Abstract:
An operator for a railroad implement is provided with a linkage which mechanically isolates an actuator from impact forces transmitted through the linkage. Isolation provided by the linkage permits the use of a low power actuators which easily lend themselves to complete energization from solar energy sources. The operator is also provided with a safety electric interlock to prevent energization of the actuator during manual operation. A spring assembly tool is incorporated into the operator housing to facilitate installations and removal of compression springs in the operator mechanism.

Description:
BACKGROUND OF THE INVENTION 
     This invention relates generally to operators for railroad implements, such implements including derails and switches. Specifically, the invention relates to actuating mechanisms and safety features for operators for railroad implements. 
     Railroad implements, such as derails and switches, typically require automatic operators for facilitating movement thereof. Such operators provide the driving force for moving the railroad implement, which is usually rather massive, between an engaged and disengaged position. In the case of a derail, the engaged position is characterized by the derail being disposed above the railroad track so as to engage and derail the wheel of an oncoming railcar. In the disengaged position, the derail is positioned adjacent the track and out of the path of the wheels of the railcar. 
     Many different types of operators are known. For example, as exemplified in U.S. Pat. No. 5,775,647 to Wyatt, an operator for a railroad switch may include a hydraulic actuator that is driven by hydraulic pressure which may be provided by a hydraulic pump. The pump may be partially energized by solar power. Such prior art operators are characterized by a direct link between the actuator and the railroad implement. As a result, impact forces experienced by the railroad implement, for example, when the implement moves to its engaged position, may be transmitted back to the actuator, thereby resulting in damage to and/or excessive wear on the actuator. Such operators therefore require rather robust and expensive actuators that can withstand such impact forces. It would therefore be desirable to provide an operator in which the actuator is isolated from impact forces, such as those that may be generated by movement or engagement/disengagement of the railroad implement or by impact forces originating within the operator itself. 
     Hydraulic systems such as the one disclosed in U.S. Pat. No. 5,775,647 typically consume large amounts of energy to operate. These energy requirements may render such hydraulic actuating systems unfeasible as a means to provide dependable low power operation, as might be required if solar energy is desired to be the sole source of power for the operator. As a result, operators that incorporate these hydraulic systems cannot rely on solar power as the sole means for providing energy to the operator. Rather, such operators require supplemental energy sources, such as hydraulic rail pumps actuated by the wheels of a passing train, to ensure dependable operation. Since there is a desire in the industry for operators which provide for maximal use of and sole reliance on inexpensive energy sources, such as solar power, it would also be desirable to provide an operator with a low power actuator that permits energization using only solar power, without the need for supplemental energy sources. 
     There is also needed an operator with improved safety features for manual operation. It is known to provide for manual operation of automatic operators. Such configurations provide for the use of a manual hand lever, actuated by a human operator to move the railroad implement between the engaged and disengaged positions. Incorporating manual features on automatic operators may present a hazard to human operators because there is potential for accidental energization of the actuator while the human operator is attempting to manually operate the railroad implement. These consequences can have catastrophic results and may result in serious injury. It would therefore be desirable to provide an automatic operator that has manual features with improved safety features that would prevent injury to a human operator during manual operation. 
     There is also needed an improved operator which provides for easy on-site assembly, maintenance or repair. Many operating mechanisms, including the one disclosed in U.S. Pat. No. 5,775,647, rely on compressed spring members to provide a locking mechanism or to store energy to later be used to provide momentum or power to move the railroad implement. Such springs or biasing elements make assembly and repair of the operator difficult because spring installation typically requires compression of the springs and the application of large forces, sometimes on the order of 150 pounds or more. It would therefore be desirable to provide that a railroad operator provides for the easy and safe installation and removal of spring members which are used in the operator assembly. 
     SUMMARY OF THE INVENTION 
     The aforementioned problems and others are solved by the present invention which, in a preferred embodiment, provides an operator incorporating a linkage that isolates the actuator from impact forces. The actuator is adapted to rotate a cam shaft with cams that selectively engage the linkage. In a preferred embodiment, the linkage may take the form of a spring biased toggle which is provided with a pair of tapered rollers to engage respective cams on the cam shaft. Spring elements in a biasing assembly bias the toggle into one of first and second positions and assist rotation of the linkage and movement of the implement without contact from the cam. When the implement moves into its engaged position, the linkage is not in contact with the cam. Thus, impact forces are not transmitted back to the cam, camshafts or actuator. Adjustable stop members may be provided on the toggle to limit its movement. First and second stop positions of the toggle are defined by contact of the adjustable stop members with a stop block that is formed on the operator case. 
     In accordance with another primary aspect of the invention, the aforementioned isolation permits the operator to be provided with a low power, low-cost actuator, for example, a ball screw driven by an electric motor through a reduction gear assembly. Because the actuator need not be constructed to withstand impact forces transmitted through the linkage, low power actuators suitable for energization using only solar power without the need for hard wiring or supplemental energy sources, may be incorporated into the operator. Alternatively, in accordance with this same aspect of the present invention, a low cost and low power hydraulic actuator may be provided 
     In accordance with another primary aspect of the invention, the operator is provided with an electric interlock for a hand lever. The hand lever is stored on the battery and controller pack which is provided with a bracket assembly that includes a micro switch engaged by the stored hand lever and in electrical communication with the electric circuit that provides power to the actuator. Removal of the hand lever from the bracket opens the power circuit and prevents accidental energization of the actuator. Thus, the present invention ensures that the actuator will not be energized when a human operator is manually operating the operator using the hand lever. 
     In accordance with another primary aspect of the invention, a spring assembly tool is provided on the case of the operator so as to assist a technician in installing or removing the compression springs utilized in the operator biasing assembly. In a preferred embodiment, the spring assembly tool includes an angled bracket mounted to the case and an extendable element, such as a threaded fastener extending through the angled bracket and adapted to engage the biasing assembly. When the biasing assembly is moved to an appropriate position, rotation of the extendable member results in compression of the springs to thereby permit an operator to safely assemble or disassemble the biasing assembly. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The accompanying drawings which are incorporated into and form a part of the specification, illustrate several embodiments of the present invention and, together with the description, serve to explain the principles of the invention. The drawings are only for the purpose of illustrating a preferred embodiment of the invention and are not to be construed as limiting the invention. Appendix A includes 6 sheets of detailed assembly technical drawings which are intended to form a part of this specification in addition to the following Figures described herein in which: 
     FIG. 1 is an isometric illustrating the environment of an operator according to a preferred embodiment of the present invention; 
     FIG. 2 is an isometric depicting the elements of an operator according to the present invention, 
     FIG. 3 is a view of the internal working components of an operator according to a preferred embodiment of the present invention; 
     FIG. 4 is a cross-sectional view taken along lines  4 — 4  in FIG. 3; 
     FIG. 5 is a rear view of an electric interlock according to a preferred embodiment of the present invention; and 
     FIG. 6 is a side view of an electrical interlock according to a preferred embodiment of the present invention. 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     Referring to FIG. 1, there is shown an operator  100  according to a preferred embodiment of the present invention. Operator  100  is situated adjacent railway  10  which includes a number of railroad ties and two rails, the operator  100  being secured to the ties via spikes and brackets. A railroad implement  20  is operatively associated with the operator  100  connecting rod  102  which extends from operator  100  to railroad implement  20  for moving the implement  20  from an engaged to a disengaged position. Implement  20 , which is illustrated as a derail, is shown in an engaged position in FIG.  1 . Operator  100  has a mast  106  extending upward therefrom. Mast  106  is provided on a distal end with a solar module  108  for converting solar power or solar energy into electrical energy for use by operator  100 . Mast  106  houses electrical conductors to provide energy from solar module  108  to operator  100 . Disposed on mast  106  is a battery and controller pack  114  which houses a storage battery (not shown) as well as conventional control components for remotely controlling operator  100  from an oncoming rail vehicle, for example. A hand lever  112  is secured to the back of battery and controller pack  114 . As illustrated by the dotted lines  116 , hand lever may be moved to an operating position so as to manually permit a user to manually actuate the operator  100 . 
     Referring additionally to FIG. 2, the internal components of operator  100  are illustrated. A low power actuator  120  is situated within a case  110 . One end of the actuator  120  is secured to an inside surface of case  110  via a mounting bracket  124 . According to the present invention, actuator  120  is provided in the form of a ball screw, such as Model No. D12-20B72-06CC manufactured by Warner Electric Inc. As will be apparent to those of ordinary skill in the art, the ball screw includes a threaded internal member which rotates within a race having a number of ball bearings situated therein. Rotational motion of the threaded internal member results in extension of the ball screw. The motive force for driving the screw member is provided by an electric motor  130 , which may rotate the threaded internal member through a reduction gear assembly  132 . Alternatively, actuator  120  may be provided as a low power hydraulic actuator. An end of actuator  120  opposite the end connected to mounting bracket  124  cooperates with a cam shaft  140 , which is provided with a cam shaft crank  146  such that extension or retraction of actuator  120  results in rotation of cam shaft  140 . 
     Cam shaft  140  may be mounted within a series of journals or bushings  144  which are situated on the interior of case  110 . Referring additionally to FIGS. 3 and 4, cam shaft  140  is provided with a first cam  148  fastened thereto and a second cam  150  fastened thereto. Both first cam  148  and second cam  150  are provided with rounded outer surfaces  152  to engage linkage  160 , which will be described below. First cam  148  and second cam  150  may be secured to the cam shaft  140  by a threaded fastener for example. As illustrated, the first cam is fixed to cam shaft  140  to extend 90° or orthogonal to the longitudinal extent of second cam  150 . 
     Linkage  160  is secured to a main shaft  194  and mounted for pivotal movement within case  110 . Linkage  160  is preferably in the form of a toggle which comprises a generally triangular shaped body  164 , which includes a pair of forks  162  adapted to pivotally secure a first roller  166  and a second roller  170  to body  164 . First roller  166  and second roller  170  are provided with tapered surfaces, the angle of the taper being chosen to maximize the engagement surface with respective cam elements previously described. As can be seen best in FIG. 3, first roller  166  is adapted to engage outer surface  152  of first cam  148  and second roller  170  is adapted to engage the outer surface  152  of second cam  150 . Linkage  160  is provided with a pair of stop bolts  180  disposed on opposite sides of main shaft  194 . The function of stop bolts  180  is to limit the pivotal movement of the linkage  160 . As can be seen in FIG. 3, the heads of stop bolt  180  are positioned to engage a stop block  182  which is cast, formed integrally or fastened to the case  110 . Extending opposite forks  162  is a toggle arm  172  which is provided with a pivot  173  at a distal end thereof. Secured to toggle arm  172  via pivot  173  is a biasing assembly  200  which functions to bias the linkage  160  towards the first and second stop positions defined by stop bolts  180 . 
     Biasing assembly  200  includes a first spring retainer block  204  fastened to pivot  205  via bracket  214  extending from and fixed to case  110 . Extending from spring retainer block  204  are a pair of spring rods  212 , movably received in apertures in spring rod guide  208 . Spring rod guide  208  is pivotably fastened to toggle arm  172  via pivot  173 . Disposed around the outer circumference of the spring rods  212  are compression springs  202  whose ends abut respective surfaces on spring rod guide  208  and spring retainer block  204 . As will be apparent to those of ordinary skill, biasing assembly  200  is constructed to provide a biasing force in the axial direction of springs  202  and spring rod guides  208 . Thus, as the distance between the pivot  173  disposed at the distal end of toggle arm  172  and the pivot  205  extending through the bracket  214  is reduced, the compressive forces in springs  202  increase. Biasing assembly  200  therefore operates to bias linkage  160  in the first position, shown in solid lines in FIG. 3, or in the second position which is shown by dotted lines  280  in FIG.  3 . 
     A main shaft  194  extends downward, as shown in FIG. 4, through the case  110  and is provided with a main shaft crank  232  on a distal end thereof. Main shaft crank  232  is provided with a fastener  233  at an end opposite the main shaft so that a connecting rod (not shown in FIGS. 3 or  4 ) may be secured thereto so as to actuate the railroad implement. 
     Automatic operation of the operator  100  proceeds in the following manner. Motor  130  is selectively energized by the storage battery stored in battery and controller pack  114  and appropriate conductors (not shown) and switching and control elements (not shown). Rotation of motor  130  results in rotation of gears in reduction gear assembly  132  and rotation of the lead screw provided in the actuator  120  thereby extending or retracting actuator  120 . This linear movement results in a displacement of the cam shaft crank  146  which results in rotation of the cam shaft  140  and engagement of one of either first cam  148  or second cam  150  with a respective one of first roller  166  or second roller  170  on linkage  160 . As cam shaft  140  continues to rotate, the appropriate cam  148 ,  150  will impart a force to linkage  160 . As linkage  160  rotates, biasing assembly  200  is compressed until reaching its dead center position, defined by minimal distance between pivot  173  and pivot  205 . Further, rotation of cam shaft past dead center will result in the stored compressive forces in biasing assembly  200  being imparted to and assisting rotation of linkage  160 , thereby resulting in a movement of one of the first roller  166  or second roller  170  out of contact with the respective camming surface and isolation of the linkage  160  from the cam shaft  140  and actuator  120 . As linkage  160  continues to rotate under the compressive forces provided by biasing assembly  200 , rotation will continue until one of stop bolts  180  encounters the stop block  182 . 
     In accordance with another aspect of the invention, also provided within the case  110  is spring assembly tool  218  which is provided with an extendable member  220 , for example, a threaded fastener such as a hex bolt, movably received in an aperture in wall  219  of spring assembly tool  218  and positioned to engage a surface on spring rod guide  208 . Extendable member  220  is provided with an end surface  221  which, when the biasing assembly is in the position shown by dotted lines  282 , will engage a surface on the spring guide block  208 . As will be appreciated by those of ordinary skill, installation of the compressive springs  202  may proceed in the following manner. First, the compressive springs  202  are installed on the spring rods  212 . Next, spring rod guide  208  is installed over the ends of spring rod guides  212  and the assembly is moved to the position shown in dotted lines  282  shown in FIG.  3 . Then, extendable member  220  is rotated, using a wrench for example, until surface  221  engages spring rod guide  208 . Continued rotation of extendable member  220  results in compression of the springs  202  until an aperture in the spring rod guide  208  is aligned with a corresponding aperture in linkage arm  172  such that pivot  173  may be installed to pivotally secure spring rod guide  208  to linkage arm  172 . Extendable member  220  is then retracted such that surface  221  is brought out of engagement with the spring rod guide  208 , thereby permitting movement of the linkage  164  and biasing assembly  200 . Removal of the compression springs  202  occurs by reversing the aforementioned steps. 
     Referring now to FIGS. 5 and 6, there is illustrated a preferred embodiment of an electrical interlock in accordance with another aspect of the invention. Battery and controller pack  114  (FIG. 1) is provided on a back surface thereof with a hand lever storage assembly  250 , which includes an interlock bracket  262 . Interlock bracket  262  is provided with an aperture  264  through which the switching element of a micro switch  266  protrudes so as to engage the peripheral surface of the hand lever  112  when it is stored in the interlock bracket  262 . A second upper bracket  256  may be provided to further secure the hand lever. Micro switch  266  is in electrical communication with the power circuit (not shown) for providing power from the storage battery and/or solar module to actuator  120 . The power circuit will be an open circuit when the actuator of micro switch  266  is not engaged by hand lever  112 . Hand lever  112  may be used to manually engage the operator  100  in the following manner. Hand lever  112  is removed from the hand lever storage assembly  250  and inserted into a suitable fastener disposed on the end of cam shaft  140 . Hand lever  112  is then used as a lever to manually turn the cam shaft  140 . As will be apparent to those of ordinary skill, the electrical interlock assembly  260  prevents energization of the motor  130  during manual operation of the cam shaft  140 . 
     Those skilled in the art will recognize that the preferred embodiments may be altered or amended without departing from the true spirit and scope of the invention, as defined in the accompanying claims.