CA1096680A - Vibratory split roll - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A steerable split roll for a road roller includes a pair of roll shells containing means by which vibratory force is applied to each. Between adjacent ends of the roll shells a "turntable" type of bearing both connects the roll shells together for rotation relat-ive to each other and maintains them in axial alignment.

Description

8~ l l~hen one or more rolls of a road roller, especially one for compacting asphaltic road material, is or are also steerable, it is desirable that each roll be split into two or more roll shells ~hich are rotable relative to each o~her. This is because otherwise scuff~
S ing of a newly laid asphalt ma~ ~ill likely occur, the tighter the turn the greater the likelihood o~ scu~fing. At the same time, modern asphalt paving practice has turned more and more toward the use o vibratory rolls in order to increase the density and uniformity of the mat and yet reduce the weight of the roller and the time required ~o do so. -But split rolls which can also be vibrated are not found inthe prior art without many complications and deficiencies. The root of these lies in the substantial extra weight inherent in kno~n vi-bratory split roll designs compared with non-vibratory split rolls.
This is true not only when the vibratory mechanism is located outside the roll itself, and acts upon the ov~rall roll assembly, but espe-cially when the vibratory mechanism is disposed within and largely carried by the roll itself, acting just upon the outer roll shell. A-part from whether the vibratory mechanism is within or without the roll, some additional means in the case of split rolls must be employ-ed ~hich not only allows the rolls to vibrate together as a unit rel-ative to the remainder of the roller, but which also allows them to rotate relative to each other and yet maintains them together in rigid axial alignment. One approach in the prior art has been to use an ~
additional center frame member carrying the adjacent ends of a pair of heavy shafts upon which the roll shells are journaled, thus also leav-~ng a gap between the shells. Another approach which has been consid-ered is to use a single, large rigid sha~t upon which both roll shells are journaled and associated with which is a vibratory mechanism of the eccentric type.
The trouble with all these approaches, however, is that they very materially increase the weight or mass of the roll. The greater the mass to be vibrated the less the amplitude of the roll for a given :

~668(3 applied force at a ~iven frequency. To increase the amplitude a great-er applied force is required ~hich in turn means greater eccentricity or heavier eccen-tric weights unless frequency is sacri-ficed. Reduc-ing frequency, however, reduces eficiency of the roller because it decreases the speed at which the roller can tra~el along the new mat, Higher frequencies are desirable because they both increase the vib-ratory force and permit greater road speeds without impermissible skipping or gaps between the compactive thrusts upon the mat. But in-creasing the effective eccentric ~ass or the frequency, that is to say, the applied force, in order to compensate for increased weight of the roll demands larger bearings and more drive power with conse~
quent greater frictional losses and problems of dissipating heat trans-mitted to the bearing lubricant, Indeed, it is these difficult~es>
perhaps, which account for the scarce use of v'~bratory split rolls for steering a roller, despite their desirability. Rather, the much more common practice is to use a relatively smaLl, non-vibrating split roll or "tiller roll" for steering purposes ~hile incorporating the vibra-tory mechanism in a single large roll which is non~steerable. How-ever, when both rolls must necessaril~ be steered, as for inst~nce in a tandem double articulated roller of the type shown in Canadian pat-ent 1,019,997, the problems of also incorporating vibratory mechanis~
within them become more acute. The present invention ar~se in th~t context and while it is particularly designed for that type of rol~er, it is also applicable to any roller us:ing the split rolls, The invention in its broad aspect comprehends a road roller which includes at least one steerable roll having at least two co-ax'ially adjacent roll shells which provide a substantially continuous cylindrical road engaging surface. Mounting means for the roll shells permit vibratory movement thereof relative to remaining portions o~
the roll and further provide for rotation of the roll shells relative to each other. Vib:ratory means, effecti~e upon each roll shell, are also included. The mounting means itself includes ~earing means dis-posed between the adjacent axial ends o~ the roll shells effect~ve to

-2-permit their rotation relative to each other, as well as being dis-posed sufficiently adjacent the periphery of ~he roll shells so that the bearing means by itself is effective to prevent displacement of the roll shells from their co-axial relati~nshi~.
The invention in another of its broad aspects comprehends a steerable roll for a road roller, which roll includes a pair of hub assemblies at and supporting the outer axial ends of the roll and a p2ir of co-axially adjacent roll shells ~hich pr~vide a substantially continuous cylindrical road engaging s~Lrface. The roll shells are 10 mounted for vibratory movement relative to the hub assemblies in di-rections transversely of the axis of the roll, the two roll shells being capable of rotation relat~ve to each other. Vibratory means are disposed within the roll and carried by the roll shells e~fective to provide their vibratory movement. Means are disposed adiacent the 15 inner axial ends of the roll shells effective to support and maintain their ends in co-axial relationship and to provide for rotation of the roll shells relative to each other. The latter means inc~ude an annu-lar bearing assembly co-axial with and carried by the roll shells, the bearing assembly having a sufficiently large diameter to provide sub-20 stantially all of the effective support and maintenance of the inneraxial ends o~ the roll shells.
The disclosed exemplary embodiment of the invention elimi~
nates the need for any central frame member between the split rolls or the need for any hea~y central shaft or other weighty carrying means 25 for the individual roll shells. Instead, the adjacent ends o~ the roll shells are joined near their outer peripheries by a single,large annular bearing of the well-known "turntable" type so that axi~l de-flection of the two rolls relative to each ot~ler is very effectively resisted. At the sarne time the two races of the bearing overlap in a 30 manner such that, in cooperation with the bearing members between them, axial separation of l:he two shells is also prevented. Hence, at a single stroke, the two roll shells are rigidly mounted to each other, yet ~ree to rotate independently, all achieved with an insignif~cant

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increase in weight, complexity and cost, Consequently, the eccentric mechanism within the roll, since it is relieved of.any load carry-ing duties and must contend with minimally increased roll weight, can itself be smaller and lighter and yet produce a required amplitude and/or per~it higher frequencies without the concomitant dfficulties of doing so, as previously set forth~ with heavier split rolls. In-deed, both higher frequencies, besides allowing greater travel speed for the roller, and relatively modest amplitudes are usually more de-sirable than large amplitudes and lower frequencies. In the example to be described, ~ small, flexibly jointed shaft rom a hydraulic motor mounted in the non-vibratory hub of the roll drives a pair of short, relatively light eccentric shafts journaled in the roll shells at their adjacent ends, each of which.shafts carries.a pair o ec-centric weights. Hence, weight, power requiremen~s, bearing size$, heat dissipation problems, costs and the like are all minimized with-out impairing the compacting a~ility o~ the rolls.
~ Other and further features and advantages o the present in-vention will become apparent rom the drawing and-the more detai.led description which follows.
The single drawing Figure is a sectional view taken general-ly axially through a vibratory split roll according to the invention.
The split roll illustrated, which is specifically for an articulated expandable type of roller, is carried between the. lower ends of the hat-section legs 10 of a yoke which is swlngable about a vertical axis for steering purposes, all as further shown in Canadian patent 1,019,997 mentioned above. To one leg 10 is bolted th.e outer end o~ a hollow hub 11 in which is mounted a hydraulic tractîon drive motor 12 whose inner end carries a hydraulic brake 13 bolted to a ~ub inner end plate 14. The latter plate also carries the inner end of the stationary portion 15a of a planetary wheel or gearbox 15 ha~ing a ~lange 16 on its rotating portion lSb which is bolted to and forms the inner end of a sleeve 17 concentrically enveloping the hub 11, To the outer end of the sleeve 17 is affixed ar. annular roll shell

-4-mounting plate 18. The opposite yoke leg 10 is similarly provided ~qith a hollow hub 20 bolted to it having an inner end wall 21 to which is secured a hydraulic vibrator drive motor 22. An annular mounting flange 23 is welded to the hub 20 intermediate its ends to whose periphery is bolted the inner race of an annular bearing 24, its outer race in turn being bolted to a second annular roll shell mountin~ plate 25. Spaced about the inner faces of the mounting plates 18 and 25 and bolted to them adjacent their peripheries are the outer ends of a number of elastomeric roll shell mounting cush-ions 26.
The two halves 30a and 30b forming the split roll 30 areessentially identical in structure, consisting oE co-axial cylindri-cal roll shells 31a and 31b whose inner axial ends c~osely abut each other. Adjacent their outer ends the two shells 31a and 31b are pro-vided with annular mounting plates 32 and 33 to which the inner endsof the cushions 26 are also bolted. The adjacent inner ends of the shells 31a and 31b are also provided with annular mounting plates 34 and 35 which concentrically surround and carry a pair of hollow cy-lindrical drums 36 and 37. The latter drums axially mount a pair of axially adjacent short shafts 38 and 39 in bearings 40, the ends of each shaft 38 and 39 exterior of the drums 36 and 37 carrying a pair of eccentric weights 41. The two weights 41 at the adjacen~ ends of the shafts 38 and 39 are pinned together at 42 so that the shaft 38 can be driven by the shat 39. The drums 36 and 37, shafts 38 ~nd 39 and~ the weights 41 thus form a vibratory assembly which is driven .
from the outer end of the shaft 39 by the motor 22 through a small hollow drive shaft 4:3 and flexible couplings 44.
Between the drums 36 and 37 and adj.acent the inner axial ends of the roll sheLls 31a and 31b are welded a pair of opposed annu-lar bearing mounting plates 45 and 46, the plate 46 being radiallydeeper than the plate 45. Bolted between an annular seat on the opposing face of the plate 46 and that of a smaller annular sand~
wiching plate 47, closely adjacent the peripheries of the shells 31a .. . . .
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and 31b, is the inner race 51 of ~ large annular bea,ring 50 of the turntable type 7 i~S outer race 52 in t~rn ~eing bolted in an annular seat on the opposing face of the plate 45~ The joint ~ces, between the races 51 and 52 are paralleI ~o the axis of the roll halves 30a and 30b and are provided with opposed annular ch~nnels carrying ball bearin~ 53. Finally, the plates 45 and 46 are addi,tionally braced against the plates 34 and 35 by means of we~ plates 54, and the beà,r-ing 50 is lubricated by an exterior fittin~ 55 and conduit 56 leadi,ng into the outer bearing race 52, ~ spring loaded plungex mechanism 57, sho~m in its withdrawn position~ w~en released by the exterior handle 58 couples the two roll halves 30a and 30b togeth.er ~y means of a bolt 59 which engages an aperture (not sho.wn~ in th.e ~late. 47.
AccQrdingly, the tractiqn m,otor 12 through the geaxbox 15, sleeve 17, plate 18 and cushi.ons. 26 norm,a,lly- dr.i,~es the.ro,ll h.a~,f 30a,only (for the reasons explaine.d in th.e foregoing C~na'dian patent 1,019,997), the outer end of that roll being ~,n effect suppQrted by the stat;onary hub 11 to which'the motor 12, brake 13? ,and gear~o~
portion 15a are bolted, while the gearbox porti,on 15b, slee~e. l7, plate 18 and cush;~ons 26 rotate with the. roll h.alf 3Qa, The puter.end, ~
of the roll half 3Qb,however, IS supported ~y ~he bearing 24 so tha~ -the plate 25 and cushions 26 rotate with the roll half 3~b ~ela,~ye to the stationa.ry hub 2Q and plate 23, T~e ~ibrator ~Qtor 22'dri~e~
the two eccentric shafts '38 and 39 through their pinned connect~o"~:42 and the drive shaft 43 and couplings 44, The fo,r,ce produced by ~he 2S eccentric weights 41 is there~y transmi.tted to and throug~ the d~u~s.
36 and 37 and plates 34 and 35 directly to each roll s.hell 31a, and,:
31b. Owing to the cushions 26 the two r~ll h.alves 30a and 3nb t~us .
vibrate as a unit relative to the stationary yoke le~s 10, hu~$ 11 ,a,~nd 20, and the sleeve 17, the flexible. coupl~ngs 44 a,bsoxb~ng the c~ae-quent annular deflections of the vibrator dri~e shaft 43, ~ eanwhile, the adjacent ~nner ends of the xoll ha,lYe.s 30aand 30b are supported by the'turntable'be~ri,ng 50 ~Qr; rot,at~on ~nde.-pendently of each other, At the'sa~e'time tKe bear,ing 5Q, as will be observed, also both secures the two roll halves 30a and 30b against movement in either axial direction as well as against axial deflect~
ion relative to each other, all wlth a minimurn of extra weight, com-plexity and cost. The bearing 50 is basically a standard item but with little or no internal clearance in order to minimize axial de-flection of the roll halves 30a and 30b, the minimal clearance in the bearing 50 being accommodated by careful machining of the annular seats in the mounting plates 45 and 46 for the bearing races 51 and 52. The joint faces between races 51 and 52 of the bearing 50, as will be apparent, could be at an angle rather than parallel to the axis of the roll halves 30a and 30b and yet secure the latter against axial movement. Indeed, even if those faces were perpendicular to that axis, axial deflection of the roll halves 30a and 30b would ~till be precluded, though t~en some other means would be required ~o prevent axial separation o the two, Finally, in those instances where extra traction is needed, the plunger mechanism 47 can be re- :
leased so that the bolt 59 locks the two roll halves 30a and 30b to-gether, whence the traction motor 12 will thereby drive both as a unitary roll 30.

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Claims (20)

The embodiments of the invention in which an exclusive property or privilege is claimed are defined as follows:

1. In a road roller including at least one steerable roll having at least two co-axially adjacent roll shells providing a sub-stantially continuous cylindrical road engaging surface, mounting means for the roll shells permitting vibratory movement thereof rel-tive to remaining portions of the roll, the mounting means further providing for rotation of the roll shells relative to each other, and vibratory means effective upon each roll shell, the improvement where-in the mounting means includes bearing means disposed between the ad-jacent axial ends of the roll shells effective to permit said rotat-ion thereof relative to each other, the bearing means being further disposed sufficiently adjacent the periphery of the roll shells so that the bearing means by itself is effective to prevent displacement of the roll shells from said co-axial relationship.

2. The machine of claim 1 wherein the bearing means also resist axial displacement of the roll shells away from each other.

3. The machine of claim 2 wherein the bearing means in-cludes spaced bearing blocks secured adjacent the adjacent axial ends of respective ones of the roll shells, the bearing blocks having com-plementary opposed races therein co-axial with the roll shells, said races overlapping each other in a direction transversely of the rad-ius of the roll shells, and a plurality of rotatable bearing members disposed in said race effective to provide an interlocking relation-ship between the bearing blocks to thereby resist said axial and co-axial displacement of the roll shells.

4. The machine of claim 3 wherein the race of each bearing block forms a continuous circular raceway co-axial with the roll shells.

5. The machine of claim 4 wherein the bearing blocks in-clude opposed faces generally parallel to the axis of the roll shells said raceways being formed in said faces.

6. The machine of claim 5 wherein said raceways are also circular in cross section and the rotatable bearing members are spher-ical in shape.

7. The machine of claim 6 wherein the bearing blocks are generally annular in overall configuration.

8. The machine of claim 1 wherein at least a first one of the roll shells is provided with drive means for propelling the ma-chine along a road.

9. The machine of claim 8 wherein the second one of the roll shells is normally undriven and free to rotate independently of the first roll shell.

10. The machine, of claim 9 including means to optionally in-terconnect the roll shells effective to cause the first roll shell al-so to drive the second roll shell.

11. The machine of claim 8 wherein the vibratory means in clude vibration inducing members disposed within and carried by the roll shells, the inducing members being mounted for driven rotation relative to and co-axially with the roll shells.

12. The machine of claim 11 wherein the bearing means in-cludes a pair of spaced bearing members of generally annular config-uration, the bearing members being secured adjacent the adjacent ax-ial ends of respective ones of the roll shells, the bearing members having complementary opposed circular raceways therein co-axial with the roll shells, said raceways overlapping each other in a direction transversely of the radius of the roll shells, and a plurality of rotab-able members disposed in the raceways effective to provide an inter-locking relationship between the bearing members to thereby resist axial and co-axial displacement thereof.

13. The machine of claim 12 wherein the raceways are also circular in cross section and the rotatable members are spherical in shape.

14. In a steerable roll for a road roller, the roll includ-ing a pair of hub assemblies at and supporting the outer axial ends of the roll and a pair of co-axially adjacent roll shells providing a substantially continuous cylindrical road engaging surface, the roll shells being mounted for vibratory movement relative to the hub assemblies in directions transversely of the axis of the roll, the two roll shells being capable of rotation relative to each other, and vibratory means disposed within the roll and carried by the roll shells effective to provide said vibratory movement, the improvement comprising: means disposed adjacent the inner axial ends of the roll shells effective to support and maintain said ends in said co-axial relationship and to provide for said rotation of the roll shells re-lative to each other, said means including an annular bearing assem-bly co-axial with and carried by the roll shells, the bearing assem-bly having a sufficiently large diameter to provide substantially all of said effective support and maintenance to the inner axial ends of the roll shells.

15. The roll of claim 14 wherein the vibratory means com-prise vibratory members rotatable relative to the roll shells and co-axially therewith, and including vibratory drive means for the vib-ratory members disposed at one of the hub assemblies and an axially flexible drive shaft interconnecting the vibratory members and drive means.

16. The roll of claim 15 wherein the vibratory members in-clude a pair of interconnected vibrator shafts, each shaft being jour-naled in supporting means extending radially of one of the roll shells and secured thereto adjacent its inner axial end, said drive shaft being connected to one of said vibrator shafts.

17. The roll of claim 15 including roll drive means disposed, at the other of the hub assemblies and operative upon at least one of the roll shells for driving rotation thereof about its axis.

18. The roll of claim 17 wherein the other of the roll shells is normally undriven and free to rotate about its axis independently of the driven roll shell.

19. The roll of claim 14 wherein the annular bearing assem-bly also prevents axial movement of the roll shells away from each other.

20. The roll of claim 19 wherein the annular bearing assem-bly includes a pair of annular members secured to respective ones of the roll shells, the annular members having complementary opposed circular raceways therein co-axial with the roll shells, and a plu-rality of rotatable members disposed in the raceways, the raceways overlapping each other in a direction transversely of the radius of the roll shells effective to cause the rotatable members to provide an interlocking relationship between the annular members and thereby maintain said co-axial relationship of the roll shells and prevent said axial movement thereof.