Abstract:
A conversion apparatus (10) for converting a vehicle (V) for travel on a railway comprises first and second assemblies (20, 20&#39;) connected by an axle (23). Each assembly (20, 20&#39;) comprises a first support member (11) rigidly mounted to the vehicle frame and a second support member (13) pivotally mounted to the vehicle frame. The second support member is coupled to the first support member for limiting the pivotal movement of the second support member relative to the vehicle frame. A pair of railway wheel support arms (18, 18&#39;) are pivotally mounted to the second support member (13) for movement between raised and lowered positions and carry a railway wheel (21) rotatably mounted thereon. A hydraulic cylinder (22) moves the railway wheel support arms between the raised and lowered positions. An extendable and retractable tongue (37) is provided for coupling and decoupling the assembly to the vehicle suspension while providing a slidable supporting engagement with the vehicle suspension when the tongue is coupled to the vehicle suspension. The tongue is moved by a linkage (42) connected to the railway wheel support arms so that as the railway wheel support arms are moved between the raised and lowered positions the tongue is moved between the retracted and extended positions.

Description:
TECHNICAL FIELD 
     This invention relates to a road and railway vehicle, and more particularly to an auxiliary railroad wheel assembly mounted to a road vehicle, which can be retracted when the vehicle is traveling on a flat road surface or distended downwardly into engagement with the tracks of a railroad for supporting and guiding the vehicle along the tracks, thereby converting the road vehicle to a railroad vehicle. 
     BACKGROUND OF THE INVENTION 
     In many instances the best or only way to move a vehicle to a particular destination is via a railway track. This may be because the railway offers a smoother surface than paved roads, or because the railroad track is the only available cleared surface that reaches a particular destination. In addition, railway maintenance vehicles are often expected or required to travel on both roads and railway tracks, and require means for converting from one travel surface to the other. Most surface vehicles designed for use on paved roads and for use off-road are not suitable for use on a railway. As the railway is made up of two parallel steel tracks supported by spaced cross ties, and the typical lateral distance between the wheels of most surface vehicles is different than the spacing of the parallel railroad tracks, the road wheels cannot stably ride upon the railway but instead usually have to ride over the spaced apart cross ties, which places enormous demands on the vehicle suspension. 
     It is known in the art to provide an apparatus for converting road vehicles for railway travel. Examples of such vehicles are disclosed in U.S. Pat. Nos. 4,077,328; 804,025 and 3,730,105. Such a conversion apparatus typically includes railway wheels movably mounted to the frame of the vehicle for movement between a raised, retracted position for road travel and a lowered, distended position for rail travel. A drawback to this arrangement has been the lack of suitable suspension means interposed between the vehicle frame and the railway tracks, resulting in a harsh ride. Also, when the railroad wheels support the vehicle, the road wheels tend to extend downwardly toward the track which sometimes causes the road wheels to engage other objects and interfere with the movements of the vehicle on the railroad tracks. 
     This problem has been addressed in the art by mounting the conversion apparatus at one point to the vehicle suspension and at another point the vehicle frame to transmit some of the load of the vehicle through the vehicle&#39;s own suspension to provide some cushioning of the ride along the railway. For example, U.S. Pat. No. 4,488,494 teaches a conversion apparatus in which a support arm is pivotally attached at one of its ends to the vehicle frame and is pivotally attached at its opposite end to the vehicle suspension. A railway wheel support plate carries a railway wheel and is pivotally mounted to the support, arm. 
     While arrangements of this general type provide a more cushioned ride through the use of the vehicle road wheel suspension to partially support the railroad wheels, it does so at the expense of decreased service life of various components of both the vehicle road wheel suspension and the conversion apparatus. This is so because the arcuate path of travel of the end of the pivoted support arm which is attached at one end to the vehicle suspension and pivots at its other end about the vehicle frame does not match the designed path of travel of the suspension apparatus of the vehicle road wheels. Therefore, as the vehicle suspension moves up and down, and as the support arm of the conversion apparatus pivots, longitudinal stresses are placed on some components of the vehicle suspension as well as on some components of the conversion apparatus, which ultimately damage or shorten the life thereof. These unwanted stresses result both when the vehicle is driven over the road and when the vehicle is driven on the railway because the conversion apparatus is permanently attached to the vehicle road wheel suspension, regardless of the use of the vehicle. 
     Accordingly, it is seen that a need yet remains for an apparatus for converting road vehicles for railway travel which utilizes the suspension of the vehicle road wheels to provide a cushioned ride to the railroad wheels without damaging the suspension or diminishing the service life thereof. It is the provision of such an improved vehicle and the conversion apparatus therefore that the present invention is primarily directed. 
     SUMMARY OF THE INVENTION 
     Briefly described the present invention comprises a convertible road and railway vehicle. More particularly the invention comprises an apparatus for converting a self propelled, wheeled road vehicle to a vehicle for travel on a railway, the vehicle having a frame and a suspension, with railroad wheels retractable to a raised position out of engagement with the railroad tracks and distendable to a lowered position which guide and support the vehicle on railroad tracks. A converting apparatus is mounted adjacent the front road wheel assemblies of the vehicle and the converting apparatus includes a pair of assemblies each having a main support arm oriented parallel to the normal direction of movement of the vehicle and pivotally mounted at a first end portion thereof to the vehicle frame. A railway wheel support arm is pivotally mounted at a first end portion thereof to the main support arm for pivoting movements between raised and lowered positions. A railway wheel is rotatably mounted to the other end of the railway wheel support arm remote from the pivoted end portion of the railway wheel support arm. Means are provided for moving the railway wheel support arm between the raised and lowered positions and for securing the railway wheel support arm in the raised and lowered positions. Further means are provided for temporarily supporting the vehicle road wheel suspension with the main support arm in response to the railway wheel support arm being moved to its lowered position. 
     Preferably, the means for temporarily supporting the vehicle suspension comprises a movable suspension engagement member which can be moved between a retracted position and an extended position in which the movable suspension engagement member is positioned slidably beneath the vehicle road wheel suspension so as to support the vehicle road wheel suspension and to allow the vehicle road wheel suspension and the movable suspension engagement member to travel through differing paths of movement. 
     Therefore, it is an object of this invention to provide an improved convertible road and railway vehicle which utilizes the road wheels suspension system to cushion the ride for the railroad wheels. 
     It is another object of the present invention to provide a road wheel and railroad wheel conversion apparatus which utilizes the road wheel suspension for the railroad wheels substantially without interfering with the path of travel of the road wheel suspension. 
     It is yet another object of the present invention to provide a conversion apparatus for self propelled vehicles which supports the vehicle road wheel suspension when the apparatus is to be used to convert the vehicle for use on a railway and which is readily decoupled from the vehicle road wheel suspension when the vehicle is not being used on a railway. 
     It is yet another object of the present invention to provide a conversion apparatus for self propelled vehicles which makes use of the vehicle road wheel suspension for cushioning the ride on a railway and yet which does not significantly diminish the durability of the vehicle suspension. 
     Other objects, features and advantages of the present invention will become more apparent upon reading the following specification in conjunction with the drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     FIG. 1A is a perspective illustration of a conversion apparatus according to the present invention in a preferred form, shown attached to a portion of a vehicle frame. 
     FIG. 1B is a perspective illustration of the conversion apparatus of FIG. 1A, with some elements removed for clarity of illustration. 
     FIG. 2A is a side view of the conversion apparatus of FIG. 1A, with a railway wheel portion of the apparatus shown in a lowered position. 
     FIG. 2B is a side view of the conversion apparatus of FIG. 2A, with the railway wheel portion of the apparatus shown in a raised position. 
     FIG. 3 is a perspective illustration of a portion of the conversion apparatus of FIG. 1A. 
     FIGS. 4A and 4B are schematic illustrations of a portion of the conversion apparatus of FIG. 1A shown coupled to representative vehicle suspensions. 
     FIG. 5 is a front view of the conversion apparatus of FIG. 1 with some elements omitted for clarity of illustration. 
     FIG. 6 is a side view of a conversion apparatus according to the present invention in a second preferred form. 
     FIG. 7 is a side view of a portion of the conversion apparatus of FIG. 6. 
     FIG. 8 is a perspective illustration of the conversion apparatus mounted to a vehicle for use on a railway. 
    
    
     DETAILED DESCRIPTION 
     Turning now in more detail to the drawings figures, in which like reference numerals represent like parts through out the several views, FIGS. 1-5 show a conversion apparatus 10 according to the present invention in a preferred form. It is to be understood in this discussion that much of the conversion apparatus 10 comprises substantially duplicate pairs of parts, with the duplicate part denoted by a prime (&#39;) mark next to its reference numeral. The conversion apparatus 10 comprises a first assembly 20, and, as best seen in FIG. 5, a second assembly 20&#39; which is substantially a mirror image of assembly 20. The assemblies 20, 20&#39; are linked by a common rigid axle 23 extending between them. FIGS. 1-3 and 5 show assembly 20 mounted to a vehicle frame F and comprising rigid support arms 11, 11&#39; depending from frame F and secured rigidly thereto by unshown fasteners or weldments. An elongated slot 12 is formed through a portion of support arm 11 distal from frame F. A similar unshown slot is formed in support arm 11&#39; in a corresponding position. 
     A second pair of rigid support arms 13, 13&#39; are each pivotally coupled at one end thereof to the frame F by means of a pivot pin 14 extending between the support arms 13, 13&#39; and through pivot support plates 15, 15&#39;. The pivot support plates are rigidly secured to the vehicle frame F by unshown bolts or weldments and are spaced from the support arm 11. Pivoting support arms 13, 13&#39; are generally wedge-shaped and extend from the pivot pin 14 beyond the depending support arms 11, 11&#39;. 
     A support pin 17 extends through the pivoting support arms 13, 13&#39; distal from the pivot pin 14 and is received within slots 12 formed in the rigid support arms 11, 11&#39;. The support pin 17 is securely retained within the pivoting support arms 13, 13&#39; and movably received within the slots 12. The slots 12 are slightly arcuate and are perpendicular to an axis drawn between the slots 12 and the pivot pin 14. In this manner, the slots 12 and the support pin 17 support the pivoting support arms 13, 13&#39; and allow them to pivot through an arc of limited dimension. 
     A pair of railway wheel support arms 18, 18&#39; are pivotally mounted to a pivot pin 19 mounted in a lower portion of pivoting support arms 13, 13&#39; and generally intermediate of support pin 17 and pivot pin 14. Preferably the pivot pin 19 is closer to the suspension than to a vertical axis 16 extending through pin 14. The railway wheel support arms 18, 18&#39; carry a railway wheel 21 rotatably mounted to an axle 23 mounted to the wheel support arms 18, 18&#39;. The railway wheel support arms are adapted for movement between a lowered position shown in FIGS. 1A and IB and a raised position shown in FIG. 2B. A hydraulic cylinder 22 is pivotally mounted at one end thereof between and to the pivoting support arms 13, 13&#39; and the opposite end of hydraulic cylinder 22 is pivotally mounted to the railway wheel support arms intermediate of pivot pin 19 and railway wheel axle 23. 
     A pair of stops 24 are rigidly mounted between the pivoting support arms 13, 13&#39; for engaging an upper surface 26 of each railway wheel support arm with the railway wheel support arm in the lowered position. Each stop acts as a positive means of preventing the railway wheel support arm from rotating past the generally vertical orientation of the lowered position. 
     As illustrated in 1A-2B, an L-shaped safety lock pin 27 is secured to pivoting support arm 13 by means of a flexible link chain 28. An aperture 29 is formed through railway wheel support arms 18 and 18&#39; spaced from an axis extending between pivot pin 19 and axle 23. A first pair of aligned apertures 30 are formed in pivoting support arms 13, 13&#39; and a second pair of aligned apertures 31 are formed in the pivoting support arms as well. The apertures 30 are positioned so that with the railway wheel support arms in the lowered position, the lock pin 27 may be inserted through the aperture 30 in the pivoting support arm 13, through the railway wheel support arm apertures 29 and then through the corresponding aperture in the pivoting support arm 13&#39;. In this manner the railway wheel support arms may be positively locked in the lowered position. Likewise, apertures 31 may be used in a similar fashion for securing the railway wheel support arms in a raised position. 
     A coupling and decoupling mechanism 36 comprises a means for temporarily supporting the vehicle suspension with the pivoting support arms and is mounted in an end of the pivoting support arms 13, 13&#39; distal from the pivot pin 14. The coupling/decoupling meechanism, as best seen in FIGS. 1B, 2A, 2B and FIG. 3, comprises a broad, flat elongated tongue 37 having a smooth upper surface and slidably received within a hollow box section 38 which is secured between the pivoting support arms 13, 13&#39;. Tongue 37 includes a beveled portion 39 and raised tabs 40. Raised tabs 40 extend through an opening 41 in an upper portion of the rectangular box section 38. The tabs 40 are connected to the railway wheel support arms 18, 18&#39; by means of a linkage 42 which is rotatably mounted to the tabs 40 and rotatably mounted to the railway wheel support arm by means of a pin 34. An access hole 33 is provided in each support arm 13, 13&#39; for allowing the pin 34 to be driven in or out of the linkage 42, as for service or assembly. A half round bar 45 with a smooth outer surface is rigidly secured beneath a lower portion of the vehicle&#39;s suspension indicated generally by S. FIGS. 4A and 4B show the half round bar 45 mounted beneath typical vehicle suspension systems, with FIG. 4A representing a coil spring suspension and FIG. 4B representing a leaf spring suspension. 
     Pivoting support arms 13, 13&#39; are braced to each other to form a rigid structure by means of additional pins, bolts or plates extending between the pivoting support arms. If desired, a plate may be welded between the pivoting support arms 13, 13&#39; at the upper edges thereof to seal the upper portion of the pivoting support arms from weather. 
     FIGS. 6 and 7 shows the conversion apparatus comprising assembly 20 according to the present invention in a second preferred form in which the linkage 42 is replaced with a hydraulic cylinder 47 for actuating the tongue 37 through the raised tabs 40. Furthermore, FIGS. 6 and 7 show a modified railway wheel support arm 18 having a rounded top portion to provide additional clearance as the railway wheel support arm pivots about pin 19. Accordingly, stops 24, 24&#39; are replaced with lower stops 56, 56&#39; and upper stops 55, 55&#39; each mounted to pivoting support arms 13, 13&#39;. Apertures 29, 29&#39; in the railway support arms 18, 18&#39; and apertures 30, 30&#39; and 31, 31&#39; in the pivoting support arms 13, 13&#39; are replaced with apertures 53, 53&#39; and 54, 54&#39; in the railway wheel support arms and apertures 52, 52&#39; in the pivoting support arms. Additionally, slots 12, 12&#39; in the rigid support arms 11, 11&#39; are made rectangular rather than arcuate to minimize manufacturing expense, with the width of the slot exceeding the diameter of pin 17. FIG. 6 more clearly shows the pivot pin 19 to be closer to the half-round bar 45, and therefore closer to the vehicle suspension, than to the vertical axis 16 extending through pivot pin 14. 
     FIG. 8 shows a vehicle V equipped with a conversion apparatus 10 at the front end of the vehicle for use on a pair of railway tracks R. Of course, to raise the rear end of the vehicle V above the railway tracks requires the use of an additional conversion apparatus 10 or some other type of conversion apparatus, and in most instances it is anticipated that some apparatus different the present invention is indicated. 
     OPERATION 
     The conversion apparatus 10 can be used as follows. With the conversion apparatus 10 mounted at the front end of the vehicle, and with the railway wheel support arms 18, 18&#39; in the raised position, the vehicle is driven onto a railway track to a position in which the road wheels of the vehicle straddle the track and in which the railway wheels 21 are positioned directly over the railway tracks. An operator then removes the lock pins 27 from within the apertures 30 in each assembly 20, 20&#39; to allow the railway wheel support arms 18, 18&#39; to be moved to the lowered position. With the railway wheel support arms in the raised position, the pivoting support arms are suspended by the pins 17 and the tongues 37 are at a level that is below that of half-round bars 45. Upon the removal of both lock pins, hydraulic pressure is supplied, as by an unshown hydraulic pump with manual controls, to the hydraulic cylinders 22 to move the railway wheel support arms from the raised position shown in FIG. 2B to the lowered position of FIG. 2A. 
     As the railway wheel support arms 18 move downwardly, the linkages 42 extend the elongated tongues 37 under the vehicle suspension. As the tongues 37 slip beneath the half round bars, the beveled portion 39 of the elongated tongues work to help ease the tongues past the half round bars in the event that the tongues are not completely below the level of the half-round bars. As the railway wheel support arms 18, 18&#39; are sWung completely down to the lowered position of FIG. 2A, the pivoting support arms 13, 13&#39; are lifted engaging the tongues with the half-round bars. The front end of vehicle is thereby lifted by the conversion apparatus 10 acting through the elongated tongues 37 and the pivot pins 14. In other words, some of the weight of the vehicle is transferred through the vehicle suspension to the conversion apparatus 10 through the elongated tongues 37 and the pivot pins 14 to cushion the ride of the vehicle on the railway. Preferably, a majority of the weight of the vehicle borne by the conversion apparatus is transferred through the vehicle suspension owing to the placement of the railway wheel support arm closer to the vehicle suspension than to the pivot pin 14. 
     Furthermore, as the railway wheel support arms move from the initial raised position of FIG. 2B to the lowered position of FIG. 2A, the elongated slots 12 and pins 17 move from the configuration of 2B in which the pins 17 are supported by a lower portion of the slots 12, the rigid support arms 11 thereby supporting the pivoting support arms 13, to a configuration in which the support pins 17 are &#34;free floating&#34; near the middle of the slot. This occurs as the weight is transferred from the road wheels to the railway wheels 21 and allows the apparatus to follow the suspension as it moves through some travel up and down to provide a cushioned ride. The length of the slots provide some absolute limits on the amount of travel of the support pins 17 and thereby limits the amount of travel and rotation of the pivoting support arms 13. The locks and pins also provide a safety support should the tongues fail to lift the vehicle suspension. In that event, the slots and pins support the vehicle sufficiently to allow emergency travel. 
     With the railway wheel support arms in the fully lowered position of FIG. 2A, the lock pins 27 are inserted into the aligned apertures 30 to securely lock the railway wheel support arms in the lowered position. The vehicle is then ready for travel on the railway. 
     As shown in FIGS. 2A and 6, with the railway wheel support arm in the lowered position, axle 23 is not aligned with a vertical axis 57 extending through pivot pin 19. With the railway wheel support arm in this &#34;past center&#34; position, the railway wheel support arm is stably and safely held in the lowered position as follows. The weight of the vehicle supported on the railway wheel support arm tends to urge the arm in the direction of arrow 58. Motion in this direction is limited by the stop 24 shown in FIG. 2A or by the stop 56 shown in FIG. 6. Forces tending to urge the railway wheel support arm in the direction of arrow 59 are opposed by the weight of the vehicle acting through the railway wheel support arm as well as by the hydraulic cylinder 22. 
     With the railway wheel support arms in the fully lowered position the vehicle suspension is supported by the tongues 37 contacting the half-round bars 45. The smooth round surface of the bars engages the smooth upper surface of the tongues 37 to allow the tongues to slide beneath the bars while supporting the vehicle suspension. This sliding contact is particularly important to allow the pivoting support arms and the vehicle suspension to go through differing paths of travel as the vehicle travels over a railway. Coupling the conversion apparatus to the suspension in this manner allows the suspension and the pivoting support arms to go through independent paths of travel and avoids placing undesirable lateral stresses on both the suspension and the conversion apparatus. To that end it may be possible to replace the half-round bars with one or more rollers similarly situated. 
     To convert the vehicle from railway use to road use, the reverse of the above process is naturally employed. 
     By coupling and decoupling the conversion apparatus with the vehicle suspension, the vehicle suspension is unencumbered by the conversion apparatus when the railway wheel support arm is raised, thereby avoiding any possible negative effect on the suspension performance when the vehicle is not being used on a railway. 
     While the invention has been described as suitable for converting road vehicles for travel on a railway, it will be readily apparent that principles of the invention are equally applicable in converting for railway travel vehicles not primarily considered road vehicles. 
     While the invention has been described in preferred forms, it will be obvious to one skilled in the art that many modifications, additions and deletions may be made thereto without departing from the spirit and scope of the invention as set forth in the following claims.