--8 in FIG. 7;

FIG. 9 is a schematic view illustrating the string line controls;

FIG. 10 is a view similar to FIG. 9, showing the control attitude for a sloped trim;

FIG. 11 is a side view of the schematic controls as seen from the right in FIG. 9; and

FIG. 12 is an enlarged front view of the adjustable mount at one end of the cross leveling control apparatus.

PREFERRED EMBODIMENT OF THE INVENTION

While the present apparatus can be used for the support of various types of transverse surfacing equipment, such as trimming devices, excavating devices and paving devices, it is shown in the accompanying drawings in conjunction with a rotary trimmer. Such a trimmer is used for fine grading, to excavate and trim the soil base along a longitudinal path in preparation for final pavings. The apparatus can be used to excavate an existing soil base or for the spreading and grading of base material supplied thereto. The present structure is self-supporting on the surface area prepared by the surfacing apparatus mounted across its forward end. It requires no external support such as tracks. The trimmer shown was designed primarily for small scale use in the trimming of sidewalks and curbs, but it can also be applied to the widening of highways and roads by making multiple passes of the apparatus.

The apparatus essentially comprises two machine sections. The first is the trimming head 10, which is the surfacing apparatus that trims or excavates the surface being graded. The second is a mobile supporting unit 20 carried by transversely spaced crawler track assemblies 24. The trimming head 10 is mounted across the front end of the mobile supporting unit 20 and is both elevationally supported and guided longitudinally by the unit 20.

The trimming head is best seen in FIGS. 5 and 6. It comprises a supporting housing 11 which rotatably journals a transverse shaft 12. The shaft 12 has a plurality of digging teeth 13 which protrude outwardly from its axis on housing 11. Auger blades are mounted to the digging teeth 13 to move soil from the ends of shaft toward its center. Paddles are provided on the center digging teeth 13 to throw soil rearwardly of the shaft 12.

Also extending across housing 11 is a trim blade 14, having an adjustable lower section which provides an accurate final trim to produce a smooth finished surface free of debris. The trim blade 14 extends across housing 11 immediately rearward of digging teeth 13.

The shaft 12 is powered by a drive unit generally shown at 15. The drive unit rotates shaft 12 in the counterclockwise direction as seen in FIG. 8. Rotation of shaft 12 causes excess material at the center of the apparatus to be thrown rearwardly. This material is directed through an aperture 16 formed through the trim blade 14. It is received on a feed conveyor 17 described below.

The trimming head 10 is supported at the forward end of mobile supporting unit 20. Unit 20 essentially comprises a rigid frame 21 which in turn is mounted by a pair of transversely spaced crawler track assemblies 24.

The connections that exist between the frame 21 and the track assemblies 24 are best seen in FIGS. 1-4, 7 and 8. First, frame 21 is connected to each track assembly 24 for pivotal movement about a common transverse axis. This is accomplished by means of a transverse main axle 22 at the rear of unit 20. The outer ends of axle 22 are designated at 23. They are respectively journaled by the supporting framework 25 of each track assembly 24. The axle 22 is movably connected to rigid frame 21 by a longitudinal pin 26 carried by two transverse members 27 that form a part of the rigid frame 21. The axis of pin 26 is a longitudinal axis located centrally between the track assemblies 24.

To prevent the front ends of the track assemblies 24 from wandering from their required longitudinal positions, stabilizer assemblies are provided at each side of the rigid frame 21. As seen in FIGS. 7 and 8, each stabilizer assembly includes an upright pin 33 carried by a supporting bracket 34 mounted to the respective track assembly framework 25. Encircling the respective pins 33 are projecting horizontal rings 36 fixed to the rigid frame 21. Adequate tolerance is provided in the design of rings 36 to permit a limited amount of pivotal movement of frame 21 about the axes defined by the connections between the main axle 22 and the crawler track assemblies 24.

The rigid frame 21 is adjustably suspended by its longitudinal and transverse axes with respect to the crawler track assemblies 24. This is accomplished by a pair of upright hydraulic cylinder assemblies 30 shown located immediately forward of the stabilizer units. The upper end of each cylinder assembly 30 is pivotally connected to the upper surface of rigid frame 21 by a pivotal upper mount 31. The lower end of each cylinder assembly 30 is similarly connected to the framework 25 of the respective crawler track assembly 24 associated with it. The lower pivotal mount is designated in the drawings by the numeral 32. The respective connections at the ends of the cylinder assemblies 30 as provided by mounts 31, 32 essentially constitute universal joints permitting free pivotal movement of the cylinder assemblies 30 about both transverse and longitudinal axes, thereby permitting complete freedom of orientation of the rigid frame 21 with respect to it axes on the axle 22.

The trimming head 10 is connected across the front of the rigid frame 21 and during operation of the equipment is moved integrally with the frame 21. The principal support comprises transverse mounting pins 37 at the lower front corner of the frame 21, which serve to support the trimming head 10 about a common transverse axis. Extending rearward from the upper portion of the trimming head housing 11 are upper connecting arms 38 at each of its respective sides. These are selectively locked to the rigid frame 21 by releasable bolts 40, bolts 40 serving to permit selective angular adjustment of the attitude of the trimming head 10 relative to the axis of pins 37.

The rigid frame 21 is constructed so as to be substantially open longitudinally throughout its length. It is preferably constructed as a rectangular open box, permitting the mounting of auxiliary equipment within the frame 21 as required by the particular surfacing equipment with which it is utilized. In the illustrated structure, a feed conveyor 17 extends longitudinally from a forward location immediately rearward of the trimming head 10. It is preferably located along the center of the frame 21 so as to receive material directed rearwardly through the previously described aperture 16. The rear end of feed conveyor 17 is directly above a discharge conveyor 18 supported by a boom 19 on the frame 21. The discharge conveyor 18 can be directed rearwardly of the machine or can be directed to either side of the machine to direct excess material either onto a receiving vehicle or to the side of the graded path.

While many different power plants could be used with respect to the apparatus, it is preferably powered by a single engine 47, using hydraulic circuits to individually power the crawler track assemblies 24, and the operating elements of the trimming head 10 and unit 20. All of these units can be controlled by a single operator located on an upper deck 51, using manual control elements on an instrument panel 52.

The described apparatus readily lends itself to automatic grade and steering control units. Examples of such devices are illustrated in U.S. Pat. No. 3,247,771. An example of a cross leveling apparatus using a mercury level switch arrangement is described in U.S. Pat. No. 2,716,169.

As shown, the present apparatus can be controlled by a single string line 41, supported by longitudinally spaced posts 46. String line 41 is preset by a survey crew to the exact grade desired and it extends parallel to the desired path of the machine. In a preferred operation, the same string line 41 will be subsequently utilized in the control of paving equipment along the path being graded. As illustrated, the width of the trimming head 10 is preferably at least as wide as the operating portion of the supporting unit 20. Thus, the crawler track assemblies 24 will travel on the graded surface, minimizing the number and amount of correctional movements required to maintain proper orientation and positioning of mobile supporting unit 20.

The grade and steering control elements are illustrated at the front of the machine, mounted on the trimming head 10. They include a grade control unit 42 suitably positioned on a supporting bracket and having a movable sensor 43 that engages the lower surface of the string line 41. Sensor 43 and unit 42 detect variations in the elevation of the trimming head 10 with respect to the desired grade indicated by string line 41. They are used in the hydraulic controls that operate the cylinder assembly 30 at the side of frame 21 adjacent to the string line 41.

Also mounted on the trimming head 10 is a steering control unit 44 having a vertical sensor 45 that contacts string line 41. Sensor 45 is sensitive to lateral movement of the trimming head 10 relative to the path indicated by string line 41, and is utilized to automatically correct steering direction by controlling the relative speeds of the crawler track assemblies 24.

Mounted across the forward portion of trimming head 10 is a level control unit 47. This might be of the general type shown in U.S. Pat. No. 2,716,169. Essentially, such a device is preset in orientation across the trimming head 10 to relate the transverse orientation of the unit 47 to the transverse orientation of the trim blade 14. The control unit 47 operates the cylinder assembly 30 at the side of frame 21 opposite to string line 41.

When unit 47 is mounted parallel to the lower edge of the trim blade 14, the mercury switches or other leveling devices (such as a pendulum) will always seek this same level position and will therefore operate the cylinder assembly 30 to maintain the trimming head 10 at a horizontal condition. In such an instance, the cylinder assemblies 30 at both sides of the apparatus will make identical corrections as required for grade control.

When a transverse inclination is desired across the graded surface, one or the other end of the unit 47 is lifted or lowered with respect to the remaining end, so that unit 47 is inclined relative to the lower edge of the trim blade 14. This is illustrated in FIG. 10. Adjustment is available by means of an adjustable bracket 48 at one end of the level control unit 47, controlled by a hand wheel 50. A suitable screw adjustment might be utilized in this bracket 48 (FIG. 12). Since unit 47 will continually seek a level position itself, one or the other side of the trimming head 10 will be lowered or raised to maintain the preset transverse inclination. Thus, the trimming head 10 is automatically steered, held to grade and maintained at a preset transverse orientation by devices controlled from the single string line 41.

Claims

Having thus described my invention, I claim:

1. In combination with a transverse trimming head for producing a trimming cut from a pavement base while moving forwardly along a longitudinal path wherein said trimming head comprises:

a transverse forwardly and downwardly open housing having an upright rear wall and spaced upright side walls;

a transverse shaft rotatably journalled to the housing side walls about a first transverse axis;

a plurality of soil engaging elements projecting outwardly of the shaft and spaced along the width thereof; and

a trim blade mounted to the rear wall;

the improvement in a mobile supporting unit comprising:

a rigid frame connected to said trimming head as an operative unit and extending rearwardly therefrom;

first and second transversely spaced ground engaging drive units at the respective sides of the rigid frame, each of said drive units being located rearwardly of the trimming head and within the effective operating width thereof;

a transverse axle assembly mounted to said rigid frame, said axle having its respective ends pivotally journalled by said drive units about a second transverse axis rearward of said first transverse axis;

said axle assembly being pivotally mounted to the frame at its center about a longitudinal axis extending along the center line between the drive units; and

suspension means located intermediate said second transverse axis and the trimming head operatively connected between the rigid frame and said drive units for selectively positioning said drive units about said second transverse axis with respect to the rigid frame.

2. An apparatus as set out in claim 1 wherein said ground-engaging drive units comprise individually driven crawler track assemblies in parallel longitudinal positions at the respective sides of the rigid frame;

said suspension means comprising upright hydraulic cylinder assemblies at the respective sides of the rigid frame, each cylinder assembly being connected between the rigid frame and the respective crawler track assembly associated therewith.

3. In a grade trimming apparatus:

a transverse trimming head having rotating teeth extending across the width thereof and a final trim blade immediately rearward of the teeth;

a rigid main frame;

support means for mounting the trimming head to said main frame at a location wherein the trimming head extends across the front end of said main frame;

a pair of transversely spaced ground-engaging drive units mounted respectively alongside the main frame rearward of the trimming head and located within the width of the trimming head;

a transverse main axle having the respective ends thereof pivotally connected to the drive units about a common transverse axis;

means pivotally connecting the axle and said main frame about a longitudinal axis located centrally between the drive units; and

independently operable suspension means connected between the main frame and the respective drive units for selectively positioning the main frame about said transverse axis and said longitudinal axis relative to the guide units;

said support means comprising:

a pivotal connection between the main frame and the trimming head about a second transverse axis forward of and parallel to the first-named transverse axis; and

selectively adjustable holding means operatively connected between the main frame and said trimming head at locations spaced radially from said second transverse axis.