Machine and method for finegrading roadbedsDownload PDF
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- US1990362A US1990362A US58054131A US1990362A US 1990362 A US1990362 A US 1990362A US 58054131 A US58054131 A US 58054131A US 1990362 A US1990362 A US 1990362A
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- E—FIXED CONSTRUCTIONS
- E02—HYDRAULIC ENGINEERING; FOUNDATIONS; SOIL SHIFTING
- E02F—DREDGING; SOIL-SHIFTING
- E02F3/00—Dredgers; Soil-shifting machines
- E02F3/04—Dredgers; Soil-shifting machines mechanically-driven
- E02F3/76—Graders, bulldozers, or the like with scraper plates or ploughshare-like elements; Levelling scarifying devices
- E02F3/78—Graders, bulldozers, or the like with scraper plates or ploughshare-like elements; Levelling scarifying devices with rotating digging elements
Feb. 5, .1935. R DfBAKER 1,990,362.
MACHINE AND METHOD FOR FINE GRADING .ROADBEDS Filed Dec. 12, 1951 11 Sheets-Sheet 1 Feb. 5, 1935. R. D. BAKER MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1951 ll Sheets-Sheet 2 Feb. 5, 1935. R. D. BAKER 1,990,362
MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1931 1; Sheets-Sheet s Feb. 5, 1935. R. D. BAKER MACHINE AND METHOD FOR FINE GRADING ROADBEDS u 0 L m I G mm Mai iga Jeri o o 0m 0 e o o o v.3 w w w WA 5% ii v 2; $1: w] H o M & Mg 4 mm a g 2 mmmfii Q 1i-|:|1-| mu w ma a Q Nb Nb L W ||ll|. Q U Q Feb. 5, 1935.
R. D. BAKER MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1931 11 She etS-Sheet s Feb. 5, 1935. R. D. BAKER I MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1931 11 Sheets-Sheet 6 III VMHZ I I,
Feb. 5, 1935. R. o. BAKER- MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1931 ll Shets-Sheet 7 Feb, 5, 1935. R BAKER 1,990,362
MACHINE AND METHOD FOR FINE GRADING RO'ADBEDS Filed Dec. 12. 1931 ll Sheets-Sheet 8 Infleniar Feb. s, 1935. R. D. BAKER 1,990,362
MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1931 11 Sheets-Sheet 9 w v i R. D. BAKER MACHINE AND METHOD FOR FINE GRADING ROADBEDS Feb. 5, 1935.
Filed Dec. 12, 1931 ll Sheets-Sheet 10 a h h M 0.
Feb. 5, 1935. R. D. BAKER 1,990,362
MACHINE AND METHOD FOR FINE GRADING ROADBEDS Filed Dec. 12, 1931' 11, Sheets-Sheet 11 M N @WHI Ww w Patented Feb. 5, 1935 -.AND anon son 1 GRADING aonnns Robert D. Baker,
-- ham, Mich.
Application December 12, 1931, Serial No. 580,541
11 Claims. (Cl. 37-108) This invention relates to improvements in machines for fine-grading pavement strips between the side-forms or fails bordering the area to be paved and has for its several objects:
the rapidity of operation of the said cutting blades with respect to the number ofJcutting strokes thereof per foot of travel of the machine along the pavement may be varied in accordance with the depth and character of the earth to be removed from the pavement strip.
Second-To provide a machine of the type specified which is equipped with mechanism for 7 completely removing earth loosened by the said cutting blades from the pavement'strip so as to leave the latter entirely free from surplus earth behind the machine, thereby eliminating all hand labor in clearing. the fine-grade preparatory to deposit of paving material upon the same. Third-To provide a machine of the character above indicated wherein a mound of loose earth is maintained in advance of the earth cutting blades for automatically filling hollows encountered in travel of the machine along the paving strip.
Eourth.To equip the said machine with mechanism for limiting the height of the said mound of loose earth disposedin front of the cutting blades by casting such earth as may accumulate above a predetermined level over the rear edges of said cutters.
Fifth-to provide. a machine of the type described with cutter-blades and conveying mechanism, both of the general character above indicated, which are appreciably spaced from each other inorder that the loose earth cast by the mechanism referred to in the next preceding after passage of the conveying mechanism over thesame and for disposing all surplus loose earth not compacted by said means again in the path of said conveying mechanism for removal by the latter. I
' Seventh-To provide a machine of the type indicated wherein the cutter-blades, the said means for casting the earth at the crest of the mound back of said blades, and the conveying mechanism cooperate with each other to break upand finely divide the earth loosened by the cutter-blades and wherein th'ecutter-blades may be adjusted to cut away earthto a plane parallel with and lower than the ultimate fine-grade plane and wherein the conveying means is so disposed as to remove loosened earth to a level or plane parallel with but higher than the ultimate fine-grade plane for the purpose of prosuperficial layer is of uniform compactness or density and wherein the final compacting means levels, smooths, and compacts loose earth to the exact level of the ultimate fine-grade plane.
Eighth.-To provide a machine of the character indicated, which is equipped with cablewindup mechanism for propelling the machine along the pavement strip and wherein said mechanism includes means for varying the speed of travel of the machine and for reversing the. windup mechanism for purposes of permitting the machine-to be propelled reversely, and for paying out cable for anchorage at farther advanced points preparatory to further travel of the machine.
Ninth-To equip a machine of the character defined with means for preventing breakage or distortion of the cutting-blades and the mechanism for actuating the same in the event that any one of said cutting-blades encounters an obstruction, such as a boulder or tree-root embedded in the paving strip in the path of said blade.
' Tenth-To provide a machine of the character set forth, which is amply strong enough to perform its intended functions in soil of practically every character that may be encountered and which is also of sumciently light weight to enable it to be removed easily from the side forms on which it is supported and disposed at one side of the paving strip or to be transported from place to place.
The invention also comprehends a novel method of fine-grading pavement strips for the purpose of providing a fine-grade of uniform density with respect to a thin, superficial earth- 'viding an ultimate fine-grade plane whereof the cushion immediately below the'paving material and supporting the latter.
Other objects and advantages of the invention will be hereinafter pointed out in or will be apparent from the following specification.
A suitable embodiment of the invention is illustrated in the accompanying drawings,
Figs. 1 and 1a together constitute a complete plan view of a machine constructed in accordance with the invention.
Fig. 2 is a side elevation of the same.
Fig. 3 is a rear elevation of the same.
Fig. 4 is a front elevation of the same.
Figs. 5 and 6'are vertical transverse sectional views of the machine on the lines 5-5 and 6-43, respectively, of Fig. 1a.
Fig. l is a vertical longitudinal section of the machine on the line 7-7 of Figs. 1 and 1a.
Fig. 8 is a fragmentary plan section of the machine on the line 8-3 of Fig. 4.
Fig. 9 is a diagrammatic view illustrating the gearing between the engine and the operating mechanisms of the machine.
Fig. 10 is a fragmentary detail plan section of the machine on the line 10-10 of Fig. 12.
Fig. 11 is a detail perspective .view showing an axle of one of the traction wheels of the machine.
Fig. 12 is a fragmentary detail vertical sectional view on the line 12-12 of Fig. 2.
Fig. '13 is a perspective view showing one of the plates of an element of the conveying mechanism of the machine.
Fig. 14 is a perspective view of a bucket of another element of the conveying mechanism ofthe machine.
Fig. 15 is a fragmentary detail vertical sectional view, on an enlarged scale, on the line 15-15 of Fig. 1.
Figs. 16 and 1'7 are detail perspective views showing component parts of the earth compactingand smoothing means at the rear end of the machine.
Figs. 18 and 19 are fragmentary vertical transverse sectional views on the line 18-18 and 19-19, respectively, of Fig. 1a, the conveyor chains being omitted.
Figs. 20 and 21 are detail fragmentary sectional perspective views showing certain details of construction of the conveyor chain supporting and guidingmeans.
Fig. 22 is a fragmentary detail vertical section on the line 22-22 of Fig. 18, showing a strike-off device disposed at the side of the machine opposite the elevator.
'Fig. 23 is a fragmentary detail plan section of the same on the line'2323 of Fig. 22.
Fig. 24 is a :1' longitudinal sectional view of a roadway or pavement strip to be fine-graded, including parts of the machine of the present invention and is illustrative of the method of fine-grading a pavement strip as comprehended within the present invention.
The machine comprises a suitable frame composed of conventional structural steel elements, consisting mainly of a series of main transverse channel bars 1, 2, and 3, and pairs of longitudinal channel bars 4 and 5 disposed upon the end,
of the frame. Each bracket '1 is provided with a' vertical slot 8 in which the flat end portion of an axle 9 (Fig. 11) of a'wheel 6 is slidable. In the top wall of Y each of said slots there is an opening,
devoid of thread, to receive a screw-shaft 1o having a threaded engagement with a nut 11 disposed in the upper enlarged portion of the slot, each screw-shaft bearing at its lower end upon an end portion of an axle 9, said screw-shafts being rotatable to effect raising and lowering of the frame relatively to the side-forms.
An internal combustion engine 12 is mounted upon the frame 01108111888 at one side thereof and-substantially midway between the front and rear ends of the said frame. posed at the side of the frame opposite that on which elevator bucket mechanism is disposed. as hereinafter described, for purposes of balance or substantially uniform distribution of load in order that each of the side-forms may carry substantially one-half the weight of the machine. This balanced relation of opposite sides of the machine is important in the handling of the machine, as will hereinafter appear.
The engine shaft enters a conventional changespeed gear box 13 and is tha geared to a variablespeed countershaft 14. By reference toFig. 9, the gearing between the shaft 14 and the operating mechanisms of the machine will be fore readily understood than by reference to other figures.
Said shaft 14 is geared to shaft 15 by means of sprocket'wheels and chains 16. The shaft 15 is equipped with pairs of eccentrics 1'1 for reciprocating the cutter-blades'of the machine and is, in turn, geared to a shaft 18 by means of the spur gears 19 and 20, and is also geared to a shaft 21 by means of the intermeshing spur gears 22 and 23. The shaft 21 is geared to a shaft 24, which drives the earth conveying mechanism, by means of the bevel gears 25 and 26.
The spur-gear wheel 20 is rotatable on the shaft 18 and drives the same through the intermediacy of a conventional reversing gear mechanism 2'1 controlled by the lever 28. Said shaft 18 is geared, by means of the sprocket wheels. and chains 29 and 30, respectively, to the shafts 31 and 32 which are, in turn, geared to the cable wind-up drums 33 for propelling the machine.
-Said shafts 31 and 32 constitute the high-speed shafts of speed reduction gear sets, such as the planetary type, disposed in the casings 34 and 35,
for driving the low-speed shafts 36 and 37. The
sprocket wheels on the shafts 31 and 32 are rotatable relatively to the said shafts and are caused to drive the latter through the intermediacy of the friction clutches 38 and 39 which are suitably manually controlled.
The said shafts 36 and 37 are equipped with pairs of spur-gear wheels 40 and d1, of different pitch diameters, which are slidable on said shafts to any one of three different positions by means of the hand-levers 42. In Fig. 9 said pairs of gear The engine is dis-- wheels 40.and 41 are shown as disposed in neutral position. By sliding these pairs of gears in oppos'ite directions from this neutral position, one wheel of each pair will mesh with one of the spurgear wheels 43 or 44, rigid with the drums 33, to drive said drums at either of two selective speeds, in a well-known manner.
The cables 45 are secured, at one end each, to the drums 33 and, at their other ends, are adapted to be secured to the side forms at points in advance of said drums which are disposed at the front end portions of the frame members 4 and 5. Said cables are trained under the sheaves 46 rotatable and slidable on axles 4'7 mounted in the extreme front end portions'of the said frame members 4 and 5 and serve to cause said cables to wind themselves helically upon thedrums during rotation thereof.
In Figs. 1 and 1a, 2, 3, 4, and 5, the positions of the several shafts shown in Fig. 9 are different from their positions as illustrated in Fig. 9 from out varying the speed of rotation of the shaft 15 or interrupting its rotation.
Earth cutting mechanism Referring now to Figs. 5, 8, and 15, it will be noted that the bearings for the shaft 15 are mounted on the channel bar 2 and also, that each of the eccentrics 1'7 carries an eccentric strap 48 rigid with a reciprocable plunger 49. The said eccentrics 1'7 and plungers 49 are arranged in pairs; that each pair of said plungers 49 carries a cutting or shovel plate 50; and that the several pairs of eccentrics are so disposed relatively to each other that no more than two of said shovel blades or cutters 50 are simultaneously disposed at the forward limits of their movement. In the instance illustrated, there are nine of said members 50. Consequently, less than twenty-five per cent of the total number thereof are penetrating earth at any time during a revolution of the shaft 15.
Mounted upon the rear face of the front channel bar 1 are bearings 51 in which the trunnions of sleeves 52 are journalled. Threaded links 53 pass through said sleeves and are held rigid therewith by means of the nuts 54. At their lower ends, the said links 53 are pivotally connected with the heads of bolt elements 55, the shanks of which are engaged in projections 56 of the plungers 49, the forward ends of the latter being thus suspended from the rocking sleeves 52. The said cutters or shovel plates 50 are removably mounted on the said plungers 49 and have cutting edges which project appreciably forward of the pivotal axes of the connections .of the links 53 with the projections 56 of the plungers 49.
The shaft-15 rotates clockwise when viewed as in Fig. 15 and thus causes the cutting edges of the members 50 to move slightly upwardly throughout their forward or cutting strokes as will be obvious. This compound movement of said 'cutting edges is very effective in that an undercutting and slight lifting of the superficial earth layer occurs simultaneously and effects breaking up of said layer into small lumps or pieces or to a relatively finely divided state.
The threadsof the links 53 and the nuts 54 thereon enable the positions of the members'50 to be adjusted relatively to each other to cause the cutting edges of all of the members 50 to be disposed in a plane substantially parallel with the predetermined fine-grade plane. The position of said cutting edges relatively to said fine-grade travelof the machine while providing loose'earth to fill hollows encountered in such travel. Said hollows are usually of limited area and are found in spots between the side forms as they must necessarily be filled at the sides of the pavement strip before the side forms'are set. Thus, as the cutter blades 50 pass over said hollows or voids, the earth of said mound will drop into and fill the same at least in part.
To limit the height of said earth mound, I provide a rocking bar 57 which is mounted upon the lower ends of levers 58 which are somewhat Z-shaped and are provided between their ends with projections 59 secured to a rock-shaft .60
journalled in hearings on the channel bar 2 above the shaft 15.
Referring again to Fig.9,it will be noted that the shafts 31 and 32 are provided at their inner ends with cranks 61 which, as shown in Fig. 6, are connected by means of connecting rods 62 with the upper extremities of the levers 58.
The bar 57 projects earth from the top of said mound over the rear edges of the cutter or shovel blades 50 so that it then rests upon the surface or grade cut by said blades 50. This bar 5'7 also serves to break up lumps of earth occurring in said mound.
Earth conveying mechanism wheel 64 on a countershaft 65 journaled in bearings carried by a bracket mounted on the said channel bar 3. Thesaid shaft 65 is geared by means of sprocket chain gearing 66 to a shaft 67 journalled in berings at the upper ends of a pair of plates or brackets 68 secured to the channel bars 2 and 3 and extending angularly to project appreciably outwardly from the extreme ends of said last-named channel bars at the side of the frame opposite to that upon which the engine 12 is mounted.
The shaft 24 is equipped with a pair of sprocket wheels 69 over which a pair of sprocket chains '70 are trained. The latter are also trained over a pair of sprocket wheels '71 on a shaft 72 journalled in bearings mounted on the channel bars 2 and 3 at the side of the machine upon which the en'- gine 12 is mounted. Said chains '70 are also trained under pairs of idle sprocket wheels '73 and 74 (Fig. 7) mounted upon idle shafts '75 and '76,.
The sprocket chains 70 are equlpp with conveyor blades or plates '17, shown in detail in Fig.
13. Each of the said plates is provided at its ends with flanges 78 to which plates Z9, integral with and extending perpendicularly to links of the chains '70, are suitably secured.
Each plate '17 is also equipped with removable teeth or projections 80 along its lower edge.
The shaft 67 is equipped with a pair of sprocket wheels 81 over which the sprocket chains 82 carrying elevator buckets 83 and 84 are trained. The said sprocket chains 82 are also trained over sprocket wheels 85 on an idle shaft 86 which is so disposed as to cause the buckets 83 and 84 to take up earth delivered into their'path by the plates '7'! of the conveyor. The said buckets 83 and 84 are of greater width than the plates 77 and are disposed between the chains 82, the latter being spaced appreciably farther apart than the chains '70. The chains 70 and 82 are also trained over idle sprocket wheels 8'! and 88, respectively. The shafts 67 and 86, sprocket wheels 81 and 85, sprocket chains 82 and buckets 83 and 84, oocupy substantially the full width of the space between the channel bars 2 and 8, the plates or brackets 68 being spaced apart co-incidentally with the said channel bars 2 and 3.
The lower portions of the chains '70 must follow a path of travel parallel with the predetermined flne-grade plane and this path of travel must be adjustable to coincide with the various fine-grade planes with respect to height of crown,
- specified by the highway department under whose supervision the work is being done.
As the paths of travel of the respective chains 70 are spaced appreciably less distance apart than the channel bars 2 and 3, I provide Z-shaped, vertically disposed brackets 89 on the inner opposed faces of the said channel bar 3. To the inner opposed flanges of these brackets 89, the plates 90 are secured (see Figs. 18 to 20, inclusive) by means of large stove bolts 91 engaging in vertical slots 92 in said flanges.
Angle irons 93 define the plane of travel of the lower edges of the plates '17 and are secured to the said plates 90 of the channel bar-8 by means of bolts 94, said angle irons being flexed to curvature corresponding with and substantially parallel or concentric with the crown of the predetermined fine-grade plane by adjusting said plates 90. The chains '10 rest upon flanges of the said angle irons 93 which span substantially the entire space between the sprocket wheels over which the chains 70 are trained. 4
As shown in Figs. 6 and 19, the angle iron 93 which'is supported by the channel bar 2, is secured to the depending flange of the angle iron 93*, the other flange of which is secured to the lower face of the lower flange of said channel bar 2. The
vertical flange of the last-named angle iron 93 is provided with vertical slots 98 at intervals which permit the reception of the shanks of securing bolts which permit flexing and other adjustment of the said channel bar. The rear channel bar 93 is flexed and adjusted by vertically adjusting the plates 90.
The bearings for the shafts '72 and 87 are slid.- able in suitable guides 96 and are adjusted there-- in by means of the set-screws 97 in a well-known manner to take up or allow slack in said chains 70 as desired.
The scraper plates '17 and elevator buckets 83 are equally spaced apart on' their respective sprocket chains and the latter travel at the same speed, said plates 77 and buckets 88 being so disposed that each travels partly in the path of travel of the other but in alternate or staggered relation so as not to interfere with each other (Fig. 'l).
The said buckets 83 are provided with straight earth-penetrating edges to take up looseearth. In the instance illustrated, there are seven buckets 83 and two buckets 84 which are interposed between buckets 83' at two pointswhich are substantially equidistant from each other.
The said buckets 84 are equipped with removable teeth similarly to the plates 77 to adapt them to more readily take up' large lumps of earth than the straight edges-of the buckets 83. These additional buckets 84 may be termed "clearing buckets, which I have found to be. very de-.
sirable in practice.
The path of travel of the earth-penetrating edges of the buckets 83 and 84 is suchthat they will define an arc tangential to the plane of the I path of travel of the lower edges of the plates 7'7 which, obviously, carry the loose earth into the path of the said buckets. The said buckets 83 and 84'discharge the earth upon the inclined apron from which said earth is discharged by gravity.
Earth compacting and smoothing means The plates 99 and 100 (Figs. 16 and. 17) are secured to the plates 90 by means of bolts. The plates 99 are also provided with recesses 102 to accommodate the lower ends of the 2-bit! brackets 89. In order to accommodate the rear bearin for the shaft '72, the plate 100 is set back rearwardly of the plates 99 and is provided at one side with a flange 101, which abuts against the adjacent side edge of the plate 99.
The lower fiat faces of the said shoes 98 are adapted to be disposed in the predetermined finegrade plane as accurately as possible and with sufficient accuracy to meet the requirements of all'fine-grade specifications known to me, the plates 99 and 100 being vertically adjustable relatively to the plates 90 for effecting such disposition or the said shoes. The latter also function as strike-01f devices which move surplus earth, not compacted and smoothed thereby, forward for eventual removal by the conveyor mechanism, the latter preventing accumulation of more than a limited amount of earth in front of said shoes 98 'and plates 99 and 100.
The plate 100 and shoe 98 at the elevator side of the machine carry a sliding shoe 103 which rides in part upon said shoe 98 and is provided with guide slots 104 in which the shanks of bolts 105 engage, said sliding shoe being yleldingly held in contact with the inner face of the side form by means of the compression spring 106.
On the engine side of the machine (Fig. 7), I provide a vertical plate ,10'! which is secured to the channel bar 3 by means of a pivot element passing through one of several horizontal slots 108 in said plate for vertical adjustment thereof. A brace 109 connects the said plate 107 with a frame member.
1,990,362 A tension spring 110 engaged with said plate and with a bracket at the end of the channel bar 3 -holds said plate in yielding contact with the inner face of the other of said side forms and causes surplus loose earth accumulating in its path to become heaped up until a part thereof lies in the path of the plates '7'? and is removed by the latter.
The said plate 107 and the sliding shoe 103 permit a slight lateral motion of the machine in travel without displacing the side-forms, and also prevent any loose earth from remaining disposed upon the fine-grade formed by the machine and thus obviates the hand-labor necessary to remove such excess loose earth before deposit of paving material upon the said fine-grade.
Operation of the machine The side-forms bordering a pavement strip vary in height to accord, generally, with the thickness of the ultimate pavement slab, especially along the side edges of the latter. The bases of the said side-forms are disposed in the plane of the side edges-of the predetermined fine-grade upon which the paving material is subsequently deposited. Consequently, the predetermined fine-grade plane is parallel with the crowns or tread surfaces of the side longitudinally of the pavement strip.
In some instances, the predetermined finegrade is flat but in most instances it is slightly convex to afiord a crown which is usually coincident with the crown of the finished pavement.
The several shovel blades may be relatively positioned so that their cutting edges are disposed as accurately as possible to the exact contour of the predetermined fine-grade plane transversely of the pavement strip, this being accomplished by manipulation of the nuts 54 on the threaded shanks of the members 53, in an obvious manner. These adjustments may be made either before or after the machine has been mounted on the side-forms, but is preferably done after it is so mounted.
For this purpose, the machine frame is raised, by operating the set or jack-screws 10, until the shovel blades are disposed above the level of the earth disposed between the side-forms.
By then reversing the rotation of the jackscrews 10, the machine frame and shovel blades are lowered until the cutting edges thereof are disposed low enough to remove a part or all of the superficial earth layer overlying the predetermined fine-grade plane. Unless this earth layer is very deep as, for example, six inches or more, or unless the said earth layer presents other conditions rendering several cuts most advisable, the machine frame will be lowered until the shovel blade edges are disposed in or slightlybelow the predetermined fine-grade plane.
During the operation of lowering the machine, it is preferable that the engine 12 be running so that the shovel blades will, so to speak, dig themselves into the earth to the desired depth though, preferably, a transverse trench is dug by hand to approximately the depth of the predetermined fine-grade plane to receive the shovel blades.
Before the machine is lowered as aforesaid, the shoes 98 and the angle irons 93 are also adjusted so that the bottoms or treads of the said shoes will be disposed in proper relative positions to present a contour coincident with that of the cross-section of the fine-grade plane and likewise so that said bottom faces of said shoes willlie in the predeterminedfine-grade plane when the machine is lowered.
The angle irons 93 will be flexed to an are substantially concentric with the crown of the ultimate fine-grade, unless the latter is to be flat.
These last-mentioned adjustments are very slight and easily effected. When so efiected, the draft-cables are anchored to the side-forms some distance in advance of the machine and the cable windup drums are then, operated to first take up slack in the cables until both are equally taut. To equalize the initial tautness of the cables, the operator manipulates the friction clutches 38 and 39.
During this period, the shovel blades and conveyor mechanisms are also operating at low speed. As soon as the machine begins to move forward on the machine-formed grade, the change-speed gears are shifted to increase the speed of travel of the machine without increasing the speed of the shovel blades and conveyor mechanisms. Generally speaking, the shovel blades and conveyor mechanisms will be operated at low speed while the machine travels at either,
of the speeds determined by the gears 40 to 44 inclusive. This gearing, in the instance illustrated, is such that the machine will progress at the low speed of about three feet per minute, and the higher speed'of about six feet per minute. With the shovel blades and conveyor mechanisms ,running at maximum speed, the travel speed of the machine will be increased to a low speed of about four feet per minute and the higher speed of about eight feet per minute, the speed selected being dependent mainly upon the condition or depth of the superficial earth layer being removed, or upon both these factors.
If the earth layer exceeds an average of about two inches, the last-mentioned lower speed of tra'vel of the machine is preferable in order that the conveyor mechanism and the elevator mechanism may remove the loosened earth as rapidly as it accumulates behind the shovel blades.
If, for example, the distance between the sideforms is twenty-four feet and the earth layer averages two or more inches in depth, the volume of earth to be removed per lineal foot of pavement strip will. be approximately four cubic feet. This volume will vary greatly because of the usually somewhat rolling surface left after completion'of the customary rough-grading of the pavement strip-preceding the fine-grading thereof. .Thus, for every three feet of travel of the machine in one minute, the conveyor mechanism is required to remove an average of twelve cubic feet of earth. Its capacity is fully twice the lastnamed' requirement. But in spots, the earth layer to be removed mayexceed six inches in depth and, in other spots, hollows will occur that require filling in.
When the shovel blades are operated at maximum speed, they approximate one hundred and sixty strokes per minute and thus, if the machine travels three feet per minute, each shovel blade will penetrate the earth in its path a distance chine such as would result from a slower motion sary to clear away excessive accumulations behind the shovel blades.
In instances where the layer of earth to be removed is fairly uniform in thickness or depth and the latter does not at any point exceed a depth which would cause an accumulation of loose earth behind the shovel blades of a volume greater than the conveyor mechanism can remove, and assuming that said earth is of a soft, easily penetrable nature and free from boulders and the like, the speed of travel of the machine may be increased to its maximum and thus in a very-short time provide a fine-grade of sufflcient length to meet the fulldays requirements with respect to the capacity of the paving material mixer or other means employed for progressively depositing the paving material upon the fine-grade.
In order that one operator may easily control the machine, the friction clutches 38 and 39, whichare widely spaced from each other, are rendered operable, each independently of the other, as for the purpose of slewing the machine aroimd curves or back to a properposition in event that one side thereof shall become advanced, as frequently happens in instances of greater resistance to progress at one side of the pavement strip than the other which would cause slippage of the clutch at that side, and are a'no simultaneously operably manipulated by disposing levers controlling said clutches in close proximity to each other.
Thus the lever 138 controlling the friction clutch 38 is suitably pivotally mounted upon a rigid portion of the frame and is connected with the lever 138', which is pivotally secured to the channel bar 1, by means of the rod 111. The said lever 138 is disposed so closely proximate to the lever 139 controlling the clutch 39 as to enable the operator to manipulate both said levers simultaneously or alternately in rapid succession to thus control the direction of travel of the machine and, generally, without appreciably interrupting such travel.
The lever 28 controlling the reversing gear 2'1 may be operated to throw the latter into neutral position to interrupt travel of the machine or relieve strain thereon in the event that such travel shall have been interrupted by an obstruction such asaboulderorlargerootor the likedisposedin the road bed,
The friction clutches 38 and 39 are adjusted to cause the same to slip and thus automatically interrupt travel of the machine, in event that an obstruction is encountered, without distorting or breaking the shovel blade affected or causing a cable to part or otherwise imposing undue strain or stress on the machine.
In the event that the travel of the machine is stopped by a boulder or by extreme resistance offered by the earth being penetrated, it becomes necessary for the operator to throw out the said friction clutches 38 and or the clutch 127, but.
also to reverse the direction of rotation of the cable windup drums to pay out cable equally from both thereof and thus relieve the strain on the shovel-blades and machine frame. Generally this interruption of travel will cause one of the said friction clutches to slip and thus slew the machine to an angular position relatively to the side-forms and render it necessary for the operator to re-adjust the position of the machine after removing the obstruction. The slippage of either of the said friction clutches produces instant noise to apprise the operator who may then throw the reversing mechanism 2"! over to reverse the rotation of the cable drums to relieve said strain.
The machine frame covers a span ranging from a minimum of ten feet to a maximum of twenty-four feet in most instances and the resistance to travel, due to penetration of earth by the shovel-blades, causes the stresses and what may be termed back-pressure" on the shovel blades, to be applied in the direction in which the channel bars 1, 2, and 3 are most flexible and, therefore most likely to bend. Cross-bars or braces are, therefore, provided to connect these channel bars for stiffening purposes but are limited as to number, character, and location by the operating mechanisms and limitation'as to load on the side-forms so that a. type of earth cutting mechanism which minimizes the last-mentioned stresses and pressures without sacrifice of utmost eflicisncy is of vital importance. It is also very obviously necessary to suitably guard against distortions and bredkages due to obstruce tions as above mentioned, suitable speed controls to enable the operator to control the amount of earth removed by the conveyor mechanism without overtaxing the same. The above described mechanisms and controls have been found to meet amply and efficiently all of the requirements and conditions incident to the work to be done by a machine 6f The space between the shovel blades and the conveyor mechanism is" such that if a stone or boulder should beY-removed by the shovel blades and find its-way-into said space, the operator may instantly stop travel of the machine and remove the. said boulder before the latter is engaged by the conveyor mechanism. If, however, such boulder or the like should become en a ed in the and also to provide conveyor mechanism before it is observed by the operator, it may become lodged at the point where the elevator buckets take up the earth and may be tossed about there without being taken up. In that event, it may be necessary or advisable to reverse the direction of travel of the conveyor m and, to this end, the change-speed gear includes a reversing gear operable similarly to that found in automotive vemoles. Such reverse travel is also sometimes desirable to convey earth into a hollow or depression in the pavement strip.
The of fine-grading roadway:
Generally speaking, it is customary to plow and scarify roadways over the area of the pavement strip and road shoulders, remove part of the surplus earth from high portions and fill in hollows and depressions. The plowing and scarifying usually extend to a depth of about six inches below the predetermined fine-grade plane and has for one of its purposes, the location and removal of boulders-roots and other obstructions preparatory to rolling and compacting the road bed to render it of substantially uniform density to an appreciable depth below the predetermined fine-grade plane.
This rough-grading and rolling leaves an appreciable depth of excess earth in the roadway and particularly within the area of the ultimate pavement strip. This excess earth is not uniformly distributed so that in spots it may exceed more than six inches in depth to the predetermined fine-grade plane, in other spots, it may be less than an inch in depth and, in still other spots, the rough-grade surface will dip below the finegrade plane. The last-mentioned spots must be filled in in due course,
After completion of the rough-grade, the trenches or paths to receive the side-forms bordering the pavement strips are prepared, the sideforms set up, and the fine-grading done.- This is required to be quite accurate, because if too little earth is removed from one area of the fine-grade, the pavement slab disposed over this area will be too thin to meet the specified requirements, and,
if too much earth is removed, a waste of paving material occurs. The specifications to be complied with by the contractor are very drastic with respect to penalties for failure to remove sufiicient earth but allow no extra compensation for excess thickness of the finished pavement slab.
Consequently, the contractor finds it best to avoid penalization by removing too much rather than too little earth in preparing the fine-grade and thus, frequently penalizes himself in supplying appreciably more paving material than is required by the specifications.
When it is considered that contracts frequently cover the construction of many miles of pavement by a single contractor and that the average width of the pavement is twenty feet, it will be apparent that the removal of earth to an average depth of one-sixteenth of an inch below the predetermined fine-grade plane involves very costly waste by the contractor as it approximates three hundred and twenty cubic feet per mile.
Hence, an accurate fine-grade is greatly desired by both the contractor and the highway department.
An accurate fine-grade can only be produced most efiiciently and economically under conditions of uniform density and condition of the earth underlying the fine-grade plane. The condition of the earth has reference, mainly, to the absence of boulders, roots, and other hard and unyielding matter and the absence oflumps of earth immediately below or projecting above the fine-grade plane.
The rough-grading of clay, hard-pan, and similar soils is nsufiicient to eliminate the hard lumps and large pebbles or stones up to perhaps four to six inches mean diameter which remain as more or less superficial obstructions to hinder accurate fine-grading.
I am informed, also, that in some localities, the preliminary rough-grading above referred to is not permitted on the theory that the natural density of the earth underlying the fine-grade plane affords a firmer support for the pavement than a plowed, scarified and re-compacted road bed will afford. Soils of this character are very apt to present widely varied characteristics with respect to hardness, presence of gravel and roots, etc. which render cutting thereof to the exact fine-grade plane very difiicult.
The method of the present invention consists, therefore, in primarily cutting down the pavement strip to a level slightly below and substantially parallel withthe predetermined fine-grade plane; leaving the. loose earth deposited upon the surface thus provided; then leveling; then leveling the said loose earthto a plane substantially parallel with but slightly higher than the predetermined fine-grade plane by leaving the most finely divided loose earth upon the said surface and removing coarse earth and surplus finer earth; and then compacting and smoothing the earth still remaining disposed upon said surface to substantially the exact predetermined finegrade plane and, while so smoothing and compacting said earth, also removing all surplusage thereof still remaining in advance of the compacted and smoothed earth.
In this way a fairly thinlayer of compact earth of uniform density immediately underlies the fine-grade and forms a cushion between the pavement slab and the road bed which prevents cracking or rocking of said slab when set by reason of its support upon a very hard and dense point in the road bed and otherwise upon softer and yielding portions. This layer or cushion of earth is also advantageous in providing a uniform absorbent of the excess moisture presented by Portland cement concrete and the like 'and consequently promotes uniform density of the slab of this material.
The above described method may be carried out by hand but is obviously also and most advantageously carried out by the machine of this invention.
In Fig. 24, I have diagrammatically illustrated the manner in which the method of this invention is carried out. In said Fig. 24, the dotted line A indicates the predetermined fine-grade plane. The dotted line B indicates substantially the depth to which the road bed is plowed and scarified in the rough-grading in instances in which such plowing and scarifying is required. The dotted line C indicates the plane of first cut parallel with and below the predetermined fine-grade plane. The dotted line D indicates the plane of the finely divided earth remaining deposited upon the surface indicated by the dotted line C after removal of the remainingearth from said surface.
Obviously, if the nature of the earth is such that the absorption of water from concrete and the weight of the pavement slab or the weight of the latter alone will further depress and compact the thin layer of earth remaining uponthe surface represented by the dotted line C, the compacting'and smoothing of said layer may be in a planevery slightly higher than and parallel with the predetermined fine-grade plane to allow for this further or increased compaction.
From the drawings and the foregoing description, it will be noted that the entire frame of the machine is of no appreciably greater height than is necessary to enable it to ride upon the highest side-forms used plus the height of the channel bars 1, 2, and 3, and the necessary clearance between their lower flanges and the crowns of the side-forms. forms to be ten inches from base to crown and the channel bars 1, 2, and 3 to be nine-inch, then the elevation of the tops of said channel bars above the fine-grade plane will approximate nineteen and one-half inches. This will hold true in instances where the side-forms are of less height because, in such cases, the machine frame is elevated above the side-forms by lowering the supporting wheels thereof.
This low structure is advantageous in that the main frame elements are thus disposed as closely as possible to the plane or planes of the stresses imposed thereon resulting from the resistance to travel occasioned by the earth being penetrated Thus, assuming the highest side- V by the shovel blades and being removed by the partial disassembly thereof.
conveyor mechanism. It is also advantageous in .other respects as, for example, in being bridged for passage of material trucks over the same as pointed out in my Patent No. 1,934,289 patented December 12, 1933, and in applying transporting means to the same as pointed out in my Patent No. 1,940,659 patented December 26, 1933. It is very necessary; also, that the total length of the machine, front to rear, shall be no greater than the width of a fiat-car in order that the machine may easily and readily be transported by railway when desired without necessitating This limitation concerning the length of the machine, the limitation as to selling-price, and the limitation concerning its gross weight to prevent overloading of the side-forms, have rendered difficult the solution of the problem of producing a machine of this character capable of being advantageously used under almost ii not every soil condition encountered in highway construction and which will also stand the rough usage and abuse to which outdoor equipment is usually subjected. The machine of this invention has successfully withstood every test to which 'vating mechanism disposed behind said firstnamed mechanism and comprising 'a bucket elevator disposed at an incline and intersecting the vertical plane of a side edge of the pavement strip, and an endless conveyor equipped with scraper blades for moving loose earth laterally into the path of said buckets of said elevator and reducing the level of said loose earth to a predetermined degree, said bucket elevator including a series of equally spaced apart buckets having straight earth gathering edges, and additional buckets equipped with toothed edges interposed between certain of the successive buckets of the first-named sets, the said scraper blades and said first-named buckets being equally spaced apart and having partially overlapping paths of travel wherein the same alternate with each other.
2. The method of fine-grading a pavemen I strip after the same has been ploughed and scarified to an appreciable depth below the predetermined fine-grade plane and thereafter compacted to a substantially uniform degree, which consIsts in first undercutting and loosening the superficial earth layer to a depth slightly below the predetermined fine-grade plane and to a plane substantially parallel therewith, then :s moving the thus loosened earth to a level or plane substantially parallel with but slightly higher than the predetermined fine-grade plane, then pressing down and compacting the loose earth remaining in the pavement strip to the level of the predetermined fine-grade plane.
3. The method of fine-grading a pavement strip after .the same has been ploughed and scarified to an appreciable depth below the predetermined fine-grade plane and thereafter compacted to asubstantially uniform degree, which consists in first undercutting and loosening the superficial earth layer to a depth slightly below the predetermined fine-grade plane and to a plane substantially parallel therewith, then removing the thus loosened earth to a level or plane substantially parallel with but slightly higher than the predetermined fine-grade plane, then pressing down and compacting the loose earth remaining in the pavement strip to the level of the predetermined fine-grade plane, and at the same time striking off surplus loose earth in excess of the volume thereof required to produce the compact accurately fine-graded strip, and then removing the last-mentioned surplus earth.
4. The method of fine-grading a pavement strip which consists in first undercutting and loosening the superficial layer of earth to a plane parallel with and below the predetermined finegrade plane, then removing surplus loose earth to a plane parallel with-and sufiiciently higher than the predetermined fine-grade plane to provide a volume of remaining loose earth in excess .of that required to be compacted down to the predetermined fine-grade plane, then compacting and smoothing part of said earth to a level coinciding with the predetermined fine-grade plane, and thereafter removing all remaining excess loose earth.
5. The method of fine-grading a pavement strip which consists in first undercutting and loosening the superficial, layer of earth to a plane parallel with and below the predetermined finegrade plane, then removing surplus earth to a plane parallel with and sufficiently higher than the predetermined fine-grade plane to provide a volume of remaining loose earth in excess of that required to be compacted down to the predetermined fine-grade plane, then compacting and smoothing part of said earth to a level coinciding with the predetermined fine-grade plane,
and at the same time striking ofi excess loose earth, and thereafter removing the latter.
6. The method of fine-grading a pavement strip which consists in first undercutting and loosening the superficial layer of earth to a plane parallel with and below the predetermined finegrade plane, progressively along the pavement strip, then progressively removing surplus loose earth to a plane parallel with and above the predetermined fine-grade plane, then progressively compacting the loose earth to the predetermined fine-grade plane and at the same time progressively striking off excess loose earth and progressively removing the latter.
'7. The hereindescribed method of fine-grading a pavement strip which consists in first undercutting and breaking up an earth layer to a level below that of the predetermined ultimate finegrade, removing a portion of said loose earth deposited upon the grade first produced and distributing the remainder of said loose earth substantially uniformly over said last-named grade, and then compacting and smoothing said lastnamed looseearth to provide a surface coincident with the desired fine-grade.
8. The hereindescribed method of fine-grading a pavement strip to a prescribed contour and level which consists in first detaching a superficial earth layer overlying the ultimate desired fine-grade to a level below and substantially parallel with the said ultimate fine-grade, leaving a portion of the detached earth layer upon the underlying earth surface and distributing the same substantially uniformly over the entire 1,990,362 width of the pavement strip and thereafter com-.
pacting said last-mentioned detached earth-to the level and contour substantially coincident with the ultimate desired fine-grade.
9. The hereindescribed method of fine-grading a pavement strip which consists in progressively detaching from said strip and breaking up an earth layer overlying and partially underlying the level and contour of the ultimate desired fine-grade, progressively removing a portion of said earth and progressively distributing the remainder thereof substantially uniformly over the underlying earth surface from which said. earth was detached and thereafter progressively compacting said distributed earth to the level and contour of the desired ultimate fine-grade.
10. The hereindescribed method of fine-grading a pavement strip which consists in first progressively forming a grade of substantially the exact contour of the ultimate desired fine-grade and disposed below the level of the latter, then disposing a layer of. loose earth progressively over the prepared grade, and then progressively compacting said layer of loose earth to substantially the level and contour of the ultimate desired fine-
Priority Applications (1)
|Application Number||Priority Date||Filing Date||Title|
|US1990362A US1990362A (en)||1931-12-12||1931-12-12||Machine and method for finegrading roadbeds|
Applications Claiming Priority (1)
|Application Number||Priority Date||Filing Date||Title|
|US1990362A US1990362A (en)||1931-12-12||1931-12-12||Machine and method for finegrading roadbeds|
|Publication Number||Publication Date|
|US1990362A true US1990362A (en)||1935-02-05|
Family Applications (1)
|Application Number||Title||Priority Date||Filing Date|
|US1990362A Expired - Lifetime US1990362A (en)||1931-12-12||1931-12-12||Machine and method for finegrading roadbeds|
Country Status (1)
|US (1)||US1990362A (en)|
Cited By (2)
|Publication number||Priority date||Publication date||Assignee||Title|
|US2619748A (en) *||1948-01-16||1952-12-02||George R Mcintosh||Reciprocating blade for carry-type scraper|
|US2713217A (en) *||1955-07-19||Subgrading machine|
Cited By (2)
|Publication number||Priority date||Publication date||Assignee||Title|
|US2713217A (en) *||1955-07-19||Subgrading machine|
|US2619748A (en) *||1948-01-16||1952-12-02||George R Mcintosh||Reciprocating blade for carry-type scraper|
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