Patent Publication Number: US-6662917-B1

Title: 2 rail to 3 rail conversion apparatus for use in model trains

Description:
FIELD OF THE INVENTION 
     The present invention relates to an apparatus that allows for model trains to be operated on either a track layout having 2 rails or a track layout having 3 rails, and more particularly, to an apparatus that readily allows the operator to configure the model train to operate in either a 2 rail configuration or a 3 rail configuration. 
     BACKGROUND OF THE INVENTION 
     The use of both 2 rail track layouts and 3 rail track layouts are well known in the model train industry. For example, when “O Gauge” model railroading systems were first introduced in approximately the 1940&#39;s, the systems employed a 3 rail track layout. In such 3 rail systems, the third rail, which is disposed in the center of the track between the two outside rails, functions to supply power to the locomotive. The locomotive is provided with a pickup roller, which extends downward from beneath the bottom of the locomotive and engages the third rail. The pickup roller functions to couple the power signal on the third rail to the motor of the locomotive. The two outside rails function as the ground source (or return path) for the motor of the locomotive, and are coupled to the motor of the locomotive via the left and right wheel assemblies of the locomotive. In such systems, the left and right wheel assemblies are electrically coupled together. Typically, the power signal provided on the third rail by a power supply is an AC signal in a range of 5 to 22 volts. The motor utilized by the locomotive can be either an AC or DC motor, with the latter requiring rectification of the power signal. 
     One long standing compliant about such 3 rail systems was that the “look” of the track was not realistic due to the inclusion of the middle rail (i.e., third rail). In response to these complaints, “HO-Gauge” systems, which utilized a 2 rail track, were introduced during the 1950&#39;s. The 2 rail system solved the problem of the “unrealistic” appearance of the  3  rail track systems. HO-Gauge systems utilized locomotives having only DC motors, which were powered by a DC power supply coupled to the tracks. The power supply was coupled to the motor of the locomotive via the wheels of the locomotive, with one track coupled to the positive terminal of the DC power supply, and the other track coupled to the negative terminal of the DC power supply. Of course, this power supply configuration mandated that the wheel structure on one side of the locomotive be electrically isolated from the wheel structure on the opposite side of the locomotive. 
     Shortly after the introduction of the 2 rail HO-Gauge systems, 2 rail O-Gauge systems were introduced. However, such 2 rail O-Gauge systems have never been widely accepted in the industry due to various problems associated with their use. For example, the use of AC power over the track rails, as opposed to DC power, greatly simplifies and enhances the operation of model train systems. More specifically, when utilizing AC power, the polarity of the current supplied to the track rails is not an issue. However, the polarity of the power signal applied to the tracks is an issue when utilizing DC power, because if the power supply leads coupled to the track rails are reversed, the locomotive will go in the opposite direction. Thus, powering the system utilizing an AC power supply makes wiring the system a far simpler task in comparison to powering the system utilizing a DC power supply. In addition, by employing an AC power signal on the rails, it is possible to utilize small amounts of DC power, which are sent over the rails, as a signaling method for the activation of various features of the system (e.g., blowing the locomotive&#39;s whistle, ringing bells, etc.). As a consequence of the foregoing problems with 2 rail O-Gauge systems, 3 rail O-Gauge systems still exist and are being utilized today. 
     As a result of the continuing existence of both 2 rail and 3 rail systems, model train enthusiasts often undertake the task of converting locomotives initially designed for use with 3 rail systems to ones that are capable of operating on 2 rail systems (and vice versa). However, such a conversion is extremely time consuming and requires both special tools and considerable mechanical skill. For example, when converting a model train designed to operate on a 3 rail system to one that operates on a 2 rail system, the conversion process requires the removal of the third rail pickup from the locomotive, as well as the modification of the wheel and axle design of the locomotive. While the removal of the third rail pickup is a fairly simple process, the modification of the wheel and axle design is not. This part of the conversion process requires that the locomotive be modified such that a first set of wheels located along the same side of the locomotive be insulated from a second set of wheels located on the opposite side of the locomotive. In addition, one of the sets of wheels must also be insulated from the chassis of the locomotive. Further, a set of wipers (i.e., contacts) must be installed so as to brush against the set of wheels insulated from the chassis (the wipers must also be insulated from the chassis). The wipers are connected to a wire harness and function to couple the power signal transmitted over one rail and through the insulated set of wheels to the motor or electronics inside the locomotive. A second wire harness is also required to couple the ground signal from the other rail through the non-insulated set of wheels to motor or electronics inside the locomotive. 
     As is evident from the foregoing description, converting a model train design to operate on a 3 rail configuration to one that operates on a 2 rail configuration is an extremely complex and time consuming process. Converting the model train in the opposite direction (i.e., 2 rail to 3 rail) is equally complex. Moreover, the process is not one that can be performed unless the operator has substantial knowledge about the design and construction of model trains, and a sophisticated set of tools. Clearly, the average train hobbyist does not have such knowledge, or the necessary tools to perform this process. 
     Accordingly, there exists a need for a model train conversion system that allows an operator to easily convert the model train from a 2 rail configuration to a 3 rail configuration (and vice versa), and that does not require the operator to have any knowledge regarding model train design, or require the operator to disassembly the locomotive in order to perform the conversion. 
     SUMMARY OF THE INVENTION 
     The present invention relates to a conversion system, which is incorporated, for example in the locomotive of the model train set, that allows the operator to easily and quickly configure the model train for either 2 rail operation or 3 rail operation. 
     More specifically, the present invention relates to a model train capable of operating on either a two rail system or a three rail system. The model train includes: an electrical device having a first power terminal and a second power terminal; a first wheel assembly for engaging a first rail; a second wheel assembly for engaging a second rail; a pickup member for engaging a third rail; and a switch member coupled between the motor, the first wheel assembly, the second wheel assembly and the pickup member, the switch operable in a first state and a second state, wherein in the first state the switch couples the pickup member to the first power terminal, and couples the first wheel assembly and the second wheel assembly to the second power terminal, and in the second state the switch couples the first wheel assembly to the first power terminal and couples the second wheel assembly to the second power terminal. 
     As described below, the 2 rail to 3 rail conversion system provides important advantages over prior art conversion techniques. For example, in accordance with the present invention, the operator can essentially configure the locomotive for either 2 rail or 3 rail operation simply by flipping a switch. As such, the present invention eliminates the need for performing a time consuming and complicated conversion process. Moreover, the present invention allows any operator, even one without any knowledge of model train designs, to readily perform the conversion. 
     Additional advantages of the present invention will become apparent to those skilled in the art from the following detailed description of exemplary embodiments of the present invention. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 illustrates a simplified exemplary embodiment of a 2 rail track layout. 
     FIGS. 2A and 2B illustrate an exemplary schematic diagram of the internal wiring of a model train incorporating the 2 rail to 3 rail conversion system of the present invention. 
     FIGS. 3 a - 3   c  illustrate an exemplary wheel and axle design for electrically isolating one of the wheel assemblies from the other wheel assembly and the model train chassis. 
     FIG. 4 is a bottom view of an exemplary model train which incorporates the 2 rail to 3 rail conversions system of the present invention. 
    
    
     The invention itself, together with further objects and attendant advantages, will best be understood by reference to the following detailed description, taken in conjunction with the accompanying drawings. 
     DETAILED DESCRIPTION OF THE DRAWINGS 
     The following detailed description of the 2 rail to 3 rail conversion system of the present invention sets forth exemplary embodiments of the device. It is noted, however, that the present invention as claimed herein is not intended to be limited to the specific embodiments disclosed in the following discussion. Clearly other implementations of the novel 2 rail to 3 rail conversion system are possible. 
     FIG. 1 illustrates a simplified exemplary embodiment of a 2 rail track layout  10 . As shown, the layout  10  includes a two rail track  13 , trains  11  and a power supply  12 , which is preferably an AC power supply. In such a 2 rail system, as mentioned above, an electrical device (e.g., motor) of the model train (e.g., locomotive) receives a power signal transmitted on one of the rails by the power supply  12  via the set of wheels in contact with the given rail. Again, it is noted that this set of wheels is electrically isolated from both the chassis of the model train and the set of wheels of the locomotive in contact with the opposite rail. The chassis and opposite set of wheels operate as a return path for the power signal supplied to the electrical device within the model train. The power signal is returned to the power supply  12  via the opposite rail. 
     In a 3 rail system, as noted above, the power signal is coupled from the power supply  12  to the third rail (not shown) and a pickup roller  95  provided on the bottom of the model train so as to contact the third rail (see, FIG. 4) couples the power signal to the electrical device within the model train. Further, both sets of wheels and the chassis are electrically coupled together, and act as the return path for the power signal. The power signal is returned to the power supply  12  via the two outside rails. The pickup roller  95  is electrically isolated from both sets of wheels and the model train chassis in the 3 rail configuration. 
     In accordance with the present invention, the internal wiring configuration of the model train is designed such that by toggling a switch provided on the model train between one of two states (i.e., 2 rail configuration state or 3 rail configuration state), the internal wiring of the model train is automatically configured to either the 2 rail wiring configuration or 3 rail wiring configuration noted above. 
     FIGS. 2 a  and  2   b  illustrate an exemplary schematic diagram of the internal wiring of a model train incorporating the 2 rail to 3 rail conversion system of the present invention. Referring to FIG. 2 a , in the given embodiment, the wiring design includes a connector  20  having pins  7 ,  8  and  11  designated “right wheel”, “roller  1 ” and “left wheel” respectively. Connector  20  is coupled to connector  30 , which is illustrated in FIG. 2 b . Connector  30  also has corresponding pins  7 ,  8  and  11  designated “right wheel”, “roller  1 ” and “left wheel”. The wires coupled to pins  7 ,  8  and  11  of connector  30  are hard wired to the respective component in the manner set forth below. It is noted that the components included in sections  22 ,  23  and  31  of the wiring schematic illustrated in FIGS. 2 a  and  2   b  are related to other components of the model train and do not form part of the 2 rail to 3 rail conversion system of the present invention. 
     Referring again to FIG. 2 a , the wiring design further includes switch  24  and connector  25 . Referring first to connector  25 , the connector  25  includes pins  4  and  6 , which are designated “engine chassis” and “roller  1 ”, respectively. Pin  4  designated “engine chassis” is electrically coupled to the model train chassis and to the negative return of the electrical device of the model train. In the given embodiment, the chassis is always coupled to at least one set of wheels of the model train, and functions as part of the path of the power supply return line. Pin  6  designated “roller  1 ” is coupled to the positive power terminal of the electrical device of the model train, and functions to couple the power supply signal to the positive terminal of the electrical device of the model train. As explained below in more detail, pin  6  can be coupled to either an isolated set of wheels or the pickup roller disposed on the bottom of the model train. 
     Turning to switch  24 , as will be described below, the state of switch  24  determines whether the model train is configured for operation in a 2 rail system or a 3 rail system. In the given embodiment, switch  24  is a two pole, two throw mechanical switch having pins  1 - 6 . As shown, pin  2  is coupled to the chassis (pin  4  of connector  25 ) of the model train and to the right wheel assembly (pin  7  of connector  20 ) of the model train. It is noted that in accordance with the given embodiment, the right wheel assembly (pin  7  of connector  20 ) is always coupled to the chassis (pin  4  of connector  25 ). Pin  5  of switch  24  is coupled to the positive power terminal of the electrical device of the model train as it is coupled to the pin designated roller  1  (pin  6  of connector  25 ). Pin  1  and pin  6  of switch  24  are coupled to the left wheel assembly (pin  11  of connector  20 ), and pin  4  of switch  24  is coupled to the pickup roller (pin  8  of connector  20 ) disposed on the bottom of the model train. Pin  3  of switch  24  is coupled to ground. 
     The conversion between 2 rail and 3 rail configurations in now described in conjunction with the operation of switch  24 . When switch  24  is controlled such that pin  2  contacts pin  1  and pin  5  contacts pin  4 , the model train is configured for 3 rail operation. More specifically, in this state, pin  6  and pin  2  of switch  24  are coupled together which results in the left wheel assembly (pin  11  of connector  20 ), the right wheel assembly (pin  7  of connector  20 ) and the chassis (pin  4  of connector  25 ) all being electrically coupled to one another. In addition, the roller (pin  8  of connector  20 ) disposed on the bottom of the model train, which is positioned so as to make contact with the third rail, is electrically coupled to roller  1  (pin  6  of connector  25 ). Accordingly, power is supplied from the third rail to the roller and thereafter coupled to the positive power terminal of the electrical device within the model train. Both the left wheel assembly and the right wheel assembly are electrically coupled to one another and operate in conjunction with the chassis as a return path for the power supply  12 . The left wheel assembly and right wheel assembly are electrically coupled to the power supply  12  via the outside rails of the track  13 . 
     When switch  24  is toggled to its other position, the model train is configured for 2 rail operation. Specifically, in this state, within switch  24 , pin  2  contacts pin  3 , and pin  5  contacts pin  6 . As such, the left wheel assembly (pin  1  of contact  20 ) is no longer electrically coupled to the right wheel assembly or the chassis as pin  2  of switch  24  is no longer in contact with pin  1  of switch  24 . The left wheel assembly is electrically coupled to roller  1  (pin  6  of connector  25 ). Accordingly, power is supplied from the track rail in contact with the left wheel assembly to the roller and thereafter coupled to the positive terminal of the electrical device within the model train. The right wheel assembly and chassis, which are electrically isolated from the left wheel assembly, function as a return path for the power supply. The right wheel assembly is electrically coupled to the power supply via the track rail in contact with the right wheel assembly. It is noted that the pickup roller (pin  8  connector  20 ) is not coupled to anything when switch  24  is in the 2 rail configuration state. 
     As is clear from the foregoing description, in the design of the model train chassis, the right wheel assembly and the left wheel assembly is such that at least one of the wheel assemblies is electrically isolated from the other wheel assembly and the chassis. The wheel assemblies should only be electrically coupled to one another when switch  24  is toggled to the 3 rail mode of operation. In the foregoing embodiment, it is the left wheel assembly that can be isolated from the right wheel assembly and the chassis. However, it is also clear that this can be reversed. Further, it is noted that while the foregoing exemplary embodiment of the wiring configuration for implementing the 2 rail to 3 rail conversion system illustrates the use of various connectors referred to above, such connectors only serve to facilitate the wiring and manufacture of the model train. Clearly, such connectors are not required for practicing the present invention as the various contacts of switch  24  can be directly wired to the various components. 
     FIGS. 3 a - 3   c  illustrate an exemplary wheel and axle design for electrically isolating one of the wheel assemblies from the other wheel assembly and the model train chassis. As noted above, such isolation of one of the wheel assemblies is necessary for implementing the 2 rail to 3 rail conversion system. FIG. 3 a  illustrates the wheel and axle design in an assembled state, and FIG. 3 b  illustrates an exploded view of the design. Referring to the figures, the exemplary design includes a left wheel assembly  140  and a right wheel assembly  150 . Both the left wheel assembly  140  and the right wheel assembly  150  has an axle member  41  and  51  securely fastened to a conductive wheel  40  and  50 , respectively, such that the wheel  40  and  50  and corresponding axle member  41  and  51  rotate in unison with one another. Each axle member  41  and  51  has a conductive bearing member  42  and  52  disposed thereon, which abuts the inner surface of the corresponding wheel  40  and  50 . The design further includes a housing member  80  (i.e., the model train engine chassis), which functions to receive the axle members  41  and  51 . 
     More specifically, referring to the FIG. 3 b , the housing member  80  includes openings  43  and  53 , which function to receive the bearing members  42  and  52  of axle members  41  and  51 , respectively. The bearing members  42  and  52  allow the axle members  41  and  51  to rotate relative to the housing member  80 . In other words, the axle members rotate inside the bearing members  42  and  52  when the wheels  40  and  50  rotate. It is noted that the axle members  41  and  51  are mechanically coupled together in the assembled design. As shown in FIGS. 3 b  and  3   c , axle member  51  has a plug member  54  which extends into an opening  44  formed in axle member  41  when the axle members  41  and  51  are properly positioned within the housing member  80 . 
     In order to prevent axle member  41  and axle member  51  being electrically coupled to one another, insulators  14  and  15  are positioned on the bearing member  42  and the opening  44  of axle member  41  so as to isolate axle member  41  (and wheel  40 ) from axle member  51  and the housing member  80 . It is noted that the housing member  80  includes another opening  81 , which has an insulator  16  and a contact member  17  disposed therein. Insulator  16  is configured such that it isolates contact member  17  from the housing member  80 , but allows contact member  17  to be in electrical contact with the bearing member  42 . In the current design, the insulator  16  and the insulator  14  have aligned openings so as to allow the contact member  17  to physically contact the bearing member  42  when the device is assembled. 
     As a result of the foregoing structure, an electrical connection is formed between the wheel  40  and the contact member  17  so as to allow a power signal, which is transmitted over the track in contact with wheel  40 , to be coupled to the contact member  17 . Specifically, the conductive wheel  40  couples the power signal to the conductive axle member  41 , which couples the power signal to the conductive bearing member  42 , which couples the power signal to the contact member  17 . 
     Similarly, an electrical connection is formed between the conductive wheel  50  and the housing member  80 , which in the current embodiment corresponds to the model train chassis and which is formed of a conductive material. Specifically, the conductive wheel  50  is electrically coupled to the conductive axle member  51 , which is electrically coupled to the conductive bearing member  52 , which is electrically coupled to the housing member  80 . 
     Referring again to the wiring schematics of FIGS. 2 a  and  2   b , it is noted that in accordance with the current embodiment, pin  11  of connector  30  is coupled to contact  17 , which is coupled to the left wheel assembly  140 , and pin  7  of connector  30  is coupled to the housing member  80 . As a result, it is possible to isolate the left wheel assembly  140  from both the right wheel assembly  150  and the chassis  80 , while the right wheel assembly  150  is always electrically coupled to the chassis  80 . Lines  58  and  59  illustrated in FIG. 3a represent the electrical path of the left wheel assembly  140  and the right wheel assembly  150 , respectively. 
     FIG. 4 is a bottom view of an exemplary model train locomotive which incorporates the 2 rail to 3 rail conversion system of the present invention. As shown, access to switch  24 , which in the current embodiment is a mechanical switch, is provided via the bottom surface of the locomotive. By simply toggling switch  24  into either the 2 rail configuration or the 3 rail configuration, the operator can control/select the desired mode of operation. Moreover, the operator can switch the configuration of the model train back and forth between the 2 rail and 3 rail configuration states as often as her/she likes simply by changing the position of switch  24 . 
     FIG. 4 also illustrates an example of a pickup roller  95 , which is utilized to contact the third “middle” rail when operating in the 3 rail configuration mode. As shown in this exemplary embodiment, the pickup roller  95  is disposed on the bottom surface of locomotive in a position so as to allow the pickup roller  95  to contact the middle rail of the track when the model train is properly placed on the track. The pickup roller  95  must be isolated from both the left wheel assembly and right wheel assembly. Referring to FIG. 2 b , the pickup roller is electrically coupled (e.g., via a wire) to pin  8  of connector  30 . As a result, when operating in the 3 rail configuration, the pickup roller  95  functions to couple the power signal present on the third rail to pin  8  of connector  30 , which in turn couples the power signal to the positive terminal of the motor of the locomotive. 
     When operating in the 2 rail configuration, it is possible to remove the pickup roller  95  from the locomotive. Alternatively, pickup roller could be designed so as to be a spring loaded/retractable device, wherein in a first state the pickup roller would be locked in a position parallel and adjacent the bottom surface of the locomotive and would not contact the third rail, and in a second state (once the lock is released) the pickup roller would be forced by a spring member into contact with the middle rail of the track. Indeed, any type of connector that allows for repetitively connecting and disconnecting the pickup roller member  95  could be utilized. 
     As described above, the 2 rail to 3 rail conversion system of the present invention provides important advantages over prior art techniques for reconfiguring model trains to operate on the different rail systems. Most importantly, in accordance with the present invention, the operator can essentially configure the model train for either 2 rail or 3 rail operation simply by flipping a switch. As such, the present invention eliminates the need for performing a time consuming and complicated conversion process. Moreover, the present invention allows any operator, even one without any knowledge of model train design, to readily perform the conversion. 
     In addition, as the number of 3 rail layouts owned by hobby train enthusiasts significantly exceeds the number of 2 rail layouts, prior to the present invention, hobbyists were reluctant to purchase 2 rail systems or locomotives capable of operation on 2 rail systems because there was no resale value associated with two rail systems due to the small market share thereof (e.g., a locomotive designed for a 2 rail system could not operate on a 3 rail system without performing the extensive conversion process discussed above). However, the present invention eliminates this issue by allowing locomotives to be easily and quickly converted between 2 and 3 rail operation. As a result of the present invention, there is no longer any need to buy a locomotive of a given layout (i.e., 2 or 3 rail). 
     It is further noted that numerous variations are possible to the exemplary embodiment disclosed above. For example, while switch  24  was illustrated as a mechanical relay manually controlled by an operator, it is also possible to implement switch  24  as an electronic switch device, which is controllable, for example, by a remote control device, or via a microcontroller. Indeed, any switching device capable of performing the function of switch  24  as detailed above can be utilized. 
     In another variation the model train chassis does not comprise a conductive material, and an additional contact member such as the one utilized to contact the bearing member  42  is utilized to contact bearing member  52 . 
     In yet another variation, the connector for allowing the connection and disconnection of the pickup roller from the model train includes a contact switch which indicates whether or not the pickup roller is coupled to the model train (i.e., when the contact switch is in a closed state the pickup roller is coupled to the model train, and when the contact switch is in an open state the pickup roller is removed). Such a switch can be utilized in connection with a microcontroller contained in the model train to automatically configure switch  24  (which in this embodiment would be an electrically controllable switch) to the proper state based on the presence or absence of the roller pickup. 
     Of course, it should be understood that a wide range of other changes and modifications can be made to the preferred embodiment described above. It is therefore intended that the foregoing detailed description be regarded as illustrative rather than limiting and that it be understood that it is the following claims including all equivalents, which are intended to define the scope of the invention.