Impact roller

An impact roller for applying blows cyclically to a surface over which the roller is rolling. The roller has flail members pivotally connected thereto and also has recesses to accommodate the flail members when inoperative. In operation, when the roller rolls along a surface, the flail members fall forwardly under gravity and impart cyclic downward blows to the surface over which the roller is rolling. Upon faster rolling of the roller, the magnitude of the blows increases under the action of centrifugal force.

BACKGROUND OF THE INVENTION 
1. Field of Invention 
This invention relates to impact compaction or slab breaking apparatus. It 
relates in particular to an impact roller. Such a roller can consolidate 
or compact soil or earth by impact. It can also break up a hard, brittle 
layer such as a slab of concrete or concrete paving. 
2. Description of the Prior Art 
The applicant is aware of impact rollers which consolidate earth by dynamic 
impact rather than by mere rolling mass. Such rollers are non-circular and 
provide impact blows in operation. Such rollers, because of variations in 
the tractive effort, required, have a punishing effect on the draft 
vehicles pulling them. Shock-absorbing couplings are expensive and not 
always satisfactory when used between such rollers and their draft 
vehicles. The impact rollers of which the applicant is aware are described 
in U.S. Pat. Nos. 2,909,106 and 3,788,757. 
It is an object of this invention to provide an impact roller which will 
not have the same disabilities as the impact rollers known to the 
applicant. 
SUMMARY OF INVENTION 
Accordingly, the invention provides an impact roller for applying blows 
cyclically to a surface over which it is rolling, which comprises a roller 
assembly adapted to roll along a surface, and which includes a roller body 
portion; and at least one flail member pivotally connected remote from the 
impact surface to the roller body portion about an axis parallel to the 
roller assembly rolling axis and adapted in use while the roller assembly 
is rolling to have the impact surface impart downward blows to the surface 
along which the roller assembly is rolling. 
A plurality of flail members may be provided, all pivotally connected to 
the roller body portion in symmetrical circumferentially spaced 
relationship about axes parallel to the roller rolling axis. 
Alternatively, or in addition, the flail members may be pivotally 
connected to the roller body portion in axially and circumferentially 
spaced relationship about axes parallel to the roller rolling axis. Each 
flail member may conveniently be shaped to have its mass concentrated 
towards its free end portion for increasing the flailing impact provided 
by each flail member during use. The flail members may be mounted in an 
appropriate staggered relationship to balance the apparatus and to 
encourage the apparatus to follow a desired path. 
In one embodiment of the invention, the roller assembly may have two flail 
members which are mounted in diametrically opposed relationship on the 
body portion. In an alternative embodiment of the invention, the roller 
assembly may have three or four flail members which are mounted at equally 
spaced circumferential intervals adjacent the periphery of the body 
portion. The pivotal axis of the or each flail member may be at least half 
but may be two-thirds or even three-quarters of the roller assembly radius 
from the roller assembly rolling axis. Conveniently the pivotal axis is 
provided as close to the roller assembly periphery as possible without 
disfiguring the roller assembly profile when viewed axially. 
The roller assembly may comprise a plurality of roller sub-units mounted in 
series axial relationship on an axle, each roller sub-unit comprising a 
pair of axially spaced flanges and at least one flail member pivotally 
connected between the flanges about an axis parallel to the roller 
assembly rolling axis. The sub-units may be mounted to be independently 
rotatable relative to each other about the axis of the axle. 
The roller assembly may have recesses to accommodate the flail members when 
inoperative, within the profile of the roller assembly when viewed in an 
axial direction. 
The or each flail member may have its impact surface profile shaped to 
conform to the profile of the roller assembly when viewed in an axial 
direction, and may have a replaceable impact insert providing the impact 
surface for the flail member. 
The roller may have a frame in which the roller body portion is rotatably 
mounted, and a drawbar for attachment to a draft vehicle. The drawbar may 
form part of a propelling vehicle or may be adapted for connection to a 
propelling or draft vehicle. The frame may have means to receive ballast. 
The roller may include stop means to limit the displacement arcs of the 
flail members thereby preventing one flail member in a bank from entering 
the flail recess of a leading flail member during use. 
The roller may also include locking means to lock the flail members to the 
roller body portion within the profile of the roller assembly when viewed 
in an axial direction, to permit transfer of the roller from one working 
zone to another without impact blows during transfer. 
The roller may, if desired, include restraining means for restraining 
pivotal displacement of the flail members during use, towards their 
operative positions until a sufficient centrifugal force has been 
generated by rolling of the roller at a sufficient speed. The restraining 
means may, for example, comprise frictional means operative between the 
flail recesses and the flail members in the recesses. 
While the roller of this invention is particularly suitable for the impact 
compaction of surfaces, it may also be used for breaking up surfaces. 
Where the roller is to be used for breaking up surfaces, the impact 
surfaces of the flail members may have hammer or pick-like projections. 
For breaking up surfaces, a flail member may have a mass of about 100 kg. 
But for compaction purposes a flail member may be much heavier and may 
have a mass of up two tonnes or even more. Thus, the total mass of an 
impact roller according to the invention may be upwards of twenty tonnes. 
An impact roller according to this invention may be made of any desired 
size, depending upon the surfaces to be treated, upon the capacity of a 
draught vehicle for propelling the roller, and the degree of compaction 
required. In an embodiment of the invention, each flail member may be 
provided with a plurality of mounting bores thereby allowing variation of 
the flailing action by selecting desired bores for pivotally mounting the 
flail members on the body portion. 
The impact compaction apparatus of this invention may be made of any 
suitable hard wearing material or materials. The flail members and body 
portion may conveniently be made of mild steel, or of a suitable surface 
hardening steel, or manganese steel, or the like. Thus, a flail member may 
have a suitable seat to accommodate a replaceable insert of high grade 
wear-resistant material such as manganese steel, and having a hard-wearing 
impact surface. 
The invention extends also to a method of imparting impact blows cyclically 
to a surface, which includes rolling an impact roller along the surface 
and allowing at least one mass connected to such roller to fall forwardly 
under gravity from a recess within the roller profile onto the surface 
along which the roller is rolling, and thereafter rolling the roller to 
straddle the mass and allowing the straddled mass to be pulled up by the 
roller into the recess, upon further rolling of the roller along the 
surface, so as to be ready for the next cycle of operations. 
The invention extends still further to a method of imparting impact blows 
cyclically to a surface, which includes rolling a roller at speed along 
the surface and allowing at least one mass connected to the roller to be 
flung by centrifugal force out of a recess within the roller profile and 
to have a downward impact blow imparted to the surface while the roller is 
rolling along the surface, and thereafter rolling the roller to straddle 
the mass and allowing the straddled mass to be pulled up by the roller 
into the recess upon further rolling of the roller along the surface, so 
as to be ready for the next cycle of operations. 
An embodiment of the invention is now described by way of example with 
reference to the accompanying diagrammatic drawings.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
With reference to the drawings, reference numeral 10 refers generally to an 
impact roller adapted to roll along a surface 13 and comprising a roller 
assembly 11 which includes a body portion 12 and a plurality of flail 
members 14 which are pivotally mounted on the body portion to exercise a 
flailing action during displacement of the roller 10. The body portion 12 
comprises five circular flanges 16 which are mounted on a shaft 18 in 
axially spaced relationship. Recesses 17 are defined between the flanges 
16 to accommodate the flail members 14. 
In the embodiment illustrated in the drawings, the apparatus 10 is intended 
for use in compacting roadway surfaces, and each flange 16 has a diameter 
of about 1.5 meters and a thickness of about 50 mm. The shaft 18 has a 
diameter of about 200-300 mm. The flanges 16 and the shaft 18 are 
conveniently formed out of mild steel, or out of a surface hardening 
steel. Each flange 16 has twenty-four circumferentially spaced flail bores 
20 provided therein. 
Three circumferentially spaced flail members 14 are mounted between each 
pair of adjacent flanges 16 so that four banks of flail members 14 are 
provided across the width of the apparatus 10. Each flail member 14 is 
pivotally mounted in position between a pair of adjacent flanges 16 by 
means of a pivot pin 22 (as can be seen in particular in FIG. 3). Each 
flail bore 20 is countersunk, and each pivot pin 22 comprises two 
complementary sections 24.1 and 24.2 which co-operate to support a flail 
member pivotally. The section 24.1 has a threaded socket 26, whereas the 
section 24.2 has a threaded complementary spigot portion 28. Each section 
24.1 and 24.2 further has a recess 30 for receiving an Allan-type key. 
In use, the sections 24.1 and 24.2 can be inserted into the flail bores 20 
from opposed sides, and can then have their spigot and socket 28 and 26 
engaged to form a rigid supporting pivot pin 22. The pivot pins 22 can 
thus be readily inserted into position, and can readily be removed for 
maintenance or replacement of the flail members 14. As can be seen in 
particular in FIG. 3, each flail member 14 has a flail bore 32 for 
receiving a pivot pin 22. Each flail member 14 is supported on its pivot 
pin 22 via bearing sleeves 34. Each pivot pin 22 further has a pair of 
spacer rings 36 provided thereon to maintain a required minimum clearance 
of about 4 to 10 mm between each flail member 14 and the flanges 16 
adjacent thereto. Once a flail member 14 has been mounted on a pivot pin 
22, the sections 24.1 and 24.2 of each pivot pin 22 may be fixed to the 
flanges 16 by, for example, spot welds 38. Each flail member 14 is formed 
out of mild steel or surface hardening steel and has a width of about 250 
mm. 
As can be seen in particular in FIG. 2 of the drawings, each flail member 
14 is shaped to have its mass concentrated near its free end to provide 
the maximum flailing impact during use. Each flail member 14 has an impact 
surface 14.1 and an abutment surface 14.2. The impact surface 14.1 is 
provided by a manganese steel replaceable insert 14.3 seating in a seat in 
the flail member 14 and secured in position by countersunk set screws 
having centre lines 14.31. Each impact surface 14.1 is curved to 
correspond with the curvature of the flanges 16. Each flail member 14 is 
further shaped so that in its inoperative position, its abutment surface 
14.2 abuts the shaft 18. 
The arrangement of the flanges 16 and shaft 18 is such that the adjacent 
pairs of flanges 16 define flail recesses 17 for housing the flail members 
14 when they are in their inoperative, retracted positions. The mounting 
and shaping of the flail members 14 are such that when they are in their 
inoperative, retracted positions, the abutment surfaces 14.2 will abut the 
shaft 18, whereas the impact surfaces 14.1 are in alignment with and lie 
within the peripheral surfaces of the flanges 16 when viewed axially. 
The roller 10 also includes stop means in the form of stop bars 40 which 
are mounted in appropriate flail bores 20 to limit the displacement arcs 
of the flail members 14 thereby preventing a flail member 14 from entering 
into the flail recess of a leading flail member 14 during use. The stop 
bars 40 may conveniently correspond in diameter with the pivot pins 22. 
The roller 10 further has a frame 43 in which the roller assembly is 
rotatably mounted. It also has a drawbar 42 for connecting the apparatus 
10 to a suitable draft vehicle. The roller assembly is mounted on a shaft 
18 which is rotatably mounted in bearings 44 supported by the frame 43. 
With the dimensions and materials of the roller 10 as indicated, it is 
expected that the mass of the roller 10 will be about 20 tonnes. 
It will be noted that the flail members 14 in the four separate banks, are 
suitably staggered for balancing purposes and for encouraging the roller 
10 to follow a generally straight path during use. 
In the embodiment illustrated in the drawings, the mounting of the flail 
members 14 is such that, during use, a flail member 14 in the righthand 
outer bank will become operative, followed by a flail member in the 
lefthand outer bank, followed by a flail member in the righthand inner 
bank, followed by a flail member in lefthand inner bank, and so on. 
In use, when the apparatus 10 is drawn at a relatively low speed of, say, 
3-4 kilometers per hour, the effects of centrifugal force will be 
neglible. Therefore, as the roller assembly 11 rolls, the flail members 
will, fall forwardly under the action of gravity alone, and be pivotally 
displaced out of the body portion 12 for their impact surfaces 14.1 to 
impart downward blows cyclically on a surface 13 being compacted. 
However, as the rolling speed of the roller 10 increases so centrifugal 
force increases and causes the flail members 14 to become pivotally 
displaced out of their recesses 17 towards their operative positions. 
Thus, during use, each flail member will be caused to impart an impact blow 
on a surface being treated under the effect of the centrifugal force as 
well as under the effect of gravity. 
When the roller is to be taken from one work place to another then it may 
be necessary to render the flail members inoperative while travelling 
between such work places. This may be done by lock bars 41 engaging with 
suitably positioned flail bores 20 and with recesses 14.4 in the flail 
members 14. 
In preliminary experiments conducted by applicant, it was found that once 
the roller 10 was being propelled at a sufficient speed in relation to its 
mass and in relation to the type of surface being treated, the body 
portion 12 tended to be raised above the surface being compacted, so that 
the roller 10 was supported during use solely by the impact surfaces 14.1 
in contact with the surface being impacted. 
It follows therefore that in such a case the mass of the body portion 12 
will contribute to the compaction impact of the impact surfaces 14.1. If 
it is found that the body portion 12 is being maintained above the surface 
being compacted, the mass of the roller 10 may be increased, or may be 
added to by providing means 43.1 to receive suitable ballast 43.2 on the 
frame 43. 
It is an advantage of the embodiment of the invention as illustrated in the 
drawings, that an effective and robust compaction apparatus is provided 
for the impact compaction of surfaces and for breaking up concrete paving 
and road surfaces, when required. 
It is a further advantage of the embodiment of the invention as illustrated 
in the drawings, that since the body portion 12 is of circular cross 
section, the roller 10 will not present the type of resistance to 
displacement which would be presented by compaction rollers of 
non-circular section. The embodiment provides the further advantage that 
it can be propelled at relatively low speeds where reliance is placed only 
on the gravitational effects of the flail members 14, and can also be 
propelled at relatively higher speeds where both gravitational and 
centrifugal forces contribute to the flailing effect and thus the impact 
compaction force of the flail members 14. 
As each flail member 14 comes into contact with a surface being compacted, 
the compaction force will be directed primarily in the downward direction. 
Without wishing to be bound by theory, applicant believes that each impact 
will not provide a substantial retarding effect on the roller 10 and thus 
on a draught vehicle for the roller 10, since continued motion of the 
roller 10 will cause each flail member in turn, after impact, to be rolled 
into the recess within the body portion thereby limiting its resistance 
effect on forward displacement of the roller 10. 
The embodiment of the invention as illustrated in the drawings, provides 
the further advantage that because the flail members 14 exercise a 
flailing action at a radius far greater than the radius of the body 
portion 12 during use, the compaction impact of the flail members 14 would 
tend to be substantially greater than they would be at lesser radii. 
From preliminary experiments conducted by applicant, applicant believes 
that the roller 10 as illustrated in the drawings, will tend to be less 
destructive insofar as draught vehicles are concerned, than are compaction 
rollers of non-circular section. In addition, greater impact forces can be 
generated and relatively lower capacity draught vehicles can be employed 
for drawing the roller 10 than in the case of compaction rollers of 
non-circular section and of equivalent mass. 
In an embodiment of the invention, where a plurality of axially spaced 
banks of flail members are provided, the body portion may be divided into 
a plurality of axially spaced sections, with each section supporting one 
or more banks of flail members. In this embodiment of the invention, by 
selecting a desired number of sections and associating them together, a 
roller having a required width can readily be provided. Further, in this 
embodiment of the invention, the roller may include an axle for connection 
to a drawbar assembly, and each section may have a bore for rotatably 
receiving the axle, so that the sections can be rotatably supported on the 
axle via suitable bearings. 
Thus by simply selecting an axle of an appropriate length, a desired number 
of sections can be mounted on the axle. The sections may be permanently or 
removably coupled together so that they will be rotated as a unit during 
use. If desired, the sections may be mounted on the axle so that at least 
some sections can rotate independently thereby facilitating turning of the 
apparatus during use. Each section may therefore comprise two or more 
axially spaced flanges which are mounted on a hollow shaft for receiving 
the axle, with adjacent pairs of flanges having the flail members mounted 
between them. 
The invention may broadly be seen as a method of imparting impact blows to 
a surface 13 over which a roller 10 is being rolled, the method including 
the steps of permitting a flail member 14 pivotally connected to a roller 
body portion 12 cyclically in every revolution of the roller as it rolls 
to extend forwardly beyond the roller profile and cyclically to be 
retracted into the roller profile during every such revolution of the 
roller as it rolls, and of permitting the flail member during each forward 
projection to impart an impact blow under the action of gravity to the 
surface over which the roller is being rolled. 
The method may include the further step of increasing the speed of the 
rolling of the roller 10 to a value such that the impact blow is imparted 
also under the action of centrifugal force.