Abstract:
A rail conversion module for a tractor allowing the tractor to be driven either on the ground or on railroad tracks wherein a hinged module frame fits under the tractor with front rail wheels on a frame front section being attached to the tractor and adapted to be raised for ground travel or lowered for rail travel and driven rear rail wheels on a frame rear section which by a hinge mounting can be raised for ground travel or lowered for rail travel.

Description:
BACKGROUND OF THE INVENTION 
     For many years specially constructed traction vehicles have been available which operate both on roads and on railroad tracks. Typically they are small rail locomotives with four road wheels which can be raised to permit ordinary railroad travel on rail wheels or lowered to the ground so as to lift the rail wheels and permit road travel. Examples are the vehicles described in U.S. Pat. Nos. 3,198,137, 3,884,156, 4,067,259, 4,167,142 and 5,168,815. They are of relatively complicated design and quite expensive. 
     The object of the present invention is to achieve all of the major functions of these known specially built road-rail vehicles at a small fraction of their cost. This is achieved by utilizing a conventional farm tractor for whatever road travel is required of the road-rail vehicle, whether to pull loads or simply to move on the ground from one rail site to another. Then for rail operation a special conversion module is to be attached beneath the farm tractor. This module is to have vertically movable rail wheels which can be retracted upwardly to allow the farm tractor to continue its ordinary functions travelling on the ground. When rail travel is required the rail wheels are to be lowered to tracks so as to lift the tractor and elevate its road wheels off the ground. The tractor engine through its conventional power take-off is to drive the rail wheels and move the vehicle along the railroad track either alone or pulling railroad cars. 
     SUMMARY OF THE INVENTION 
     The present invention is for use with a conventional engine driven tractor having a chassis with a rear power take-off and a fluid power system, preferably hydraulic. Respective pairs of coaxial front steering and rear driving ground wheels are on the tractor each spaced differently, usually wider, than rails of a railroad track. A rail conversion module is provided in accordance with the invention mountable on the tractor chassis and it includes respective pairs of coaxial front and rear rail wheels spaced for rolling engagement on the tracks. A module frame is provided having hinged front and rear sections with the front rail wheels on the front section and the rear rail wheels on the rear section. Attachment means are included on the module frame for affixing the front section to the tractor chassis. An articulated connector is included for placing the rear rail wheels in driving relation with the tractor power take-off. Lifting means are located on the module frame operable by the tractor fluid system for raising and lowering the front rail wheels with respect to the frame front section. Pivoting means are also on the module frame operable by the tractor fluid power system for turning the rear section so as to raise and lower the rear rail wheels with respect to the front section. With this structure upon driving the tractor over the module frame front section with all rail wheels raised, the front frame section is affixed to the tractor chassis, the rear rail wheels are connected to the tractor power take-off and the lifting and mounting means are connected to the tractor fluid power system. Thus when the tractor is driven over the tracks the front and rear rail wheels can be lowered onto the tracks to raise the tractor permitting it to be driven along the rails. 
     Locking means may also be included for securing the front and rear frame sections in position when the rear wheels are lowered onto the tractor. They may be a rigid bar hinged at one end to one of the front and rear frame sections and securable at the other end to the other of the front and rear frame sections. 
     The lifting means may comprise an arm pivoted to the front section of the frame with the front rail wheels on one end of the arm remote from the pivot. At least one front hydraulic piston and cylinder are provided between the arm and frame front section for turning the arm and raising and lowering the front rail wheels. 
     The pivoting means may comprise at least one rear hydraulic piston and cylinder between the rear and front sections of the module frame for turning the rear section and raising and lowering the rear rail wheels. 
     It is also contemplated that this rail conversion module may be in combination with the engine driven tractor. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is an elevation of a conventional engine driven tractor shown in broken lines in combination with the rail conversion module of the invention shown in solid lines, the tractor being on the ground with the rail wheels of the module elevated; 
     FIG. 2 is an elevation similar to FIG. 1 showing the tractor and rail conversion module on the rails of a railroad track with the ground wheels of the tractor elevated; and 
     FIG. 3 is a plan view of the tractor and rail conversion module of FIG.  2 . 
    
    
     DESCRIPTION OF PREFERRED EMBODIMENT 
     Referring to all of the drawings, a conventional  100 HP farm tractor is shown in broken lines adapted to travel on the road or ground  10 . Preferably its chassis  11  is of wide front form with a pair of coaxial small diameter front steering ground wheels  12  spaced apart more widely than rails  13  of a conventional gauge railroad shown in FIG.  2 . Its pair of larger diameter coaxial rear ground wheels  14  are even more widely spaced as shown in FIG.  3 . The engine of the tractor may have an hydraulic power system and a conventional engine-driven rear power take-off  16 . It has conventional brakes and other standard equipment. As in all tractors, a steering wheel  18  and a driver&#39;s seat  19  are included. 
     In accordance with the invention a rail conversion module  18  is provided shown in the drawings in solid lines. The module includes a frame  21  essentially in two hinged parts, namely a front section  22  and a rear section  23  joined at pivots  24 . A pair of conventional coaxial front rail wheels  25  are included displacably mounted with respect to the front section  22  of the frame  21  in a manner described below. A pair of somewhat larger driven rear rail wheels  26  are mounted on a common axle  27  on the rear section  23  of the frame  21 . The pairs of rail wheels  25  and  26  are shown in rolling engagement with the railroad track  13  in FIG.  2 . 
     The front section  22  of the module frame  21  is releasably and rigidly secured to the tractor chassis  11  by suitable attachment means part of which is illustrated in FIGS. 1 and 2 as a transverse plate  28  on the front section  22  with U-bolts  29  extending upwardly and around a member  30  anchored to the chassis  11  of the tractor. 
     An articulated connector  32  is secured to the power take-off  16  of the tractor and through a suitable drive train  33  is joined in driving relation with the real rail wheels  26 . This articulated connection permits the rear rail wheels  26  to be driven by the engine of the tractor perferably through a hydrostatic system and permits the drive train  33  to move with the module rear frame section  23  on which it is mounted between the positions shown in FIGS. 1 and 2. An operator can control the driving of the rear rail wheels  26  by the tractor engine from a position in a module cab  35  mounted on the rear section  23  of the module frame  21 . 
     It is to be understood that the rail conversion module  18  may include various rail functions with the tractor furnishing the prime power. For example, the module  18  may include a specific form of the hydrostatic drive system mentioned previously, an auxiliary hydraulic system for a traction booster as described below and a train brake system. 
     When the rear rail wheels  26  are on the tracks  13  the rear frame section  23  can be secured in level position as shown in FIG. 2 by a pair of movable locking bars  38 . As shown in FIG. 1 the locking bars  38  are mounted on pivots  39  to the front frame section  22  and can be swung downwardly to the position shown in FIG.  2 . When in that downward position the locking bar ends remote from the pivots  39  fit within appropriate sockets in the rear frame section  23  and thus hold the rear frame section  23  in its level position shown in FIG.  2 . 
     Lifting means are provided for raising and lowering the front rail wheels  25  with respect to the frame front section  22 . The lifting means comprises a pair of arms  37  for the respective two front rail wheels  25  which are mounted by pivot pins  38  to the front section  22  of the frame  21 . The front rail wheels  25  are rotatably mounted on a lower end of the arms  37  remote from the pivot pins  38 . The end of each arm  37  remote from the associated front rail wheel  25  is connected to a piston  40  associated with a hydraulic cylinder  41  and the other end of each cylinder  41  is movably attached at  42  to the front section  22  of the frame  21 . Each of the pistons  40  and cylinders  41  are double acting and therefore hydraulic lines  44  and  45  from the ends of each cylinder  41  are connected to the hydraulic power system of the tractor. With the engine of the tractor in operation, the pistons  40  and cylinders  41  can turn the arms  37  about the pivot pins  38  and thereby raise or lower the front rail wheels  25 . 
     Pivoting means on the frame  21  can also raise and lower the rear rail wheels  26 . The pivoting means comprises a pair of rear pistons  48  and cylinders  49  on the respective sides of the module frame  21 . One end of each piston  48  is secured at a pin  50  to the front frame section  22 . The remote end of the associated cylinder  49  is movably attached at  51  to the hinged rear section  23  of the module frame  21 . Hydraulic lines  53  and  54  extend from the opposite ends of each cylinder  49  to associated hydraulic power lines in the tractor. When operating the pistons  48  within their cylinders  49  the rear section  23  of the module frame  21  may be moved from its raised position shown in FIG. 1 where the rear rail wheels  26  are off the tracks  13  to the lower position shown in FIG. 2 where they are in rolling engagement with the tracks  13 . 
     A conventional coupler  55  is located on the rear of the rear section  23  for connection to a rail car. It is known to combine such a coupler  55  with a traction booster system to increase the downward force of the rear rail wheels  26  on the rails  13 . In such a system the coupler  55  is mounted on an arm  56  angularly movable on the rear frame section  23  and one or more hydraulic pistons and cylinders are located at  57  to force the arm  56  upwardly and thereby force the rear rail wheels  26  downwardly when the module is attached to a rail car by the coupler  55 . 
     The operation of the rail conversion module of the invention will now be described. It is mounted on the chassis  11  of the tractor by first backing the tractor over the front section  22  of the module frame  21  with its rail wheels  25  and  26  in the position shown in FIG.  1 . The lifting means for the front rail wheels  25  are operatively connected to the tractor by the hydraulic lines  44  and  45  and the pivoting means for the rear rail wheels  26  are connected to the tractor by the hydraulic lines  53  and  54 . The module frame  21  is elevated by downward movement of the rail wheels  25  and  26  to the position shown in FIG.  2  and the front section  22  thereof is affixed to the tractor chassis  11  by the U-bolt  29  and whatever other attachment means are deemed appropriate. At this point both pairs of rail wheels  25  and  26  are in the raised position shown in FIG.  1 . The drive for the rear rail wheels  26 , namely the articulated connector  32 , is operatively joined to the power take-off  16  of the tractor. At this point the rail conversion module is as shown in FIG.  1  and the tractor can be driven about in the conventional manner on the ground  10  as desired. 
     For rail travel the tractor is driven over the tracks  13 . By operation of the pistons  40  and cylinders  41  the pair of front rail wheels  25  are lowered from the position shown in FIG. 1 to the position shown in FIG.  2 . Similarly by operation of the pistons  48  and cylinders  49  the rear rail wheels  26  are lowered from the position shown in FIG. 1 to the position shown in FIG.  2 . In this lowered position the front and rear rail wheels  25  and  26  are in appropriate rolling engagement with the tracks  13 . The locking bar  38  is swung downwardly from the position shown in FIG. 1 to the aligned position shown in FIG. 2 to secure the front and rear frame sections  22  and  23  in the level position shown in FIG.  2 . At this point the entire tractor is slightly elevated so that its ground wheels  12  and  14  are above the tracks  13  as shown in FIG.  2 . 
     The scope of the invention is to be determined from the following claims rather than the foregoing description of a preferred embodiment.