US2669915A - Paving machine - Google Patents

Description

Feb. 23, 1954 K. E. MccoNNAUGHAY PAVING MACHINE 2 Sheets-Sheet l Filed March 14, 1946 Feb. 23, 1954 K. E. MccoNNAuGl-IAY 2,669,915

PAVING MACHINE Filed March 14, 1946 2 Sheets-Sheet 2 Patented Feb. 23, 1954 UNITED STATES PATENT oFFIcE 8 Claims.

My invention relates to a machine for mixing and spreading paving compositions. It is an object of my invention to produce a machine which can be moved over a surface to be paved and which, while being so moved, will mix and spread a paving composition. A further object of my invention is to produce a machine in which the paving composition will be spread and leveled within a short period of time following its mixing. Another object of my invention is to produce a machine which will `quickly and readily produce a paving-material slab of varying thickness. Still another object of my invention is to provide a machine which will lay a slab of paving material having a composition which varies transversely of the slab.

In carrying out my invention in its preferred form I employ a Vehicle adapted to be driven or drawn over the surface to be paved. Such vehicle may be supported in any convenient manner, as on wheels or on a combination of wheels and skids. Carried by the vehicle there is a transversely extending bin adapted to receive the aggregate which is to be incorporated in the paving composition. Also carried by the vehicle is a means providing a mixing compartment into which aggregate from the bin is fed at regulated rate desirably in the form of a thin sheet having a width approximately equal to that of the nished slab. Aggregate entering the mixing compartment is sprayed with a binder and is then subjected to the action of one or more longitudinally rotating mixing elements having fingers which engage the material and throw it violently upwardly against the upper wall of the mixing compartment. Such mixing elements rotate on axes extending transversely of the vehicle and consequently do not tend to displace any of the aggregate particles from the respective planes they occupy in entering the mixing compartment. An adjustable gate regulates discharge of mixed material from the mixing compartment, while a blade located in rear of the mixing compartment and mounted for vertical adjustment distributes and levels the mixed material. Individual-gates extending in a series transversely of the vehicle `permit regulation of the amount of aggregate fed from the bin at various points, and consequently control the transverse distribution of the mixed material discharged from the mixing compartment. The binder is desirably sprayed upon the aggregate through a spray bar embodying a series of individually controllable nozzles extending transversely of the vehicle, whereby the amount of binder may likewise be varied.

The machine can be adapted for the laying of a composite pavement by providing it with a second bin, feed-regulating gates, and spray bar. For example, the second bin might contain Portland cement, and the two spray bars might be respectively supplied with water and a bituminous binder. By proper adjustment of the gates respectively associated with the two hoppers and by proper regulation of the independently controllable valves of the spray bars, the machine may be used to lay a concrete pavement embodying a portion containing a suilicient quantity of bitumen to enable it to function as an expansion joint; or a bituminous slab might be layed simultaneously with a concrete edge or shoulder.

The accompanying drawing illustrates my invention. Fig. 1 is a plan view of the complete machine with portions thereof broken away; Fig. 2 is a side elevation of the machine, likewise with portions thereof broken away; Fig. 3 is a fragmental longitudinal vertical section illustrating details of construction; Fig. 4 is a fragmental section on the line 4-4 of Fig. 3; and Fig. 5 is a view similar to Fig. 3 illustrating a modified form of construction.

The machine illustrated in the drawings comprises a vertical frame supported in part on wheels I0 and provided with hitches II by which the vehicle is adapted for connection to a truck or other means suitable for drawing it over the surface to be paved.Y Extending transversely across the front end of the vehicle is an aggregate hopper or bin I2 desirably provided with a grille I3 and below such grille with a distributing screw I4 adapted when rotated to distribute the aggregate outwardly toward the ends of the bin. As shown, the bin is provided with an intermediate divider I5, but such divider may be omitted or additional dividers may be employed as desired. The arrangement of the hopper I2 and hitch II is desirably such that the body of a dump truck connected to the hitch II may discharge into the hopper.

Associated with the hopper is a feeder I1, here shown as of the belt type, which discharges rearwardly into a mixing compartment I 8 having end walls I9, a top wall 20, and bottom wall 2l. In the specific construction illustrated, the bottom wall ZI serves as a skid engaging the road surface and cooperating with the wheels I0 to support the vehicle. It is to be understood, however, that other means may be used in co-operation with the wheels Il) to support the vehicle and that in such a case the bottom wall 2| of the mixing compartment may be omitted Aand the material discharged from the feeder l1 directly on to the surface to be paved.

Extending transversely of the vehicle within the mixing compartment I8 are a pair of parallel, horizontal shafts each provided with a plurality of axially extending rows of mixing teeth 25. Desirably, the teeth 26 are curved in such a direction as will aid them in lifting the aggregate which is discharged into the mixing compartment. As shown, the two shafts 25 rotate in opposite directions, the front one rotating in a direction such that the teeth 26, when below it, will be moved rearwardly and the rear one rotating in the reverse direction, the two shafts being so angularly related that the teeth of one do not interfere with the teeth yof the other. In this particular shaft-arrangement, which is not essential to my invention, the shafts may be interconnected by spur gears 21 of equal diameter, as indicated -in Fig. 3.

In 'the machine illustrated in Figs. 1 to 3, 'means is provided for regulating the rate at which aggregate is fed from the hopper 'i12 'into the mixing compartment. vSuch means desirably comprises a 'plurality of gates 319 mounted at the rear of the hopper l2 vfor sliding movement toward and away 'from the feeder vl'l 'tolim'it the height of the opening through which aggregate leaves the hopper. As shown vin Fig. 4, two of the gates 'are employed, but itis to 'be Vunderstood that the number 'of -gates may be varied as desired. Whatever the number of gates -embodied in the machine, `each is yarranged for independent adjustment. As shown, each of the gates is provided with a pair of spaced racks 3l vcooperating respectively with fpinions v32 xed on a shaft 33 which 'can be manually rotated 'to .ad- 'just 'the gate. -By rotating veither shaft 33, its associated gate can be adjusted independently of the other gate.

Incorporated in the 'machine shown in the drawing is a means 'for 'discharging ya binder upon the aggregate as it enters the :mixing compartment. Conveniently, thism'eans 'takes the form of a plurality of spray bars 235, 4one for each of the gates 39, arranged respectively in rear of such gates. Each 'spray .bar is provided with a series of discharge nozzles 35 'extending -into the mixing compartment l'81an'd individually controllable by valves 3l'. is connected through ea supply pipe 38 with -a pump 39 (Fig. l) suitably mounted on the :frame of the vehicle.

Discharge Aof mixed 'material from `the mixing compartment t8 .is controlled by 'swinging -gate means `lll connected through links 132 7with adjusting levers 43 pivotally supported .from the frame 'of the vehicle tand adjustable to vary the eifec'tive height fof 'the discharge "opening through which the mixed material escapes 'from'the mixing compartment l'.

LSupported for vertical 'adjustment from lthe frame of the vehicle inrear'o the discharge'eom'- partrnent i8 :is va .distributing blade 45. 'Conveniently, `vertical va'djustineni'. fof the 'blade :'45 Lis .secured 'through the :medium .of two .laterally :spaced adjusting screws 56 which are rotatably `mounted lin the frame of the vehicle 'and 'which Iare received'in nuts'attached to the blade #5. By vappropriate adjustment yof -the 'screws 4-6 the blade 45 may be placed at any desired elevation above and at any-desired .inclination .to the road surface. If desired, there may be :mounted in advance `of .the xblade -45 .a `distributing :screw `48 adapted to feed material loutwardly -of the -ve- Each o'f 'the spray bars v35 1.

4 hicle. To confine material discharged from the mixing compartment l 8, the end walls I 9 of such compartment may extend rearwardly to a point adjacent the distributing blade 45.

Power for operating the various parts of the machine may be derived from an engine 59 mounted in any convenient manner on the vehicle frame. As shown, .the engine 59 drives two countershafts 5T and 52, one located in front of the engine and the other in rear thereof. The feed screw i4 associated with the hopper l2 and the feeders Il are desirably driven directly from the countershaft 5|, as through chain drives 53 and 54 respectively. One of the shafts 25 of the mixing element is' operatively connected to the .rear countersh'aft 52, as through the medium of a chain drive 55, while a second chain drive 51 interconnects the countershaft 52 with the distributor screw 48. Idlers 58 and 59, respectively 4associated with the chains E59 and 5l, may be employed to maintain such chains at the desired tightness.

'The two pumps 39 are `conveniently driven from the Acountersh'aft .52 through chain drives 5l. jD'esirabiy, for reasons that will hereinafter become apparent, the drive to each of the pumps 39 is individually controlled lso that either or both ypinilps can be operated, las desired. As shown, earch of the chain drives 6| has associated with it a manually controllable iclutch B2 which can be operated alternatively either to connect the 'drive to lor disconnect it .from the countershaft 252. .Bin-der may be supplied independently to the two pumps k3d in any yconvenient manner, as through a supply "tank mounted -on .the vehicle itself or from 'a supply tank carredon a separate vehicle adapted to operate beside the paving machine.

1n the operation of the machine illustrated in Figs. l to 4, thebin 2l 2 is lledwith aggregate and the gates '39 and binder-discharge control valves 3l are :adjusted Eto provide tor the supply of aggregate and 'binder at the desired rates. With the 'engine 50in operation `and driving the mixing r'element-s Aand rthe binder-.supply pum-ps 3-9, the vehicle is drawn over the surface to be paved. As previously indicated, :the paving machine may v'be drawn by 4a dump `truck ib-ywhich the supply of 'aggregate in the -bi-n t2 .may be continuously replenished. Fed V:from the bin +2 by the vfeeder VVIfl the 'aggregate receives a supply of 'binder discharged from the nozzles 36 asitentersthe mixing compartment I8. Because the Abinder is distributed yover substantially the entire length of .the mixing compartment, much of the coating operation 4`will beperformed lwhen the binder-jets Afrom the nozzles .36 fimping-e Vupon the aggregate. rCoa'ling of .the :aggregate .particles is :promptly 'completed by y'operation of the rapidly rotating ixing elements. 'I he .action -of these elements .in 4throwing the aggregate violently against the lupper wall 29 fof the mixing compartment breaks @up :any agglom'erated lumps of aggregate to ex- Ipose the enti-refsurfaoe of all theragglegate Dal- -ticles tothe binder. ilheainountof material in 'the mixing conipa-iitmerit is `vcontrolled by .adjustment fof ithegate 4l. .Escaping past the gate M, ythe material :rests on fthe #road surface and is ,leveled by `the action of Athe -`distributor blade 45 aided by thedistributorscrew 48, when such distributor .screw is used.

=It is 'to be noted .that zthe movement of aggregate particles Ifrom `the bin 'ft2 through the feeder aandfmixing compartment isfgenerallylongitudinal of the vehicle, .AS .a result, `thegates 130, which control the discharge of aggregate from the bin I2, may be adjusted to vary the discharge of the mixed paving composition laterally of the machine as it is discharged from the mixing compartment. For example, assuming that it is desired to lay aslab which is materially thicker near its left-hand edge than near its right-hand edge, the left-hand gate 30 may be opened wider than the right-hand gate to cause aggregate to be fed more rapidly from the left-hand end of the bin I2 than from the right-hand end, and the valves 31 associated with the nozzles 36 in rear of the left-hand gate may be opened further than are the valves 31 associated ,with the nozzles in rear of the right-hand gate 30, to maintainsubstantially the same aggregate-binder ratio at both sides of the machine. With the gates and nozzles so adjusted, the paving composition discharged from the mixing compartment I8 will have a substantially uniform composition, but much more of the material will be discharged at the left-hand side of the machine than at the right-hand side. The leveling blade 45 will of course be set with its left-handend higher than its right-hand end, to produce `the slab of the desired graduated thickness. However, because the material as discharged from the mixer already is distributed approximately in the desired graduated thickness, the distributor blade has little to do by way of causing the paving material to move laterally. If desired, the ends of the distributor 48 may be made independently vertically adjustable by adjusting mechanisms 63.

It will be understood, of course, that the speed of the mixing machine over the surface to be paved will be proportioned to the rate at which the paving composition is discharged from the mixing compartment I8. Where the vehicle which draws the paving machine is incapable of operating at a speed suiiiciently low to prevent the exhaustion of mixed paving composition from the space ahead of the blade, such vehicle may be stopped periodically while a supply of paving composition is permitted to accumulate ahead of the distributor blade and between the walls I9.

The divider I5, with which the bin I2 is shown as provided, is intended primarily to prevent the escape or" aggregate from the bin when the feeder embodies two spaced belts I1. belt is used extending throughout the width of the bin, or if some other type of feeder free from gaps or interruptions is employed, the divider I5 may be omitted.

Independent control of the gates 30 and of the pumps 39 permits the machine to be operated to lay a relatively narrow slab of paving material. Independent control of the binder nozzles 35 permits the paving material produced in the machine to have a varying composition. For example, the respective quantities of binder discharged from the several nozzles 36 may be varied to take account of the eiTect of any binder previously applied to the sub-grade upon which the pavement is to be laid.

In the modincation of the invention illustrated in Fig. 5, an auxiliary hopper'10 is mounted on the frame of the machine in rear of the main hopper I2, such hopper being provided with its own feeder 1I discharging into the mixing compartment I8 and with its own series of dischargecontrol gates 12. An auxiliary set of spray bars 13, having its own discharge nozzles 14 and nozzle-controlling valves 15, is also employed to supply liquid to the paving composition.

If a single feeder The machine illustrated in Fig..5 is extremely ilexible, as it permits the incorporation of additional ingredients, liquid orl solid, in the mix and also permits such additional ingredients to be distributed in any desired manner transversely of the slab which the machine produces. For example, the bin 10 may be supplied with Portland cement and the spray bars' 13 with water. By discharging aggregate from the bin I 2 and cement from the bin I0 into the mixing compartment for the full lateral extent thereof, a concrete slab of paving may be produced. If desired, one of the valves 31, or a plurality of successive valves 31, may be opened to supply a bituminous'binder. Binder so suppliedthrough nozzles 36 will not be distributed laterally of the vehicle but will remain more or less confined in a narrow portion of the slab. By incorporating bituminous binder in a portion of the slab, the machine will produce a slab of pavement in which expansion joints are incorporated after the manner vof my copending application Serial No. 573,938, filed January 22, 1945, now Patent No. 2,524,395.

An alternative method of operating the machine shown in Fig. 5 may be employed in producing a concrete edge or shoulder for a bituminous slab of paving material. To effect this result, gates 12 and water-supply valves 15 are closed over that portion of the machine in which a bituminous slab is to be formed, while the gates 'i2 and valves 13 are opened and the valves 31 closed over the remaining portion of the slab. A concrete mix, comprising aggregate, Portland cement, and water, will then be discharged from the mixing compartment through onel portion of the lateral extent thereof, while a bituminous composition will be discharged throughout the remaining lateral extent of thev mixing compartment. The two different characters of mixes will not be separated by a sharp line of demarcation, of course; but instead there will be a region in which the paving composition will include both Portland cement and bituminous binder, `with the proportion of cement decreasing and the proportion of binder increasing ,in one direction laterally of the slab. The absence of any sharp line of demarcation separating the cement-bound aggregate from the bituminous-bound aggregate tends to prevent the occurrence of cracks in the finished slab.

It will be understood, of course. that the distributor screw I8 will not lbe employed when the slabof paving material to be produced varies ln composition.

Because of the very rapid mixing produced by the longitudinal rotating mixing elements and because, by appropriate adjustment of the gates and nozzles, the necessity for lateral movement of paving material by the distributor blade may be eliminated, only a very short time need elapse between the application of the binder or other liquid constitutes and the completion of the slab. In fact, no difficulty is encountered in completing the distribution of the paving composition by the distributor blade within two minutes or less of the time at which the binder first comes into contact with the aggregate. As a result, it is possible to incorporate in the bituminous binder or in the aggregate material such as hydrated lime, or metallic salts such as aluminum sulfate, which will result in a very quick setting of the paving material. The same factors which contribute to the rapid mixing and laying of the paving material also contribute to an efcient use E claim as; my invention;

1. Inf a paving' machine, a vehicle adapted to traverse. a surface' to be paved, an aggregate bin extending transversely of the vehicle, a mixing compartment extendingtransverselyl of the vehicle for substantially the full width of the pavement to be. laid, a mixing element located in said mixingv compartment and rotatable on a transverse axis extending transversely of the vehicle, said compartment having, a top Wall disposed above said mixing element and at its rear a discharge opening extending transversely of the vehicle, said mixing lelement having a plurality ofv teeth. distributed axially of the element to engage and lift material in the mixing compartment without effectingany substantial displacement of" such. material axially of the element, means for feeding aggregate from said bin simultan'eousiyy to poi-nts distributed along the extent of said mixing compartment, means for driving said mixing element at, a speed great enough to cau-se it to: tlirovvv material in` said compartment against' said top wall and in a direction such that said teeth move rearwardly' in the upper portion of their rotation, adjustable means to vary the relative quantities of aggregate simultaneously fed by said feeding means to selected points dis,- tributed along the transverse extent ofthe mixing compartment, and means. for supplying a liquid binder at a predetermined rate to aggregate as it enters said mixing compartment and for regulating the. distribution of said binder throughout' the transverse extent of the mixing compartment. l

' 2'. The invention set. forth in claim 1 with the 1 addition of a. leveling blade adjustably supported from. the vehicle in position to level material. discharged from said discharge opening.

3. The invention set forth in claim 1, with the addition that said binder-supply means comprises a plurality of spray bars arranged to discharge on different portions of the aggregate entering the mixing compartment, and means for independentlysupplying binder to said spray bars.

4. The invention set forth in claim l, with the addition that said binder-supply means comprises a series of discharge nozzles extending transversely of the vehicle, and means for independently controlling the binder-discharge from each nozzle.

5. The invention set forth 'in claim 1, with the addition that said means forv regulating the rate of aggregate feed comprises a pluralityA of gates distributed along said aggregatev bin, each oi said gates. being independently adjustable.

6., The invention set forth in claim 1 with the addition thatsaid vcompartment has a bottom, aggregate-supportingwall closely adjacent which thev tips of` said teeth pass in the rotation of said mixing elements.

7. In a paving machine, a vehicle adapted to traverse a surface tobe paved, a mixing compartment extending transversely of the vehicle,v said mixing compartment having inlet and discharge openings extending along and generally co-extensive With its front and rear sides, feeding means for supplying aggregate to said compartment through and simultaneously throughout substantially the entire extent of said inlet opening and for varying the relative quantity of aggregate fed by said feeding means to selected points distributed along the transverse extent of the mixing compartment, means for supplying a liquid binder to said compartment and for varying the distribution of such binder aloner the compartment, a mixing element disposed in said compartment and rotatable about an axis extending transversely of the vehicle and provided with aggregate-engaging teeth to move the particles of aggregate inl planes extending longitudinally of the vehicle and Without substantial displacement of such particles laterally of the vehicle, and means for rotating said mixing elements in such direction that its upper portionmoves generally rearwardly during rotation.

8. The invention set forth in claim 7 With the addition that said compartment has a bottom, aggregate-supporting wall closely adjacent which the. tips of said teeth pass in the rotation of said mixing elements.

. KENNETH E'. McCGNNAUGl-IAY.

References Cited in the'file of this patent UNITED- STATES PATENTS Number Name Date 1,748,141 Nickerson Feb. 25, 1930 1,997,037 Barber Apr. 9, 1935 2,035,627 Nest Mar. 31, 1936 2,064,807 Barber Dec. 22, 1936 2,201,493 Jorgensen May 21, 1940 2,215,455 Abernathy et al. Sept. 24, 1940 2,252,717 Lundbye Aug. 19, i941 2,267,022 Gledhill Dec. 23, 1941 2,394,017 Seaman Feb. 5, 1946 2,424,459 Hettelsater July 22, 1947

Images