US2069376A

US2069376A - Apparatus for producing mineral aggregate roads

Info

Publication number: US2069376A
Application number: US645499A
Authority: US
Inventors: Madsen Martin
Original assignee: MADSEN IRON WORKS
Current assignee: MADSEN IRON WORKS
Priority date: 1932-12-03
Filing date: 1932-12-03
Publication date: 1937-02-02
Anticipated expiration: 1954-02-02

Description

M. MADSEN 2,069,376

APPARATUg FOR PRODUCING MINERAL AGGREGATE ROADS Feb. 2, 1937.

Filed Dec. 3, 1932 3 Sheets-Sheet l f/VL/E/V roe. Warf/h WacAse/e,

W ArTo/QNEV.

Feb. 2, 1937. M. MADSEN 2,069,376

APPARATUS FOR PRODUCING MINERAL AGGREGATE ROADS I Filed Dec. 5, 1932 3 Sheets-Sheet 2 6r P m 25M Feb. 2, 1937. M. MADSEN 2,069,375

APPARATUS FOR PRODUCING MINERAL AGGREGATE ROADS Filed Dec. 3, 1932 3 Sheets-Sheet 3 Illllllllll nmmulumu f/v v/v TOR..-

' Mar/m Mast sen,

A 7"7'ORNEK Patented Feb. 2, 1937 UNITED STATES PATENT OFFICE 2,089,378 APPARATUS FOR PRODUCING MINERAL AGGREGATE ROADS Application December 3, 1932, Serial No. 645,499

18 Claims.

My invention relates to a device for making surfaces of macadam character wherein aggregate materials such as earth, clay, gravel, or

crushed rock are combined with a bituminous material such as asphalt or road oil, and relates particularly to a machine for making roads either from the aggregate materials present in the surface mixture from which the road is to be made or from aggregate materials which are obtained from other sources.

My invention comprehends a simple but superior method and apparatus adapted to replace the methods and apparatus at present employed in road construction. Some roads are made or resurfaced by scarifying the road surface and then applying a coating of oil which is either left to soak into the divided materials on the road surface produced by scarification or mulching thereof, or a layer of sand or gravel 9 or both may be spread over the oil. Roads of this character are very temporary in their nature owing to the fact that the bonding effect of the road oil or asphalt penetrates only the surface structure of the road. Other methods employed include the mixing of asphalt materials with aggregate materials at a plant situated at more or less distance from the place of road construction, the road surfacing material thus formed being spread over the road surface and rolled down to a finished condition.

My invention provides a portable structure comprising a vehicle having means whereby it may be driven slowly along the road which is to be made or a road which is to be resurfaced, this 35 device having a mill adapted to pick up aggregate material from the road surface and to thoroughly mix and knead the material with a binder such as heavy road oil or asphalt and to discharge the mixture again to the road surface whereby it may be spread and rolled to produce a road structure of relatively durable character at a minimum cost and with a minimum expenditure of time. The divided materials or aggregate which are taken into the mixer 45 may be formed by scarifying the surface of a road which is to be refinished so as to break up the materials constituting the road surface into such small sizes that they will enter the mixer.

As the device is moved slowly along the road these materials are delivered into the mixer and a proper quantity of binder is added thereto, with the result that the mixed materials delivered from the mixer to the road surface are of proper consistency and are thoroughly mixed together, so that a road surf-ace structure of maximum durability is obtained. Although it is preferable to add the binder to the divided aggregate materials as they enter the mixer or mill, such binder may, of course, be applied to the aggregate by spraying road oil along the path ahead of the movement of the machine. To the divided materials produced by scarii'ying the surface of the road reinforcing materials such as sand, gravel or crushed rock may be added so that a better consistency of road surfacing materials is produced. As a further alternative all of the materials entering into the surface structure of the road may be brought from distant points and placed in windrows or continuous ridge-like piles along the path of the road to be made. 1

The machine hereinafter disclosed is capable of a forward speed of twenty-two feet per minute and of handling nine cubic yards of aggregate materials for each one hundred feet of forward movement, this .permitting the completion in one eight-hour day of one mile of full width roadway of eighteen cubic yards of road surfacing materials per each one hundred lineal feet at a cost much lower than the present cost of producing a road structure of the same strength, quality and durability.

Accordingly, it is an object of my invention to making method may be employed, having a mixing mill supported by .a vehicle, and simplemeans for delivering the divided materials from the road surface into the mixing mill.

I is a further object of the invention to provide road making machine of the above character having an improved and novel device for mixing the divided materials with a very thorough kneading action, whereby a complete intermixture of the divided materials with the binder is obtained.

It is an object of the invention to provide a mixing mill or pug mill adapted to receive materials to be mixed at one end thereof and to transport the materials to the other end of the mill during the mixing thereof. It is an important object of this invention to provide therein means for bringing the divided materials pres,- surally together during the mixing action, whereby to obtain the improved mixing effect present in my device.

A further object of the invention is to provide a pug mill 0' the above character having mixing vanes or paddles placed at varying angles to the lines of movement thereof, so as to accomplish the forcing of the materials being operating on provide a machine whereby my simple road into coengagement with sufficient pressure to produce a thorough kneading of the mix.

Further objects and advantages will be brought out in the following part of the specification and will be shown in the drawings in which:

Figure 1 is a partly sectioned side elevation of a preferred embodiment of my invention.

Figure 2 is a horizontal section taken substantially as indicated by the line 2-2 of Fig. 1.

Figure 3 is an enlarged cross-section on a plane represented by the line 3--3 of Fig. 1.

Figure 4 is an end view looking at the front end of Fig. 1 along an upwardly sloping line, as indicated by the arrow 4 of Fig. 1.

Figure 5 is a cross-section on a plane represented by the line 5-5 of Fig. 1.

Figure 6 is a diagrammatic perspective view illustrating my new method of making surface structures of the character herein described.

The preferred form of a machine embodying my invention and for exemplifying my new road making method includes a vehicle II having means for permitting movement thereof, such means being represented by front wheels I2 and rear wheels I3. As shown in Figs. 1 to 4 the front wheels I2 are carried by an axle I4 mount ed so that it may rotate relative to a vertical axis for steering purposes and may rotate relative to a longitudinal axis for adjustment of the wheels to uneven road surfaces. For this purpose a forked member 45 or clevis is secured centrally to the axle I4 by means of a longitudinal pin l6, this clevis being secured to the lower end of a cylindrical member II which projects upwardly into a cylindrical column I8 mounted in a substantially vertical position at the forward end of horizontal frame members 20 of the vehicle, which may readily consist of structural channels mounted in converging relation at the forward ends of horizontal channels I9 and being secured to the column I8 by some such suitable means as welding. The upper end of the column I8 is provided with a cap or head structure 2i through which a vertical screw 22 extends into engagement with a threaded body 23 which is vertically slidable in the column and is prevented from rotation within the column I8 by interengagement therewith, as represented in Fig. 5, by radial projections 24 which extend into vertical grooves 25 in the inner face of the column I8. The upper end of the post I'I rests against a lower face provided by the threaded body or nut 28, and by rotating the screw 22 the column I8 may be vertically moved relative to the post II so as to raise or lower the forward end of the vehicle II for purposes which will be hereinafter explained. Rotation of the screw 22 is accomplished through the use of a bevel gear 26 mounted on the upper end of the screw 22 and adapted to be engaged by a bevel pinion 21 secured to a longitudinally extending shaft 28, the forward end of which is supported by a bracket bearing 3| which extends upwardly from the head 2i. The shaft 28 has its rearward end 32 supported in a bearing 38, and is connected through a universal joint 84 with a shaft 35 supported by bearings 36 and 31 and having a handle or hand wheel 38 at the rearward end thereof in position to be operated by the driver of the vehicle who occupies a drivers seat 40 situated at the rearward end of the vehicle I I. A cross shaft 42 extends between the channels I9 of the vehicle frame and has drums or

spools

43 and 44 at the ends thereof on which

cables

45 and 46 are respectively wound, the forward ends of t se cables being connected to attachment means 41 and 48 at the respective ends of the axle l4. One of the cables is wound clockwise and the other is wound anti-clockwise so that one cable will wind and the other will unwind when the shaft 42 is rotated, thereby producing a steering rotation of the axle I4 relative to a vertical axis. The shaft 42 is rotated by turning a hand wheel 50 disposed in proximity to the driver's seat 40 and on the forward end of the shaft 5| which has a bevel pinion 52 at its forward end engaging a bevel gear 53 mounted on the shaft 42.

For propelling the vehicle II a combustion motor 54 is shown which, through a selective transmission mechanism 55 of standard automotive type, drives a rearwardly projecting shaft 56 supported at its outer end by a bearing 51 carried on the upper face of a cross frame member 58 of the vehicle frame, which may be formed from a structural I-beam. On the shaft 56 is a grooved pully 60 which drives a jack shaft 6| through the use of V-belts 62 which extend over a larger V-grooved pulley 63 mounted on the shaft 6|, set to one side, as shown in Fig. 2, so that a pinion 64 thereon will engage a gear 65 mounted on the rearward end of the left hand shaft 66 of the mixing or pug mill 61. Extending rearwardly from the gear 64 is a shaft 68 rotatably carrying a sprocket 69 thereon adapted to be engaged by a clutch mechanism I0 carried by and rotating with the shaft 68. A shift yoke II is shown in Fig. 1 for operation of the clutch I0, it being understod that this shift yoke is to be manipulated by the driver through the use of a shift lever of standard form. Through a chain I2 the sprocket 69 drives a sprocket I3 keyed to a horizontal shaft I4 which projects rearwardly into a differential 15 mounted on the cross member 58. The differential has shafts I6 and 11 extending laterally therefrom and through bearings 18 and I9. Sprockets 80 and 8| on the outer ends of the shafts I6 and

I1 drive chains

82 and 84, which extend over

sprockets

85 and 86 associated with the right hand and left hand rear wheels I3 of the vehicle. It will be noted that the drive arrangement between the power source 54 and the rear wheels I3 provides a large speed reduction so that the vehicle II may be propelled forwardly at a very slow speed such as necessary in the making of a road in accordance with the method herein disclosed. An initial speed reduction is accomplished in the selective transmission 55, this being subsequently multiplied through the belts 62, the gears 64 and 65, the chains I2 and 82 and 84.

The pug mill 61 is swung below the side channels I9 of the vehicle II and includes a body or shell 90 which may be readily formed from sheet steel bent to provide an essentially flat bottom 9i and side walls 92 which meet the bottom portion through curved portions 93. The forward end of the shell 90 may be laterally flared, as shown at 94 in Fig. 2. By means of downwardly extending brackets 95, 96 and 91 the shaft 66 is rotatably supported at one side of the shell and a second shaft 98 is supported at the opposite side of the shell, this shaft 98 having a gear I00 at its rearward end which meshes with the gear 65 so as to rotate in unison therewith but in an opposite direction. Along the length of each

shaft

66 and 98 mixing members I02 are mounted, these members having radially extending arms I03 with paddles I04 mounted at the extremities thereof. Means are provided for delivering divided materialsinto the forward end of the pug mill 61, such means being in the form of a replaceable steel blade I which is secured to and projects forwardly from a lip I 06 of the shell.

The blade I05 is essentially straight and horizontal, with the exception of the end portions I08 thereof which are curved upwardly. The cutting plane I I0, Fig. 1, of the blade I05-is adjusted relative to the surface III on which the front wheels I2 roll by raising or lowering the forward end of the vehicle frame through rotation of the screw 22 in the manner previously described.

The vehicle II may be provided with a reservoir III for containing a binder material consisting of an asphalt oil or tar substance such as employed in roadwork. The spray means I I3. which may consist of a horizontal perforated pipe, is connected to the reservoir II2 through piping II3a having a control valve II4 therein.

A use of the invention may be as follows:

If a road is to be refinished without the addition of new materials other than the tar or oil binder, the surface of such road is first scarified and hardened or disked so that the materials previously forming the surface structure of the road are broken up into relatively fine form. These divided road materials are then preferably formed by the use of scrapers into several longitudinal ridges or windrows extending lengthwise with respect to the road. If the road isv eighteen feet in width, the divided materials are formed into two windrows, one on each side of the road. The machine shown in the drawings is then propelled along a path of movement coinciding with a windrow and in such position that the windrow, as indicated by dotted lines H6 in Fig. 1, extends between the forward wheels I2 and in the line of forward movement of the pug mill 61. The blade- I05 being adjusted to proper depth will out under the windrow as it is moved forwardly, thereby directing the divided materials into the forward end of the pug mill 61 where it is engaged, mixed and moved rearwardly by the action of the mixing members I02. The spraying means H3 is preferably situated so that it will spray the divided materials with oil or tar substance as they enter or just after they enter the forward end of the pug mill. It will be recognized that if a heavy tar is employed it may be desirable to use heat to fiuidify the same before it is sprayed onto the divided materials.

An improved feature of my pug mill resides in its ability to very thoroughly knead and mix the divided materials by forcing these materials and rolling and churning them in pressural contact. This I accomplish by decreasing the angularity of the blades I04 toward the rearward end of the pug mill. For example, the blades indicated at I04a at the forward end of the pug mill are turned into diagonal positions of approximately 45 relative to their circular lines of movement about the

shafts

66 and 98. As clearly shown in Figs. 1 and 2, the angles of the blades I04 are gradually decreased relative to the planes in which they move so that the driving or propelling effect thereof is reduced toward the rearward end of the pug mill. As will be noted, the blades indicated at I04b are swung to angles of approximately 20 relative to their planes of movement. This variation in the angles of the blades or paddles I04 causes the movement of the divided materials, as shown at I20, to be retarded toward the rearward end of the pug mill 6! so that the height of the mass of divided materials builds up to considerable depth at a point I2I near the rearward end of the pug mill. The

rearward movement of the materials is also resisted by the use of a lateral wall I22 which extends downwardly at the rearward end of the pug mill and protects the gear mechanism through which the

shafts

86 and 98 are driven. As shown at I23 the thoroughly mixed road material formed of divided materials and the impregnating substance are delivered to the road surface, where they may be thereafter levelled off by use of scrapers and rolled to a desired finish.

The foregoing method may be varied by the addition of aggregate materials to the divided materials formed by the breaking up or scarification of the previous surface structure of a road; for instance, to the divided materials, sand. gravel or crushed rock may be added to improve the properties of the road-forming composition delivered from the pug mill of the machine. As a further alternative the entire surface structure of a road may be formed from new materials which are placed along the path which the road is to follow and are picked up and mixed with a binder by the machine, to be subsequently delivered from the machine in condition to be spread out to form a road structure.

The process is simply illustrated in the perspective diagram of Fig. 6 in which a layer of divided materials I30 is formed along a path I3I as by the use of a scarifler I32 to break up existing road materials or by the addition of new road materials. Oil or tar substance of suitable character is then applied to the divided materials.

- For this purpose an oiler I33 is illustrated which may be moved along a head of a continuous mixer 61 which is adapted to deliver a composition 68 suitable for formation into a surface structure of a road by being subsequently spread thereover through the use of a scraper-or leveller I34. The thickness of the road structure may be varied as desired by' varying the volume of divided materials for a given width of road and by controlling the speed of the vehicle II to accommodate the volume of materials continuously delivered by the blade I05 into the forward end of the pug mill 61.

The features of my invention are readily embodied in an apparatus which is moved by a separate tractive vehicle. or in one having a caterpillar drive. These details may be changed to suit conditions or preferences.

Although I have herein shown and described my invention in simple and practical form, it is recognized that certain parts or elements thereof are representative of other parts, elements, or mechanisms which may be used in substantially the same manner to accomplish substantially the same results; therefore, it is to be understood that the invention is not to be limited to the details disclosed herein but is to be accorded the full scope of the following claims.

I claim as my invention:

1. A road making machine of the character described. including: a vehicle; means for propelling said vehicle; a mix ng mill ca ried by said vehicle, said mill compris ng a shell forming a channel having inlet and outlet openings at its opposite ends and a mixing member rotatable on a longitudinal axis in said channel, said mixirv member having sp rally disposed blades radirlly projec ing relative to said axis, the angles of spiral of sa d blades being decreased at a position toward the rearward end of said mix ng member; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill delivering the mixed materials to the road surface.

2. A road making machine of the character described, including: a vehicle; means for propelling said vehicle; a mixing mill carried by said vehicle, said mill comprising a shell forming a channel having inlet and outlet openings at its opposite ends and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis. the angles of spiral of said blades being gradually decreased from maximum to minimum respectively from the forward end to the rearward end of said mixing member, said mill having a wall adjacent said outlet opening for holding back the movement of material at the rearward end of said mill; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill deliveringthe mixed materials to the road surface.

3. A pug mill of the character described, comprising: a shell forming a channel having inlet and outlet openings at its opposite axial ends; and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis, the angles of spiral of said blades being decreased near the rearward end of said mixing member so as to produce a relatively rapid rearward feeding action in the forward part of said mixing member and the accumulation of a relatively large body of material in the rearward part of said mixing member.

4. A pug mill of the character described, comprising: a shell forming a channel having inlet and outlet openings at its opposite axial ends; and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis, the angles of spiral of said blades being gradually decreased from maximum to minimum respectively from the forward end to the rearward end of said mixing member.

5. A road making machine of the character described, including: a vehicle; means for propelling said vehicle; a mixing mill carried by said vehicle, said mill comprising a shell forming a channel having inlet and outlet openings at its opposite ends and a plurality of mixing members in sideby-side position and rotatable on longitudinal 'axes in said channel, each of said mixing members having spirally disposed blades radially projecting relative to said axes, the angles of spiral of said blades being gradually decreased from maximum to minimum respectively from the forward end to the rearward end of said mixing member; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill delivering the mixed materials to the road surface.

6. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine; a mixing mill carried by said frame, said mill comprising a shell forming a channel having inlet and outlet openings at its opposite ends and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis, the angles of spiral of said blades being consistently decreased from the forward end to the rearward end of said mixing member so as to produce a relatively rapid rearward feeding action in the forward part of said mixing mill and the accumulation of a relatively large body of material in the rearward part of said mill; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill delivering the mixed materials to the road surface.

'7. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine; a mixing mill caried by said frame, said mill comprising a shell forming a channel having inlet and outlet openings at its opposite ends and a plurality of mixing members in side-by-side position and rotatable on longitudinal axes in said channel, each of said mixing members having spirally disposed blades radially projecting relative to said axes, the angles of spiral of said blades being gradually decreased from maximum to minimum respectively from the forward end to the rearward end of said mixing member, there being a transverse wall adjacent said outlet opening for retarding the movement'of materials in the rearward end of said mill to assist in the accumulation of a relatively large mass of materials in the rearward end of said mill; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill delivering the mixed materials to the road surface.

8. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine; a mixing mill carried by said frame, said mill comprising a shell forming a channel having inlet and outlet openings at its opposite ends and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis, the angles of spiral of said blades being consistently decreased from the forward end to the rearward end of said mixing member so as to produce a relatively rapid and spread-out movement of material in the forward part of said mill and a slow movement of the material and a consequent accumulation of a large body of material near the rearward end of said mill; means for feeding a binder to the material as it moves in spread-out condition in the forward part of said mill; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill delivering the mixed materials to the road surface.

9. A pug mill of the character described, comprising: a shell forming a channel having inlet and outlet openings at its opposite axial ends; a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis, the angles of spiral of said blades being gradually decreased from maximum to minimum respectively from the forward end to the rearward end of said mixing member so as to produce a relatively rapid and spread-out movement of material in the forward part of said mill and a slow movement of the material and a consequent accumulation of a large body of material near the rearward end of said mill; and means for feeding a binder to the material as it moves in spread-out condition in the forward part of said mill.

10. A pug mill of the character described, comprising: a shell forming a channel having inlet and outlet openings at its opposite axial ends; and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting rela- 2,069,376 tive to said axis, the angles of spiral of said blades 7 being gradually decreased from maximum to minimum respectively from the forward end to the rearward end of said mixing member, there being a transverse wall adjacent said outlet opening for retarding the movement of materials in the rearward end of said shell to cause the accumulation of a relatively large body of material in the rearward part of said shell.

11. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine; a mixing mill carried by said frame, said mill comprising a shell forming a channel having inlet and outlet openings at its opposite ends and a mixing member rotatable on a longitudinal axis in said channel, said mixing member having spirally disposed blades radially projecting relative to said axis for mixing and moving road materials from said inlet opening to said outlet opening, said mill having a wall adjacent said outlet opening for holding back the movement of material at the rearward end of said mill; and means for operating said mill, there being means for delivering road materials from the road to said mill, said mill delivering the mixed materials to the road surface.

12. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine over a road surface; means for raising and lowering said frame relative to the plane of the road; a mixing mill carried by said frame having an inlet member forwardly directed to the travel of said machine for delivering divided materials from said road surface to said mill; guide means for guiding said machine over said road surface; a pick-up blade secured to said mixing mill so as to be raised and lowered in accordance with the raising and lowering of said frame; and means positioned contiguous to said guide means for adjusting the position of said pick-up blade.

13. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine over a road surface; means for raising and lowering the forward end of said frame relative to the plane of the road; a mixing mill carried by said frame, said mixing mill having a horizontal blade portion directed forwardly therefrom adapted to be raised and lowered in accordance with the raising and lowering of the forward end of said frame so as to deliver divided materials from said road surface to said mixing mill, the adjustment of said blade portion being under direct control of the operator of said machine.

14. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine over a road surface; means for adjusting the position of the forward end of said frame relative to the plane of the road; walls providing a mixing mill on said frame; a blade member on the forward end of said mixing mill for delivering divided materials from said road surface to said mill; and means responsive to the adjustment of said frame for moving said blade member to diflerent positions relative to the plane of said road.

15. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine over a road surface: means for adjusting the position of the forward end of said frame relative to the plane of the road; walls providing a mixing mill on said frame; a blade member on the forward end of said mixing mill for delivering divided materials from said road surface to said mill; and means responsive to the adjustment of said frame for moving said blade member to different positions relative to the plane of said road, the adjustment of said frame being under direct control of the machine operator.

16. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine over a road surface; a mixing mill carried by said frame; a blade member on the forward end of said mixing mill for delivering divided materials from said road surface to said mill; means for raising and lowering the forward end of said frame so as to move said blade member to different positions relative to the plane of the road; and means for operating said mill, said mill mixing said materials and delivering the mixed materials to the road surface.

1'7. A road making machine of the character described, including: a wheeled-frame; means for propelling said machine over a road surface; a mixing mill carried by said frame; a blade member on the forward end of said mill for delivering divided materials from said road surface to said mill; means for raising and lowering the forward end of said mill so as to move said blade member to different positions relative to the plane of the road; and means for mixing said materials and delivering said materials to the road surface.

18. A road making machine of the character described, including: a wheeled-frame; means for propellingsaid machine over a road surface; means for raising and lowering said frame relative to the plane of the road; a mixing mill carried by said frame; a pick-up blade on the for ward end of said mill for delivering divided materials from said road surface to said mill; means for moving said pick-upblade to different positions relative to the plane of the road; a mixing member rotatable on a longitudinal axis in said mill, said mixing member having spirally disposed blades radially projecting relative to said axis for mixing and moving said road materials from the forward end of said mill to the rearward end thereof, there being a wall for holding-back the movement of material at the rearward end of said mill; and means for operating said mixing member and delivering the mixed materials to the road surface.

MARTIN MADSEN.