WO2001085524A2

WO2001085524A2 - Rail frog controllers

Info

Publication number: WO2001085524A2
Application number: PCT/US2001/013391
Authority: WO
Inventors: Jonathan D. Moscato; David A. Schrantz; Michael E. Peters
Original assignee: Vibratech Inc
Current assignee: Vibratech Inc
Priority date: 2000-04-25
Filing date: 2001-04-25
Publication date: 2001-11-15
Anticipated expiration: 2002-10-25
Also published as: WO2001085524A3; AU2001255684A1

Abstract

New railroad rail frog controllers are disclosed. The rail frog controller has a collapsible and expandable housing having a rail frog wing rail connection portion and a stationary connection portion. The housing has a first expansion stage and a subsequent second expansion stage. A piston head is slidably positioned within a pressure tube in the housing. The pressure tube has first and second fluid chambers on opposite sides of the piston head. A first fluid flow regulator fluidly connects the first and second fluid chambers together, and controls fluid flow between the first and second fluid chambers during the first expansion stage. A second fluid flow regulator fluidly connects the first and second fluid chambers together, has a higher fluid flow rate capacity than the first fluid flow regulator, and controls fluid flow between the first and second fluid chambers during the second expansion stage. A third fluid flow regulator fluidly connects the first and second fluid chambers together, and has a fluid closed position during expansion of the housing and a fluid open position during collapse of the housing. A third fluid chamber is on the outside of the pressure tube. The third fluid chamber is fluidly connected to the second fluid chamber by a fourth fluid flow regulator, particularly a high pressure relief valve. When excessive high actuation velocities occur during expansion, the fourth fluid flow regulator will be in a fluid open position after the fluid pressure in the second fluid chamber exceeds the required pressure to open the fourth fluid flow regulator. The fourth fluid flow regulator will subsequently close upon reduction in fluid pressure within the second fluid chamber.

Description

RAIL FROG CONTROLLERS

FIELD OF THE INVENTION

The present invention generally relates to controllers for rail frogs. More specifically, the present invention relates to controllers for controlling the opening and closing of railroad frogs. The present invention also relates to methods of controlling railroad rail frogs.

BACKGROUND OF THE INVENTION

Rail frogs are commonly used in railroad tracks to allow the railroad tracks to split from one track into two tracks. The rail frog is a portion of the railroad track connected to a track switch that allows railroad equipment riding on the track to switch to another track. One type of rail frog is a movable rail frog.

Referring to Fig. 1, a railroad track 10 has a movable rail frog 12. The railroad track 10 has various rails 14 secured to railroad ties 16. The main components of the movable rail frog 12 are a movable wing rail 18 and a spring box 20. The wing rail 18 is a portion of the track 10 that is forced open by the train wheel as a train passes through the rail frog 12. The spring box 20 has a linear compression spring within a steel housing. The spring box 20 is attached to a base plate that is rigidly mounted to a railroad tie 16. A piston 22 of the spring box 20 is biased outward from the spring box housing by the compression spring and into contact with the movable wing rail 18.

The movable wing rail 18 of the rail frog 12 remains in the closed position by the spring box 20 until a train is switched from one track to an alternate track. As the train passes through the rail frog 12, the train wheel contacts and pushes the movable wing rail 18 to an open position against the biasing force of the compression spring by forcing the piston 22 into the spring box housing. When the movable wing rail 18 is in the open position, the linear spring of the spring box 20 is compressed. And as the train wheel moves past the rail frog 12, the movable wing rail 18 returns to its closed position by the linear compression spring in the spring box 20. As the linear spring of the spring box 20 decompresses, the amount of force exerted on the movable wing rail 18 by the spring box 20 is progressively reduced. Therefore, the closing force exerted by the spring box 20 linearly decreases as the spring box 20 and the movable wing rail 18 move from their respective open positions to their closed positions.

Existing rail frogs have problems. One problem with existing rail frogs is with the movable wing rail returning to the closed position after each train wheel passes the wing rail. Generally, the movable wing rail moves from the closed position to the open position and back to the closed position as each individual rail car wheel enters and passes through the rail frog. The rail frog open and close cycle is repeated for each and every train car wheel passing through the rail frog. The rail frog opens at a high velocity and closes at a high velocity for every wheel that passes through the rail frog. The excessive cycles of opening and closing the rail frog -causes repeated impact loading on the rail car wheels and railroad track, including the rail frog system. The repetitious impact loading caused by the rail frog opening and closing may cause train car wheel wear, rail wear, and damage to the rail frog, such as fatigue to the movable wing rail. The various rail car and railroad track components may require higher maintenance or more frequent replacement, and may even ultimately fail. Thus, these and other needs exist to improve rail frogs. Examples of railroad rail frogs can be found in U.S. Patent Nos. 4,624,428; 5,544,848; 5,782,437; and 5,806,810.

U.S. Patent No. 4,624,428 pertains to a spring rail frog. The 28 patent describes a railroad spring frog assembly for trackwork installations which includes a rigid rail and a flexible spring wing rail. The flexible spring wing rail is rigidly affixed between one end which engages a wing point rail and the other end which connects to a closure rail at the toe end of the frog support means. When a rail car enters the frog and a wheel flange engages the spring wing rail to pass between it and the long point rail the spring wing rail bends away from the long point rail to define a flangeway therebetween. U.S. Patent No. 5,544,848 pertains to a railroad spring frog. The 848 patent describes a railroad trackwork frog with a relatively fixed rigid wing rail, a relatively movable spring wing rail, a base plate, and at least one roller outrigger and ramp plate assembly which is attached to the spring wing rail and to the base plate, and which functions to cause limited upwards vertical movement of the spring wing rail relative to the base plate when the spring wing rail is moved laterally relative to the rigid wing rail by the engaged wheel flange of a passing rail car.

U.S. Patent No. 5,782,437 pertains to a spring rail frog having a bendable rail with a modified cross- section. The 437 patent describes a spring rail frog that includes a movable wing rail, a fixed wing rail and a nose rail. The movable wing rail is provided with a bendable portion and a non-bendable portion. The bendable portion can include any or all of a reduced width base portion, a reduced width head portion and an increased width web portion. The height of the movable wing rail can also be smaller in height than the height of the nose rail. A fixing plate can also be provided between a base plate and the movable wing rail to adjust the relative height of the movable wing rail and the nose rail.

U.S. Patent No. 5,806,810 pertains to a spring rail frog having a switchable magnet for holding a wing rail open. The 810 patent describes a railroad frog assembly with a switched magnet that immediately retains a frog flexible wing rail in its open position in response to a railcar wheel passing through the frog assembly, and that delayably releases the frog flexible wing rail from its open position for subsequent closure by an included frog compression spring.

SUMMARY OF THE INVENTION

The present invention is a rail frog controller which controls movement of the movable wing rail of a rail frog. The rail frog controller reduces or prevents rapid opening and closing of the movable wing rail as rail cars pass through the rail frog. The rail frog controller holds the wing rail in the open position until the train cars pass through the rail frog. The rail frog controller then allows the movable wing rail to move back into the closed position after a time delay. A hydraulic timing device can be used as the rail frog controller.

The rail frog controller of the present invention acts as a damper within a spring-driven rail frog system to control the rate of closure movement of the rail frog system. The rail frog controller permits rapid opening of the rail frog (wing rail opening) and controls the rate of closure travel of the wing rail during and after a train passes through the rail frog. The rate of closure travel is controlled within the rail frog controller by using a restrictor valve. The restrictor valve allows the rail frog controller to move at a rate that is proportional to the amount of force exerted upon the controller by the rail frog spring box. The spring box force exerted on the rail frog controller linearly decreases as the compression spring expands; therefore, the rail frog controller' s closure velocity decreases as the wing rail closes. For the rail frog application, the rate of travel immediately after the wing rail is fully opened needs to be slow enough such that the wing rail will not close appreciably between train wheels as each wheel passes through the rail frog. Generally, train velocities are equal to or greater than 20 miles per hour.

Because the rail frog closure velocity of the rail frog controller system needs to be controlled within the first portion of the total amount of travel and the system is driven by a linearly decreasing spring force, a relief port within the rail frog controller is provided within the second portion of travel to circumvent the piston restrictor valve. The restrictor valve and the relief port allow the rail frog controller to have a controlled rate within the first portion of travel and then actuate at a much greater rate within the second portion of travel. The combination of the restrictor valve and the relief port regulates the total rail frog close time and the close rate during the first and second portions of rail frog closure travel. The rail frog controller preferably has a pressure relief valve which protects the hydraulic timing device from excessive high pressure inside the device. When the internal hydraulic pressure reaches a predetermined maximum allowed pressure, the pressure relief valve opens to reduce the pressure. High pressure spikes may be caused by forced extension of the controller or high velocity impact by the train wheel with the rail frog, for example . Objects and advantages, which may be desired but not necessarily required to practice the present invention, can become apparent from reading this disclosure with reference to the accompanying drawings, and the appendant claims .

BRIEF DESCRIPTION OF THE DRAWINGS

Fig. 1 is a plan view of a railroad track having a rail frog controller according to the principles of the present invention.

Fig. 2 is an elevational view of the rail frog controller of Fig. 1.

Fig. 3 is another elevational view of the rail frog controller of Fig. 1.

Fig. 4 is a cross-sectional view of the rail frog controller of Fig. 2 taken along the line IV - IV.

Fig. 5 is an elevational view of a restrictor valve of the rail frog controller of Fig. 4.

Fig. 6 is an end view of the restrictor valve of Fig. 5. Fig. 7 is a cross-sectional view of the restrictor valve of Fig. 5 taken along the line VII - VII.

Fig. 8 shows an alternative coiled micro-tubing for a restrictor valve.

Fig. 9 shows the coiled micro-tubing of Fig. 8 encased in a valve body.

Fig. 10 shows the coiled micro-tubing of Fig. 8 encased in a exterior threaded valve body.

Fig. 11 is a cross-sectional view of a pressure tube of the rail frog controller of Fig. 4.

Fig. 12 is another cross-sectional view of the pressure tube of the rail frog controller of Fig. 4.

Fig. 13 is a schematic diagram of a rail frog controller system according to the principles of the present invention.

DETAILED DESCRIPTION OF PRESENTLY PREFERRED EMBODIMENTS Although the present invention can be made in many different forms, the presently preferred embodiments are described in this disclosure and shown in the accompanying drawings. This disclosure exemplifies the principles of the present invention and does not limit the broad aspects of the invention only to the illustrated embodiments.

Fig. 1 shows a railroad track 10 having a rail frog 12. The rail frog 12 has a movable wing rail 18 which allows a train car to switch from one track to another track. A spring box 20 is 'provided to maintain the movable wing rail 18 in its closed position under the pressure of a constant stiffness compression spring until a rail car wheel passes through the rail frog 12 and moves the wing rail 18 to its open position. The spring in the spring box 20 compresses when the movable wing rail 18 moves to its open position and then expands to force the wing rail to its closed position after the rail car wheel leaves the rail frog 12.

Referring to Figs. 1-3, a rail frog controller 24 is connected at one end 26 to the movable wing rail 18 of the rail frog 12. Another, opposite end 28 of the rail frog controller 24 is connected to a stationary object, such as a railroad tie 16. This embodiment of the rail frog controller 24 is a hydraulic cylinder (hydraulic timing device) which compresses as the movable wing rail 18 opens against the force of the spring box 20 and extends as the wing rail 18 closes under the force of the spring box 20.

Figs. 2 and 3 show the rail frog controller 24 in its collapsed, compressed position when the movable wing rail 18 is in its open position. Figs. 2 and 3 also show the end 28 of the rail frog controller 24 in phantom when the rail frog controller 24 is in its extended position and the movable wing rail 18 is in its closed position. Although Figs. 2 and 3 show the end 28 of the rail frog controller 24 as moving between collapsed and extended positions, the other end 26 could have collapsed and extended positions depending on the orientation that the rail frog controller 24 is mounted to the rail frog 12.

Preferably, the rail frog controller 24 allows for relatively rapid opening of the movable wing rail 18 (collapsing of the rail frog controller 24), and multistage control of closing of the movable wing rail 18 (expansion of the rail frog controller 24) . The multistage control of the rail frog controller expansion includes a first expansion stage of relatively slow expansion, and a second expansion stage of faster expansion. After a rail car wheel opens the movable wing rail 18, the slow, first expansion stage retards rapid closing of the movable wing rail 18 so that the wing rail 18 does not completely close before a next rail car wheel passes through the rail frog 12. Accordingly, excessive repeated opening and closing of the wing rail 18 is prevented, as are impact forces caused by the wing rail 18. The faster, second expansion stage occurs after the slow, first expansion stage and allows the movable wing rail 18 to complete the end of its closing travel quickly, for example, after the entire train passes through the rail frog 12.

Referring to Figs. 1-4, the rail frog controller 24 can be mounted by the ends 26, 28, such that there are various degrees of freedom of movement at the mounts. For example, spherical bearings 30 can be used on each mounting end 26, 28 to allow for independent movement of either mounting end 26, 28 without transmitting misalignment forces to the rail frog controller 24. The spherical bearings 30 or end-mounts having similar degrees of freedom for rotation are used for the mounting ends 26, 28 of the rail frog controller 24. End mounts of this type are used to prevent transmission of forces resulting from excessive out-of-plane movement of the wing rail 18 into the rail frog controller 24. Fig. 4 shows a cross-sectional view of the rail frog controller 24 taken along the line IV - IV of Fig. 2. The rail frog controller 24 has a pressure and reservoir tube assembly 32 connected to a shield tube 34 by a piston 36. The pressure and reservoir tube 32 and the shield tube 34 form a collapsible and expandable housing. The piston 36 is rigidly connected to a piston head 38 which is slidable within a pressure tube 40. A seal 42 seals the piston head 38 against the inside surface of the pressure tube 40. The pressure and reservoir tube assembly 32 has a reservoir bearing cap 44 which seals the pressure and reservoir tube assembly 32 at one end. The piston 36 is sealed against and slidable through the reservoir bearing cap 44. Accordingly, the pressure and reservoir tube assembly 32 and the shield tube 24 are collapsible and extendable relative to each other. The rail frog controller 24 is shown in an extended position in Fig. 4.

A hydraulic fluid is contained in a fluid chamber 46, which varies in volume as the piston 26 and the piston head 38 slidably change positions within the pressure tube 40. Preferably, silicone fluid is used as the hydraulic fluid for the rail frog controller 24 because silicone fluid has a viscosity-temperature coefficient which is much lower than viscosity- temperature coefficients for organic oils. The lower coefficient allows for a smaller viscosity change with temperature changes. Therefore, the actuation rate of the rail frog controller 24 will be less affected by ambient temperature than if typical organic hydraulic fluids are used. Also, relatively high viscosity silicone fluid can be used for the rail frog controller 24. The higher viscosity silicone fluid allows the sizes, such as inner diameters, of the fluid passageways to be relatively larger, thereby decreasing the likelihood of plugging the passageways and fluid valves. Also, filtration of the high viscosity silicone fluid is easier. One example of a high viscosity silicone fluid useable with the rail frog controller 24 is 1.45e-4 Reyn (1000 cs) silicone fluid.

Referring to Fig. 4, the rail frog controller 24 has a collapsing control valve 48 which controls the collapsing of the rail frog controller 24 when the movable wing rail 18 of the rail frog 12 moves to its open position. The rail frog controller 24 also has first and second expansion control valves 50, 52, respectively, which control expansion of the rail frog controller 24 when the movable wing rail 18 of the rail frog 12 moves to its closed position. A pressure relief valve 54 can also be provided which allows for a high pressure relief of the hydraulic fluid inside of the rail frog controller 24.

The first expansion control valve 50 is shown in Figs. 4-7 and the second expansion control valve 52 is shown in Figs. 4, 11, and 12. The first expansion control valve 50 is a restrictor valve in the piston head 38 which allows hydraulic fluid to pass through the piston head 38. The restrictor valve 50 fluidly connects the fluid chamber 46 and a fluid chamber 56 in the pressure tube 40 together.

The restrictor valve 50 is used to control the rate of expansion of the rail frog controller 24 during the first portion of travel, i.e. during the first expansion stage. Referring to Figs. 5-7, the particular restrictor valve 50 shown in the drawings has constant orifice micro-tubing 58 in a valve body 60. The micro- tubing 58 has a precisely held interior diameter dimension and a desired length, for example, a length about equal to a length of the valve body 60. The precise interior diameter dimension of the micro-tubing 58 and the length of the micro-tubing 58 restrict the hydraulic fluid flow through the restrictor valve 50 to a desired rate. Although the particular restrictor valve 50 shown in the drawings is a valve having micro- tubing, other mechanisms can be used to perform the function of controlling the expansion rate of the rail frog controller 24. For example, a tortuous flow path or other fluid flow restrictor could be used.

The micro-tubing 58 is inserted into the valve body 60, which may be constructed from brass, for example. The valve body 60 consists of a slip fit hole concentric with the valve body outer diameter, and which has a diameter slightly larger than the outer diameter of the micro-tubing 58. The slip fit hole runs most of the length of the valve body 60 and allows the micro-tubing 58 to be easily inserted most of the way into the valve body 60. A press fit hole is adjacent the slip fit hole and extends the remainder of the length of the valve body 60. The press fit hole allows the micro-tubing 58 to be press fit and locked axially into position within the valve body 60. Other methods for securing the micro-tubing 58 to the valve body 60 could also be used. Referring to Fig. 4, as the piston 36 moves outward from the pressure and reservoir tube assembly 32 (i.e., in Fig. 4, from the right side toward the reservoir bearing cap 44 on the left side) , the hydraulic fluid in fluid chamber 56 passes through the restrictor valve 50 and into the fluid chamber 46. By controlling the rate of hydraulic fluid flow through the restrictor valve 50, the rate of expansion of the rail frog controller 24 and the rate of closure of the movable wing rail 18 are controlled. According to the Law of Continuity for fluids, this type of restrictor valve 50 allows the velocity of extension of the rail frog controller 24 to be proportional to the expansion load applied to the rail frog controller 24, and inversely proportional to the viscosity of the hydraulic fluid and the length of the micro-tubing 58 in this restrictor valve 50.

The hydraulic fluid flow rate through the this type of restrictor valve 50 can be adjusted; thus, adjusting the expansion rate of the rail frog controller 24 and the closure rate of the movable wing rail 18. For example, adjustments can be made to the fluid flow rate by changing the total length of the restrictor valve 50 because the rate of fluid flow is proportional to the length of the orifice restriction (micro-tubing 58). Greatly increasing the length of the micro-tubing 58 can be achieved by coiling the micro-tubing 58. Also, the coiled micro-tubing can be encased by the valve body. For example, Fig. 8 shows a coiled micro-tubing 62, Fig. 9 shows the coiled micro-tubing 62 encased with a brass casting, and Fig. 10 shows the coiled micro-tubing encased in an exterior threaded brass casting 66. The restrictor valve 50 can be adjusted after the micro-tube 58 is seated into the valve body 60 by machining away small portions of the valve assembly length (shortening the length of the micro-tubing 58) until the exact fluid flow rate is achieved. Additional design parameters that may be changed to effect the fluid flow rate are the orifice diameter and the viscosity of the fluid, for example . Relatively slow hydraulic fluid flow rates (and slow wing rail closure rates) may be achieved by using a large diameter orifice and a relatively low viscosity hydraulic fluid. An advantage of using a larger diameter orifice is that the orifice is less likely to clog and the fluid flow rate is less dependent upon variations of the valve orifice diameter.

Referring to Figs. 5-7, the restrictor valve 50 may have a filter assembly 68. The valve filter assembly 68 includes a filter 70 and a filter cap 72 which mounts the filter 70 to the valve body 60. The valve filter assembly 68 prevents particles in the hydraulic fluid from clogging the restrictor valve 50. A reservoir 74 between the micro-tubing 58 and the filter 70 reduces the velocity gradient of the fluid passing through the filter 70. The reduced velocity gradient decreases the maximum velocity of the fluid and particulates, thereby decreasing the likelihood of particles jamming the filter 70 and increasing the usable surface area of the filter 70.

The second expansion control valve 52 of the rail frog controller 24 is shown in Figs. 4, 11, and 12. The second expansion control valve 52 is a relief slot or relief port 76 (Figs. 11 and 12) in a portion of the pressure tube 40. The relief port 76 is recessed into the inside wall of the pressure tube 40 and extends longitudinally. The relief port 76 in the pressure tube 40 allows hydraulic fluid to by-pass around the piston head 38 rather than being forced through the restrictor valve 50. The relief port 76 fluidly connects the fluid chamber 46 and a fluid chamber 56 in the pressure tube 40 together when the piston head 38 is positioned within the length of the relief port 76.

The relief port 76 is used to control the rate of expansion of the rail frog controller 24 during the second portion of travel, i.e. during the second expansion stage. The relief port 76 is designed such that when in operation, as the piston seal 42 of the piston head 38 passes over the relief port 76 the hydraulic fluid will circumvent the restrictor valve 50 and hydraulic fluid will rapidly empty from the fluid chamber 56 under pressure to the fluid chamber 46. Because the cross-sectional flow area of the relief port 76 is greater than the orifice of the micro-tubing 58, hydraulic fluid flows faster through the relief port 76 than through the restrictor valve 50. Accordingly, the first and second expansion control valves 50, 52 (restrictor valve 50 and relief port 52) allow the rail frog controller 24 and thus, the movable wing rail 18 to close slowly during the first portion of travel and rapidly during the second portion of travel.

The relief port 76 is constructed by machining a slot into the interior wall of the high-pressure cylinder or pressure tube 40. The profile of the slot is created using a tangent filleted cutting-tool. This profile allows for a smooth transition for the piston seal 42 while moving across the relief port 76, thereby decreasing the piston seal wear. The slot profile also allows for exposure fo the slot-bore edge. The exposed edge is then eliminated within a blending operation. The resulting relief port 76 has a very smooth filleted edge, thereby reducing piston seal wear.

The rail frog controller 24 may have a nylon-coated piston bearing surface to avoid metal-to-metal contact between the piston head 38 and the inside cylinder wall of the pressure tube 40. The likelihood of contact over time is appreciable because there is a large load exerted on a small amount of surface area of the piston seal 42 while traveling across the relief port 76. In addition, large side loads are exerted upon the piston 36 and piston head 38 due to the high speed impact of the rail frog wing rail 18, which actuates the rail frog controller 24 at a relatively high velocity. Although the collapsing control valve 48 reduces or eliminates pressure buildup during collapse of the rail frog controller 24, viscous and momentum forces may cause metal-to-metal contact along the relief slot. Additionally, if eventual piston seal wear occurs, metal-to-metal contact will be unavoidable and scoring of the pressure tube cylinder 40 will likely follow. The nylon coating addresses these potential problems. They nylon-coated piston is created by coating a metal rod with nylon/metal primer and then covering the primer with nylon or a similar material. The piston is then machined, leaving the nylon to act as a bearing.

Referring to Fig. 4, the collapsing control valve 48 includes at least one fluid passageway 78 and a spring-valve 80 at one end of the fluid passageway 78.

During collapsing of the rail frog controller 24 (piston 36 and piston head 38 moving into the pressure and reservoir assembly 32) , the spring-valve 80 opens under force of the hydraulic fluid and the hydraulic fluid easily flows from the fluid chamber 46 through the fluid passageway 78 to the fluid chamber 56. Conversely, during extension of the rail frog controller 24 (piston 36 and piston head 38 moving outward from the pressure and reservoir assembly 32) , the spring-valve 80 closes under pressure from the hydraulic fluid in the fluid chamber 56 and prevents fluid flow through the fluid passageway 78. Accordingly, the collapsing control valve 48 allows rapid compression of the rail frog controller 24 under low force, while forcing hydraulic fluid to flow through the first expansion control valve 50 (restrictor valve) during expansion of the rail frog controller 24.

The rail frog controller 24 may also have a mechanism for preventing excessive pressure build-up within the controller. For example, Fig. 4 shows the pressure relief valve 54 in the reservoir bearing cap 44. The pressure relief valve 54 opens when the pressure in the fluid chamber 56 is excessively high, such as during rapid extension of the rail frog controller 24. The pressure relief valve 54 protects the rail frog controller system 24 from sudden overloads due to forced high velocity extension of the rail frog controller 24 during high velocity impact by a train car on the rail frog. The pressure relief valve 54 for the rail frog controller 24 remains closed until the pressure within the fluid chamber 56 reaches about 2,000 psi, and then opens. The open pressure relief valve 54 allows hydraulic fluid to flow from the fluid chamber 56 through fluid passageways 82 to a fluid chamber 84 surrounding the pressure tube 40. Fluid accumulator material 86 may be provided in the fluid chamber 84 to absorb the hydraulic fluid that is released from the fluid chamber 56 by the pressure relief valve 54. One example of a pressure relief valve 54 usable with the presentation is a 281 PRI relief valve available from The Lee Company.

A schematic diagram of a rail frog controller system 24 according to the present invention is shown in Figure 13. For convenience, the schematically represented components of Fig. 13 are identified by name and reference numerals which correspond to like components previously described and shown in this disclosure. However, as with the other embodiments described in this disclosure, Fig. 13 shows an example of the present invention, which may be practiced in many different forms.

The collapsed position of the rail frog controller 24 is designated by the letter A. The extended position of the rail frog controller 24 is shown in phantom and designated by the letter B. During expansion of the rail frog controller 24, the piston 36 and the piston head 38 first move the distance identified by the letter C, which is the first stage expansion. The first stage expansion (relatively slow expansion rate) occurs until the piston head 38 moves within the relief slot 52 such that the relief slot 52 opens a by-pass around the piston head 38. The second stage expansion (relatively fast expansion rate) occurs subsequent to the first stage expansion and continues until the total travel distance of the piston 36 and the piston head 38 is reached, designated by the letter D. The second stage expansion distance is the difference between the total expansion distance D and the first stage expansion distance C.

While the presently preferred embodiments have been illustrated and described, numerous changes and modifications can be made without departing from the spirit and scope of this invention. Therefore, the inventors intend that such changes and modifications are covered by the appended claims .

Claims

THE INVENTION IS CLAIMED AS:

1. A rail frog controller comprising: a collapsible and expandable housing having a rail frog wing rail connection portion and a stationary connection portion, the housing having a first expansion stage and a subsequent second expansion stage; a piston head slidably positioned within a pressure tube in the housing, the pressure tube having first and second fluid chambers on opposite sides of the piston head; a first fluid flow regulator fluidly connecting the first and second fluid chambers together, the first fluid flow regulator controlling fluid flow between the first and second fluid chambers during the first expansion stage; and a second fluid flow regulator fluidly connecting the first and second fluid chambers together, the second fluid flow regulator having a higher fluid flow rate capacity than the first fluid flow regulator and controlling fluid flow between the first and second fluid chambers during the second expansion stage.

2. The rail frog controller of claim 1, wherein the first fluid flow regulator comprises a restrictor valve positioned in the piston head.

3. The rail frog controller of claim 2 , wherein the restrictor valve comprises micro-tubing.

4. The rail frog controller of claim 3, wherein the micro-tubing is coiled.

5. The rail frog controller of claim 1, further comprising a fluid filter in a fluid flow path between the first and second fluid chambers.

6. The rail frog controller of claim 1, wherein the second fluid flow regulator comprises a relief port in the pressure tube.

7. The rail frog controller of claim 1, wherein the second fluid flow regulator comprises a by-pass fluid passageway around the piston head.

8. The rail frog controller of claim 1, further comprising a third fluid flow regulator fluidly connecting the first and second fluid chambers together, the third fluid flow regulator having a fluid closed position during expansion of the housing and a fluid open position during collapse of the housing.

9. The rail frog controller of claim 8, wherein the third fluid flow regulator comprises a fluid passageway through the piston head and a one-way valve in the fluid passageway.

10. The rail frog controller of claim 1, further comprising a high pressure relief valve fluidly connected to at least one of the first and second fluid chambers .

11. The rail frog controller of claim 10, further comprising fluid accumulator material downstream of the pressure relief valve.

12. A rail frog controller comprising: a collapsible and expandable housing having a rail frog wing rail connection portion and a stationary connection portion, the housing having a first expansion stage and a subsequent second expansion stage; a piston head slidably positioned within a pressure tube in the housing, the pressure tube having first and second fluid chambers on opposite sides of the piston head; a first fluid flow regulator fluidly connecting the first and second fluid chambers together, the first fluid flow regulator controlling fluid flow between the first and second fluid chambers during the first expansion stage; a second fluid flow regulator fluidly connecting the first and second fluid chambers together, the second fluid flow regulator having a higher fluid flow rate capacity than the first fluid flow regulator and controlling fluid flow between the first and second fluid chambers during the second expansion stage; and a third fluid flow regulator fluidly connecting the first and second fluid chambers together, the third fluid flow regulator having a fluid closed position during expansion of the housing and a fluid open position during collapse of the housing.

13. The rail frog controller of claim 12, wherein the first fluid flow regulator comprises a restrictor valve positioned in the piston head, and the second fluid flow regulator comprises a relief port in the pressure tube.

14. The rail frog controller of claim 13, further comprising a high pressure relief valve fluidly connected to at least one of the first and second fluid chambers, and fluid accumulator material downstream of the pressure relief valve.

15. A rail frog system comprising: a railroad rail frog having a movable wing rail; a collapsible and expandable rail frog controller connected to the wing rail and to a stationary object, the rail frog controller having a first expansion stage and a subsequent second expansion stage; a piston head slidably positioned within a pressure tube in the rail frog controller, the pressure tube having first and second fluid chambers on opposite sides of the piston head; a first fluid flow regulator fluidly connecting the first and second fluid chambers together, the first fluid flow regulator controlling fluid flow between the first and second fluid chambers during the first expansion stage; and a second fluid flow regulator fluidly connecting the first and second fluid chambers together, the second fluid flow regulator having a higher fluid flow rate capacity than the first fluid flow regulator and controlling fluid flow between the first and second fluid chambers during the second expansion stage.

16. The rail frog system of claim 15, further comprising a third fluid flow regulator fluidly connecting the fist and second fluid chambers together, the third fluid flow regulator having a fluid closed position during expansion of the rail frog controller and a fluid open position during collapse of the rail frog controller.

17. The rail frog system of claim 16, wherein the first fluid flow regulator comprises a restrictor valve positioned in the piston head, and the second fluid flow regulator comprises a relief port in the pressure tube.

18. The rail frog system of claim 17, further comprising a high pressure relief valve fluidly connected to at least one of the first and second fluid chambers, and fluid accumulator material downstream of the pressure relief valve.

19. A method of controlling a rail frog comprising the steps of: moving a wing rail of the rail frog from an open position toward a closed position through a first closure stage; and subsequently moving the wing rail further toward the closed position through a second closure stage at a faster closure rate than the first closure stage.

20. The method of controlling a rail frog of claim 19 wherein the step of moving the wing rail through the first closure stage comprises the step of restricting fluid flow through a first flow regulator, and the step of moving the wing rail through the second closure stage comprises the step of restricting fluid flow through a second flow regulator at a faster flow rate than the first flow regulator.