Patent Publication Number: US-2005126424-A1

Title: Hi-rail vehicle

Description:
CROSS-REFERENCE TO RELATED APPLICATION  
      This application claims the benefit of U.S. provisional patent application Ser. No. 60/529,554, filed Dec. 15, 2003. 
    
    
     FIELD OF THE INVENTION  
      The present invention relates to vehicle construction and more particularly to a vehicle capable to traveling on railroad track or highway.  
     BACKGROUND OF THE INVENTION  
      Part of the ongoing cost and responsibility of the continuing operations of any rail system is the maintenance of the infrastructure. There are two approaches to the provision of ongoing maintenance: developing an in-house maintenance organization or contracting those services out to firms specializing in such work. In a railroad environment there are needs for both routine transportation of the staff overseeing the daily operations and for the work equipment to perform the corrective and preventative maintenance functions.  
      The railroads of today, as with any infrastructure-based industry, have developed a unique set of highly specialized equipment for the performance of maintenance functions. The procurement of such specialized equipment not only requires a substantial initial capital investment, but also is paired with the need to provide those individuals trained to operate, repair and maintain that equipment.  
      In a railroad environment there is the need for transportation and maintenance equipment that is not found in other transportation fields such as the highway, marine, or air travel industries. Special vehicles are required to provide rail-borne access to locations along the right-of-way that may not be accessible to standard highway vehicles.  
      For both inspection of the right-of-way and for general rail-borne access, it is common practice to equip normal highway vehicles with “hi-rail” gear. This equipment is mounted to the frame of the vehicle front and back and consists of a set of steel wheels found on railroad rolling stock. This hi-rail gear is retractable and enables the vehicle to operate either on roads or on the rails of the track via the steel wheels. To operate on a railroad track a hi-rail equipped highway vehicle is typically positions longitudinally over the track at a grade crossing or other area where the roadway surface is approximately level with the top of the rails. The hi-rail gear is lowered into position, which raises the vehicle&#39;s front steering wheels off of the crossing surface and raises the rear wheels slightly to allow the weight of the vehicle to bear on the steel wheels of the hi-rail gear. The vehicle is then ready to proceed. The hi-rail gear allows the steel wheels to ride along the rails, and the rear rubber tires, which are still in enough contact with the rail to provide traction and propel the vehicle. In the same manner heavy construction vehicles ranging from cranes to dump trucks can also be fitted with hi-rail gear to provide access to the railroad right-of-way by means of the rails.  
      Besides the hi-rail equipment there are also numerous pieces of maintenance equipment manufactured specifically for work on the railroads. These range from ballast tampers that are used to consolidate and stabilize the track bed, to equipment used to handle crossties. These are all highly specialized, often single-function pieces of equipment, and their maintenance and procurement represent a significant portion of every railroad&#39;s capital expenditures.  
      There is an acknowledged need to be able to provide hi-rail access to portions of the proposed right-of-way that may not be accessible to highway vehicles. It is assumed that there would be a fleet of vehicles provided for the personnel assigned to the management of a rail system. The number and type of vehicles to be provided and the means of doing so (purchase or lease) would be determined once staffing issues are resolved.  
      The installation of hi-rail equipment represents a relatively small capital investment and will provide unrestricted access to all areas of the right-of-way. It should be noted that the operators of those vehicles would need to be specially trained on the railroad operating rules and the proper operation of on-track equipment. The remainder of the fleet vehicles should be strictly highway vehicles to serve miscellaneous transportation needs as necessary.  
      Amongst the objectives in the design of hi-rail equipment is the inherent characteristic of the ability to readily traverse rail tracks having ever decreasing radii. As the tracks are caused to assume smaller radii, the conventional hi-rail equipment tends to cause the leading and/or trailing ends of the associated chassis to extend an unreasonable degree beyond the track bed. Such conditions expose the overhanging portions of the hi-rail equipment to unwanted collision or impact with equipment on adjacent tracks and other stationery objects, which are normally out of the zone of contact.  
      Accordingly, it is an objective of the present invention to produce a hi-rail equipment vehicle wherein the track engaging wheels are disposed to reduce the amount of overhang of the chassis permitting the equipment to traverse track configuration of ever-decreasing radius.  
     SUMMARY OF THE INVENTION  
      The above, as well as other objectives of the invention, have surprisingly been achieved by a hi-rail vehicle including a vehicle chassis; ground engaging wheels attached to the underside of the chassis including at least a pair of ground engageable steerable front wheels and a bogie unit of front and rear driving wheels; at least a first pair of rail engaging wheels mounted for selective vertical movement in front of the pair of ground engaging steerable front wheels; and at least a second pair of rail engageable wheels mounted for selective vertical movement interdigitated between the front and rear driving wheels of the bogie unit. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
      The above, as well as other objects and advantages of the invention, will become readily apparent to those skilled in the art from reading the following detailed description of the invention when considered in the light of the accompanying drawings, in which:  
       FIG. 1  is a side elevational view of a hi-rail equipment vehicle produced in accordance with the present invention; and  
       FIG. 2  is a diagrammatic top plan view illustrating the disposition of the rail engaging wheels in respect of the hi-rail equipment vehicle chassis and an associated curved section of railway track. 
    
    
     DETAILED DESCRIPTION OF THE ILLUSTRATED EMBODIMENT  
      Referring to the drawings, there is illustrated a hi-rail equipment vehicle generally designated by reference numeral  10  having a chassis  12 . The chassis  12  is fitted with couplers  14  and  16  on the front end and the rear end of the chassis  12 , respectively.  
      The vehicle  10  includes an operators cab  18  and an associated drive engine within a normally closed hood  20 . The chassis  12  is provided with suitable structural details for supporting any desired equipment having a centrally disposed crane  22 . However, it will be understood the crane assembly can be substituted by many other types of railway maintenance equipment, for example.  
      The vehicle chassis  12  is provided with sets of rail track engaging and guiding wheels and highway engaging wheels positioned in spaced relation along the length thereof. More particularly, the chassis  12  of the vehicle  10  is adapted to travel along a highway on a pair of steerable front wheels  24 . The wheel assembly and associated steering mechanism are conventional and are typically mounted to the chassis  12  by means of a conventional spring suspension mechanism. In the highway mode, the vehicle  10  is further provided with a bogie or tandem unit  26  consisting of spaced apart forward and rear sets of drive wheels  28  and  30 , respectively. The bogie  26  is mounted to the chassis  12  by a suspension assembly. The sets of drive wheels  28  and  30  are connected to a drive shaft through a standard differential drive gear assembly, not shown. The other end of the drive shaft typically extends to a conventional transmission used to transmit power from the drive engine to the sets of drive wheels  28  and  30 .  
      In the rail mode, there is provided railway track front engageable wheels  32  mounted, for selective vertical movement to the chassis  12 . It will be noted that the wheels  32  are mounted in front of the front steering wheels  24  and are mounted to the chassis  12  through independent torsion spring suspension mechanism. The torsion spring mechanism is adapted to be selectively moved vertically. Normally, the wheels  32  are carried in an elevated position, as illustrated in  FIG. 1 . When it is desired to guide the front of the chassis  12  along a railway track, the torsion spring mechanism is energized to force the wheels  32  downwardly into engagement with the railway track  46 . Sufficient downward force is applied to move the wheels  32  downwardly into engagement with the railway tracks, and simultaneously cause the steering wheels  24  to be urged upwardly. The procedure continues until the wheels  24  are out of contact with the supporting surface. At this point in the operation, the railway track engaging wheels  32  carry the load previously carried by the steering wheels  24 , and are thereby in position to guide the front of the vehicle  10  along the railway tracks  46 .  
      Interdigitated between the rear drive wheels  28  and  30  is disposed a rear railway engageable wheel set  34  mounted to the chassis  12  for selective vertical movement. The wheel set  34  typically includes an associated axle  36  which is mounted to extend between a forwardly extending set of spaced apart arms  38 . The rearward ends of the arms  38  are affixed to a shaft  40  which, in turn, is pivotally disposed within a hollow mounting member  42  secured to the vehicle chassis  12 .  
      The loading of the front railway engaging wheels  32  is typically carried by suspension means such as torsion springs for example. The suspension springs are employed control the vertical movement of the wheels  32  to effect a suitable loading of the rail engaging wheels  32  to effect a suitable loading of the rail engaging wheels and a simultaneous unloading of the steerable wheels  24  carrying a pneumatic tires for highway use, as explained in some detail above.  
      The loading of the rear railway engageable wheel set  34  is typically carried out by a hydraulic system  44  which effectively connects the railway engageable wheels  34  and the associated axle  36  to the chassis  12 .  
      The rear railway engageable wheels  34  are positioned between the drive wheels  28  and  30  of the rear tandem to facilitate the travel of the associated vehicle  10  on very tight curves of the railway track  46 , as illustrated in  FIG. 2 .  
      It will be understood that during railway track travel, the railway engaging wheels  34  are caused to be lowered from the normal position, as illustrated in  FIG. 1 , to a position contacting the railway track  46 . Sufficient unloading of the drive wheels  28  and  30  is accomplished to permit enough tractive effort to occur between the drive wheels  28  and  30  and the railway tracks  46 , and simultaneously allow the railway engaging wheels  34  to guide the rear of vehicle  10 . The hydraulic system  44  is deemed to be particularly beneficial to the overall operation of the hi-rail vehicle  10  due to the inherent ability to apply a constant force between the wheels  34  and the supporting railway track  46  no matter the irregularities the drive wheel  28  and  30  may encounter. Amongst the types of irregularities which may be encountered are “frogs” in the region of track switching mechanism. Such irregularities could cause the railway engaging wheels  28  and  30  to encounter a raised surface of some two inches above normal track height. In such instances, the hydraulic system  44  will instantly compensate, by rapidly causing the wheels  34  to maintain constant contact with the railway  46 .  
      Thereby, the vehicle  10  is able to work in transit rail yards. Where the railway tracks are oftentimes formed on very short radii. Currently, hi-rail equipment is provided with front rail engaging wheels located behind the front road wheels in an attempt to reduce the on-rail wheel base. However, such arrangement results in a structure wherein the front overhang of the chassis is excessive and can interfere with adjoining track vehicles and other obstructions. The arrangement of the present invention effectively reduces on-track vehicle overhang.  
      In accordance with the provisions of the patent statutes, the present invention has been described in what is considered to represent its preferred embodiment. However, it should be understood that the invention can be practiced otherwise than as specifically illustrated and described without departing from its spirit or scope.