US3041946A

US3041946A - Scratch coat leveling attachment

Info

Publication number: US3041946A
Application number: US806132A
Authority: US
Inventors: Jerry G Watters
Original assignee: Iowa Manufacturing Company of Cedar Rapids
Current assignee: Cedarapids Inc
Priority date: 1959-04-13
Filing date: 1959-04-13
Publication date: 1962-07-03
Anticipated expiration: 1979-07-03

Description

J. G. WATTERS 3,041,946

SCRATCH COAT LEVELING ATTACHMENT July 3, 1962 Filed April 15, 1959 2 Sheets-Sheet 1 INVENTOR.

Jamey G M ATTEES A rrozxvs July 3, 1962 J. G. WATTERS 3,041,946

SCRATCH COAT LEVELING ATTACHMENT 2 Sheets-Sheet 2 Filed April 13, 1959 INVENTOR. (lower 6. )Marrnay i wx f.

A r roams-y FIG 2 United States Patent @fifice 7 3,0413% Patented July 3, 1962 3,041,946 SCRATCH COAT LEVELING ATTACHlVIENT Jerry G. Watters, Cedar Rapids, Iowa, assignor to Iowa Manufacturing Company of Cedar Rapids, Cedar Rapids, Iowa, a corporation of Iowa Filed Apr. 13, 1959, Ser. No. 806,132 1 Claim. (Cl. 94-46) The present invention pertains to bituminous paving machines and more particularly to a leveling attachment for such machines.

Paving machines for laying bituminous road surfaces are well known in the art and in wide use. The present invention is designed for that type of machine in which the screed is trailed from the rear ends of two screed arms, which extend rearward on each side of the ma chine from pivots at their forward ends to the machine proper, so that substantially the entire weight of the screed rests upon the bituminous mat.

When such a machine is used to construct an entirely new road, the new mat is applied to a road bed which has been graded beforehand so that it is relatively free of bumps, depressions and other irregularities. When the machine is used, however, to resurface old concrete or other paving, the leveling or scratch coat is applied to a surface which is usually rough owing to wear, weather and other causes. No matter how carefully the paving machine may be designed, bumps and irregularities in the old surface will nevertheless cause a certain amount of vertical movement of the forward pivot points of the screed arms which in turn will cause the screed to impress a waviness to the scratch coat.

The present invention is designed to minimize the effect of such bumps and irregularities upon the screed so that these irregularities will not be transmitted to the scratch coat. For this purpose a pair of rigid, rearward extensions, removably secured to the screed arms, is employed, and across their trailing ends is connected :1 sled-like plate which rides directly on the scratch coat itself. These extensions and the plate provide an additional point of suspension for the screed in such a way that the effect of vertical movements of the forward pivot points of the screed arms upon the screed is greatly reduced. In addition, the plate, inasmuch as it trails the screed, tends to smooth out whatever irregularities in the old surface may nevertheless be relayed to the scratch coat. Various means for adjusting the rake and crown of the plate are also provided.

While the present invention is primarily useful when laying the scratch coat upon old paving, yet it can, if desired, be employed when laying the finish coats as well, or even in the construction of an entirely new road upon a prepared road bed, although in such cases it is usually not necessary.

Accordingly, the primary object of the present invention is the provision of a leveling attachment for a paving machine which minimizes vertical deflection of the screed as the paver passes over a rough surface.

An additional object of the present invention is to provide a paving machine screed leveling attachment incorporating rearward extensions of the screed arms and a supporting and leveling surface at the rear of the latter and engaging the new mat surface.

Another object of the present invention is the provision in a paving machine leveling attachment of a plate engaging the new mat surface rearward of the screed.

A further object of the present invention is to provide means in a leveling plate attachment for a paving machine to adjust the plate relative to the screed and to the new mat surface.

Other and further objects, features and advantages will be apparent from the description of the preferred form of the invention which follows, read in connection with the accompanying drawings, in which:

FIGURE 1 is a plan view of a paving machine with the leveling device attached thereto in operative position;

FIGURE 2 is a side elevation of a paving machine with the leveling device attached thereto in operative position; and FIGURE 3 is a perspective view of a portion of the leveling device.

In order to facilitate understanding of the invention reference is made to the improvement thereof shown in the accompanying drawings and detailed descriptive language employed. It will, nevertheless, be understood that no limitation of the invention is thereby intended and that various changes and alterations are contemplated such as would ordinarily occur to one skilled in the art to which the invention relates.

Referring now to the drawings, 10 designates generally a bituminous paving machine of a well-known type provided on each side with crawlers 11 driven by sprockets 12. Bogies 13 bear against crawlers 11 in the usual manner. The direction of movement of paver 10 when engaged in paving is indicated by arrows adjacent FIG- URES 1 and 2. Accordingly, the terms forward, rearward," trailing and the like are used hereafter with reference to such direction of movement. Screed arms 14 are pivoted at their forward ends at points 15, between sprockets 12, to frame 16 of the paving machine, and frame 16 in turn is carried in the usual manner on the crawler and sprocket assembly. Screed 17 is positioned in the customary manner between the rear ends of screed arms 14, and the inclination of screed 17 relative to the old road surface 18, by which the thickness of the mat 19 laid thereon is controlled, is adjusted by hand wheels and screws 20.

Screed arm extensions 30 extend rearwardly of screed arms 14- and are rigidly and removably attached to the rear ends of the latter in overlapping relation by clamp plates and bolts 31 or equivalent means. Extensions 30 are provided with connecting brace 32 between and adjacent the rear ends thereof. Forward of brace 32 two pairs of vertical hinge plates 33 are secured opposite one another on each extension 30 and extend downwardly therefrom. Adjusting arms 34 are pivoted at their forward ends between respective pairs of hinge plates 33 by any suitable means, such as hinge pins 35, so that arms 34 are freely movable vertically thereabout. A second connecting brace 36 is secured between the rear ends of arms 34 and hand wheels and screws 37 are threaded vertically through the rear ends of extensions 30 with their lower ends suitably secured to arms 34- so that rotation of screws 37 adjusts the: angle of arms 34 relative to extensions 30. Spaced along brace 32 and secured thereto are screw jacks 38, to the lower end of which are attached casters 39. By turning handles 40 casters 3? can be lowered to or raised from contact with road surface 18 for transporting the leveling device when not in use.

The leveling sub-assembly comprises a leveling plate 50 having a smooth lower surface and upturned forward and trailing edges 51. Spaced inwardly from the ends of plate 5% and secured to the top surface thereof are mounting blocks 52, to the tops of which in turn are fastened U-brackets 53. The latter are adapted to receive the lower ends of two pairs of vertical hinge plates 54 rigidly secured at their upper ends to the trailing ends of arms 34. Hinge plates 54 are pivotally secured to brackets 53 by hinge pins 55 so that plate 50 is thereby hinged about a transverse axis with respect to arms 34. Turnbuckles 56 are provided between the forward ends of blocks 52 and the rear ends of arms 34 to adjust the position of plate 50 about hinge pins 55 with respect to the mat or scratch coat 19 laid by screed 17.

A crowning mechanism is incorporated by providing keyhole notches 60 in edges 51 midway between the ends of plate 59 to permit the latter to be flexed about the axis extending between notches 60. At each side of the aforesaid axis and longitudinal of plate 50 are adjusting levers 61 hingedly secured to plate 50 through U-brackets 62 and links 63. Levers 61 are provided along the upper portions adjacent their inner ends with U-brackets 64 between which is mounted turnbuckle 65. The construc tion, purpose and operation of the crowning mechanism is more fully shown and described in U.S. Patent 2,914,994.

T use the device of the present invention, extensions 30 are secured to screed arms 14 by clamp plates and bolts 31. Screed 17 is then adjusted in the usual manner by hand wheels 20 until a scratch coat 19 of proper depth is laid thereby. Paver is then continued forward until plate 56 engages the new mat 19. At this point, casters 40 are withdrawn, by turning handle 4%, from any contact with road 18 and hand wheels 37 and turnbuckles 56 are adjusted so that plate 50 bears squarely and evenly upon mat 19. Paver 16 is then moved ahead to lay the remainder of mat or scratch coat 19.

It will readily be understood that, despite the fact that pivot points of screed arms 1 are positioned between sprockets 12 on each side of paver 1t), bumps and dips in the old road is contacted by crawlers 11 will nevertheless cause a certain amount of vertical deflection of pivot points 15 (see FIGURE 2). Plate 50, however, aifords an additional point of suspension for screed 17 and tends therefore to minimize the effect of vertical deflections of pivot points 15 thereupon and thus also upon mat 19 laid thereby Plate 50 also acts to smooth out any waviness, which, though small, may nevertheless be imparted to the mat by vertical movements of pivots 15. However, such waviness is usually so small that it may be disregarded, and for this reason the area of the lower surface of plate 50 need be only large enough to provide a good load distribution upon the scratch coat or mat 19. Consequently, plate Stir in practice is often shorter than screed 17, to provide for which extensions 30 are convergingly angled from the ends of screed arms 14 to points just forward of hinge plates 33 (see FIGURE 1).

It will also be readily understood that the longer extensions 39 are, the more they will minimize the effect of any unevenness of the old road surface 18 upon screed 17. In practice, it has been found sufficient for most purposes if the distance between pivot points 15 and leveling plate 50 is about twice that from pivot points 15 to screed 17. Hand wheels 37 and turnbuckles 56 permit adjustment of plate 50 relative to screed surface 17 so that no matter what may be the depth of the mat or scratch coat 19 being applied, plate 50 can nevertheless be adjusted to ride evenly thereon. If a crown is i being imported by screed 17 to mat 19, adjustment of turnbuckle 65 will permit plate to be flexed or bowed about the axis between notches to conform to the crown of the mat.

When paver 10 is to be transported with the leveling device attached, casters 39 are lowered by turning handles 4% so that plate 50 is prevented from striking the ground owing to pitching movements of frame 16. Removing clamp plates and bolts 31 quickly and easily detaches the device and permits paver 16% to pave other surfaces not requiring the leveling attachment.

I claim:

In a paving machine of the kind described, including a pair of laterally spaced screed arms pivoted at their forward ends to the side of the machine for vertical movement relative thereto, a screed assembly supported by said screed arms and having a paving material applying under surface extending transversely of said screed arms, adjustable means between the trailing ends of said screed arms and the trailing end of said screed in order to alter the fore and aft inclination of said surface with respect to the roadway thereby also causing alteration of the elevation of said screed arms during operation of said machine, the combination therewith of scratch coat leveling apparatus, said apparatus comprising: a pair of laterally spaced leveling arms rigidly secured at their forward ends to the trailing ends of said screed arms to form rigid rearward extensions thereof; a pair of laterally spaced adjusting arms pivoted at their forward ends adjacent the rear ends of said leveling arms for vertical movement relative to said leveling arms, said adjusting arms being relatively short compared to said leveling arms and extending rearwardly from said pivots to just beyond the rearward ends of said leveling arms; a screed leveling plate assembly carried by said adjusting arms and having a surface adapted to slidably engage the surface of the paving applied by said screed assembly and to support the latter, said surface extending transversely of said adjusting arms and said plate assembly being pivoted about a transverse horizontal axis between and adjacent the rearward ends of said adjusting arms; and means to permit independent and fine adjustment of said plate assembly relative both to said screed assembly and leveling arms in order to compensate for said alterations in the elevation of said screed and leveling arms, said means including arm adjusting means operative between each of said leveling arm ends and their respective adjusting arms for adjustably positioning said adjusting arms and plate assembly relative to said leveling arms, and plate assembly adjusting means for adjustably positioning said plate assembly about said axis relative to said adiusting arms.

References Cited in the file of this patent UNITED STATES PATENTS 2.847,917 I-leer et a1. Aug. 19, 1958 2,890,632 Madison et a1. June 16, 1959 2,951,426 Pollitz Sept. 6, 1960