It is common to paint assorted patterns of traffic markings, such as center 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, which drive shaft is mounted in a housing by means of a pair of cooperating drive shaft bearings. 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 uncontrolled varying amounts of road surface, due to an inability to accurately control the downwardly directed pressure of the cutter heads on the road surface. It is usually not possible for prior art traffic marking removers to apply a constant cutting force by the cutter head mechanism to a road surface having a traffic marking removed therefrom, especially at locations where dips, bumps or other irregularities are encountered in the road surface. Thus, using prior art traffic marking removers, the vertical depth of road surface removed might easily vary along the length of the traffic marking being removed from virtually nothing removed, to far too much removed. As a consequence, in order to ensure that the marking is completely removed along its entire length, it is necessary with prior art equipment to remove an excessive amount of road surface, thereby creating an excessively deep rut along at least some portion of the length of the marking. 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 thus created, which is undesirable, and unsafe, especially if the water freezes.
Indeed, it has been found, that in many jurisdictions, governmental bodies responsible for the maintenance of roads have set forth specifications for traffic marking removal on some road surfaces, such as highways, which specifications usually cannot be met by prior art traffic marking removers, especially if the road surface is uneven. It is often only through chance that a traffic line removal done by a prior art traffic marking remover apparatus conforms to such specifications.
Also, since prior art traffic marking removers have only a single cutter head assembly, the torque from the engagement of the single 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 such torque. Even at that slow speed, however, prior art traffic marking removers tend to draw themselves off the course intended by the operator, which is unacceptable. 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 degrees 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, which dust and debris tend to settle in the bearings. Accordingly, the bearings tend to wear out very quickly, or suddenly seize, and therefore must be replaced as frequently as every day, or even more frequently, depending on the particular application, which replacement is extremely undesirable in terms of unproductive down time and in terms of the actual cost of the bearing replacement.
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, which 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 said cutting contact with the road surface. Accordingly, these teeth tend to become worn so as to create a "flat spot", which worn teeth do not effectively cut the road surface. Once a flat spot comes into existence on a cutter head, the cutter head will rotate until the flat spot is in contact with the road surface, and will remain in contact with the road surface, thus accelerating the wear of the already overly worn teeth. The cutter head must then be replaced in order to achieve proper cutting of a road surface. It is common for cutter heads to be replaced quite frequently, perhaps even daily, depending upon the nature of the job conditions, which is extremely undesirable in terms of unproductive down time and in terms of the high replacement cost of the cutter heads. Such frequent replacement of the cutter heads would cause traffic marking removal to be even slower than an expected rate of progress of about one kilometer per day, per machine.
Further, it has been found that using cutter heads with flat spots also tends to cause excessive wear on the cutter head bearings.
It is an object of the present invention to provide a vehicle for removing a traffic marking from a road surface, which vehicle has a vertically floating cutter head mechanism.
It is another object of the present invention to provide a vehicle for removing a traffic marking from a road surface, which vehicle has cutter heads that are intermittently in contact with a road surface, so as to ensure rotation of the cutter heads, thereby to prevent flat spotting of the cutter heads.
It is another object of the present invention to provide a vehicle for removing a traffic marking from a road surface, and having a vertically floating cutter head mechanism, which vehicle removes a readily controllable depth of underlying road surface.
It is a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle does not cut a substantially vertically sided rut in the road surface.
It is yet a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle applies a substantially constant cutting force to the road surface, irrespective of irregularities in the road surface.
It is yet another object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle does not exceed a maximum specified depth of cut in a road surface.
It is yet a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle has a significantly faster travelling speed that prior art machines for the same use.
It is yet a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle does not draw itself off course.
It is yet a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle has drive shaft bearing and cutter head bearing temperatures significantly less than prior art machines for the same use, so as to prevent bearing overheating and/or failure.
It is still a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle has increased drive shaft bearing life over prior art machines for the same use.
It is still a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle has increased cutter head bearing life over prior art machines for the same use.
It is yet a further object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle has increased cutter head life over prior art machines for the same use.
It is still another object of the present invention to provide a vehicle having a vertically floating cutter head mechanism, for removing a traffic marking from a road surface, which vehicle resists flat spots from being produced on the teeth of the cutter heads utilized in the cutter mechanism.