FLOATING HEAD CUTTER MECHANISM FOR REMOVING TRAFFIC MARKINGS

Abstract: A vertically floating head cutter mechanism (20) comprising a mounting shroud (100) having an open bottom (106) and being suspended from a vehicle (22) in substantially vertically movable relation by a plurality of vertical guides (110). The vertical guides define upper and lower limits of vertical travel of the mounting shroud. First and second cutter head assemblies (131, 132) are operatively mounted within the mounting shroud adjacent the open bottom for counter-rotation about respective first and second axes. Hydraulic drive motors (141, 142) are operatively connected to the first and second cutter head assemblies for causing the counter-rotation thereof. Biasing springs (190) and hydraulically actuated cylinders (200) act between the mounting shroud and the vehicle for biasing the mounting shroud towards the lower limit of travel and for resiliently urging the first and second cutter head assemblies into cutting engagement with the road surface through the open bottom of the mounting shroud, with a substantially constant cutting force applied by each cutter head assembly to the road surface irrespective of irregularities encountered in the road surface as the vehicle moves therealong.

Description: FLOATING HEAD CUTTER MECHANISM FOR REMOVING TRAFFIC MARKINGS TECHNICAL FIELD The present invention relates to machines for removing traffic markings from a road surface, and more particularly to a vertically floating head cutter mechanism mounted on a vehicle that permits application of a constant cutting force by the cutter head mechanism to the road surface irrespective of irregularities encountered in the road surface. BACKGROUND ART It is common to paint assorted patterns of traffic markings, such as centre lines, directional arrows, and the like, on various types of road surfaces. Such road surfaces may include roads and parking lots, and so on, made from asphalt, concrete, or similar material. Such traffic markings are usually applied using special types of paints that permeate into the asphalt or concrete perhaps as much as a millimeter, so that the traffic markings do not readily wear off. Accordingly, in the event that it is necessary to remove the traffic markings, it is difficult to perform such removal without also removing a portion of the underlying road surface. Prior art traffic marking removers comprise small manually motive powered devices having a single cutter head assembly mounted on a main body for rotation of the cutter head assembly about a vertical axis. The cutter head assembly typically comprises a base member securely mounted on a drive shaft for rotation therewith about the vertical axis. A plurality of cutter heads are rotatably mounted on the base member in radially projecting relation thereto, each by means of a pair of cooperating cutter head bearings engaged on respective stub axles secured to the base member. The cutter heads are at all times, when in use, in contact with the road surface having a traffic marking to be removed therefrom. Accordingly, prior art traffic marking removers remove traffic lines by cutting a shallow rut in the road surface, which rut has substantially vertical sides separated by a span substantially the same width as the diameter of the cutter head assembly. The creation of such ruts is undesirable, since vehicle tires tend to get caught by the substantially vertical sides, which may be dangerous, especially at high speeds. Also, most prior art traffic marking removers tend to remove varying amounts of road surface, due to an inability to accurately control the downwardly directed pressure of the cutter heads on the road surface, especially at locations where dips, bumps or other irregularities are encountered in the road surface. Thus, when using prior art traffic marking removers, the vertical depth of road surface removed might vary significantly along the length of the traffic marking. As a consequence, in order to ensure that the marking is completely removed along its entire length, it is often necessary with prior art equipment to remove an excessive amount of road surface, thereby creating an excessively deep rut. It can be readily understood that the deeper the rut, the greater the danger of a vehicle tire being caught in the rut. It is also common for water to accumulate in the ruts, which is undesirable, and unsafe, especially if the water freezes. Also, since prior art traffic marking removers have only a single cutter head assembly, the torque from the engagement of the cutter head assembly with a road surface is counteracted only by the weight of the traffic marking remover and the strength of the operator. Accordingly, prior art traffic marking removers are operated at a cutter head assembly speed of about 300 to 500 r.p.m. so as to minimize torque. Even at that slow speed, however, prior art traffic marking removers tend to draw themselves off the course intended by the operator. Also, due to the slow rotational speed of the cutter head assembly, traffic marking removal tends to be quite slow. A typical rate of progress is in the order of about one kilometer per day, per machine. Another significant problem with prior art traffic marking removers is that of an unacceptable short useful life of drive shaft bearings and cutter head bearings. The drive shaft bearings and cutter head bearings are constantly, during use, subjected to a substantial lateral load. The drive shaft bearings and cutter head bearings are not typically lubricated, and thus generate a substantial amount of heat. It has been found that the temperature of drive shaft bearings and cutter head bearings may reach temperatures in the order of 350°F. Such high temperatures tend to substantially accelerate the wear of drive shaft bearings and cutter head bearings. Further, the drive shaft bearings and cutter head bearings are subjected to asphalt or concrete dust and debris created by the cutting operation. This dust and debris tends to settle in the bearings causing the bearings to wear out quickly, or suddenly seize. Yet another significant problem with prior art traffic marking removers is that of flat spots on the generally circular perimeter cutter heads. As the cutter head bearings become worn or contaminated by dust and debris, the cutter heads rotate less freely. This increases the likelihood that a perimeter section of the teeth of the cutter head that are in cutting contact with the road surface, will remain in cutting contact with the road surface. Accordingly, these teeth tend to become worn so as to create a "flat spot", and do not effectively cut the road surface. Once a flat spot is created, the cutter head tends to rotate until the flat spot is in contact with the road surface, and then stops rotating to maintain the "flat spot" in contact with the road surface. Not only do "flat spots" require frequent replacement of the cutter heads but they also tend to cause excessive wear on the cutter head bearings. It is therefore an object of the present invention to provide a novel vertically floating cutter head mechanism for removing a traffic marking from a road surface. DISCLOSURE OF THE INVENTION In accordance with one aspect of the present invention there is provided a vertically floating head cutter mechanism for removing a traffic marking from a road surface, said head cutter mechanism being mounted on a vehicle and comprising: at least one mounting shroud having an open bottom and being suspended from said vehicle in substantially vertically movable relation by a plurality of vertical guide means, said vertical guide means defining upper and lower limits of vertical travel of said mounting shroud; first and second cutter head assemblies operatively mounted within said at least one mounting shroud adjacent said open bottom for counter-rotation about respective first and second axes; drive means operatively connected to said first and second cutter head assemblies for causing said counter-rotation thereof about said first and second axes; and biasing means acting between said at least one mounting shroud and said vehicle for biasing said at least one mounting shroud towards said lower limit of travel and resiliently urging said first and second cutter head assemblies into cutting engagement with said road surface through the open bottom of said mounting shroud, with a substantially constant cutting force applied by each cutter head assembly to the road surface irrespective of irregularities encountered in said road surface as said vehicle moves therealong. The present invention provides advantages in that since a substantially constant cutting force is applied to the road surface irrespective of irregularities, traffic markings can be removed from a road surface quickly and effectively as compared to prior art machines. Also, the design of the cutter mechanism is such so as to avoid ruts formed in the road surface and "flat spots" formed on the cutter heads. BRIEF DESCRIPTION OF THE DRAWINGS A preferred embodiment of the present invention will now be described by way of example only with reference to the accompanying drawings in which: Figure 1 is a side elevational view of a vehicle having a vertically floating head cutter mechanism according to the present invention installed thereon, in use removing a traffic marking from a road surface; Figure 2 is a top plan view of the vertically floating head cutter mechanism of Figure 1; Figure 3 is a sectional top plan view similar to Figure 1, taken along section line 3-3 of Figure 1; Figure 4 is a side elevational view of the vertically floating head cutter mechanism of Figure 1 shown in a raised inoperative position, indicated by solid lining, and shown in a lowered in-use position, with the mounting shroud of the vertically floating head cutter mechanism indicated by phantom lining; Figure 5 is an end elevational view of the vertically floating head cutter mechanism of Figure 1; Figure 6 is an end elevational view similar to Figure 5, with the vertically floating head cutter mechanism shown in a raised inoperative position, and with the mounting shroud shown in phantom lining in an in-use configuration and shown in solid lining in a rotated access configuration; Figure 7 is a horizontal sectional view of the vertically floating head cutter mechanism of Figure 1, taken along section line 7-7 of Figure 9 A; Figure 8 is a vertical sectional view of the vertically floating head cutter mechanism of Figure 1, taken along section line 8-8 of Figure 3; Figure 9 A is a vertical sectional view of the vertically floating head cutter mechanism of Figure 1, taken along section line 9-9 of Figure 3; Figure 9B is an enlarged vertical sectional view of the portion of the area of Figure 9 A encircled by dashed lining; Figure 10A is an enlarged cross-sectional side elevational view of a front cutter head assembly shown in Figure 9A; Figure 10B is an enlarged cross-sectional side elevational view of a rear cutter head assembly shown in Figure 9A; Figure 11 A is an enlarged side elevational view of a cutter head having three spaced apart annular rows of cutting teeth thereon, used on the cutter head assemblies of the vertically floating head cutter mechanism of Figure 1 ; Figure 1 IB is an enlarged side elevational view of a cutter head having four spaced apart annular rows of cutting teeth thereon, used on the cutter head assemblies of the vertically floating head cutter mechanism of Figure 1; Figure 12A is an enlarged end elevational view of the cutter head of Figure 11 A; Figure 12B is an enlarged end elevational view of the cutter head of Figure 11B; Figure 13A is a view similar to Figure 9A, with the cutter heads removing a traffic marking from a substantially flat road surface; Figure 13B is a view similar to Figure 13 A, with the cutter heads removing a traffic marking from a road surface having a shallow depression therein; Figure 13C is a view similar to Figure 13 A, with the cutter heads removing a traffic marking from a road surface having a deeper depression therein than shown in Figure 13B; Figure 13D is a view similar to Figure 13 A, with the cutter heads removing a traffic marking from a road surface having a shallow rise thereon; Figure 13E is a view similar to Figure 13 A, with the cutter heads removing a traffic marking from a road surface having a steeper rise thereon than shown in Figure 13D; and, Figure 13F is a view similar to Figure 13 A, with the cutter heads removing a traffic marking from a road surface having an irregular surface. BEST MODE FOR CARRYING OUT THE INVENTION Referring now to Figure 1 , a vertically floating head cutter mechanism in accordance with the present invention is shown and is indicated by the general reference numeral 20. The vertically floating head cutter mechanism is for use on a vehicle 22 for removing traffic markings 26, such as traffic lines, directional arrows, and the like, from a road surface 27, constructed from asphalt, concrete, or similar materials. The vehicle 22 has three or more wheels for the sake of stability, and preferably has four wheels 24, specifically two front wheels 24f and two rear wheels 24r, which wheels 24f and 24r support substantially all of the vehicle weight. A diesel engine 28 is preferably mounted toward the rear of the vehicle 22, and powers all of the systems of the vehicle 22, through first to fourth hydraulic motors 31 to 34 respectively. The first hydraulic motor 31 is used to drive the rear wheels 24r of the vehicle 22 through hydraulic lines 31'. The second and third hydraulic motors 32 and 33 are used to drive cutter heads of the vehicle 22 through hydraulic lines 32' and 33', respectively, in a conventional manner. The fourth hydraulic motor 34 is used to drive other hydraulic systems of the vehicle 22 through hydraulic lines 34', as will be discussed in greater detail subsequently. A reservoir 36 supplies hydraulic fluid to the hydraulic motors 31 to 34 in a conventional manner. The vertically floating head cutter mechanism 20 is preferably mounted on the vehicle 22 by means of a mounting frame 40. As can be best seen in Figures 1 to 6, the mounting frame 40 comprises an inverted "U"-shaped stationary member 42 having a substantially horizontally disposed cross member 44 rigidly connected at each of its opposite ends to respective transverse arm portions 46. Both the cross members 44 and the two arm portions 46 are rigidly secured to the vehicle 22 by conventional means, such as threaded fasteners and/or welding (not shown). The mounting frame 40 further comprises a smaller inverted "U"-shaped pivoting member 48 that is substantially congruent to the inverted "U"-shaped stationary member 42. The inverted "U"-shaped pivoting member 48 has a horizontally disposed cross member 47 rigidly connected at each of its opposite ends to respective transverse arm portions 49 and is operatively mounted in nesting relation within the inverted "U"-shaped stationary member 42 by means of axially aligned horizontally disposed pivot pin members 50 retained in cooperating apertures 52 in the arm portions 46 and in cooperating apertures 54 in the arm portions 49. The inverted "U"- shaped pivoting member 48 is thus mounted for selective pivotal movement through at least ninety degrees of movement, as is indicated by arrow "N" in Figure 6, about a substantially horizontal axis "H" passing through the axially aligned pin members 50, between an in-use configuration, as is best seen in Figure 5 and as is partially illustrated in phantom lining in Figure 6, and an access configuration, shown in Figure 6 in solid lining. Both Figures 5 and 6 show the vertically floating head cutter mechanism 20 in its raised inoperative position. In the in-use configuration, the vertically floating head cutter mechanism 20 is oriented for removing traffic markings 26 from a road surface 27. In the access configuration shown in Figure 6, the various components of the vertically floating head cutter mechanism 20 are more readily accessible for maintenance purposes. The vertically floating head cutter mechanism 20 is retained in the in-use configuration by selective removable insertion of two opposed pairs of pin members 58, disposed one pair in each of the two adjacent pairs of arm portions 46 and 49, through respective aligned apertures 60 and 62 in the arm portions 46 and 49. The vertically floating head cutter mechanism 20 is retained in its access configuration by selective removable insertion of the pin members 58 through apertures 64 in transverse extension plates 66 secured to the arm portions 46 into the apertures 62 in the arm portions 49. As can best be seen in Figures 4 and 9A, an intermediate platform 70 is mounted in suspended relation from the vehicle 22 by a pair of substantially parallel linking arms 72. The intermediate platform 70 is preferably made from 1/4" steel plate for reasons of strength and rigidity. The linking arms 72 are pivotally mounted at their fixed ends 72a to the vehicle 22, for concurrent pivotal movement about a common pivot axis "A", each by means of a mounting pin 74 passing through aligned apertures 76 in a pair of opposed flanges 78 rigidly secured to a horizontal support arm 80. The horizontal support arm 80 in turn is rigidly secured to one of the arm portions 49. The linking arms 72 are pivotally mounted at their opposite moving ends 72b each by means of a mounting pin 82 passing through aligned apertures 84 in a pair of inner and outer opposed mounting flanges 86a and 86b rigidly secured to a laterally disposed elongate lubricant reservoir 89 mounted on the top surface 71t of the intermediate platform 70. The opposed inner and outer mounting flanges 86a and 86b each have an extended collar portion 87 to retain the mounting pin 82 in properly aligned non-binding relation in the respective apertures 84. The inner mounting flanges 86a are each part of a vertically and longitudinally disposed mounting plate 88. The linking arms 72, assist in controlling movement of the intermediate platform 70 between the lower zone of engagement positions, as shown in Figures 5, 9 A, and 13A through 13F, and an upper zone of non-engagement positions, as shown in solid lining in Figure 4. The lower zone of engagement positions of the intermediate platform 70 correspond to lowered in-use positions of the vertically floating head cutter mechanism 20, and the upper zone of non- engagement positions of the intermediate platform 70 correspond to raised inoperative positions of the vertically floating head cutter mechanism 20. In order to assist in lifting the intermediate platform 70 from its lower zone of engagement positions to the upper zone of non-engagement positions, two lifting springs 90 are operatively disposed between the vehicle 22 and the intermediate platform 70. Each lifting spring 90 is retained at its bottom end 90a in a cap member 92 secured to a horizontally disposed longitudinally extending end portion 48e of a respective arm portion 49. Downwardly open channel-shaped extensions 94 are rigidly secured one at each end of the intermediate platform 70 in outwardly projecting relation to receive the top end 90b of the respective lifting spring 90. The two lifting springs 90 substantially offset the weight of the vertically floating head cutter mechanism 20 to resiliently assist in the suspended, floating motion thereof. The vertically floating head cutter mechanism 20 also comprises a mounting shroud 100 having a substantially horizontal central deck 102, a skirt portion 104 downwardly depending from the substantially horizontal central deck 102, a flexible skirt seal 104a adjacent the lower perimeter of the skirt portion 104, and an open bottom 106 defined by the skirt seal 104a. The mounting shroud 100 is suspended from the vehicle 22 in a substantially vertically movable relation with respect to the vehicle 22 by a pair of vertical guide assemblies 110, as can best be seen in Figure 9B. The two vertical guide assemblies 110 are operatively interconnected between the intermediate platform 70 and the mounting shroud 100. Each vertical guide assembly 110 has a vertically oriented shaft 112 disposed in sliding relation within an internal bearing sleeve 114. The internal bearing sleeve 114 is welded or otherwise rigidly affixed to the top surface 711 of the intermediate platform 70. A robust washer 116 is securely threadably engaged into the top end 112a of the vertically oriented shaft 112 by a bolt 117 to limit the downward travel of the vertically oriented shaft 112 in the internal bearing sleeve 114. A flange 118 at the bottom end 112b of the vertically oriented shaft 112 is retained within a bearing block 120 securely welded to the top surface 101 of the mounting shroud 100. The flange 118 engages a spherical plain bearing 122 mounted on an annular shoulder 124 within the bearing block 120 to accommodate limited angular movement of the mounting shroud 100 with respect to the intermediate platform 70, thus precluding the vertical guide assemblies 110 from binding in the event that the vertically floating head cutter mechanism 20 becomes slightly angled, as it will often be during use. It can be seen that the vertical guide assemblies 110 define upper and lower limits position of vertical travel of the mounting shroud 100 relative to the intermediate platform 70, and ideally accommodate about one inch of vertical travel of the mounting shroud 100. A positioning spring 126 disposed in each of the vertical guide assemblies 110 in surrounding relation to the shaft 112 biases the mounting shroud 100 away from the intermediate platform 70 thus providing spacing between the mounting shroud 100 and the intermediate platform 70. The spacing accommodates at least one half inch of upward travel of the mounting shroud 100 with respect to the intermediate platform 70. Further, there preferably exists a gap of about one half inch or more between the robust washer 116 and the top end 112a of the vertically oriented shaft 112. The two vertical guide assemblies 110, as described, locate the mounting shroud 100 in an operative intermediate position between the upper and lower limits, as can be best seen in Figure 9B. Such intermediate positioning permits for both upward and downward travel of the mounting shroud 100 to accommodate irregularities in the road surface 27 as described more fully below. The vertically floating head cutter mechanism 20 further comprises a first cutter head assembly 131, and a second cutter head assembly 132, each operatively mounted within the mounting shroud 100 adjacent the open bottom 106 for counter-rotation about a first axis "F", and a second axis "S", respectively. As can be best seen in Figure 7, the first cutter head assembly 131 preferably rotates clockwise, as indicated by arrow "CW" and the second cutter head assembly 132 rotates counter-clockwise, as indicated by arrow "CCW" when the mounting shroud 100 is viewed from the top. First and second hydraulic drive motors 141 and 142 are operatively connected to the first and second cutter head assemblies 131 and 132, respectively, for causing the counter-rotation thereof. The counter-rotation of the first and second cutter head assemblies 131 and 132 ensures counterbalancing of the centrifugal torque from the first and second hydraulic drive motors 141 and 142 to stabilize movement of the mounting shroud 100. The first and second hydraulic drive motors are each mounted above the central deck 102 of the mounting shroud 100 on a frame member 144 substantially directly above the first and second cutter head assemblies 131 and 132, respectively. Each frame member 144 extends upwardly from the mounting shroud 100 through a respective square opening 69 in the intermediate platform 70 (see Figures 3 and 4). As can be best seen in Figures 2 and 3, horizontally oriented springs 146 are disposed in operative relation between the mounting shroud 100 and each of the frame members 144 for controlling lateral movement of the first and second cutter head assemblies 131 and 132. Specifically, one end 146a of each spring 146 is retained in a cap 147. The cap 147 is adjustably mounted on the vertically and longitudinally disposed mounting plate 88 in adjustable relation by nut 149 threadably engaged on a cooperating rod (not shown), so as to permit selective compression of the respective spring 146. The opposite other end 146b of each spring 146 is intimately engaged against the side 148 of the respective frame member 144. First and second drive shafts 151 and 152 are operatively rotatably mounted in respective first and second housings 153 and 154 affixed to the central deck 102 and are connected at their top ends 151a, 152a to respective propeller shafts 155, 156 of the first and second hydraulic drive motors 141 and 142, by way of releasable couplings 157, 158, for rotation about respective first "G" and second "T" substantially vertical drive axes. In the preferred embodiment, the releasable couplings are Bowex couplings manufactured by Ontario Drive and Gear of New Hamburg, Ontario, Canada, which Bowex releasable couplings allow for about four degrees of axial misalignment between the propeller shafts 155, 156 and the respective drive shafts 151, 152. As can be best seen in Figure 10A and 10B, a portion of the first and second drive shafts 151 and 152 are rotationally mounted in substantially centrally disposed bores 159 defined in the first and second housings 153 and 154, respectively, by means of upper and lower tapered roller bearings 161u and 1611 mounted within the bores 159 against shoulders 167a, and 167b, respectively. A collar member 150 frictionally engages each drive shaft 151, 152 with an "O"-ring 150o disposed in sealing engagement therebetween. The first and second drive shafts 151 and 152 are retained within the first and second housings 153 and 154, respectively, by lock washers 143 and locking nuts 145 intimately engaged in securing relation against the collar member 150. The bores 159 are sealed off at their respective upper ends 159u each by a self expanding oil seal 173 disposed in sealing relation between the collar member 150 and the respective drive shaft 151, 152. In order to preclude backlash of the upper and lower tapered roller bearings 161u and 161b, the locking nuts 145 are preferably hand tightened until snug and are backed off about one quarter turn. The first and second housings 153 and 154 are securely mounted on the central deck 102 by means of first and second annular mounting members 163 and 164. The annular mounting members are preferably welded to the underside of the central deck 102. The first and second annular mounting members have respective first and second cylindrical passageways 165 and 166 with longitudinal axes coincident with the first "G" and second "T" drive axes, respectively. The first and second housings 153 and 154 are rigidly retained in close fitting relation within the first and second cylindrical passageways 165 and 166, respectively. As can be best seen in Figures 9 A, 10 A, and 10B, the first and second annular mounting members 163 and 164 are preferably beveled at their respective top surfaces 163t, 164t so as to incline the first cylindrical passageway 165 forwardly and upwardly and incline the second cylindrical passageway 166 rearwardly and upwardly. The first and second housings 153 and 154 are thereby angled such that the first axis "G" and second axis "T" are coincident with the first axis "F" and the second axis "S". The first "G" and second "T" drive axes are each inclined at an angle of between zero degrees and ten degrees with respect to vertical. In the preferred embodiment, the first "G" and second "T" drive axes are each inclined at an angle of about three degrees with respect to vertical, with the first drive axis "G" being inclined forwardly and upwardly, and the second drive axis "T" being inclined rearwardly and upwardly. Each of the first and second cutter head assemblies 131 and 132 comprises a base member 170 secured to a respective drive shaft 151, 152 by means of a banjo bolt 172 threadably engaged in the bottom end 151b, 152b of the drive shaft 151, 152, for coincident rotation therewith. An upper annular neck 169 of the base members 170 is seated in the lower end 1531, 1541 of each of the first and second housings 153 and 154, partially within the bores 159. A small clearance between the upper annular neck 169 and the respective first and second housing 153 and 154, and a band of Teflon® packing 168p disposed in an annular race 168r in the upper annular neck 169, together ensure free rotation of the base member 170 with respect to the respective first and second housing. The bores 159 are sealed off at the respective base member 170 by a self expanding oil seal 149 disposed in sealing relation between each bore 159 and the respective drive shaft 151, 152. The banjo bolts 172 also retain in place within a concavity formed in the bottom surface of the base member 170, a cup-shaped plug member 174. The base member 170 and the cup-shaped plug member 174 together define a central chamber 175 within the base member 170. An "O"-ring 178o seated within a cooperating annular race 178r provides a seal between the banjo bolt 172 and the cup-shaped plug member 174. The first and second drive shafts 151 and 152 are operatively connected at their respective tapered lower ends 1511, 1521 to cooperating receiving tapers 176 in the respective base members 170. As can be best seen in Figure 7, each of the first and second cutter head assemblies comprises six annular cutter heads 180a and 180b. The three annular cutter heads 180a of each assembly have three spaced apart annular rows of cutting teeth 182, while the three annular cutter heads 180b of each assembly have four spaced apart annular rows of cutting teeth 182, disposed in an alternating pattern around the base member 170, as can be best seen in Figures 11 A and 1 IB. The rows of teeth 182 are thereby offset in alternating ones of the annular cutter heads 180a and 180b. In this manner, no grooves or spaces remain when a traffic marking 26 is being removed from a road surface 27. Instead, a substantially smooth cut is made in the road surface 27. Each of the annular cutter heads 180a, 180b is rotatably mounted on a respective stub axle 181 by means of inner and outer tapered roller bearings 1831 and 183o retained in central bores 184 in the respective ones of the annular cutter heads 180a, 180b. The stub axles 181 are threadably engaged to the base member 170 in substantially evenly spaced radially outwardly projecting relation. The inner and outer tapered roller bearings are retained in place against shoulders 184i and 184o, respectively, by a lock washer 185a and a lock nut 185b threadably engaged on the respective stub axle to take up the backlash between the outer tapered roller bearing 183o and the shoulder 184o. Preferably, the stub axles 181 on the first cutter head assembly 131, which rotate clockwise when viewed from the bottom, have right hand threads thereon so that the rotation of the annular cutter heads 180 provides a continuous tightening effect on the respective stub axles 181. Similarly, the stub axles 181 on the second cutter head assembly 131, which rotates counter-clockwise when viewed from the bottom, have left hand threads thereon so that the rotation of the annular cutter heads 180 provides a continuous tightening effect on the respective stub axles 181. Each central bore 184 is closed off at an outer end by an end cap 186 retained in place by a respective "C" clip 187a seated in an annular race 187r. Similar, a mounting collar 189 and cooperating "O"-ring 189o are retained in place at the opposite inner end of each central bore 184 by a "C" clip 179a seated in an annular race 179r. The mounting collar 189 is received in rotatable relation within a respective cylindrical orifice 171 in the base member 170. A self expanding oil seal 173 is disposed in sealing relation between the mounting collar 189 and the stub axle 181. The axes of rotation "C" of each of the annular cutter heads 180 of the first and second cutter head assemblies 131 and 132, respectively, are preferably angled upwardly and radially outwardly from the base member 170 at an angle with respect to horizontal, which angle is substantially equal to the angle of inclination of the first and second drive axes. As previously mentioned, this angle is preferably between about zero degrees and ten degrees with respect to vertical, and is optimally about three degrees. In this manner, the annular cutter heads 180 intermittently contact the road surface 27 and are lifted from the road surface 27 as the first and second cutter head assemblies rotate. Accordingly, the annular cutter heads 180a, 180b are permitted to rotate between contacts with the road surface 27, even if not during contact with the road surface 27, thus helping to ensure that flat spots do not develop on the cutter head teeth 182. Further, the annular cutter heads 180 are oriented substantially horizontally to the road surface 27 when in contact therewith, in order to facilitate proper cutting. The vertically floating head cutter mechanism 20 further comprises biasing means indirectly interconnected between the mounting shroud 100 and the vehicle 22. The biasing means comprises at least one spring member 190 disposed in operatively interconnected relation between the mounting shroud 100 and the vehicle 22, to bias the mounting shroud 100 downwardly with respect to the vehicle 22 into cutting engagement with the road surface 27 in at least the operative intermediate position of the mounting shroud 100. In the preferred embodiment, the biasing means comprises an even plurality of spring members 190, specifically eight spring members 190, with each of the eight spring members 190 being mounted in a respective cap member 192 welded to the top surface 101 of the central deck 102 and engaging the bottom surface 71b of the intermediate platform 70. The spring members 190 are held in a slight degree of compression by appropriate dimensioning of the bolt 117 and the robust washer 116 of the vertical guide assemblies 110, so as to keep the spring members 190 from coming out of their cap members 192 when the first and second cutter head assemblies 131 and 132 are not in engagement with the road surface 27. When the intermediate platform 70 is in its lower zone of engagement positions, the first and second cutter head assemblies 131 and 132 are resiliently urged into cutting engagement with the road surface 27. Accordingly, the spring members 190 are compressed by the weight of the vertically floating head cutter mechanism 20 to a preferable force of about seventy five pounds each, for a total downward force on the mounting shroud 100 of about six hundred pounds. Since the weight of the vertically floating head cutter mechanism 20 is essentially offset by the two lifting springs 90, the downwardly directed force of the cutter heads 180 on the road surface 27 is about six hundred pounds. Each of the spring members 190 is preferably a progressive rate coil spring designed to keep a substantially constant downwardly directed force on the mounting shroud 100, over a vertical travel of about one half inch up and about one half inch down of the mounting shroud 100 with respect to the intermediate platform 70. Accordingly, the progressive rate coil springs 190 bias the mounting shroud 100 towards the lower limit of travel, and resiliently urge the first and second cutter head assemblies into cutting engagement with the road surface 27. Thus, a substantially constant cutting force is applied by each of the first and second cutter head assemblies to the road surface 27 irrespective of irregularities encountered in the road surface 27 as the vehicle 22 moves therealong. The biasing means additionally comprises two hydrauhcally actuated cylinders 200 each interconnected at one end 200a to the inverted "U"-shaped pivoting member 48 and connected at the opposite other end 200b to respective mounting collars 202 on the downwardly open channel-shaped extensions 94 of the intermediate platform 70. The two hydrauhcally actuated cylinders 200 produce, by hydraulic pressure, an output force proportional to the hydraulic pressure and direct the output force onto the mounting shroud 100 to downwardly bias the mounting shroud 100. The two hydrauhcally actuated cylinders 200 direct their output force indirectly onto the mounting shroud 100 through the spring members 190. The output force is selectably actuable by means of a directional valve 204 and is selectively adjustable by means of an absolute pressure control valve 206 (see Figure 1). The input of the directional valve 204 is operatively connected in fluid communication (by hydraulic line 34') to the fourth hydraulic motor 34. The input of the absolute pressure control valve 206 is from the directional valve 204 and the output of the absolute pressure control valve 206 is operatively connected in fluid communication (by hydraulic lines 206') to both of the two hydrauhcally actuated cylinders 200 to allow for selective control of the hydraulic pressure in the two hydrauhcally actuated cylinders 200. The directional valve 204 is used by the operator to selectively control the vertical position of the vertically floating head cutter mechanism 20, and thus control the engagement of the first and second cutter head assemblies 131 and 132 with the road surface 27, by raising and lowering the intermediate platform 70 between its lower zone of engagement positions and its upper zone of non- engagement positions. In use, when it is required to place the first and second cutter head assemblies into cutting engagement with the road surface 27, a control lever 205 on the directional valve 204 is manually manipulated by the operator to direct hydraulic pressure to the two hydrauhcally actuated cylinders 200. This results in the li vertically floating head cutter mechanism 20 being lowered against the upwardly directed force of the lifting springs 20, so as to bias the mounting shroud 100 towards the lower limit of travel and resiliently urge the first and second cutter head assemblies 131 and 132 into cutting engagement with the road surface 27. Once the first and second cutter head assemblies are lowered into cutting engagement with the road surface 27, the desired cutting pressure may be selected by the operator. A control lever 207 on the absolute pressure control valve 206 is manually manipulated by the operator to set the hydraulic pressure in the two hydrauhcally actuated cylinders 200, thereby to set the downwardly directed force of the cutter heads 180a, 180b on the road surface 27 in order to achieve a desired depth of cut. Further, the absolute pressure control valve 206 is adapted to maintain the operator selected hydraulic pressure within the hydrauhcally actuated cylinders 200 at a substantially constant value. Accordingly, the hydrauhcally actuated cylinders 200 maintain a substantially constant downwardly directed force on the mounting shroud 100, to urge the first and second cutter head assemblies 131 and 132 into cutting engagement with the road surface 27 with a substantially constant cutting force irrespective of irregularities encountered in the road surface 27 as the vehicle 22 moves therealong, and without operator intervention. Thus, there is maintained a substantially constant downwardly directed force by the first 131 and second 132 cutter head assemblies onto the road surface 27, when the cutter heads 180 engage the road surface 27, to thereby achieve a substantially constant cutting depth. In the preferred embodiment, the absolute pressure control valve 206 is manufactured by Sunstran Industries of Toronto, Ontario Canada. When it is required to remove the first and second cutter head assemblies 131 and 132 from engagement with the road surface 27, the control lever 205 on the directional valve 204 is manually manipulated by the operator to divert hydraulic pressure from the hydrauhcally actuated cylinders 200, causing the hydrauhcally actuated cylinders 200 to shorten. Accordingly, the two lifting springs 90 lift the intermediate platform 70 from its lower zone of engagement positions to its upper zone of non-engagement positions, and thereby lift the vertically floating head cutter mechanism 20, as indicated by arrows "L" in Figure 4. The vehicle 22 can then be moved without cutting the road surface 27. Once the vehicle 22 is again in place for removing a traffic marking 26, the control lever 205 on the directional valve 204 is manually manipulated by the operator to direct hydraulic pressure to the hydrauhcally actuated cylinders 200 to automatically return to its selected level, thus lengthening the cylinders 200 to again resiliently urge the first 131 and second 132 cutter head assemblies into cutting engagement with the road surface 27 with a substantially constant cutting force. In this manner, it will be appreciated that it is not necessary to reselect the previously selected downwardly directed force applied by the first and second cutter head assemblies to the a road surface 27. Another problem addressed by the present invention is that of lubrication and cooling of the drive shafts 151, 152 and cutter heads 180a and 180b. The bores 159 of the first and second housings 153 and 154 are each adapted to contain a bath of lubricant 210 for lubrication of an exterior portion 151 e, 152e of each of the first and second drive shafts 151 and 152 and the upper and lower tapered roller bearings 161u and 1611. Lubricant 210 placed in the bores 159 is supplied by the remote lubricant reservoir 89, and is gravity fed through two supply hoses 212a, 212b connected in fluid communication to the remote lubricant reservoir 89 through a "T" fitting 214. The first and second drive shafts 151 and 152 each have radial passageways 221, 222 extending in fluid communication between the exterior portion 151e, 152e of the respective drive shaft 151, 152 and an axially disposed longitudinal passageway 223 within the respective drive shaft 151, 152. The banjo bolts 172 also each have an axially disposed longitudinal passageway 225 in fluid communication with radial passageways 226. When the banjo bolts 172 are in place in each of the drive shafts 151, 152, their axially disposed longitudinal passageways 225 are in fluid communication with the longitudinal passageways 223 and the radial passageways 226 are in fluid communication with the central chamber 175 in the base member 170. In this manner, the bores 159 are in fluid communication with the central chamber 175 in the base member 170 of the respective cutter head assembly 131, 132. Also, the stub axles 181 of each of the first and second cutter head assemblies each have an axially disposed longitudinal passageway 230 in fluid communication at a proximal end 230a thereof with the central chamber 175 and in fluid communication at an opposite distal end 230b with one or more radial passageways 232. The radial passageways 232 are in fluid communication with the central bore 184 in the respective annular cutter head 180, so as to provide for passage of the lubricant 210 to the inner and outer tapered roller bearings 183i and 183o. As can be best seen in Figures 10A and 10B, the lubricant flows from the bores 159 into the respective radial passageway 221, 222, as indicated by arrows "D"; flows into and through the respective passageway 223, as indicated by arrows "E"; flows through the passageway 225 and the radial passageways 226 of the banjo bolt 172, and into the central chamber 175 of the respective base member 170, as indicated by arrows "I"; flows into and through the central bores 184 in the cutter heads 180, as indicated by arrows "J"; and flows into and through the radial passageways 232, so as to be introduced into the central bore 184 in the respective annular cutter head 180, as indicated by arrows "K", thus lubricating the cutter head assemblies 131, 132, especially the inner and outer tapered roller bearings 183i and 183o. Lubricating the roller bearings in this manner has been found to keep the roller bearings at an operating temperature in the order of 100°F in contrast with bearings in prior art traffic marking removers, which operate at temperatures in the order of 350°F. In addition to being gravity fed, the centrifugal force created by the rotation of each of the first and second cutter head assemblies 131 and 132 helps draw the lubricant to the inner and outer tapered roller bearings 183i and 183o, and also to the end caps 186, thus precluding dust from entering into the central bores 184 of the cutter heads 180. As can be appreciated by those skilled in the art, removal of traffic markings 26 from road surface 27, by the vertically floating head cutter mechanism 20, requires a substantial amount of cutting force applied by the cutter heads 180. Accordingly, the cutter heads 180 tend to wear, although much less frequently than with prior art traffic marking removers, and may even break occasionally. Also, the various bearings are subjected to considerable loads and may require periodic replacement, although less frequently than with prior art traffic marking removers. It is preferable to perform maintenance on location and as quickly as possible, in order to minimize unproductive "down time". It can therefore be seen that the mounting frame 40, having an inverted "U"-shaped stationary member 42 rigidly secured to the vehicle 22 and a substantially congruent inverted "U"-shaped pivoting member 48 mounted in pivotal relation within the stationary member 42 for selective pivotal movement between an in-use configuration and access configuration, as indicated by arrow "N" permits ready access to the open bottom 106 of the mounting shroud 100 and to the first and second cutter head assemblies 131 and 132 when in the access configuration. It is first necessary to lift the intermediate platform 70 from its lower zone of engagement positions to its upper zone of non-engagement positions, and thereby lifting the vertically floating head cutter mechanism 20 from its lowered in- use position to its raised inoperative position, as indicated by arrows "L" in Figure 4, before rotating the pivoting member 48 from its in-use configuration to its access configuration. Reference will now be made to Figures 7 A and 13A to 13F of the drawings to show the vertical movement of the vertically floating head cutter mechanism 20 as the vehicle 22 moves in a direction as indicated by arrows "Z". Referring now to Figures 7 and 13 A, it can be seen that as the first and second cutter head assemblies 131 and 132 rotate, the cutter heads 180a, 180b come down from a slightly lifted position to contact and cut the road surface 27. On the first cutter head assembly 131 , the cutter head 180a that is disposed adjacent the front of the mounting shroud 100 first contacts the road surface 27. Similarly, on the second cutter head assembly 132, the cutter head 180a that is disposed adjacent the rear of the mounting shroud 100 contacts the road surface 27. The cutter heads 180a, 180b mounted on the first cutter head assembly 131 cut a groove to a partial depth, and the cutter heads 180a, 180b mounted on the second cutter head assembly 131 cut more deeply so as to cut the desired depth of groove and remove the traffic marking 26 from the road surface 27. Due to the angles of inclination of the first axis "F" and the second axis "S", the cutter heads 180 contact the road surface 27 at a limited cutting sector only, as indicated by arrow "Y" in Figure 7. In this manner, a shallowly curved groove having a width of about twelve to fifteen inches and no substantially transverse side edges is cut, as can be best seen in Figures 7 and 8. If the road surface 27 has a slight depression therein, as can be best seen in Figure 13B, the spring members 190 extend slightly, as indicated by arrows "O", so as to permit the mounting shroud 100 to move downwardly from its operative intermediate position to its lower limit of travel, all the while resiliently urging the first and second cutter head assemblies 131 and 132 into cutting engagement with the road surface 27 with a substantially constant cutting force. At its lower limit of travel, the gap between the robust washer 116 and the top end 112a of the vertically oriented shaft 112 of the two vertical guide assemblies 110, disappears, as indicated by arrows "P". Accordingly, the spring members 190 cannot extend further. If the road surface 27 has a greater depression therein, as can be best seen in Figure 13C, the hydrauhcally actuated cylinders 200 are lengthened, as indicated by arrows "Q", and the two lifting springs 90 are further compressed, as indicated by arrows "R", by the pulling of the intermediate platform 70, so as to permit the intermediate platform 70 to move to a lower position in its lower zone of engagement positions. The lengthening of the hydrauhcally actuated cylinders 200 correspondingly decreases the hydraulic pressure in the hydrauhcally actuated cylinders 200. Accordingly, the absolute pressure control valve 206 compensates for the decreased hydraulic pressure and continuously increases the hydraulic pressure back to the operator selected value, thus maintaining the hydraulic pressure in the hydrauhcally actuated cylinders 200 at a substantially constant value. The mounting shroud 100 is retained in its lower limit of travel, and the first and second cutter head assemblies 131 and 132 are resiliently urged into cutting engagement with the road surface 27 with a substantially constant cutting force. If the road surface 27 has a slight rise therein, as can be best seen in Figure 13D, the spring members 190 compress slightly, as indicated by arrows "U", so as to permit the mounting shroud 100 to move upwardly from its operative intermediate position to its upper limit position, all the while resiliently urging the first and second cutter head assemblies into cutting engagement with the road surface 27 with a substantially constant cutting force. At its upper limit position, the gap between the robust washer 116 and the top end 112a of the vertically oriented shaft 112 of the two vertical guide assemblies 110 increases in size, as indicated by arrows "V", until the spring members 190 cannot compress further. If the road surface 27 has a greater rise therein, as can be best seen in Figure 13E, the hydrauhcally actuated cylinders 200 are shortened, as indicated by arrows "W", and the two lifting springs 90 are extended, as indicated by arrows "X", by the pushing of the intermediate platform 70, so as to permit the intermediate platform 70 to move to a higher position in its lower zone of engagement positions. The shortening of the hydrauhcally actuated cylinders 200 correspondingly increases the hydraulic pressure in the hydrauhcally actuated cylinders 200. Accordingly, the absolute pressure control valve 206 compensates for the increased hydraulic pressure and continuously decreases the hydraulic pressure back to the operator selected value, thus maintaining the hydraulic pressure in the hydrauhcally actuated cylinders 200 at a substantially constant value. Accordingly, the mounting shroud 100 is retained in its upper limit of travel, and the first and second cutter head assemblies are resiliently urged into cutting engagement with the road surface 27 with a substantially constant cutting force. Figure 13F illustrates that the first and second cutter head assemblies 131 and 132 can independently follow an uneven road surface whilst maintaining a substantially constant cutting force. As shown, the second cutter head assembly 132 has lowered by a significant distance, perhaps about two inches. Accordingly, only one of the hydrauhcally actuated cylinders 200 has extended, as indicated by arrow "L" and only one of the lifting springs 90 has compressed, as indicated by arrow "M", thus compensating for the uneven movement. It has been found that a rotational speed of the first and second cutter head assemblies 131 and 132 of about 1800 r.p.m. can be consistently achieved. This rotational speed is far superior to that achieved by prior art machines. Also, it has been found that a traveling speed of about two kilometers per hour can be readily sustained. This traveling speed is about ten to twenty times faster than prior art machines, and that a closely controlled cutting path can be followed at that speed. Further, the vertically floating head cutter mechanism 20 produces a cut without substantially vertical sides and having an almost unvarying central depth of between five and eight millimeters, which is not possible with prior art traffic marking removers. Although a preferred embodiment of the present invention has been described those of skill in the art will appreciate that modifications and variations may be made without departing from the spirit and scope thereof as defined by the appended claims.

Claims: WHAT IS CLAIMED IS: 1. A vertically floating head cutter mechanism for removing a traffic marking from a road surface, said head cutter mechanism being mounted on a vehicle and comprising: at least one mounting shroud having an open bottom and being suspended from said vehicle in substantially vertically movable relation by a plurality of vertical guide means, said vertical guide means defining upper and lower limits of vertical travel of said mounting shroud; first and second cutter head assemblies operatively mounted within said at least one mounting shroud adjacent said open bottom for counter-rotation about respective first and second axes; drive means operatively connected to said first and second cutter head assemblies for causing said counter-rotation thereof about said first and second axes; and biasing means acting between said at least one mounting shroud and said vehicle for biasing said at least one mounting shroud towards said lower limit of travel and resiliently urging said first and second cutter head assemblies into cutting engagement with said road surface through the open bottom of said mounting shroud, with a substantially constant cutting force applied by each cutter head assembly to the road surface irrespective of irregularities encountered in said road surface as said vehicle moves therealong. 2. A cutter mechanism as defined in claim 1, wherein said biasing means comprises at least one spring member. 3. A cutter mechanism as defined in claim 2, wherein said biasing means comprises an even plurality of generally parallel spring members. 4. A cutter mechanism as defined in claim 3, wherein said biasing means further comprises a hydrauhcally actuated cylinder acting between said vehicle and said mounting shroud and operable to present a bias to said mounting shroud. 5. A cutter mechanism as defined in claim 4, wherein said bias is adjustable by means of a directional valve in fluid communication with said hydrauhcally actuated cylinder for selectively contracting or extending said hydraulic cylinder. 6. A cutter mechanism as defined in claim 5, further comprising an automatic pressure control in fluid communication with said directional valve and being adapted to maintain said bias at a substantially constant value. 7. A cutter mechanism as defined in claim 4, further comprising an intermediate platform mounted in suspended relation between said vehicle and said at least one mounting shroud for substantially vertical movement between a lower zone of engagement positions and an upper zone of non-engagement positions, and wherein said vertical guide means are operatively interconnected between said intermediate platform and said at least one mounting shroud. 8. A cutter mechanism as defined in claim 7, wherein said hydrauhcally actuated cylinder is operatively interconnected between said vehicle and said intermediate platform so as to present said bias onto said at least one mounting shroud through said spring members, said spring members being mounted between said intermediate platform and said mounting shroud. 9. A cutter mechanism as defined in claim 8, further comprising at least one lifting spring operatively disposed between said vehicle and said intermediate platform to assist in lifting said intermediate platform from said lower zone of engagement positions toward said upper zone of non-engagement positions. 10. A cutter mechanism as defined in claim 9, wherein said vertical guide means additionally accommodates limited angular movement of said at least one mounting shroud with respect to said intermediate platform. 11. A cutter mechanism as defined in any one of the preceding claims, wherein said drive means includes first and second hydraulic drive motors mounted on a frame member above said first and second cutter head assemblies, respectively said first and second hydraulic motors including drive shaft means coupled to said first and second cutter head assemblies. 12. A cutter mechanism as defined in claim 11, wherein said first and second axes are each inclined at an angle of between zero degrees and ten degrees with respect to vertical. 13. A cutter mechanism as defined in claim 12, wherein said first axis is inclined forwardly and upwardly, and said second axis is inclined rearwardly and upwardly. 14. A cutter mechanism as defined in any one of the preceding claims, wherein each of said first and second cutter head assemblies comprises a base member secured to a respective drive shaft means and a plurality of annular cutter heads each rotatably mounted on a respective stub axle, said stub axles being affixed to said base member in substantially evenly spaced radially outwardly projecting relation. 15. A cutter mechanism as defined in claim 14, wherein the axes of rotation of each of said annular cutter heads of said first and second cutter head assemblies, respectively, are angled upwardly and radially outwardly from said base member at an angle with respect to horizontal, said angle being substantially equal to the angle of inclination of said first and second axes. 16. A cutter mechanism as defined in claim 15, wherein said plurality of annular cutter heads comprises six annular cutter heads. 17. A cutter mechanism as defined in claim 16, wherein said six cutter heads comprise three annular cutter heads having three spaced apart annular rows of cutting teeth and three annular cutter heads having four spaced apart annular rows of cutting teeth, disposed in an alternating pattern around said base member. 18. A cutter mechanism as defined in any one of claims 11 to 17 further including a reservoir of lubricant for supplying lubricant to said drive shaft means. 19. A cutter mechanism as defined in claim 18 wherein said reservoir of lubricant further supplies lubricant to said cutter head assemblies to lubricate said cutter heads. 20. A cutter mechanism as defined in any one of the preceding claims, further comprising means for controlling lateral movement of said first and second cutter head assemblies.

Inventors: BREMNER ANDREW P, BREMNER CLIFFORD P, BREMNER, ANDREW, P., BREMNER, CLIFFORD, P.
Applicants: BARTELL IND INC, BARTELL INDUSTRIES, INC.
Application year: 1998
Main classification: E01C23
IPC codes: E01C23