US3810709A - Apparatus for making a rigid road which has a textured surface - Google Patents

Abstract

A profile beam having a working surface constituted by alternate ridges and grooves and also having a rotatable shaft carrying radially outwardly displaceable weights is drawn across the surface of newly laid plastic concrete which has been laid to form a road, airplane runway or the like, whereby parallel grooves are formed in said concrete by the ridges. The shaft is rotated and the weights move radially outwardly against spring influence to an extend which is a function of the speed of rotation of the shaft and of the rate of the springs. The intensity of vibration applied to the beam is continuously variable from zero to a maximum.

Description

United States Patent [1 1 Weaver et a1.

[451*May 14, 1974 1 1 APPARATUS FOR MAKING A RIGID ROAD WHICH HAS A TEXTURED SURFACE [75] Inventors: John Weaver, Beaconsfield,

Buckingharnshire; David Payne Maynard, Slough, Buckinghamshire, both of England [73] Assignee: The Cement & Concrete Association,

London, England [21] Appl. No.: 194,859

Related US. Application Data [63] Continuation-impart of Ser. No. 63,867, Aug. 14,

1970, Pat. No. 3,683,762.

[30] Foreign Application Priority Data Nov. 7; 1970 Great Britain 53082/70 [56] References Cited UNlTED STATES PATENTS Maynard et al 94/48 X 2,542,227 2/1951 Bernhard 74/61 3,143,003 8/1964 Schmitt 74/61 X 2,989,869 6/1961 Hanggi 94/48 X 1,858,328 5/1932 Heymann et a1. 198/220 DB FOREIGN PATENTS OR APPLICATIONS 20,148 10/1894 Great Britain 74/61 Primary Examiner-Roy D. Frazier Assistant Examiner-Thomas .1. Holko Attorney, Agent, or FirmBerman, Bishoff & Platt 57] ABSTRACT A profile beam having a working surface constituted by alternate ridges and grooves and also having a rotatable shaft carrying radially outwardly displaceable Weights is drawn across the surface of newly laid plastic concrete which has been laid to form a road, airplane runway or the like, whereby parallel grooves are formed in said concrete by the ridges. The shaft is rotated and the weights move radially outwardly against spring influence to an extend which is a function of the speed of rotation of the shaft and of the rate of the springs. The intensity of vibration applied to the beam is continuously variable from zero to a maximum,

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APPARATUS F OR MAKING A RIGID ROAD WHICH HAS A TEXTURED SURFACE This is a continuation-in-part of application Ser. No. 63,867, filed by the same inventors on Aug. 14, 1970, now US. Pat. No. 3,683,762, issued Aug. 15, 1972.

This invention relates to an apparatus for making pavements for roads, runways and similar sites which have or are required to have textured surfaces.

Texturing of the surfaces of rigid roads has been carried out for a great number of years by brushing the surface of the concrete with horse-hair, brass or steel tape bristled brooms before the concrete has hardened. Such brushing has the effect of roughening what might otherwise be too smooth a surface.

It is now known'from field tests which have been made bythe Association with the co-operation of the Ministry of Transport, Road Research Laboratory and Hertfordshire County Council, that certain patterns or dispositions of grooves formed in the surface of a wornrigid road markedly improve the skidding resistance of that surface. Thus, wide grooves in such a surface which are parallel to one another and which extend transversely with respect to the general direction of flow of the traffic (hereinafter referred to as the traffic flow direction in the interests of brevity) have been found to give good results, as also have parallel grooves in two sets of which the grooves of one set cross those of the other set, each groove making an angle of substantially 45 with a line which is parallel to the traffic flow direction.

One method of formation of these grooves in the worn surfaces of existing rigid roads is to cut said grooves therein using powered machinery having diamond-impregnated steel blades. Other methods having involved the use of machinery which has included cutting heads which comprise silicon carbide blades or flails attached to drums which are rotated about horizontal axes. Whilst such methods may well be the only feasible methods by means of which worn surfaces or rigidroads can be re-textured in order to avoid the expense of and the traffic dislocation caused by removal of the worn pavement and the laying of the new concrete pavement, it is considered to be undesirable t texture in such a laborious and expensive manner the surface of any road which is either new or being repaved.

The principal object of the present invention is to provide an apparatus which is operable to carry into effeet the method of texturing the surface of a rigid road which is described and illustrated in US. Pat. application No. 63,867 filed Aug. 14, 1970 now issued as US. Pat. No. 3,683,762, in which the intensity of vibration obtained is variable from zero to a maximum, whereby a smooth start from rest is obtained. Another object of the present invention is to provide an apparatus which is operable to carry into effect the method referred to in the preceding paragraph, changes in the workability of the laid plastic concrete due for example to ambient weather conditions being capable of being accommodated by the apparatus by simple adjustment of vibratorydevices with which the apparatus is provided.

Another object of the present invention is to provide an apparatus which is operable to carry into effect the said method, said apparatus having a plurality of vibratory devices each of which is adjustable not only as to its maximum possible eccentricity in relation to the shaft axis but also as to its angular position about said shaft axis.

The present invention will now be more particularly described with reference to the accompanying drawings, in which:

FIG. 1 illustrates in side elevation one embodiment of an apparatus operable to make a textured-surface rigid road 'in accordance with the method of making such a road disclosed herein;

FIG. 2 illustrates said apparatus in top plan view;

FIG. 3 illustrates in end elevation the apparatus shown in FIG. 1, said elevation being of the left-hand end of the apparatus shown in FIG. 1;

FIGS. 4, 5 and 6 illustrate the detail views on a larger scale than that of FIGS. 1 to 3, of the traversible and vibratory groove-forming profile beam which is adjustably suspended in said apparatus and constitutes the essential component of the apparatus, said views representing, respectively, an end elevation, a side elevation and a top plan of said beam;

FIGS. 7 and 8 illustrate the preferred embodiment of the vibratory device with which said beam is provided, FIG. 7 being a section taken on the plane of symmetry of said device whose parts are stationary and FIG. 8 being an elevation of said device with the shaft being rotated; and

FIG. 9 is a graph in which five curves have been plotted and which will be discussed hereinafter.

The apparatus illustrated in the drawings consists essentially ofa gantry 10 which is made from box-section steel members 11 appropriately secured to one another to form a rigid frame, the gantry being supported by flanged wheels 12 which are mounted upon the gantry and which are intended to run on rails 13 which would extend alongside the formwork within which the concrete is to be laid on the subgrade. Some or all of said wheels 12 may be articulated, for example may be castor wheels.

The gantry 10 supports at one end a generating set 14 operable to supply the electric power necessary to drive a plurality of electric motors. Two electrically driven geared drive units 15 are mounted upon the gantry 10 and are operable to drive the two wheels 12 with which they are associated, the drive being by way of endless chain 16 and sprocket wheels 17 or some similar arrangement. The two drive units or motors 15 are both variable speed and reversible.

An hydraulic power pack 20 includes an electric motor 21, an hydraulic pump 22, a relief valve gauge 23 and a reservoir 24.

An electrically operated geared drive unit 25 is mounted upon a carriage 26, the output shaft of the unit having toothed sprockets 27 thereon which drive to other sprockets 28 by way of endless chains 29, the sprockets 28 being keyed to parallel axles 30 which are rotatably connected to the carriage. The axles 30 carry rollers 31 which are in contact with a rail 32 and also carry guide wheels 33 which, coacting with parallel guide rails 34 which between them define a rectilinear slit 35, provide guided traverse of the carriage 26 which is moved when the motor 25 causes the rollers 31 to rotate in contact with the rail 32. The motor 25 is variable speed and reversible. The carriage 26 carries tripping members 36 and limit switches 37 are mounted on one of the guide rails 34.

Connected to the carriage 26 for movement there with is an assembly which includes two substantially A- shaped beams 40 which are connected to one another by a longitudinal'beam 41, two double acting hydraulic cylinders 42 which are mounted upon said beams at the opposite ends of said beam 41 in the vicinities of the beams 40, a profile beam 43, a plurality of constant force springs 44, each of which is connected at 45 to the beam 41 and at 46 to the beam 43, the cylinders 42 having stems 47 whose free ends are connected to said beam 43 by way of a parallel-motion or scissors linkage 48.

Mounted on the profile beam 43 is an hydraulic motor 50 which is variable speed and reversible, the output shaft of said motor being connected by way of a shaft coupling 51 to a drive shaft 52 which is supported for rotation in two opposite directions of rotation in a journal box 53. Adjacent the free end of said shaft 52 is keyed a driving pulley 54 which is keyed to a vibrating shaft 57, said shaft 57 being supported by and running in pillow block bearings 58 which are carried by the profile beam 43. Secured to the shaft 57 are spaced eccentric weights or devices 59 which will here inafter be described in detail and which, when the shaft 57 is rotated by the drive from the motor 50, will cause the entire profile beam to vibrate.

The profile beam 43 whose working surface is indicated by the reference numeral 70 is connected to the lower and free ends of the two beams 40 by guide chains 60.

The gantry also supports a control console 65 into which are brought all electrical and hydraulic lines, whereby the operation of the apparatus can be conveniently controlled.

As will be seen best in FIGS. 1 and 6, the leading/- trailing edges of the beam 43 are located above the surface 80 of the plastic concrete. This canting upwardly of the relevant portions of said beam 43 is for the purpose of reducing the incidence of the beam 43 digging into and ploughing up said concrete. The guide chains 60 also assist in this preventative action.

A swinging arm boom 90 is provided in order that all of the hydraulic lines (not illustrated) may be bundled and maintained in a position in which they will not foul and be damaged by the traversing carriage.

Referring now to FIGS. 7 and 8, there is illustrated therein one of the eccentric weights or devices 59 which are mounted on the shaft 57. Each said device includes a sleeve 100 which is capable of being removably secured to the shaft in any angular position about the shaft axis, as for example by means ofa fixing screw 101. The sleeve 100 is appropriately apertured at 102 to permit the extension therethrough of the shank of a headed pin 103, a part of the length of the shank being screw-threaded as at 104 and the head 105 of the pin being so shaped as to be maintained by the shaft against movement radially inwardly of the shaft.

A generally U-shaped member consists of parallel plates 106 and a transverse plate 107, the transverse plate 107 being centrally apertured and carrying an annular bush 108 which is located in the aperture. The shank of the pin 103 extends through the annular bush 108.

A washer 109 is provided for one end of a compression spring 110 to rest against and a nut 111 is screwed on the screw-threaded partof the shank of the pin 103 with the interposition of a second washer 112.

It will be apparent that rotation of the shaft 57 will cause the U-shaped member to become displaced radially outwardly of the shaft along the pm 103 in depen' dence upon the speed of rotation of the shaft and the rate of the spring 1 10, said rate being adjustable within certain limits by the extent to which the nut has been screwed along said pin towards the bush 108. When the shaft rotation begins, the displacement of the U-shaped member along the pin 103 will be nil but, as the speed of rotation of said shaft increases, so said displacement increases together with the degree of eccentricity which stems therefrom.

Ten of such U-shaped members have been illustrated in FIGS. 4 and 5 as being spaced from one another along the shaft 57 and also secured thereto, the angular positioning of the several members about the rotational axis of the shaft 57 being capable of adjustment in order further to vary the degree of eccentricity and consequent vibration which is obtained.

Referring to FIG. 9, curves A,B,C and D are values of K equal to 0.5 inch, 0.75 inch, 1.00 inch and 1.25 inches, respectively. Curve E shows the effect on centrifugal force produced by variation in radius of gyration of the variable eccentric weight controlled by a spring 110 (FIGS. 7 and 8) whose rating is l ISIbs/inch.

The operation of the apparatus is considered to be self-evident in at least some respects and it will, therefore, suffice to point out that the working surface of the profile beam 43, consisting of alternate parallel ridges and troughs, will form parallel grooves in the plastic concrete when the carriage 26 is caused to traverse the formation by riding along the rails 32, 34, the formation of said grooves being assisted by the vibration produced by rotation of the shaft 57 to which the eccentric weights or devices are secured. At the end of each traverse, the profile beam 43 is lifted out of contact with the concrete by appropriate operation of the hydraulic actuators 42, said beam 43 thereafter being lowered again under the control of said hydraulic actuators into contact with the concrete after the gantry 10 has been moved in the requisite direction along the rails 13 by the powered wheels 12, whereupon the carriage 26 is caused to traverse the formation in the opposite direction of travel thereof to that previously effected. The limit switches 37 are tripped by the members 36 to stop the respective traverse of the carriage and also to stop the hydraulic motor 50.

Again, the wheels 12 which are shown as being powered by the motors 15 in the drawings need not be so powered because the apparatus could form the termi nal part of a train of pavementlaying machinery, being connected thereto by cables, hawsers or the like, which (in conjunction with intermittently operated but synchronously operated winches) would enable the apparatus to follow the preceding constituent elements of said machinery at the end of each traverse of the carriage 26.

If cleaning means operable to keep the working surface 70 of the profile beam 43 are provided (for example brushes, pressurised fluid jets and so on, possibly in combination with one another), it would be desirable to extend the gantry 10 to an extent sufficient to ensure that any adherent material on said working surface would not fall on the surface of the concrete which has been or which is to be textured. Thus, the gantry 10 might be lengthened to the right as seen in FIG. 1 and cleaning would be effected at the end of alternate traverses.

The parallel ridges and troughs constituting said working surface are preferably formed by working a solid block or plate. The creation of said ridges by securing parallel square-section rods to a plate is likely to give rise to trouble because there is a tendency for particles of the plastic concrete to penetrate between the rods and the plate. These particles become impossible to remove on site and lead to buckling or de-formation of the rods, said buckling or deformation giving rise the variations in depth of groove in the concrete.

Switches other than the limit switches 37 may be provided in order, for example, to actuate the cleaning means if cleaning means are provided and/or to control the operation of said winches. The switches may be time-controlled or remotely controlled from a part of the pavement-laying machine.

In conclusion, it will be useful to state that the requirements for the rotary vibration system incorporated in the apparatus which has'been described above,

are: 1

i. an intensity of vibration which is continuously variable from zero to maximum in order to accommodate changes in workability of concrete and permit a smooth start from rest ii. a maximum vibration intensity which would permit remoulding of the surface of a concrete pavement on a hot day when the concrete stiffens rapidly iii. an even distribution of vibration along the profile beam.

It is not possible to satisfy these requirements by the use of either an electromagnetic vibrator or a rotary vibrator with fixed eccentric weights because (a),a single electromagnetic vibrator has not sufficient capacity for a profile beam of the size used on the grooving apparatus and multiple units cannot be synchronized; even distribution of the vibration along the length of the beam has proved to be impossible; and (b) a rotary vibrator with fixed eccentric weights on a shaft extending the full length of the profile beam permits an even distribution of vibration under smooth running conditions but variation of the speed of rotation, and hence the length point of the shaft 57 and the eccentricity of these weights is not only adjustable by choosing a spring of the relevant rate and by adjustment of the nut 11] but also increases with speed giving a smooth variation of vibration from zero intensity upwards which can be used to accommodate changes in the consistency of the laid plastic concrete. Thus, this system fulfils the three requirements detailed above.

I claim:

1. Apga rafus foTrHEiii'gZ t extured-surface rigid road of concrete or the like, comprising a gantry adapted to span a newly laid plastic concrete road and movable along said road in the direction of intended traffic flow thereon, a carriage movable along said gantry, a profile beam having a groove-forming working surface supported from below said carriage, means to adjust the level of said profile beam so as to contact said newly laid road surface with a predetermined pressure, and vibrator means directly connected to said profile beam, said vibrator means including a rotatable shaft supported on and extending longitudinally of the profile beam, a variable-speed motor operable to rotate said shaft at varying speeds, spaced weights secured to said shaft, spring means urging each weight towards said shaft radially thereof, and each weight being displaceable radially outwardly .away from said shaft against said spring means under the action of centrifugal force generated by rotation of said shaft, the extent of. said displacement of said weight the spring means being a function of the rotational speed of the shaft and of the rate of said spring means, whereby an intensity of vibration is obtained which is continuously variable from zero to a maximum.

2. Apparatus as claimed in claim 1, wherein, for each of said weights, -a pin is secured to said shaft and extendsradially therefrom, said weight being apertured for the extension of said pin through said aperture, a compression spring disposed with its convolutions encircling said pin, said spring being located radially outwardly of the weight in relation to the shaft, and seat means carried by said pin in a manner that said compression spring acts at one end thereof on said weight and at the other end thereof on said seat means, whereby the weight is at all times urged towards said shaft by said spring.

3. Apparatus as claimed in claim 2, wherein each of said weights consists of two parallel limbs each of which has first and second ends, the corresponding first ends of said limbs being free ends, a transverse connecting piece secured to the corresponding second end of said limbs to form a U-shaped member, the aperture through which said pin extends being formed in said connecting piece centrally thereof, and an annular bush interposed between said connecting piece and said pin in said aperture.

4. Apparatus as claimed in claim 2, wherein said pin has a free end remote from the shaft, a screw-thread formed in a portion of said shaft extending from and including said free end to a location intermediate said free end and said shaft, said seat means including a nut in engagement with said screw-thread, said nut being rotatable about the longitudinal axis of said pin to adjust the rate of said spring.

5. Apparatus as claimed in claim 2, wherein the angular position of each pin about the axis of rotation of the shaft is adjustable.

Claims (5)

1. Apparatus for making a textured-surface rigid road of concrete or the like, comprising a gantry adapted to span a newly laid plastic concrete road and movable along said road in the direction of intended traffic flow thereon, a carriage movable along said gantry, a profile beam having a groove-forming working surface supported from below said carriage, means to adjust the level of said profile beam so as to contact said newly laid road surface with a predetermined pressure, and vibrator means directly connected to said profile beam, said vibrator means including a rotatable shaft supported on and extending longitudinally of the profile beam, a variable-speed motor operable to rotate said shaft at varying speeds, spaced weights secured to said shaft, spring means urging each weight towards said shaft radially thereof, and each weight being displaceable radially outwardly away from said shaft against said spring means under the action of centrifugal force generated by rotation of said shaft, the extent of said displacement of said weight the spring means being a function of the rotational speed of the shaft and of the rate of said spring means, whereby an intensity of vibration is obtained which is continuously variable from zero to a maximum.

2. Apparatus as claimed in claim 1, wherein, for each of said weights, a pin is secured to said shaft and extends radially therefrom, said weight being apertured for the extension of said pin through said aperture, a compression spring disposed with its convolutions encircling said pin, said spring being located radially outwardly of the weight in relation to the shaft, and seat means carried by said pin in a manner that said compression spring acts at one end thereof on said weight and at the other end thereof on said seat means, whereby the weight is at all times urged towards said shaft by said spring.

3. Apparatus as claimed in claim 2, wherein each of said weights consists of two paRallel limbs each of which has first and second ends, the corresponding first ends of said limbs being free ends, a transverse connecting piece secured to the corresponding second end of said limbs to form a U-shaped member, the aperture through which said pin extends being formed in said connecting piece centrally thereof, and an annular bush interposed between said connecting piece and said pin in said aperture.

4. Apparatus as claimed in claim 2, wherein said pin has a free end remote from the shaft, a screw-thread formed in a portion of said shaft extending from and including said free end to a location intermediate said free end and said shaft, said seat means including a nut in engagement with said screw-thread, said nut being rotatable about the longitudinal axis of said pin to adjust the rate of said spring.

5. Apparatus as claimed in claim 2, wherein the angular position of each pin about the axis of rotation of the shaft is adjustable.

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