SWITCH MACHINE

Abstract: There is provided a switch machine (10) for controlling the position of railroad tracks having up to five improved capabilities. First, the switch machine (10) is designed to have a low vertical profile without increasing its axial length or sacrificing its functionality. Second, the switch machine (10) has a rail point detection and indication mechanism (210) that identifies a latch out condition when the railroad tracks are not at, or near, their proper positions before or after switching the railroad tracks. Third, the switch machine (10) has a trailing device (416) coupled to a throw bar (412) for enabling throwing of the switch points. Fourth, a cam bar (530) of the switch machine (10) locks and unlocks a lock bar (520) as required for railway track systems. Finally, an improved hand throw mechanism (730) of the switch machine (10) has a ratchet mechanism (740) that permits torque to be applied to the hand throw mechanism (730) in either a clockwise or counter-clockwise direction.

Description: SWITCH MACHINE RELATED APPLICATIONS Priority of the following earlier applications is hereby claimed for this application: U.S. Patent Application Serial No. 08/293,126, filed on August 19, 1994, titled POINT DETECTION AND INDICATION WITH LATCH OUT MEANS; U.S. Patent Application Serial No. 08/293,121, filed on August 19, 1994, titled LOW PROFILE SWITCH MACHINE; U.S. Patent Application Serial No. 08/293,242, filed on August 19, 1994, titled TRAILING DEVICE FOR A RAILROAD SWITCH LAYOUT; U.S. Patent Application Serial No. 08/293,127, filed on August 19, 1994, titled SWITCH MACHINE CAM BAR; and U.S. Patent Application Serial No. 08/293,125, filed on August 19, 1994, titled SWITCH MACHINE WITH RATCHET MECHANISM ON HAND THROW MEANS. BACKGROUND OF THE INVENTION I. Field of the Invention The present invention relates generally to switch devices for switching the positions of railway tracks in order for trains to move from one track to another. More particularly, the present invention relates to an electric motor driven switch machine having a low vertical profile while retaining all of the functionality of existing switch machines and combining new or improved functions. Such new or improved functions include a point detection and indication apparatus with latch out means for determining proper or improper track switching, a cam bar that permits continued operation of the switch machine when it fails to lock properly, a trailing device that causes the railway tracks to switch automatically by the passage of rolling stock in the reverse or trailing direction, and a ratchet mechanism on a hand throw means to facilitate manual switching of railway tracks. π. Description of the Prior Art It is a requirement for operation of a railroad network to have the capability of switching railroad trains from one track to another. A common method of providing this switching capability is to install an electric motor driven switch machine along side of, and interconnected to, a switch point of a railroad track. Switch machines perform a wide variety of functions related to railway switching. For example, they often have manual operations for shifting the position of the track without the use of the electric motor for certain situations, such as when electric power is not available. Generally, a switch machine controls a switching operation by connections to the railroad tracks through a throw bar, lock bar, and point detector bar. The throw bar throws a pair of inner tracks, located between a pair of stock rails, from one track position to another. The lock bar locks the inner tracks after the throw bar has switched them into position. The point detector bar determines whether the inner tracks have moved to a proper position. A switch machine having a low vertical profile and no projections extending from its top surface is desirable for many applications. Particularly for transit applications, it is essential that a low profile be maintained by a switch machine in order to clear steps, third rail electric pick-ups and other types of ground clearing equipment extending down from a transit car or locomotive. Also, a low profile switch machine is desirable for safety and maintenance reasons. Preferably, a low profile switch machine should retain most, if not all, of the functions of existing switch machines and, also, combine new or improved functions. The following new and/or improved functions for switch machines are provided in this application: point detection and indication system, trailing device, cam bar and ratchet mechanism on hand throw means. A rail point detection and indication system is desirable, and perhaps necessary, for a switch machine. Modern switch machines are usually operated from a remote location and, thus, a remote operator must be able to determine that the switch has, in fact, been thrown as requested. The detection and indication system typically has a tolerance limit to allow for some error between the expected and actual location of the switching point, and an adjustment means for setting the tolerance limit at an acceptable level. Some switch machines include a latch out means which permits a switch machine to operate properly with some additional tolerance to error, thus, minimize excessive maintenance actions and possible train delays caused thereby. A latch out means of a switch machines can either be restorable or non-restorable from a remote location, as desired by the operator. Another desirable function for a switch machine is a trailing device. A common method of switching railway tracks is to use a motor driven throw bar or the like to throw switch points to control the switching of rolling stock. When railroad stock is moved frequently in the forward and reverse directions, it is beneficial to move such stock through switch points without hassle or delay. For a switch machine with trailing capability, passage of rolling stock through the switch in the reverse or trailing direction will cause the switch to be thrown automatically, that is, without the time delay of a manual switch operation. The traditional or conventional switch machine includes a trailing device within the housing of the machine itself. Accordingly, situating the trailing device within the switch machine increases the vertical profile of the machine and requires disassembly, which can be difficult, for maintenance and inspection. In addition, it is desirable to include a cam bar that permits a hand throw operation when the lock bar does not properly lock the inner tracks adjacent to the switch machine. Occasionally, a hand throw operation of the switch machine is necessary to manually switch the tracks by throwing a hand throw switch. In such situations, the lock bar of the switch machine locks the position of the inner tracks after they have been thrown by the hand throw switch. However, if the switch machine or its tracks has been damaged in a manner that prevents the lock bar from operating properly, completion of the hand throw operation may not be possible and the operation of trains through that vicinity will be tied up until the problem is fixed. Therefore, there is a need for a device that will permit a hand throw operation to be completed even when its lock bar does not properly lock its associated inner tracks into position until the problem can be corrected. A further function that is desirable for switch machines is a means for performing a hand throw operation. The hand throw operation permits operational personnel to switch the track, i.e., throw the switch machine, at the switch machine when control signals from a remote facility are not able or not desired to reach the switch machine. Since existing switch machines with hand throw capabilities require 180 degrees of handle rotation to complete a throw, and the switch machines are typically installed at or near ground level, an operator must lift the hand throw arm upward and then push it over and down to the opposite position. This operation results in stress and strain on the operator's back, spine, joints, muscles and other parts of the body that must exert considerable force in an awkward position without any mechanical aid from the hand throw means. Accordingly, the above desireable functions are not easily implemented within switch machines, particularly low profile switch machines. Also, due to the environmental and operational hazards exposed to switch machines and the cost of maintaining them, a simpler and more economical design over the prior art designs is preferable for switch machines. Thus, a simpler and more economical design of a point detection and indication system, trailing device, cam bar and ratchet mechanism on hand throw means would reduce the cost of manufacturing and maintaining a switch machine while retaining all necessary features and becoming less prone to environmental and operational hazards. Accordingly, it is a primary object of the present invention to overcome the aforenoted problem associated with designing a switch machine having a low vertical profile while retaining all of the various capabilities of existing switch machines, including the electric motor, hand crank and hand throw operations. Another object is to provide a switch machine having a simplified point detection and indication system by reducing the number of required parts and using position detecting elements that are directly interacting with each other instead of indirectly responding through other elements. In addition, the point detection and indication system should provide all of the functionality of a latch out feature without significantly complicating the design or increasing the first cost or live cycle cost of the system. A further object is to provide a switch machine having a trailing mechanism or device that can be used in conjunction with a low profile configuration switch machine. A related object of the present invention is to make the aforesaid trailing mechanism such that it can be placed outside the switch machine configuration. A still further object is to provide a switch machine having an override provision for operating the throw bar to switch the railroad tracks even though the lock bar does not properly lock the tracks in position. When the lock bar is not operational, the override provision should have the ability to automatically return to its normal operation once the problem with the lock bar has been cleared or fixed. A yet another object of the present invention to provide a switch machine having an improved hand throw means by reducing or eliminating the strain required for its operation and reducing the time required to install and maintain the hand throw means, while retaining all of the desired features available in existing hand throw mechanisms. SUMMARY OF THE INVENTION In fulfillment of the above stated and other objects, the problem noted above has been overcome by designing a switch machine for railroad tracks with many new improvements. One improvement is a low vertical profile without increasing the axial length or sacrificing the functionality of the switch machine. Another improvement is a rail point detection and indication means that identifies a latch out condition when the railroad tracks are not at, or near, their proper positions before or after switching the railroad tracks. Still another improvement is a trailing device coupled to a throw bar for enabling the throwing of switch points into selected positions and to control the switching of rolling stock. A further improvement is a cam bar of the switch machine locks and unlocks a lock bar as required for railway track systems. A still further improvement is a hand throw means of the switch machine has a ratchet mechanism that permits torque to be applied to the hand throw means in either a clockwise or counter-clockwise direction, as desired by an operator, with minimal exertion of force. Briefly described then, a preferred embodiment of the present invention is defined as a low vertical profile switch machine for switching a position of a railroad track having a mode selector for selecting among a plurality of modes including a power mode and a hand throw mode, comprising: a crank shaft, a crank gear freely rotatable about the crank shaft, a crank sleeve slidably mounted about the crank shaft for engaging the crank gear to the crank shaft, a hand throw shaft positioned adjacent and substantially parallel to the crank shaft, a bevel gear freely rotatable about the hand throw shaft, a hand throw assembly slidably mounted about the hand throw shaft for engaging the bevel gear to the hand throw shaft; and a shifter mechanism, having a first end connected to the crank sleeve and a second end connected to the hand throw assembly, for shifting the first and second ends based on the mode selected by the mode selector; wherein the shifter mechanism shifts the first end to engage the crank gear and the second end to disengage the bevel gear when the power mode is selected by the mode selector, and wherein the shifter mechanism shifts the second end to engage the bevel gear and disengage the crank gear when the hand throw mode is selected by the mode selector. The preferred embodiment of the present invention is also provided as a low vertical profile switch machine for switching a position of a railroad track having a mode selector for selecting among a plurality of modes including a power mode and a hand throw mode, comprising: a motor, a first gearbox driven by the motor having an input shaft and an output shaft each adapted to rotate, wherein the rotational speed of the input shaft is proportional to the rotational speed of the output shaft, a gear shaft assembly including a gear shaft having a first input end and a second input end opposite the first input end, wherein the output shaft is coupled to the first input end, a hand crank means for driving the gear shaft removably attached to the second input end, a crank shaft positioned a fixed distance from the gear shaft assembly, a crank gear freely rotatable about the crank shaft and driven by the gear shaft assembly, a crank sleeve slidably mounted about the crank shaft for engaging the crank gear to the crank shaft, a hand throw shaft positioned adjacent and substantially parallel to the crank shaft, a bevel gear freely rotatable about the hand throw shaft, a hand throw assembly slidably mounted about the hand throw shaft for engaging the bevel gear to the hand throw shaft; and a shifter mechanism, having a first end connected to the crank sleeve and a second end connected to the hand throw assembly, for shifting the first and second ends based on the mode selected by the mode selector, wherein the shifter mechanism shifts the first end to engage the crank gear and the second end to disengage the bevel gear when the power mode is selected by the mode selector, and the shifter mechanism shifts the second end to engage the bevel gear and disengage the crank gear when the hand throw mode is selected by the mode selector. Also, the preferred embodiment of the present invention is defined as a point detection and indication apparatus for an electric motor driven switch machine, comprising: a point detector bar having an outer surface, a point detector cam positioned by the outer surface, a pair of cam followers, each of the cam followers having a first end adjacent to the outer surface and a second end, wherein the second end is positioned at a first position when the first end is positioned adjacent the point detector cam, and the second end is positioned at the second position when the first end is not positioned adjacent to the point detector cam, and a link arm, directly linking the second ends of the pair of cam followers, having tension means, the tension means for retracting a length of the link arm when at least one of the second ends shifts from the second position to the first position and for extending the length of the link arm when at least one of the second ends shifts from the first position to the second position. In addition, the preferred embodiment of the present invention is defined as a point detection and indication apparatus for an electric motor driven switch machine having an activation means, comprising: a point detector bar having an outer surface, a point detector cam positioned by the outer surface, a pair of cam followers, each of the cam followers having a first end adjacent to the outer surface and a second end, wherein the second end is positioned at a first position when the first end is positioned adjacent the point detector cam, and the second end is positioned at the second position when the first end is not positioned adjacent to the point detector cam, a link arm directly linking the second ends of the pair of cam followers, a pair of latch retainers positioned on the link arm, a pair of latch bars positioned about the link arm between the latch retainers, each of the latch bars having a contact end, each of the latch bars having a first latch position such that the contact end does not contact the latch retainer, and a second latch position such that the contact end contacts the latch retainer, a latch opener cam having an unlock position for positioning the latch opener cam between the latch bars and the latch bars at the first latch positions, and a lock position for positioning the latch opener cam to one side of the latch bars and the latch bars at the second latch positions, and a latch out switch, responsive to the activation means of the switch machine, for terminating the operation of the switch machine when the latch opener cam is at the lock position and both of the cam followers are at the second position. Moreover, the present invention involves an apparatus for operating railroad switches, including operation in a trailing mode, the arrangement being such that a switch machine has a throw bar for enabling the throwing of switch points that control the switching of rolling stock; the machine also has a throw rod, the throw bar and rod being variably extendably coupled such that when a "wrong direction" load is depressed on the switch points, the throw rod will be moved, but will not cause damage because take-up space is provided in the trailing mechanism. Further, the preferred embodiment of the present invention is defined as a cam bar of a railroad track switch machine for locking a lock bar, comprising: a positioning section, a locking section having a locking position for locking the lock bar, means, located on the locking section, for interlocking the locking section to the positioning section, and the interlocking means being operative to allow the positioning section to separate from the locking section when the locking section is prevented from moving to the locking position. Still further, the preferred embodiment of the present invention is defined as a switch machine for switching railway tracks from one position to another, having a hand throw means for causing a railway track switching operation to occur, the switch machine comprising a drive shaft, a throw shaft located adjacent to the drive shaft for driving the drive shaft, and ratchet means operatively connected to the drive shaft and the throw shaft, including first means for rotating the drive shaft proportional to the rotation of the throw shaft and second means for rotating the throw shaft when the ratchet means is moved in a first direction and allowing the throw shaft to remain stationary when the ratchet means is moved in a second direction. From another view point of the preferred embodiment, the housing portion of the switch machine is defined as follows: a drive shaft, a first assembly having an aperture for supporting the drive shaft, a second assembly located adjacent to the first assembly for supporting the hand throw means, means, supported by the first and second assemblies, for rotating the drive shaft when the hand throw means is moved in a first direction and allowing the drive shaft to remain stationary when the hand throw means is moved in a second direction, and the first and second assemblies being separable from the switch machine, and from each other, so that the rotating means may be removed and disassembled without disturbing the remaining components of the switch machine. Other and further objects, features and advantages of the present invention will be understood by reference to the following description in conjunction with the annexed drawings, wherein like parts have been given like numbers. BRIEF DESCRIPTION OF THE DRAWINGS Fig. 1 is a perspective view of the base of the preferred embodiment of the present invention along with the main components of the preferred embodiment. Fig. 2 is another perspective view of the preferred embodiment as shown in Fig. 1, showing the opposite side of the switch machine, wherein covers for the speed reducer gearbox and worm drive gearbox have been omitted. Fig. 3 is a cross-sectional view through the crank shaft and hand throw shaft of the preferred embodiment of Fig. 1. Fig. 4 is a close-up perspective view of the crank shaft and hand throw shaft of the preferred embodiment as shown in Fig. 1, wherein the overhead frame, crank gear and hand throw gear have been omitted. Fig. 5 is perspective view of the preferred embodiment of Fig. 1, additionally showing the hand throw selector and hand throw arm. Fig. 6 is a cross-sectional view through the hand throw shaft and hand throw selector of the preferred embodiment of Fig. 1. Fig. 7 is a planar view, from above, of a point detector and indicator system of the preferred embodiment such that the top cover of the switch machine is omitted in order to show its inner components. Fig. 8 is a cut-view of the preferred embodiment of Fig. 7 showing a cross- sectional view of the link arm assembly through line 8-8 and a further view of its surrounding elements. Fig. 9 is a planar view of the preferred embodiment of Fig. 7 such that the switch machine is in mid-stroke. Fig. 10 is another planar view of the preferred embodiment of Fig. 7 such that the switch machine is locked and indicating, but is not "latched-out". Fig. 11 is still another planar view of the preferred embodiment of Fig. 7 such that the switch machine is "latched-out". Fig. 12A is a plan view of an exemplary switch layout, particularly illustrating a conventional switch machine connected to an embodiment of the trailing mechanism of the present invention, located as seen. Fig. 12B is an elevation view of the same layout seen in Figure 12 A. Fig. 13 is a vertical sectional view of another embodiment of the trailing mechanism. Fig. 14 is a view of the lost motion means incorporated within the trailing mechanism so as to provide adjustability in making the switch throw compatible with the switch machine throw. Fig. 15 is a perspective view of a cam bar positioned on the base plate of the preferred embodiment showing a lock bar positioned over an end portion of the cam bar. Fig. 16 is another perspective view of the cam bar of Fig. 15, wherein the lock bar has been omitted in order to more clearly show the elements hidden behind the lock bar. Fig. 17 is an elevation or side view of the cam bar of Fig. 15, without the base plate. Fig. 18 is a top plan view of the cam bar of Fig. 15, without the base plate. Fig. 19 is a cross-sectional view of the preferred embodiment without the ratchet mechanism of the present invention. Fig. 20 is cross-sectional view of the preferred embodiment with the ratchet mechanism of the preferred embodiment. Fig. 21 is a planar side view of the ratchet mechanism of Fig. 20 (viewed from the right, outer side of Fig. 20), such that certain components of the mode selector have been omitted. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to the drawings and, in particular, Fig. 1, there is generally provided a electric motor driven switch machine 10 of the present invention. The switch machine 10 has a low vertical profile and includes (1) a point detection and indication system with latch out means, (2) trailing device for a railroad switch layout, (3) switch machine cam bar and (4) switch machine with ratchet mechanism on hand throw means. I. LOW PROFILE SWITCH MACHINE Referring to Fig. 1, the electric motor driven switch machine 10 of the present invention has a low vertical profile. Fig. 1 is a partial cut-away view of the main components of the preferred embodiment, whereby the cover 12, shown in Fig. 3, of the switch machine has been removed and certain other components have been omitted. Although these other components may be essential for the full operation of the switch machine, they are not considered to be essential for the low vertical profile feature of the preferred embodiment and have been omitted from Figs. 1 through 6 in order to more clearly identify the various components of the present invention without obstruction. In order to lower the vertical height while keeping within all other dimensions of existing switch machines, the following novel means of packaging the various components has been developed. As shown in Fig. 1, viewed from left to right, the main components of the preferred embodiment comprise a motor-gearbox combination 20, worm drive gearbox 40 and crank-hand throw drive combination 70 (i.e., a combination that includes a crank shaft and a hand throw shaft). The motor-gearbox combination 20 comprises a motor 22, such as a brushless D.C. motor, that drives a speed reducer gearbox 24. An output shaft 26 extending from the side of the speed reducer gearbox 24 opposite the motor 22 rotates at a speed that is less than, and proportional to, the speed of the motor. This motor-gearbox combination 20 permits a low profile in that the motor 22 is very compact compared to other switch machine concepts in existence. Without the use of the speed reducer gearbox 24, a motor having a much larger diameter would be required. The worm drive gearbox 40 has a worm gear shaft 42 that is driven by the output shaft 26 of the motor 22 through a coupling 28. The worm gear shaft 42 drives a worm wheel 44 that is on the first of three vertical shafts, the worm drive shaft 46, shown in Figs. 2 and 3 and described subsequently. The worm gear shaft 42 extends through the outer cover 48 of the worm drive gearbox 40 such that the ends 50, 52 of the worm gear shaft are positioned outside of the outer cover. As stated above, one end 50 of the worm gear shaft is driven by the output shaft 26 of the motor 22. The other end 52 of the worm gear shaft 42 is driven by a hand crank means 54 (shown in Fig. 6) that is removably positioned within a hand crank hole 56 and a hand crank socket 58 so that the hand crank means engages the worm gear shaft at that end. This multiple use of the worm gear shaft 42, i.e., receiving power from either the motor-gearbox combination 20 or the hand crank means 54, not only saves cost, but is part of the compact packaging concept of the present embodiment. Fig. 2 shows another view of the main components of the preferred embodiment, viewed from the opposite side, wherein the outer covers 30, 48 of the speed reducer gearbox and the worm drive gearbox have been removed to show their inner components. The inner components of the speed reducer gearbox 24 comprise two engaged circular gears 32, 34 having different diameters. The smaller gear 32 is attached to the motor 22 whereas the larger gear 34 is attached to the output shaft 26 of the speed reducer gearbox 24. As stated above, the output shaft 26 rotates at a speed that is less than, and proportional to, the speed of the motor 22. For example, if the larger gear 34 has a circumference that is twice the circumference of the smaller gear 32, then the speed reducer gearbox would have a 2: 1 ratio and the output shaft 26 would rotate at half the speed of the motor 22. Adjusting the speed of the motor 22 through the speed reducer gearbox 24 permits the use of a low profile motor in the preferred embodiment. Without the outer cover 48 of the worm drive gearbox 40, the inner components of the worm drive gearbox are clearly shown in Fig. 2. In particular, there are two gears that are mounted on the worm drive shaft 46: a worm gear 60 and a drive gear 62. The worm gear shaft 42 engages one side of the worm gear 60 to drive the worm drive shaft 46 and, correspondingly, the drive gear 62. This configuration of the worm drive gearbox 40 not only allows for the multiple use described above but also reduces the speed of the drive gear 62 relative to the worm gear shaft 42. Effectively, worm drive gearbox 40 also acts as a subsequent speed reducer gearbox having a particular ratio, such as 60: 1, that follows the first speed reducer gearbox 24. As shown in Fig. 2, the crank-hand throw drive combination 70 comprises the second and third vertical shafts of the preferred embodiment, the crank shaft 72 and the hand throw shaft 74, respectively. The drive gear 62 rotates about the bottom of the worm drive shaft 46 and meshes with a main drive gear 76 that is mounted on the crank shaft 72. In addition to the main drive gear 76, a crank gear 78 is mounted near the upper end of the crank shaft 72, and meshes with a hand throw gear 80 mounted near the top of the hand throw shaft 74. The upper ends of both the crank shaft 72 and the hand throw shaft 74 are positioned at substantially the same vertical height so that neither shaft increases the height of the switch machine 10 over the other. Near the bottom end of the hand throw shaft 74 is a bevel gear 82, to be described in more detail below. Referring to Fig. 3, there is shown a cross-sectional view of the crank-hand throw drive combination 70 of the preferred embodiment. By providing a third vertical shaft, i.e., the hand throw shaft 74, that is separate and adjacent to the crank shaft 72, it is possible to reduce the vertical profile of the switch machine 10 by four (4) or more inches (101.6 millimeters) lower than existing switch machines. As described above, the crank shaft 72 and the hand throw shaft 74 support a crank gear 78 and a hand throw gear 80 near the upper ends and a main drive gear 76 and a bevel gear 82 at the lower ends, respectively. In addition the crank shaft supports a crank sleeve between the crank gear and the main drive gear, and the hand throw shaft 74 supports a hand throw assembly 84 between the hand throw gear 80 and the bevel gear 82. A crank sleeve 86 is slidably mounted on the crank shaft 72 so that it may freely slide up and down the crank shaft. This sliding movement is in contrast to the fixed, non- sliding position of the crank gear 78 and the main drive gear 76 on the crank shaft 72. Also, the crank gear 78 and main drive gear 76 are functionally different from each other in that the crank gear rotates with the crank shaft 72 but the main drive gear spins freely around the crank shaft. Similarly, the hand throw assembly 84 is slidably mounted on the hand throw shaft 74, and similar to the crank gear 78, the hand throw gear 80 is fixed to, and rotates with, the hand throw shaft. Referring to Fig. 4, the linear movement of the crank sleeve 86 is due to the fact that inner grooves 88 at the inner surface of the crank sleeve follow vertical guides 90 that are located around the outer surface of the crank shaft 72. This connection of the inner grooves 88 of the crank sleeve 86 to the vertical guides 90 of the crank shaft 72 permits the crank sleeve to slide vertically along the crank shaft but rotate in sync with the crank shaft. When the crank sleeve 86 slides down towards the main drive gear 76, teeth 92 along the bottom edge of the crank sleeve interlock with openings 94 along the top portion of the main drive gear. Whereas, normally, the main drive gear 76 rotates freely around the crank shaft 72, when the teeth 92 of the crank sleeve 86 slide down into the openings 94 of the main drive gear 76, the crank sleeve engages the main drive gear to the crank shaft, thus the main drive gear rotates with the crank shaft. Likewise, the hand throw assembly 84 slides vertically along the longitudinal length of the hand throw shaft 74 due to the inner grooves 96 of the hand throw assembly following the vertical guides 98 of the hand throw shaft. The hand throw assembly 84 comprises an inner sleeve 100, outer sleeve 102, clutch 104, an upper spring 106, and a lower spring 108. The inner sleeve 100 is slidably mounted about the hand throw shaft 74 having a flange 110 at the lower portion for supporting the bottom end of the lower spring 108. The outer sleeve 102 is located about the upper portion of the inner sleeve 100 and is support from below by the upper end of the upper spring 106. The clutch 104 is slidably mounted about the middle portion of the inner sleeve 100 and is supported between the flange 110 and the outer sleeve 102 by the upper and lower springs 106, 108. The bevel gear 82 is situated near the bottom end of the hand throw shaft 74 and rotates freely around the hand throw shaft. The flange 110 of the inner sleeve 100 is designed to engage the bevel gear 82 when the hand throw assembly 84 is lowered into the bevel gear. Thereby, when the flange 110 of the inner sleeve 100 engages the bevel gear 82, the bevel gear engages the hand throw shaft 74 by the hand throw assembly 84, and thus, the bevel gear rotates with the hand throw shaft. Also shown in Fig. 4, a shifter mechanism 112 of the crank-hand throw drive combination 70 includes a linkage arm 114 supported by a fulcrum 116. One end 118 of the linkage arm 114 is pivotally connected to the crank sleeve 86 whereas the other end 120 of the linkage arm is pivotally connected to the outer sleeve 102 of the hand throw assembly 84. Therefore, when the hand throw assembly 84 moves upward, the crank sleeve 86 will move correspondingly downward, rotating the linkage arm 114 clockwise (from the view of Fig. 4) around the fulcrum 116. Similarly, when the hand throw assembly 84 moves downward, the crank sleeve 86 will move corresponding upward, rotating the linkage arm 114 counter-clockwise around the fulcrum 116. The main control levers for the hand throw operation are shown in Fig. 5, namely a hand throw selector 122 and hand throw arm 124. The hand throw selector 122 selects between one of at least two modes: a power mode and a hand throw mode. When the hand throw selector 122 is in power mode, the hand throw arm 124 is not operational, and the gears 76, 78, 80 for switching the railroad tracks adjacent to the switch machine 10 must be driven by the motor 22 or the hand crank means 54, as described above. When the hand throw selector 122 is in hand throw mode, the hand throw arm 124 may be thrown manually by a human operator, thereby rotating the bevel gear 82, in order to switch railroad tracks using the switch machine 10. Referring to Fig. 6, the manner in which the hand throw selector 122 controls the crank-hand throw drive combination 70 is described in more detail as follows. The hand throw selector 122 comprises a hand throw shaft 126, hand throw lever 128 and eccentric pin 130. The hand throw lever 128 is supported within the hand throw shaft 126 such that it can rotate freely, up to 180 degrees. Thus, turning the hand throw selector 122 from power mode to hand throw mode (or vice versa) effectively turns the hand throw lever 128 "180 degrees" within the hand throw shaft 126. The eccentric pin 130 is positioned at one end 132 of the hand throw lever 128 and offset from the center of the end so that rotating the hand throw lever causes the eccentric pin to move slightly in a vertical motion (as well as horizontal). This vertical motion is transmitted to the clutch 104 of the hand throw assembly 84 through the eccentric pin 130, thus allowing the hand throw selector 122 to selectively move the clutch up and down. In other words, when power mode is selected by the hand throw selector 122, the clutch 104 is moved upward, and when the hand throw mode is selected, the clutch is move downward. Therefore, referring back to Fig. 3, the overall operation of the crank-hand throw drive combination 70 is described as follows. When power mode is selected by the hand throw selector 122, the clutch 104 of the hand throw assembly 84 is moved upward, thereby forcing the upper spring 106 against the outer sleeve 102 and lifting the flange 110 away from the bevel gear 82. As the outer sleeve 102 moves upward, the linkage arm 114 forces the crank sleeve 86 downward. Before the crank sleeve 86 reaches the main drive gear 76, the main drive gear freely spins about, but does not drive, the crank shaft 72. However, when the linkage arm 114 forces the teeth 92 of the crank sleeve 86 down into the openings 94 of the main drive gear 76, the main drive gear engages the crank shaft 72 through the crank sleeve. Thus, since the main drive gear 76 is indirectly driven by the motor 22 of the motor-gearbox combination 20, the motor is effectively rotating the crank shaft 72 and powers the switch machine 10 to switch the desired railroad tracks. When the hand throw mode is selected by the hand throw selector 122, the clutch 104 is moved downward, thereby forcing the lower spring 108 against the flange 110 and causing the flange to move downward and to engage the bevel gear 82. Thus, the bevel gear 82 is engaged to the hand throw shaft 74 by the flange 110. When the hand throw arm 124 is thrown by a human operator, the bevel gear 82 rotates, thereby rotating the hand throw shaft 74 and powering the switch machine 10 to switch the desired railroad tracks. At the same time, when the clutch 104 is moved downward, the outer sleeve 102 forces one end 120 of the linkage arm 114, where the outer sleeve is located, downward and forces the other end 118 upward, thus causing the crank sleeve 86 to move upward as well. The crank sleeve 86 moves away from the main drive gear 76 such that the main drive gear is no longer engaged to the crank shaft 72. In summary, the hand throw selector 122, by controlling the clutch 104, causes either the crank sleeve 86 to engage the main drive gear 76 and the flange 110 to disengage the bevel gear 82, or the flange to engage the. bevel gear and the crank sleeve to disengage the main drive gear. Another feature of the preferred embodiment is the utilization of upper and lower springs 106, 108 to support the clutch 104 between the flange 110 and outer sleeve 102 of the hand throw assembly 84. As described above, when power mode is selected by the hand throw selector 122, the crank sleeve will initially attempt to engage the openings of the main drive gear. If the teeth 92 of the crank sleeve 86 are aligned with the openings 94 of the main drive gear 76, then the crank sleeve will immediately engage the main drive gear when power mode is selected. However, if the teeth 92 of the crank sleeve 86 are not aligned with the openings 94 of the main drive gear 76, the main drive gear must turn until the teeth and openings are aligned in order for the crank sleeve to engage the main drive gear. Thus, when the clutch 104 is moved upward and the teeth 92 and openings 94 are not aligned, the upper spring 106 will compress between the clutch 104 and the outer sleeve 102. Therefore, as the main drive gear 76 rotates, the compressed upper spring 106 will force the crank sleeve 86 to engage the main drive gear 76 as soon as the teeth 92 align with the openings 94. Therefore, the upper and lower springs 106, 108 of the hand throw assembly 84 facilitate the operation of the crank sleeve 86 for engaging the main drive gear 76. The novel concept of the above described preferred embodiment has the following advantages over the existing products found in the field. The multi-function operational capability of the switch machine is maintained, including operation by electric motor, hand cranking or hand throw operation. Also, the low profile machine is only eight inches tall from bottom of the base to top of the cover, and there are no projections below the base that would interfere with existing stock rail ties, concrete pit floors or other equipment installed by railroad owners. In addition, the top of the switch machine has no local vertical projections that could catch projections from passing railroad equipment, thereby, minimizing damage to the switch from external influences. Furthermore, the axial length of the preferred embodiment has not been increased over standards in the industry. Since the various connection points of the switch machine to the railroad tracks are fixed for a given installation, the length from the centerline to either end of the switch machine has been maintained within existing industry limitations. H. POINT DETECTION AND INDICATION WITH LATCH OUT MEANS Referring to Fig. 7, there is shown a detection and indication system 210 for the switch machine 10 of the present invention. The detection and indication system 210 is part of a switch machine that is located adjacent to a set of stock rails having a set of switching rails situated therebetween (not shown). Other than the detection and indication system 210 of the present invention, the general structure and positioning of switch machines relative to railroad tracks is known in the art and, therefore, will not be described in detail. Referring specifically to Fig. 7, there is shown an overhead planar view of a portion of the switch machine 10 of the preferred embodiment where the cover (not shown) of the switch machine has been omitted from the figure. Of the various components of the switch machine 10, only the base 212 of the switch machine and the elements relevant to the operation to the detection and indication system 10 are shown. The basic design of the detection and indication system 210 is in the form of a four bar linkage 214, which includes a point detector bar 220, two cam followers 240, 260, and a link arm assembly 280. The point detector bar 220 is a long cylindrical rod positioned perpendicular across the longitudinal axis of the switch machine 10 such that movement by the point detector bar 220 corresponds to movement by switching rails relative to the position of stock rail on either side (not shown). The point detector bar 220 is capable of moving in two opposing directions: a normal direction 222 and a reverse direction 224. When the point detector bar 220 is moving toward the railroad tracks (upward in Fig. 7), the bar is moving in a normal direction 222; when the point detector bar is moving in the opposite direction away from the railroad tracks (downward in Fig. 7), the bar is moving in a reverse direction 224. A point detector cam 226 formed at a fixed position on the point detector bar 220 such that the detection and indication system 210 can identify any movement by the switching rails by monitoring the position of the point detector cam 226. The point detector cam 226 is elongated notch grooved at a small portion of the point detector bar 220 having conical slopes 228, 230 at both ends. The conical slopes 228, 230 connect the smaller-diameter surface 232 of the point detector cam to the larger-diameter surface 234 of the rest of the point detector bar. Adjacent to the point detector bar 220 is the normal cam follower 240 and the reverse cam follower 260. Since both cam followers 240, 260 have similar structures and functions, the normal cam follower is described in detail hereinafter, without equal reference to the reverse cam follower. Unless otherwise stated, the reverse cam follower 260 should be understood to have the same features as, or similar features to, the normal cam follower 240 . The normal cam follower 240 has an elongated, diamond shape having two acute-angle comers 242 and two obtuse-angle comers 244. A pivot point 246 is situated at one of the obtuse-angle comers 244 for stabilizing the normal cam follower 240 to the base 212 of the switch machine 10. At the two acute-angle comers 242 are a roller 248 and an attachment point 250, located at opposite comers of the normal cam follower 240. The roller 248 is positioned adjacent to the point detector bar 220 whereas the attachment point 250 is rotatably attached to a normal end 282 of the link arm assembly 280. For the reverse cam follower 260, an attachment point 270 is rotatably attached to a reverse end 284 of the link arm assembly 280. Also attached at the attachment point 250 of the normal cam follower 240 is a switch arm 252 extending beneath the link arm assembly 280 to a normal point detector switch 254. From the view of Fig. 7, the normal point detector switch 254 is located to the upper left of the four bar linkage 214 (and a reverse point detector switch 274 is located to the lower left of the four bar linkage). An adjustment screw 256 is integrated within the switch arm 252 so that the switch arm can be manually and adjustably aligned with the normal point detector switch 254. Operationally, when the normal cam follower 240 pivots around the pivot point 246 in a clockwise direction, the switch arm 252 presses into the normal point detector switch 254. Likewise, when the normal cam follower 240 pivots in a counter-clockwise direction, the switch arm 252 releases the normal point detector switch 254. It should be noted that both the normal point detector switch 254 described above and the corresponding reverse point detector switch 274 are push-to-open switching devices. In other words, when the switches 254, 274 are pressed inward by their respective switch arms 252, 272, their circuits are opened and in their "off" position. When the switches are released as their respective switch arms 252, 272 move away from them, their circuit are closed and the switches in their "on" position. As described above, Fig. 7 shows the two attachment points 250, 270 of the cam followers 240, 260 directly connected by the ends 282, 284 of the link arm assembly 280. The main body extending through the entire link arm assembly 280 is a link arm 286 having the capability of extending and retracting based on the lateral force applied at the ends 282, 284 of the link arm assembly. Referring to Fig. 8, the tension means 288 that provides the extension and retraction capability to the link arm assembly 280 is shown. The link arm 286 mainly comprises an inner sleeve 290 that extends for almost the entire length of the link arm 286 and an outer sleeve 292 that only extends for about half of the length of the link arm. The inner sleeve 290 includes an adjustment coupler 294 for adjusting the length of the inner sleeve, and thus the length of the link arm 286, to a desired length. The inner sleeve 290 slides into an inner bore 296 of the outer sleeve 292 and is held at that approximate position by a tension spring 298. One end of the tension spring 298 rests against a shoulder 300 of the outer sleeve 292 whereas the other end rests against a shoulder 302 of the inner sleeve 290. Therefore, the tension of the tension spring 298 pressing against the two shoulders 300, 302 of the outer and inner sleeves 290, 292 retracts the link arm 286 to its minimum length. However, the tension spring 298 also allows the link arm 286 to extend when a force pulls the link arm at either of its two ends 282, 284. For example, when the attachment point 250 of the normal cam follower 240 pulls the inner sleeve 290 of the link arm 286 away from the outer sleeve 292, the tension spring 298 compresses, thereby, allowing the entire link arm to extend in length. In the manner just described, the tension means 288 naturally tries to keep the link arm 286 at its minimum length but will allow the link arm to extend when a pulling force is applied to one or both of its ends 282, 284. Referring again to Fig. 7, the latch out means of the preferred embodiment comprises a pair of latch retainers 310, 340, a pair of latch bars 312, 342 and a latch opener cam 370 that interact with the link arm 286. The normal latch retainer 310 is attached to the inner sleeve 290 of the link arm 286 whereas the reverse latch retainer 330 is attached to the outer sleeve 292. Each latch retainer 310, 340 has a retainer body 314, 344 with a ring end 316, 346 and a non-ring end 318, 348, such that a retainer ring 320, 350 is located at the ring end of the retainer body. Referring to Fig. 9, the normal latch bar 312 and the reverse latch bar 342 are situated between the latch retainers 310, 340. Each latch bar 312, 342 has a pivoting end 322, 352 and a spring end 324, 354 with a middle abutment 326, 356 therebetween. The latch bars 312, 342 are pivotally mounted to the base 212 of the preferred embodiment at a pivot point 328, 358 at the pivoting end 322, 352. Also located at the pivoting ends 322, 352 are latch bar abutments 330, 360 that extend adjacent to, or near, the latch retainers 310, 340. A latch spring 372 attaches to the spring ends 324, 354 of the latch bars 312, 342, opposite the pivoting ends 322, 352, and draws the spring ends toward each other. The latch bars 312, 342 are not in direct contact with the link arm 286, however the latch bars are capable of extending the length of the link arm by pressing their middle abutments 326, 356 against the non-ring ends 318, 348 of the latch retainers 310, 340. The latch opener cam 370 is a bar having 45 degree angled edges at one end 374 that has two positions: an unlock position 376 and a lock position 378. In the unlock position 376, the latch opener cam 370 is fully extended and separates the latch bars 312, 342, as shown in Figs. 1 and 3. The latch bars 312, 342 rest against the latch opener cam 370 at their pivoting ends 322, 352 and rollers 332, 362 that are located on the latch bars between the pivoting ends and the middle abutments 326, 356. When the latch bars 312, 342 are in this substantially parallel position, hereinafter referred to as the first position, the latch bar abutments 330, 360 are not in contact with the latch retainers 310, 340. Referring to Figs. 10 and 11, when the latch opener cam 370 is positioned in the lock position 378, it is withdrawn from between the latch bars 312, 342. Then, the latch spring 372 will pull the spring ends 324, 354 toward each other, and correspondingly, the latch bar abutments 330, 360 shall come in contact with the latch retainers 310, 340 as the latch bars 312, 342 pivot at their pivot points 328, 358. As stated above and shown in Fig. 9, when the latch bars 312, 342 are not in contact with the latch retainers 310, 340, the latch bars are in the first position. When the latch opener cam 370 is in its lock position 378, the latch bar abutments 330, 360 shall come in contact with the latch retainers 310, 340 in either a second position or a third position. For the second position as shown in Fig. 10, one latch bar 312, 342 is resting on the retainer ring 320, 350 without touching the retainer body 314, 344, while the other latch bar is against both the retainer ring and the retainer body. In the interest of simplification, only one of these two situations is presented in Fig. 10, i.e., the situation where the reverse latch bar 342 is resting on the retainer ring 350 only and the normal latch bar 312 is against the retainer ring 320 and the retainer body 314. However, it shall be understood that all details relating this second position as described below may also apply to the situation where the normal latch bar 312 is resting on the retainer ring 320 only and the reverse latch bar 342 is against the retainer ring 350 and the retainer body 344. When the reverse latch bar 312 is in its second position, as shown in Fig. 10, the latch spring 372 pulls the spring end 354 downward, thereby, pivoting the spring end clockwise. Of course, since the latch opener cam 370 is in its lock position 378 and withdrawn from between the latch bars 312, 342, the reverse latch bar is not held in its first position and may pivot freely. Similarly, the latch bar abutment 360 will pivot clockwise and abut against the retainer ring 350 of the reverse latch retainer 340, without touching the retainer body 344. It is a requirement for the second position that the roller 268 of the reverse cam follower 260 be contiguous to the point detector cam 226 of the point detector bar 220. When the roller 268 of the reverse cam follower 260 is moved from a position not contiguous to the point detector cam 226 to a position contiguous to the point detector cam, the reverse cam follower rotates clockwise around its pivot point 266. At this time, the attachment point 270 of the reverse cam follower 260 pivots clockwise with the reverse cam follower and permits the link arm assembly 280 to retract. Normally when the link arm assembly 280 is in its extended position, the latch retainers 310, 340 are not in contact with the middle abutments 326, 356 of the latch bars 312, 342. However, in this case, where one of the two ends 282, 284 of the link arm assembly 280 is permitted to retract inward, the reverse latch retainer 340 comes in contact with the middle abutment 356 of the reverse latch bar 342. Therefore, with the reverse latch retainer 340 at this position, the latch bar abutment 360 rests on the retainer ring 350 but does not come in contact with the retainer body 344. In the third position, as shown in Fig. 11, the detection and indication system 210 of the switch machine 10 is said to be latched out and the latch out means 304 would prevent a remote operator from receiving a "safe condition" indication. The operation of the latch bars 312, 342 in order to set in the third position is similar to the operation for the second position. However, the resulting position for the third position is quite different, mainly, the latch bar abutments 330, 360 of the latch bars 312, 342 are pressed against their respective retainer rings 320, 350 and retainer bodies 314, 344. In particular, the latch bar abutments 330, 360 wedge themselves at the comers formed where the retaining bodies 314, 344 and retaining rings 320, 350 join. The difference in the resulting positions for the second and third positions is due to the positions of the rollers 248, 268 of the cam followers 240, 260 with respect to the point detector cam 226. As noted above, one of the rollers 248, 268 is adjacent to the point detector cam 226, as shown in Fig. 10, in order to be in the second position. On the other hand, in order to be in the third position, as shown in Fig. 11, both rollers 248, 268 must be on the larger diameter surface 234 of the point detector bar 220, away from the point detector cam 226. These positions of the rollers 248, 268 force the cam followers 240, 260 to pull at both ends 282, 284 of the link arm assembly 280 and extend the link arm 286. Thus, the middle abutments 326, 356 of the latch bars 312, 342 are moved away from the non-ring ends 318, 348 of the latch retainers 310, 340, and the latch bar abutments 330, 360 pivot down into the comers formed between the retainer bodies 314, 344 and retainer rings 320, 350. The three aforementioned positions of the latch bars 312, 342 determines the status of the detection and indication system 210 at any given time. When the latch bars 312, 342 are in their first position, as shown in Fig. 9, the switch machine 10 is in the process of switching the switch tracks between the stock rails. Within the switch machine 10, the point detector bar 220 is moving from one side of the switch machine to another. Also, the latch opener cam 370 moves between the latch bars 312, 342, and then withdraws therefrom, in order to reposition the latch bars. If one of the rollers 248, 268 of the cam followers 240, 260 is contiguous to the point detector cam 226 with the latch opener cam 370 withdrawn, the latch bars 312, 342 will be in the second position. If neither of the rollers 248, 268 are adjacent to the point detector cam 226 with the latch opener cam 370 withdrawn, the latch bars 312, 342 will be in the third position. When the latch bars 312, 342 are in the second position, as shown in Fig. 10, the switch machine 10 is locked and indicating but not latched-out. Since one of the rollers 268 of the cam followers 260 is contiguous to the point detector cam 226, the switch arm 272 of the corresponding cam follower is pressing the point detector switch 274, i.e., that switch is "on". As the point detector bar 220 moves from the normal to the reverse direction 224, the roller 268 on the reverse cam follower 260 rolls onto the point detector cam 226, rotating the reverse cam follower 260 and, thereby, releasing the switch arm 272 from the reverse point detector switch 274. The reverse point detector switch 274 closes and indicates that the switching rail is within a certain distance, i.e., an allowable tolerance limit, from the stock rail. A cam lock bar 380 continues to move toward the lock direction 378, similar to the latch opener cam 370, and engages a cam lock lug 382 to the lock bar 216. This motion of the cam lock bar 380 also causes the latch opener cam 370 to move in the same direction and withdraw from between the latch bars 312, 342. Thus, the latch bars 312, 342 rotate in opposite directions due to the tension of the latch spring 372. Since the roller 268 on the reverse cam follower 260, not the roller 248 on the normal cam follower 240, rolled onto the point detector cam 226, the latch bar abutment 330 of the normal latch bar 312 will contact the retainer body 314 and retainer ring 320, but the latch bar abutment 360 of the reverse latch bar 342 will be held by the retainer ring 350. The switch machine 10 will now signal a "safe condition" indication to an operator. Similarly, if the roller 248 of the normal cam follower 240 had rolled onto the point detector cam 226, a "safe condition" would also be indicated. When the latch bars 312, 342 are in the third position, as shown in Fig. 11, the switch machine 10 is latched-out. The latch out means 304 of the preferred embodiment interacts with the link arm assembly 280 in such a way as to control the extension and retraction capability. Specifically, the latch out means 304 holds the link arm assembly 280 at its extended length, thereby holding the normal cam follower 240 at its clockwise position and the reverse cam follower 260 at its counter-clockwise position. During a latch out situation, the cam followers 240, 260 are held at these positions and will not be responsive to any movement by the point detector bar 220 even when the point detector cam 226 is positioned near one of the rollers 248, 268. Also, the switch arms 252, 272 of both cam followers 240, 260 will be pushing against both point detector switches 254, 274. Thus, during the latch out condition, both point detector switches 254, 274 are at their "off" positions. Normally, after the switch machine 10 has switched tracks, the latch bars 312, 342 will be in the second position since one of the cam followers 240, 260 will have a roller 248, 268 contiguous to the point detector cam 226. However, for an abnormal condition, the latch bars 312, 342 will be in the third position since the rollers 248, 268 of both cam followers 240, 260 will not be contiguous to the point detector cam 226 at some time period after switching tracks. For example, if the tracks have not moved a certain distance that is within the tolerance limit, the point detector bar 220 will not move far enough for a roller 248, 268 to roll onto the point detector cam 226. In another example, beginning with the latch bars 312, 342 in the second position, an abnormal movement of the switching tracks may cause the point detector bar 220 to move, thereby removing a roller 248, 268 from the point detector cam 226. In such a case, even if one of the rollers 248, 268 moves back into the point detector cam 226, subsequently, the latch out means will hold the link arm assembly 280 at the extended position and the switch machine 10 would continue to be latched-out. A latch out means 304 may be restorable or non-restorable. The configuration described above is restorable from a remote location and operations personnel can attempt to clear the switch point by repeated "cycling" of the switch machine 10. Thus, the latch bars 312, 342 may always be reset to the first position by switching the tracks from a remote location. If the obstruction is cleared, the latch bars 312, 342 will be in their second position and one of the point detector switches 254, 274 will close at the end of the switching operation. Normal switch machine operation will resumed without maintenance or operational personnel action at the switch location. However, if the original problem has not been corrected and the switch point distance from the stock rails is not within allowable tolerance, the switch machine 10 will simply latch-out again and prevent normal operation. For non-restorable latch out, a latch out switch 384 is added to the restorable latch out configuration. The latch out switch 384 provides power to the motor of the switch machine 10 only during the rail switching operation. In a situation where the latch bars 312, 342 are in the third position and the switch machine 10 latches out, the switch machine may only be reset manually at the machine itself. If maintenance personnel "cycle" the machine with the hand crank or hand throw level, the latch out means 304 will be reset and normal operation may be resumed. Another requirement of the switch machine 10 is to ensure the point detector bar 220 and the lock bar 216, that is located below both cam followers 240, 260 and parallel to the point detector bar, are in correspondence before a "safe condition" indication is provided. A broken or missing lock bar connection, for example, would cause the point detector bar to be out of correspondence. If this condition exists, a "safe condition" can not be indicated. Referring again to Fig. 7 and as stated above in regard to the cam followers 240, 260, three of the comers of each cam follower 240, 260 have a pivot point 246, 266, roller 248, 268 and attachment point 250, 270, respectively. At the fourth comers of each cam follower 240, 260, opposite their pivot points 246, 266, are correspondence pins 258, 278 fixed to the cam followers. Each correspondence pin 258, 278 engages a slot 306 along one side of the lock bar 216 just below position of the pins on the cam followers 240, 260. If the lock bar 216 and point detector bar 220 are out of correspondence with respect to each other at the end of rail switching operation, one of the two correspondence pins 258, 278 will rest on the lock bar outside of the slot 306 and the switch arm 252, 272 corresponding to that pin will not release its point detector switch 254, 274 and, thus, the switch remains open. Thereafter, the switch machine 10 cannot indicate a "safe condition" until this situation is corrected. ffl. TRAILING DEVICE FOR A RAILROAD SWITCH LAYOUT Referring to Figs. 12A and 12B, there is shown the general layout, i.e., a switch layout with a first embodiment of the trailing device or mechanism located between rails. As is well understood, a switch machine 10 is located adjacent a railroad track. A throw bar 412 extends from one side of the switch machine, being operative in conventional fashion to initiate the throwing of conventional switch points. Also seen is a throw rod 414 coupled to the throw bar 412 for extending to the switch points. In the embodiment seen in Figs. 12 A, a sync bar 416 makes actual connection to the switch points, being bolted to the throw rod 414, and the trailing mechanism 416. In the embodiment seen in Figs. 12A and 12B, the throw rod 414 extends into and forms an integral is part of the trailing mechanism 416, such part being referred to as a trailing rod. The detailed construction of the trailing mechanism will be described now with reference to Fig. 13, in which an alternate embodiment thereof is provided which is adapted to be slung under the switch machine 414. As seen in Fig. 13, this embodiment of the trailing mechanism 416 is mounted at either end of the switch machine throw bar 412, by means of mounting brackets 418 and mounting clamps 420. The trailing mechanism 416 is contained within a housing 420 and also enclosed within the housing is the trailing rod 422 which engages with or forms part of the throw rod. The trailing rod 420 is configured to have a generally cylindrical shape but to provide a pocket or pockets 423 to retain or detain ball means in the form of first and second balls, 424 and 426, as seen; although, additional balls would be optionally included. The ball means acts to center the trailing rod relative to the trailing device housing. A cam surface or cam surfaces 430 are machined on either side of each pocket to provide trailing operation. Inside the housing are two compression springs 432, one on either side, and ball retainers 434 on either side of the balls. The springs are compressed to center the trailing or throw rod and to preset the desired trailing force. The normal position of each of the balls, relative to the cam surfaces 430, is in the middle pocket or detent 423. As the switch machine throw bar 412 moves the switch points from normal to reverse without trailing, the trailing device or mechanism 416 is non-operational and the ball means remains in the middle of the cam arrangement. However, to illustrate a trailing mode, consider the following: with the switch machine throw bar 412 extended to the right, let us assume that a piece of rolling stock produces a left directional load into the trailing mechanism as shown. That is to say, a rolling stock piece proceeds in a "wrong direction" against the setting of the switch points. What would normally happen in such a situation without the trailing mechanism is that the load, having a force of 1500 lbs. or greater, would have its way; that is, the switch points would be forced in the opposite direction with attendant movement of the throw rod and consequent reverse movement of the parts of the switch machine. Particularly in the event that the motor driver is in a non-operating state, severe damage could result to the motor and many of the components of the switch machine. However, in the assumed case, that is, with the trailing mechanism as seen in Fig. 13 functioning properly, the effect is that the "left load" causes the trailing rod 420 to be moved to the left and ball means to end up out of its normal position in pocket or detent 423, and into the right curved cam surface 430, responsive to this left ward movement of the trailing rod 420 of the trailing mechanism. However, with the space available within the housing on the left hand, that is, the space 440, the trailing rod portion or section 442 is free to so move without moving the throw bar. Thus, the switch is thrown back to its opposite position without damage to the equipment. The switch will then remain in this position until the switch machine throw bar is thrown to the left position. Since the rail point is already in the left throw position, it bottoms on the stock rail. When the throw bar load exceeds the roller retention load, the trailing bar will be pulled out or extended and the roller will snap into the normal position detent or pocket 423. By inspection, it is clear that the reverse mode of operation is possible. Likewise, it is clear that the position of the trailing device relative to the switch machine may be rotated 180°, if it is desired to install the switch machine on the opposite side of the tracks. As noted previously, another option for installation of the trailing mechanism is to mount such device as seen in Figs. 12 A and 12B, that is, between the stock rails as seen therein. In this mode, the trailing mechanism housing is mounted on the sync bar 450 between the switch points; the throw rod is extended out to attach to the throw bar of the switch machine as shown. As noted previously, for the present type of installation of the invention of this trailing device, some lost motion must be incorporated in the system to make up for the difference between the switch throw that is required and the switch machine throw. As will be seen in Fig. 14, the ball slot detent or pocket in the trailing device throw rod can be adjusted from a no lost motion position to 2.5 inches of lost motion. Such a configuration combines both the advantages of the trailing mechanism, as well as the lost motion function incorporated in the same device, which lost motion function is required for this type of switch installation. Referring now to Fig. 14, there is shown a fragmentary view of a modified form of trailing mechanism which is essentially the same as the mechanism 416, shown in Fig. 13. However, herein the lost motion means 452 is incorporated within the trailing mechanism 416 already described. Instead of the ball means 424 being disposed in the limited pocket 432, as seen in Fig. 13, the ball means is disposed in a much extended pocket or pockets 432, such that only when the sloping cam surfaces 432A of the pockets 432 contact the ball means 424, is it forced against the retainer means 434 such that the trailing rod 442 can move as already described. IV. SWITCH MACHINE CAM BAR Referring to Fig. 15, there is shown a preferred embodiment of the switch machine 10 having a base plate 510. For Fig. 15, the cover and several of the inner components that attach to the base plate 510 have been omitted in order to more clearly show the primary components of the preferred embodiment. Specifically, Fig. 15 shows a cam bar 530 positioned within a base groove 512 of the base plate 510 and a lock bar 520 positioned, perpendicular to, and over a lug end 532 of, the cam bar 530. Referring to Fig. 15, the lock bar 520 is supported from below and at its lower sides by a pair of supporting notches 514 formed on opposite sides of the outer rim 516 of the base plate 510. The lock bar 520 is supported from above and at its upper sides by a pair of supporting brackets 522 that are secured to upper surface of the base plate 510, just inside the supporting notches 514. A lock bar notch 524 is formed at a portion of the lower half of the lock bar 520, having a length 526 that is long enough allow a lock lug 540, located at the lug end 532 of the cam bar 530, to slide therein. As shown in Fig. 15, the length 526 of the lock bar notch 524 may be much longer than the width 542 of the lock lug 540, depending upon the variance in the position of the lock bar 520 that is tolerable by the switch machine. The length 526 must be short enough to retain the lock bar 520 within tolerable limits of its locking position. On the other hand, the length 526 should be as long as possible without extending beyond those tolerable limits in order to provide the lock lug 540 with plenty of room to position within the lock bar notch 524. By providing the lock lug 540 with as much room as possible, there is a higher probability of locking the lock bar 520 into position and the possibility of the switch machine having a problem condition is minimized. Referring to Fig. 16, the lock bar 520 (of Fig. 15) has been omitted in order to more clearly show the various elements of the cam bar 530 of the preferred embodiment without obstruction by the lock bar. The lock bar 520 is positioned within a base groove 512 of the base plate 510 so that it may slide lengthwise relative to the base plate in either a locking direction 534 and an unlocking direction 536. Also, the cam bar 530 comprises two separate but interlockable sections, namely, a locking section 550 and a positioning section 560. A separation point 538 determines the boundary between the locking section 550 and the positioning section 560 of the cam bar 530. Referring to Fig. 17, a side view of the cam bar 530 of the preferred embodiment is shown, without the base plate 510 (of Figs. 15 & 16). From the view of Fig. 17, the positioning section 560 is located on the left-hand portion of the cam bar 530 and has a ridge end 562 on the right side and a throwing end 564 on the left side. The throwing end 564 of the positioning section 560 is controlled by a shifting means for sliding the cam bar 530 in the locking and unlocking directions 534, 536 within the base groove 512 (shown in Figs. 15 & 16), such as a hand throw arm. The ridge end 562 of the positioning section 560 extends vertically upward from an upper surface 566 of the rest of the positioning section, thereby extending an outer edge 568 of the ridge end upward and forming two sloping edges 570, 572. An upper sloping edge 570 has one end converging with the outer edge 568 that slightly inclines towards another end (going from right to left for Fig. 17) that converges with an inner sloping edge 572, such that the two sloping edges form a peak 574. From the peak 574, the inner sloping edge 572 declines toward the upper surface 566 of the positioning section 560 at an angle that is much steeper than the opposing slope of the upper sloping edge 570. The locking section is located on the right-hand portion of the cam bar 530, from the view of Fig. 17, and has a lug end 532 on the right side and a connecting end 552 on the left side. The connecting end 552 is positioned adjacent to the ridge end 562 at the separation point 538 in Fig. 17, but the two ends may be separated, as will be explained subsequently. As stated above, the lock lug 540 positioned at the lug end 532 of the locking section 550. An interlocking means 580 for the locking section 550 to the positioning section 560 is located at the connecting end 552 of the locking section 550. The interlocking means 580 of the preferred embodiment comprises a point detector arm 582, an interlocking arm 584 and a tension means 600. The point detector arm 582 is the portion of the interlocking means 580 that is actually attached on the positioning section 560. It is understood that the point detector arm 582 provides a supporting base for the rest of the interlocking means 580, but does not otherwise provide any functionality for the purposes of interlocking the locking section 550 to the positioning section 560. Thus, any other type of support for the interlocking means 580 may be substituted for the point detector arm 582. The point detector arm 582 only becomes necessary as described herein for the purposes of preventing an indicator of a point detector system (not shown) from indicating a "safe condition". The interlocking arm 584 pivots around a pivot point 588 located on the point detector arm 582 and is normally held at a horizontal position between a top surface 590 of the base of the point detector arm and the tension means 600. When the interlocking means 580 is locking or unlocking the positioning section and the locking section, the interlocking arm 584 will first move clockwise around the pivot point 588, thereby compressing the tension means 600. Then, the interlocking arm 584 will move back counter-clockwise, thereby releasing the tension means 600, and returning back to its normal position. Similar to the ridge end 562 of the positioning section 560, a locking end 592 of the interlocking arm 584 extends vertically downward from the interlocking arm and forms two sloping edges: a lower sloping edge 594 and a connecting edge 596. The lower sloping edge 594 slightly declines downward towards a low point 598 (going from left to right for Fig. 17) where the lower sloping edge and the connecting edge converge 596. From the low point 598, the connecting edge 596 inclines back toward the interlocking arm 584 at an angle that is much steeper than the opposing slope of the lower sloping edge 594. Referring to both Figs. 17 and 18, the tension means 600 comprises a pair of shafts 602, a pair of springs 604 and a pair of spring supports 606. Each shaft 602 passes through an opening formed in the interlocking arm 584 and is fixed at the bottom end to the base of the point detector arm 582. At the top of each shaft 602 is a spring support 604 for supporting an upper end of the spring 604. The lower end of each spring abuts the upper surface of the interlocking arm 584, thereby applying a pair of downward forces to the interlocking arm and holding it at its counter-clockwise position against the base of the point detector arm 582. Referring back to Fig. 15 in combination with Fig. 17, when the switch machine is in operation and in the process of switching railroad tracks, the cam bar 530 travels back and forth in the locking and unlocking directions 534, 536 within the base groove 512. When the switch machine is switching railroad tracks, the initial motion of the cam bar 530 is to move the lock lug 540 out of the lock bar notch 524 in the unlocking direction 536. The following examples assume problem situations where the cam bar 530 attempts to move in the locking direction 534, but the lock lug 540 does not line up with the lock bar notch 524. In such situations, the lock lug 540 abuts a portion of the lock bar 520 other than the lock bar notch 524 and stops short of a locking position of the cam bar 530. Since full motion of the cam bar 530 has not been completed, the interlocking means 580 allows the positioning section 560 to separate from the locking section 550 by rotating the interlocking arm 584 around the pivot point 588 against the tension means 600. At the same time, the connecting edge 596 of the locking end 592 slides up the inner sloping edge 572 of the ridge end 562, thereby pushing the locking end upward toward the peak 574. The interlocking arm 584 rotates back to its normal position and the lower sloping edge 594 of the locking end 592 slides down the upper sloping edge 570 away from the peak 574 once the locking end clears the peak. Thus, the hand throw operation can be completed since the throwing end 564 of the positioning section 560 is able to move all-of-the-way back in the locking direction 534. Thus, the hand throw arm may be repositioned into a latch stand and locked into position thereon. Also, the railroad tracks can then be locked into position by positioning a spike through one of the bars or rods of the switch machine or against the railroad tracks themselves. With the hand throw arm and the railroad tracks locked and secured, the operation of the railroad through associated railroad tracks may be resumed until a more permanent repair can be made. When the problem that prevented the lock bar 520 from locking has been cleared, and the return to normal operation of the switch machine is desired, the switch machine may be cycled by an operator. In other words, an operator may control the switch machine to switch railroad tracks back and forth until it is operating normally. During this process, the cam bar 530 moves in the unlocking direction 536 and the lug end 532 hits the reset lug 608. Then, the interlocking means 580 allows the positioning section 560 to reconnect to the locking section 550 by rotating the interlocking arm 584 around the pivot point 588 against the tension means 600. At the same time, the lower sloping edge 594 of the locking end 592 slides up the upper sloping edge 570, thereby pushing the locking end upward towards the peak 574. The interlocking arm 584 rotates back to its normal position and the connecting edge 596 of the locking end 592 slides down the inner sloping edge 572 away from the peak 574 once the locking end 592 passes over the peak 574 of the ridge end 562. Optionally, the reset lug 608 can be removed from the end of the base groove 512 in order to prevent the positioning section 560 to reconnect to the locking section 550. This configuration is desirable where it is desired that only maintenance personnel are permitted to reset the interconnection of the two sections 550, 560 of the cam bar 530. Another safety feature of the preferred embodiment concerns the point detector arm 582. When positioning section 560 is separated from the locking section 550, the point detector arm 582 is not in the correct position required by a point detector system to permit an indicator to indicate a "safe condition". This feature prevents an indication of a false signal when the cam bar 530 is not able to move to its locking position. V. SWITCH MACHINE WITH RATCHET MECHANISM ON HAND THROW MEANS Referring to Fig. 19, there is shown a cross-sectional view of a switch machine 10 having a conventional hand throw means 712. The hand throw means 712 utilizes a dual shaft configuration. A mode selection shaft 714 is rotatably situated within a hollow, tube¬ like hand throw shaft 716 such that both shafts may rotate 180 degrees, independently of each other. The operation of the mode selection shaft 714 is described in detail above in regard to the LOW PROFILE SWITCH MACHINE. The hand throw shaft 716 is rotated at one end by an arm gear 718 connected to a hand throw arm 720, whereas the other end is connected to a vertical bevel gear 722. The arm gear 718 is separated from the main body of the switch machine 10 by a support bracket 724. As the hand throw arm 720 is rotated around the axis of the hand throw shaft 716 (up to 180 degrees), the arm gear 718 correspondingly rotates the hand throw shaft 716, and thus the vertical bevel gear 722, at the same rotational velocity. The vertical bevel gear 722 is engaged to a horizontal bevel gear 726 which, in turn, is operatively connected to the main railway track switching mechanism of the switch machine (not shown). Thus, the hand throw operation of a conventional hand throw means 712 simply transfers the 180 degree rotational movement of the hand throw arm 720 to the main switching mechanism. Referring to Fig. 20, there is generally provided a preferred embodiment of the hand throw means 730 of the present invention. For the embodiment shown in Fig. 20, the hand throw means 730 replaces the arm gear 718 and support bracket 724 of the conventional hand throw means 712 of Fig. 19 with a three housing configuration 778, 780 & 782. Also, a throw shaft 732 is included within the hand throw means 730 that is positioned adjacent and substantially parallel to a drive shaft 734. The operations of the throw shaft 732 and the drive shaft 734, in combination, includes all of the operations of the hand throw shaft 716 of the conventional hand throw means 712. The drive shaft 734 rotates correspondingly to the throw shaft 732 due to an interconnection between a pair of spur gears 736, 738 within the hand throw means 730. A smaller spur gear 736 is situated about one end of the throw shaft 732 and engages a larger spur gear 738 that is situated about a portion of the drive shaft 734. The sizes of the spur gears 736, 738 may vary, depending upon the ratio desired by a manufacturer, in order to provide a suitable and convenient turning ratio for an operator. For example, the larger spur gear 738 may have a circumference that is twice the circumference of the smaller spur gear 736 so that every two rotations of the throw shaft 732 will be required for every one rotation of the drive shaft 734. Since less torque will be required to rotate the throw shaft 732 than the drive shaft 734, the throw shaft 732 is substantially easier to rotate, thus providing a 2 to 1 mechanical advantage in favor of the operator. Although the gear ratio of the hand throw means 730 may vary, as stated above, the remaining description of the preferred embodiment shall referred to the 2 to 1 gear ratio just described for reasons of convenience. The advantages of having the varied yet proportional gear ratio described above, i.e., the 2 to 1 gear ratio, becomes apparent by understanding the operation of the ratchet mechanism 740 of the present invention. While the smaller spur gear 736 is mounted at one end of the throw shaft 732, a ratchet mechanism 740, and specifically a ratchet pinion 742, is mounted at the other end of the throw shaft 732. The ratchet pinion 742 is driven by a hand throw arm 744 through a pall arrangement that permits the selection of the rotational direction of the ratchet pinion. Referring to Fig. 21, there are shown two possible positions of the hand throw arm 744 of the preferred embodiment. A direction selector 746 is provided to select one of the two drive dogs 748, 756 to be engaged to the ratchet pinion 742. Although not clearly identified in Fig. 21, the ratchet pinion 742 has ragged teeth along its entire circumference. Each drive dog 748, 756 pivots about a near middle portion, i.e., a pivot point 750, and has a spring end 752 opposite its abutment end 754. The spring ends 752, 760 of the drive dogs 748, 756 are forced away from each other by a tension means 764, such as a spring, situated therebetween. Due the force of the tension means 764 and the position of the pivot points 750, 758, the abutment ends 754, 762 of the drive dogs 748, 756 are, correspondingly, normally forced toward each other. The direction of the ratchet action of the ratchet mechanism is controlled by the position of the direction selector 746. When the direction selector 746 is positioned to the left, as shown in Fig. 21, the abutment end 762 of the right drive dog 756 is shifted outward by the direction selector, thereby clearing the abutment end away from the teeth of the ratchet pinion 742. When the direction selector 746 is at this position, only the left drive dog 748 abuts the teeth of the ratchet pinion 742 and so the hand throw arm 744 may rotate the ratchet pinion in the counter-clockwise direction (from the viewpoint shown in Fig. 21) but not in the clockwise direction. Likewise, when the direction selector 746 is positioned to the right, the hand throw arm 744 may rotate the ratchet pinion 742 in the clockwise direction but not the counter-clockwise direction. The hand throw arm 744 has a dual-section configuration for adjusting its position with respect to the switch machine 10. An outer section 766 of the hand throw arm 744 has a 90 degree elbow 768 at one end that may be attached to an inner section 770 by two bolts. This feature of the hand throw arm 744 may be necessary in order to properly install the hand throw means 730 of the present invention to existing switch machine 10 designs. For example, the latch stand (not shown) of an existing switch machine 10 is more than likely positioned at a height position that is even with the drive shaft 734, due to the straight arm form of existing hand throw arms 720. Therefore, the vertical position of a new hand throw arm 744 must be adjusted so that it may be locked to a latch stand of an existing switch machine 10. In order to permit the hand throw means 730 of the present invention to be readily moved from one side of the switch machine 10 to the other, the hand throw arm 744 must be angled in the opposite direction when switch to the other side of the switch machine. Thus, the two-section configuration of the hand throw arm 733 allows it to be modified as necessary when the hand throw means 730 is moved to the opposite side. The hand throw means 730 of the preferred embodiment has two mounting bolts 772 that attach to mounting flanges of the switch machine 10. Also, there are two smaller module bolts 774 that keep the hand throw means 730 together, even when it is not mounted to the switch machine 10. In addition, a face plate (shown in Fig. 20) is mounted to the outer side of the hand throw means 730 at two face plate holes 776 in order to provide it with added protection from outside elements and hazards. The face plate holes 776 are designed to allow the mounting of existing mode selector components 728 to the new hand throw means 730. The hand throw means 730 described herein is a self contained module that contains all machine elements required to perform its desired function, i.e., switching railway tracks. The module can be easily bolted to a switch machine during its assembly or subsequently in the field when the switch machine requires a hand throw capability. The module can be readily moved as a unit from one side of the switch machine to the other by removing the face plate on the switch machine, inserting the hand throw shaft into the machine and securing the module with bolts. Then, the hand throw arm must be installed on the appropriate side for left and right handed operation. Another feature of the hand throw means of the present invention is the 2 to 1 mechanical advantage in favor of the hand throw operator provided by its unique gear system. Also, a ratchet means is provided that permits an operator to raise the throw handle to approximately the vertical position before the application of force is required. Operation of the ratchet means permits the operator to position himself in a favorable position for the application of force with minimum stress and strain on his or her body. The ratchet means includes a direction selector that permits torque to be applied in either a clockwise or counter-clockwise direction as desired by the operator. Furthermore, the hand throw arm retains the capability of accommodating a mode selector and returning to a latch stand to be secured by a pad lock. For maintenance, the hand throw module is sealed and packed with a lubricant to ensure ease of operation, prevent entry of external contaminants and prevent rust and corrosion of internal components. The invention having been thus described with particular reference to the preferred forms thereof, it will be obvious that various changes and modifications may be made therein without departing from the spirit and scope of the invention as defined in the appended claims.

Claims: Wherefore, we claim: 1. A switch machine for switching a position of a railroad track having a mode selector for selecting among a plurality of modes including a power mode and a hand throw mode, comprising: a crank shaft; a main drive gear freely rotatable about said crank shaft; a crank sleeve slidably mounted about said crank shaft for engaging said main drive gear to said crank shaft; a hand throw shaft positioned adjacent and substantially parallel to said crank shaft; a bevel gear freely rotatable about said hand throw shaft; a hand throw assembly slidably mounted about said hand throw shaft for engaging said bevel gear to said hand throw shaft; and a shifter mechanism, having a first end connected to said crank sleeve and a second end connected to said hand throw assembly, for shifting said first and second ends based on the mode selected by the mode selector; wherein said shifter mechanism shifts said first end to engage said main drive gear and said second end to disengage said bevel gear when the power mode is selected by the mode selector, and wherein said shifter mechanism shifts said second end to engage said bevel gear and disengage said main drive gear when the hand throw mode is selected by the mode selector. 2. A switch machine for switching a position of a railroad track having a mode selector for selecting among a plurality of modes including a power mode and a hand throw mode, comprising: a motor; a first gearbox driven by said motor having an input shaft and an output shaft each adapted to rotate, wherein the rotational speed of said input shaft is proportional to the rotational speed of said output shaft; a gear shaft assembly including a gear shaft having a first input end and a second input end opposite said first input end, wherein said output shaft is coupled to said first input end; a hand crank means for driving said gear shaft removably attached to said second input end; a crank shaft positioned a fixed distance from said gear shaft assembly; a main drive gear freely rotatable about said crank shaft and driven by said gear shaft assembly; a crank sleeve slidably mounted about said crank shaft for engaging said main drive gear to said crank shaft; a hand throw shaft positioned adjacent and substantially parallel to said crank shaft; a bevel gear freely rotatable about said hand throw shaft; a hand throw assembly slidably mounted about said hand throw shaft for engaging said bevel gear to said hand throw shaft; and a shifter mechanism, having a first end connected to said crank sleeve and a second end connected to said hand throw assembly, for shifting said first and second ends based on the mode selected by the mode selector; wherein said shifter mechanism shifts said first end to engage said main drive gear and said second end to disengage said bevel gear when the power mode is selected by the mode selector, and said shifter mechanism shifts said second end to engage said bevel gear and disengage said main drive gear when the hand throw mode is selected by the mode selector. 3. A switch machine for switching a position of a railroad track having a mode selector for selecting among a plurality of modes including a power mode and a hand throw mode, comprising: a base; a first shaft positioned to rotate on, and substantially perpendicular to, said base; a drive gear mounted about said first shaft; a second shaft positioned to rotate on said base and substantially parallel to said first shaft; and a main drive gear freely mounted about said second shaft for engaging said drive gear; a crank gear mounted about said second shaft above said main drive gear; a third shaft positioned to rotate on said base and substantially parallel to said second shaft; and a hand throw gear mounted about said third shaft for engaging said crank gear. 4. A switch machine for switching a position of a railroad track having a point detection and indication apparatus comprising: a point detector bar having an outer surface; a point detector cam located on said outer surface; a pair of cam followers, each of said cam followers having a first end which is contiguous to said outer surface, and a second end; said second end is positioned at a first position when said first end is positioned adjacent said point detector cam, and said second end is positioned at a second position when said first end is not positioned contiguous to said point detector cam; and a link arm, directly linking said second ends of said pair of cam followers, having tension means; said tension means being operable for retracting a length of said link arm when at least one of said second ends shifts from said second position to said first position and for extending the length of said link arm when at least one of said second ends shifts from said first position to said second position. 5. A switch machine for switching a position of a railroad track having a point detection and indication apparatus and an activation means comprising: a point detector bar having an outer surface; a point detector cam positioned on said outer surface; a pair of cam followers, each of said cam followers having a first end adjacent to said outer surface and a second end, wherein said second end is positioned at a first position when said first end is positioned adjacent said point detector cam, and said second end is positioned at said second position when said first end is not positioned adjacent to said point detector cam; a link arm directly linking said second ends of said pair of cam followers; a pair of latch retainers positioned on said link arm; a pair of latch bars positioned about said link arm between said latch retainers, each of said latch bars having a contact end; each of said latch bars having a first latch position such that said contact end does not contact said latch retainer, and a second latch position such that said contact end contacts said latch retainer; a latch opener cam having an unlock position for positioning said latch opener cam between said latch bars and said latch bars at said first latch positions, and a lock position for positioning said latch opener cam to one side of said latch bars and said latch bars at said second latch positions; and a latch out switch, responsive to the activation means of the switch machine, for terminating the operation of the switch machine when said latch opener cam is at said lock position and both of said cam followers are at said second position. 6. A switch machine for switching a position of a railroad track having a point detection and indication apparatus comprising: a point detector bar having cam means; a pair of follower means, each having a roller end which is contiguous to said point detector bar and a non-roller end; a switch means controlled by said pair of follower means; and means for latching out said switch means responsive to the position of said rollers to said cam means, including means for holding said non-roller ends at a predetermined distance away from each other. 7. A switch machine for operating railroad switches, including operation in a trailing mode comprising: a throw rod; a switch machine having a throw bar, coupled to said throw rod, for enabling the throwing of switch points into selected positions so as to control the switching of rolling stock; a trailing device, including means for providing variably extendible coupling of said throw bar with said throw rod, said device including means responsive to a wrong direction load impressed on said switch points which acts to move said throw rod, for allowing the movement without damage to said switch machine. 8. The switch machine of claim 7, wherein said means responsive to a wrong direction includes take-up space for that trailing portion of said throw rod. 9. The switch machine of claim 8, wherein said means for providing variably extensible coupling includes a ball means associated with said throw rod which rod is shaped to provide a pocket for said ball means in a central location. 10. A switch machine having a cam bar for locking a lock bar comprising: a positioning section on said cam bar; a locking section on said cam bar having a locking position for locking the lock bar; means, located on said locking section, for interlocking said locking section to said positioning section; and said interlocking means being operative to allow said positioning section to separate from said locking section when said locking section is prevented from moving to said locking position. 11. The switch machine of claim 10, further comprising means for locking said locking section to the lock bar. 12. The switch machine of claim 11, further comprising a notch positioned on said lock bar wherein said locking means is positioned within said notch when said locking section is in said locking position. 13. A switch machine for switching railway tracks from one position to another, having a hand throw means for causing a railway track switching operation to occur, said switch machine comprising: a drive shaft; a throw shaft located adjacent to said drive shaft for driving said drive shaft; and ratchet means operatively connected to said drive shaft and said throw shaft, including first means for rotating the drive shaft proportional to the rotation of said throw shaft and second means for rotating said throw shaft when said ratchet means is moved in a first direction and allowing said throw shaft to remain stationary when said ratchet means is moved in a second direction. 14. The switch machine of claim 13, wherein said first means for rotating comprises a first spur gear positioned about said drive shaft and a second spur gear positioned about said throw shaft and is engaged to said first spur gear. 15. A switch machine for switching railway tracks from one position to another, having a hand throw means for causing a railway track switching operation to occur, said switch machine comprising: a drive shaft; a first assembly having an aperture for supporting said drive shaft; a second assembly located adjacent to said first assembly for supporting the hand throw means; means, supported by said first and second assemblies, for rotating said drive shaft when the hand throw means is moved in a first direction and allowing said drive shaft to remain stationary when the hand throw means is moved in a second direction; and said first and second assemblies being separable from the switch machine, and from each other, so that said rotating means may be removed and disassembled without disturbing the remaining components of the switch machine. AMENDED CLAIMS [received by the International Bureau on 28 December 1995 (28.12.95) ; original claim 12 amended ; original claims 7-11 and 15 amended ; remaining claims unchanged (3 pages )] means for latching out said switch means responsive to the position of said rollers to said cam means, including means for holding said non-roller ends at a predetermined distance away from each other. 7. A switch machine for operating railroad switches, including operation in a trailing mode comprising: a throw rod; a switch machine having a throw bar, coupled to said throw rod, for enabling the throwing of switch points into selected positions so as to control the switching of rolling stock; a trailing device, including means for providing variably extendible coupling of said throw bar with said throw rod, said device including means responsive to a wrong direction load impressed on said switch points, further including a trailing rod forming a portion of said throw rod, and in which said means responsive to the wrong direction load includes take-up space for said trailing rod, whereby such movement of the trailing rod avoids damage to said switch machine. 8. The switch machine of claim 9, wherein said ball means includes a plurality of balls spaced around the trailing rod, such trailing rod having spaced detents forming pockets for the respective balls; and cam surfaces on either side of each of the pockets. 9. The switch machine of claim 7, wherein said means for providing variably extensible coupling includes a ball means associated with said trailing rod, which rod is shaped to provide a pocket for said ball means in a central location. 10. A switch machine having a cam bar for locking a lock bar comprising: a positioning section on said cam bar; a locking section on said cam bar having a particular locking position in the switch machine; means, located on said locking section, for interlocking said locking section to said positioning section; and said interlocking means being operative to allow said positioning section to separate from said locking section when said locking section is prevented from moving to said locking position. 11. The switch machine of claim 10, further comprising means for locking said locking section at said particular locking position. 15. A switch machine for switching railway tracks from one position to another, having a hand throw means for causing a railway track switching operation to occur, said switch machine comprising: a drive shaft; a first assembly having an aperture for supporting said drive shaft; a throw shaft supported by said first assembly for driving said drive shaft; a second assembly located adjacent to said first assembly for supporting the hand throw means; means, supported by said first and second assemblies, for rotating said drive shaft when the hand throw means is moved in a first direction and allowing said drive shaft to remain stationary when the hand throw means is moved in a second direction; and said first and second assemblies being separable from the switch machine, and from each other, so that said rotating means may be removed and disassembled without disturbing the remaining components of the switch machine.

Inventors: ALBRECHT HARRY A, BONNER GEORGE A, EGGEBRECHT CHARLES M, GORDON KEITH J, LUDWICK GEORGE E, MYERS STEVEN W, VAN ALSTINE DANIEL W, ALBRECHT, HARRY, A., BONNER, GEORGE, A., EGGEBRECHT, CHARLES, M., GORDON, KEITH, J., LUDWICK, GEORGE, E., MYERS, STEVEN, W., VAN ALSTINE, DANIEL, W.
Applicants: GEN RAILWAY SIGNAL CORP, GENERAL RAILWAY SIGNAL CORPORATION
Application year: 1995
Main classification: E01B7
IPC codes: B61L5