Abstract:
An electromechanical switch operable with systems for controlling and monitoring vehicular traffic includes switch modules carried within a housing for mounting on a system control panel. Selected switch modules are slidable mounted within pockets and positioned for operation with a shaft that is rotatable and slidable in a push-pull fashion for displacing a preselected module for movement thereof and activation of a switch module button by causing the module to be moved from a neutral position to a button operating position which presses the button against a stop for activation of the switch module. The shaft is suitably mounted for rotation within the housing about a longitudinal axis and is operable for activating the selected switch modules by a pushing/pulling movement and a rotational movement of the shaft by a user for activating one or a combination of switch modules. Alternate switching is provided by alternate switch modules fixed within the housing for activation of their respective buttons by a disk carried on the shaft, which disk includes apertures therein aligned for activating preselected buttons of the alternate switch modules by contact with the disk while having certain buttons of the alternate modules fall within the apertures for avoiding activation thereof.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of and hereby incorporates by reference the disclosure of application Ser. No. 09/266,070, filed on Mar. 10, 1999, now U.S. Pat. No. 6,130,386 for “Controller Switch Assembly” which is commonly owned and assigned with the present invention. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to electromechanical switches, and more particularly, to controls that are primarily used in complex signal systems for monitoring and controlling the flow of vehicular and railroad traffic or industrial processes including electric utilities, petrochemical, water treatment and materials handling systems. 
     BACKGROUND OF THE INVENTION 
     Design engineers and manufacturers of both large and small control panels are continually striving to maximize the amount of control function they can provide within the smallest amount of panel space. In addition to the cost savings achieved by using less mechanical equipment and a smaller amount of floor space, higher density control panels allow an operator to view and control more functions for a given amount of space and therefore require fewer personnel to operate. 
     The majority of traffic flow control systems interface with programmable logic controllers that actually direct traffic flow control situations. Customers are generally not interested in having redundant spare switches in case of a failure. This is because there are now multiple electrical/electronic system driven safety backups should an electrical circuit malfunction for any reason. Also, wiring is both heavy and expensive and duplicate function spare wires consume too much space in panels. Because spare wires also consume connector and terminal block space and the labor to assemble them, wire cables and harnesses to these controller switches carry the fewest number of individual wires necessary for the required signals. Rewiring of connectors or harnesses to access backup switch modes in a controller switch is neither practical nor reliable once a panel is completely installed in the field. 
     Today, designers are more interested in circuit flexibility and maximizing the number of circuit functions that can be accessed for a given panel space. Design engineers also often prefer to identify certain specific operating motions to circuit activation. Perhaps, as an added safety feature to prevent inadvertent operation, a designer may require an operator to pull or push and then quickly turn a knob before a circuit can operate. Conversely, the designer may require a specific degree of rotation to activate a specific circuit or require a circuit be momentary in one direction of rotation and maintained or latching in the opposite direction of rotation. 
     OBJECTS AND SUMMARY OF THE INVENTION 
     It is an object of the invention to provide a switch. 
     A further object is to provide a switch capable of push only, pull only, push-pull, left turn, right turn, left and right turn, or push-pull left turn right turn combinations of action. 
     Another object is to provide a switch capable of maintained switch action, momentary switch action, or combinations of both in any switch with multiple positions. 
     Still another object is to provide a switch which can incorporate multiple means of mounting, multiple means of signal wire termination, an extensive variety of circuit possibilities, and an array of multiple LED illumination capability packaged in the smallest possible controller switch footprint available today. 
     Yet another object of the invention is to provide a control panel switch which provides for an improvement in panel density and an increase in signal functions per cubic volume of panel space, thereby providing customers with unparalleled cost savings. 
     In view of the above considerations, the present invention provides a modular family of multi-function high circuit density controls that can realize a range of specific types of circuits and actions that can be easily matched to the needs of particular applications. The invention can be used in a family of controls that can be adapted to a variety of behind panel depth limitations while still providing the maximum number of discrete circuits for a given cubic volume of space. The control density provided by the invention is unmatched by any currently available device or series of devices. 
     The modular concept of a switch according to the invention is to allow them to be easily replaced in a panel or grid system by removing one nut and disconnecting the plug connector. A new switch can be quickly mounted in the grid or panel, and the malfunction unit can be repaired at a remote site. 
     A switch according to the invention allows for push only, pull only, push-pull, left turn, right turn, left and right turn, or push-pull left turn right turn combinations of action, with the switch actions being maintained, momentary, or combinations of both in any switch with multiple positions. The Switch incorporates multiple means of mounting, multiple means of signal wire termination, an extensive variety of circuit possibilities, and an array of multiple LED illumination capability packaged in the smallest controller switch footprint available today. The resultant improvement in panel density and signal functions per cubic volume of space provides customers with unparalleled cost savings. 
     Switches incorporating the present invention are designed around a single unit base structure with a simple “drop-in design” mechanical operating mechanism that allows for interchangeable mounting bushings and operating shafts of various lengths for different panel or grid/title thickness&#39;. All switches feature either cable or connector control wire termination and the “drop-in” electrical switching contact elements can be varied to customize individual control circuit requirements. The design provides for simple, but unique, precise operating shaft and control surface stops to insure that millions of operating cycles will be possible under severe field conditions. 
     By incorporating all of the push/pull/turn forms of action into a primary internal shaft support bearing the overall length of the control is reduced while a higher level of protection from the elements is achieved. That is, external control open areas which allow dust and dirt to enter moving parts are eliminated by encapsulating the shaft and its associated switch modules within a common enclosure. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The following detailed description, given by way of example and not intended to limit the present invention solely thereto, will best be appreciated in conjunction with the accompanying drawings, wherein like reference numerals denote like elements and parts, in which: 
     FIG. 1 is a top plan view of one switch assembly of the present invention illustrated in an open arrangement. 
     FIG. 1A is a front view of the switch assembly depicted in FIG.  1 . 
     FIG. 2 shows a grid plate suitable for use with a switch assembly in accordance with the invention. 
     FIGS. 2A and 2B illustrate top and side views of a lid suitable for the assembly of FIG.  1 . 
     FIGS. 3A and 3B include detailed illustrations of the torsion spring sub-assembly of the switch assembly depicted in FIG. 1 as the sub-assembly is viewed from two perspectives. 
     FIG. 4 is a plan view of a  14  module switch assembly in accordance with the invention. 
     FIGS. 4A and 4B illustrate single and double clamps in exploded views, respectively. 
     FIG. 5 is a plan view of a  4  module rotation switch assembly in accordance with the invention. 
     FIG. 6 is a plan view of a  4  module push-pull switch assembly in accordance with the invention. 
     FIGS. 7A,  7 B, and  7 C illustrate several views of switch modules and switch module drivers which are suitable for use with the invention. 
     FIG. 7D includes several views of push switch modules and pins according to the invention for the purpose of showing how the push modules and pins are integrated into the invention&#39;s switch assembly. 
     FIG. 8 is a plan view of the switch assembly of FIG. 1 in which the wiring associated with the switch modules is shown. 
     FIGS. 9 a - 9   e  show several operating disks which may be used in the switch assemblies of the invention. 
     FIG. 10 is a plan view of an  8  switch module push-pull switch assembly according to the invention. 
     FIG. 11A is a plan view of an LED carrier with LEDs in accordance with the invention. 
     FIG. 11B shows the LED carrier of FIG. 11A as attached to a switch assembly of the invention. 
     FIGS. 11C and 11D show alternative embodiments of switch assemblies incorporating LED carriers in accordance with the invention. 
     FIG. 12A shows three different types of switch assemblies and their respective grid connections in accordance with a control grid of the present invention. 
     FIG. 12B is a detailed illustration of a grid mounted switch assembly of the invention. 
     FIG. 13A shows an LED indicator incorporated into the shaft of a switch assembly according to the invention, the LED indicator being easily replaceable from the front of a panel in which the switch assembly is incorporated. 
     FIG. 13B shows an alternative technique for incorporating an LED indicator into the shaft of a switch assembly according to the invention, the LED indicator being easily replaceable from the front of a panel in which the switch assembly is incorporated. 
     FIG. 13C shows an another alternative technique for incorporating an LED indicator into the shaft of a switch assembly according to the invention. 
     FIGS. 13D-13H illustrate an LED incorporated into the shaft of a switch assembly according to the invention. 
     FIGS. 14A,  14 B and  15  show various types of illumination layouts which can be realized with the switch assemblies of the invention. 
     FIG. 16 shows an alternative grid plate suitable for use with a switch assembly of the invention. 
     FIG. 17 shows a top view of a switch assembly mounted in a grid according to the invention. 
    
    
     DETAILED DESCRIPTION 
     A family of push, pull, push-pull, left turn only, right turn only, left and right turn, push turn, pull turn and push-pull turn switches as herein described, accept from 1 to 14 (but expandable to more) Form C (one normally open, one normally closed) switching modules from a variety of different manufacturers. The switch actions can be maintained, momentary, or combinations of both in any switch with multiple positions. 
     A preferred embodiment of a switch assembly  2  of the present invention includes a rectangular housing  6  accessible by removal of a lid  13  currently attached with 3 screws (longer versions may require two additional lid screws). The housing  6  can be machined, molded or die cast and is designed to accept a variety of different diameter and length bushings at one end and a variety of wiring means at the other end with connectors, individual wires or cable sets being the most popular interfaces. The housings  6  are consistent in overall rectangular face panel size and, for the same number of circuits, are 30% smaller in volume than any other switch assembly being sold. The housings  6  will accept a main one piece operating shaft  8  located on both horizontal and vertical centers and running longitudinally approximately ¾ of the length of the housing. The operating shaft  8  will operate in rotational and/or longitudinal directional modes with either maintained (latching) or momentary shaft  8  positions. Movement of the shaft  8  with its integral key, attached disks, or both items will actuate a single or multiple drop-in switch module elements in a precise fashion. Operation of some of the drop-in switch module elements through their direct movement and rotation of the mounting position of other modules to permit variation in switch operating actions, provides unique design elements allowing for a significantly wider array of circuits and operating actions. The inclusion of a modular single or multi-LED illumination system for a variety of panel thickness&#39; or grid and tile mount systems results in panel density space savings of up to 50%. The unique LED illumination system easily mounts to switch controllers and is adjustable for switches mounted on a variety of different thickness panels. The same unique LED system is also designed to mount to grid and tile systems of different thickness or different size and type tiles, thereby supplying a universally mountable family of products. Therefore, the end users (railroads, electric utilities, etc.) of these control panels now have the ability to select from a variety of competitive panel builders without having to sacrifice on overall panel size for a given area of control density. 
     The present invention allows for controller switches (without indicators) to be stacked on 0.630″ vertical centers and 0.950″ horizontal centers providing an unequaled panel density of this type of control in the industry. In addition, in the case of controllers supplied with up to 3 LED indicators, the density is 0.950″ on center enabling designers of grid and tile systems to achieve as much as a 50% reduction in panel space as all other 24 mm to 25 mm grid and tile systems marketed require illumination indicators that use a completely separate tile space in the grid structure. 
     Another advantage of the present invention is that the basic design allows for easy repair of controller switches installed in the field should a switch element fail mechanically or electrically. The all drop-in components are housed within an enclosure with a lid. The simple removal of the three screws holding the lid in place will provide access to the mechanism and the malfunctioning switch element can be easily replaced. In many other designs, the switch contacts or elements are permanently assembled and the control must be scraped if there is a failure of any circuit. For customers that do their own routine maintenance on large control systems, this is a significant advantage. They can maintain a much smaller and less costly inventory as only switch modules need to be stocked. These switch units are compact and are only a small fraction of the cost of a full controller switch assembly. 
     FIG. 1 is a plan view of a switch assembly  2  in accordance with the present invention. The switch assembly  2  includes eight switching modules  4   a - 4   h  which are within an enclosure including a one-piece compact housing  6  and are actuated by a shaft  8 . Of course, the number of switching modules  4  that may be included in the assembly  2  is a design choice that will be discussed in more detail below. 
     The enclosure includes a lid  13  which is not shown in FIG. 1 for purposes of clarity. FIG. 2A shows top and side views of the lid  13  suitable for attaching to the housing  6  as illustrated with reference again to FIG.  1 . As shown in FIG. 2A, the lid  13  preferably includes three through holes  15   a ,  15   b  and  15   c  to accommodate screws for fastening the lid  13  to the housing  6  of FIG. 1 via cover retaining screw points  11   a ,  11   b  and  11   c.    
     The compact housing  6  is designed to minimize the vertical, horizontal and depth profile of the assembly  2 , thereby permitting high density stacking of multiple assemblies and allowing for control of all critical dimensions regarding parts alignment via one part of the assembly  2 . The front of the housing  6  is designed with an alignment slot  10  to provide for easy loading of any number of mounting bushings  20  of variable lengths or diameters. This provides the ability to easily mount the switch assembly  2  in a variety of different panel types and thickness&#39; with only two simple changes in parts (the bushing style and shaft diameter and length). As seen in FIG. 1A, two opposing screw holes  12  in the face of the housing  6  placed along a center line of the bushing/shaft  20 / 8  allow for mounting with various designs of grid plates that will permit easy indexing of the switch assembly  2  to a particular style of grid. One style of grid plate  14  is shown in FIG.  2 . The grid plate  14  lies in a plane parallel to the face of the housing  6 , and includes a through hole  16  for the shaft  8  and a hole  17  for an LED indicator (to be described below). 
     When mounting in a panel other than a grid, an index anti-turn locating pin  18  (FIGS. 1 and 1A) is supplied at the 90° position to keep the switch assembly  2  from rotating after installation in the panel. Although the anti-turn pin  18  is shown to be positioned at 90° in the figures, it should be noted that the pin may be located at other locations on the face of the switch assembly  2 . In any event, two screws from the underside of the housing (not shown) secure the bushing  20  square to the housing  6  to provide perfect front alignment of the main one piece operating shaft  8 . All front bushings  20  have been designed to house the push-pull return compression spring  22  in such a fashion as to maximize compaction of the switch length and provide for an accurate alignment of the front main shaft bearing. The rear surface of the slot  10  has also been designed to act as the rear compression spring seat  24  retainer  24  allowing the seat to remain stationary while the shaft is pushed through the rear seat. This allows the compression spring  22  to compress (“load”) and it will then return the shaft  8  to a neutral position  3  when the shaft is released. 
     The C-ring  26  behind the spring seat  24  was designed to hold the compression spring  22  in a loaded (partially compressed) state in the proper place to permit assembly of the shaft components carried by the shaft  8  prior to their being “dropped in” to the housing  6 . The C-ring  26  has been designed to clear the housing  6  and retain the rear spring seat as it travels with the shaft when the shaft is pulled. This permits the rear seat to slide on the shaft  8 , compressing the main compression spring  22  in the pull mode loading it to a point that it will force the shaft fully back to the neutral position  3  when the shaft is released. As can be seen from FIG. 1, a front spring seat retainer  25  is also provided and is held in position by an undercut in the diameter of the shaft  8 . 
     The design of the moving action of these components is such that the enclosed and protected spring seats also act as bearings within the bushing  20 , aligning the spring forces precisely relative to the shaft  8 . The tight tolerances between the bushing bore and spring seat diameters seal the spring  22  from dirt and other contaminants that can reduce operating life and promote sticking problems that would inhibit the shaft  8  from returning to the neutral position from the push or pull mode as illustrated by way of example with reference again to FIG.  1 . This insures a more durable structure that will extend mechanical life significantly over other compression spring designs that allow much greater exposure of the compression spring to elements in the air. 
     The rear shaft bearing  28  also “drops in” and has two screws (not shown) from the underside of the housing  6  that secure this rear bearing  28  square to both the base of the housing and the front bearing. This design allows for nearly perfect alignment of the two shaft bearing points enabling precise control of shaft motion without binding and minimizing wear at the interface points on the shaft  8  and bearings. The alignment facilitates operating both the push-pull and turn motions of the main operating shaft  8  over millions of cycles with little mechanical wear. The rear shaft bearing  28  has been designed to allow incorporation of a series of slots or channels, such as slot  30  (see also slots  31   a - 31   f  in FIG.  10 ), to provide for or restrict various motions or actions of the switch assembly  2  when a pin is inserted into the shaft  8  in a preselected location to mate with the slots. A partial list of possible slot geometry&#39;s along with brief descriptions is provided in Table I. 
     Incorporating the slot  30  feature directly into a critical main bearing, the rear shaft bearing  28 , is unique. Housing this critical shaft control feature within a sealed enclosure, the lid  13  and housing  8 , also protects the contents thereof from contaminants like dust and dirt which are prevalent especially in wayside railroad control applications. To date, designs presently known in the art do not provide for the ability to easily tailor a variety of control motions and/or actions to customer needs. 
     The rear bearing  28  also acts with the shaft/slot pin  32  as a tertiary redundant mechanical stop to the switch push action by preventing any damage to internal switches  4   a - 4   h  operated by this shaft motion due to operator over-stressing the operating switch assembly  2 . This bearing slot/pin design also serves as a secondary safety stop to the pull action and the right and left turn actions. While the slot  30  configurations include those shown in Table I, other configurations not shown could be established within this bearing  28  depending upon customer requests for specific shaft motions. The slots and detents in the slots provide points to “latch” the switch assembly  2  in a particular position. The main compression spring  22  in the front bearing/bushing provides the pre-load thus enabling the index pin  32  to engage the detent with sufficient force to overcome the rotational force of the torsion spring  23  that returns the shaft to the neutral position from either the left or right turn modes. 
     FIGS. 3A and 3B provide a more detailed illustration of the torsion spring  23  sub-assembly. As can be seen from FIGS. 3A and 3B, the left and right turn torsion spring  23  used to return the shaft  8  to the neutral position, as illustrated with reference again to FIG. 1, has a unique sliding shoe  40  to hold it in place and supply the proper pre-load to the spring  23 . This shoe  40  eliminates the wear on the inside ends of this spring  23  inherent in other designs due to rubbing of the spring edge on the pin  34  that provides the stop surface and holding point for the ends of the torsion spring during the push-pull cycles on the switch main shaft  8 . This unique shoe  40 , spacers  44  and collar  38  assembly allow the spring ends to remain fixed during the linear motion of the shaft  8  with the shoe absorbing any linear travel wear. The effect of this design greatly extends spring life and reduces the possibility of spring end fracture which would result in loss of the clockwise or counter-clockwise rotational spring return function. The shoe  40  position on the shaft  8  is fixed by a retaining C-ring  36  on one end and the position of the collar  38  on the other end. The spacers and washers provide proper compression and alignment of the torsion spring  23  to insure the spring ends engage the shoe  40  at right angles. This maximizes the return spring tension and extends the life of this spring  23  to its designed life. 
     The shoe  40  is also designed to allow from 0°+/− to 110° of rotation from either side of the center neutral (0°) position. The design of the torsion spring  23  assembly consists of a collar  38  with a stainless steel groove pin  34  pressed into it. The pin  34  will rotate either end of the torsion spring (depending on which way the shaft is rotated) while the other end is held stationary by the shoe  40 . This eliminates any sliding wear on the spring end edges. The collar  38  was designed to be fixed to the shaft  8  with either a set screw or pin  42  (FIG.  1 ). A spring spacer  44  slides over the shaft  8  and controls the distance between the shoe  40  and the collar  38 . Washer spring seats at both ends of the spacer  44  along with the spacer provide precise positioning of the torsion spring  23  throughout its rotation cycles while minimizing the drag friction of the spring on the spring return function of this assembly  2 . One effect of the design of this portion of the switch assembly  2  is that the rotational spring return life is extended to millions of mechanical cycles, enhancing the overall switch performance over other designs known in the art. 
     Integrated into the shaft is a unique long key  46  (FIGS. 1 and 3) that is used to drive the unique inserts that operate the switch modules in either the right or left turn positions. This single key  46  will operate both the right ( 4   c ,  4   d ) and left ( 4   a ,  4   b ) turn position switch modules  4  in either the push or pull shaft positions throughout the total linear travel of the main shaft  8 . 
     Additional or fewer circuits could be added or subtracted simply by extending or reducing the length of the housing  6  and shaft  8  by adding or reducing the number of switch pockets provided and extending or reducing the key length. The number of circuits provided can also be easily altered by adding or eliminating switches within a specific enclosure design. The housing  6 , as illustrated by way of example with reference to FIG. 1, accepts up to two (2) independent Form C switch contact modules  4  in the left turn position  4   a ,  4   b  and two (2) independent switch contact modules  4  in the right turn position  4   c ,  4   d . It also has two (2) independent modules  4  for the push function  4   f ,  4   h  and two (2) independent modules  4  for the pull function  4   e ,  4   g . This specific housing will accept up to eight (8) modules each being a Form C contact arrangement, by way of example and convenience of description. An example of a switch assembly  48  having  14  switch modules  50   a - 50   n  is shown in FIG.  4 . Switch assembly  48  has three (3) independent Form C switch contact modules  50   a ,  50   b ,  50   c  in the left turn position and three (3) independent modules  50   d ,  50   e ,  50   f  in the right turn position. It also has four (4) independent modules,  50   h ,  50   j ,  50   l ,  50   n  for the push function and four (4) independent modules  50   g ,  50   i ,  50   k ,  50   m  for the pull function. 
     Examples of switch assemblies having four switch modules are shown in FIGS. 5 and 6. Switch assembly  52  of FIG. 5 has two independent switch modules  54   a ,  54   b  in the left turn position and two independent modules  54   c ,  54   d  in the right turn position. Switch assembly  56  of FIG. 6 has two independent switch modules  58   b ,  58   d  in the push position and two independent modules  58   a ,  58   c  in the pull position. Several views of Form C contact are shown in FIG. 7, parts A and B. The contact has three (3) terminals: one terminal is a common contact  60  that can open or close, a second terminal (contact)  62  that is normally open, and a third terminal (contact)  64  that is normally closed. Besides wiring to the common terminal, wiring to either or both of the other terminals allows for great flexibility in specific circuits being activated in different switch shaft positions. 
     One preferred embodiment of the present invention, herein described, includes drivers  66  that are inserted in left-right turn switch modules. Profiles of two types of drivers  66 ,  70  which may be used with the invention are depicted in FIG. 7, Part C. 
     Driver  66  has a shelf  68  suitable to allow for 90° shaft rotation. Driver  70  has a shelf  72  suitable to allow for 45° shaft rotation. A simple alteration in the position of the shelf  68 ,  72  on the driver  66 ,  70  that interfaces with the long key  46  within the shaft  8  will activate these modules at any degree of rotation of the shaft from 20° to 110° of rotation either side of center 0°. Also note the drivers have been designed with flat surfaces  74  (Part A) on their adjacent sides. This minimizes rotation of these parts after assembly in the switch module  4  insuring that they will self align during engagement of the long key  46 . This insures a more uniform transmittal of rotary to linear forces which aids in driving both switches ( 4   a ,  4   b , by way of example with reference again to FIG. 1) on each side at the same time. Such an arrangement also minimizes the friction generated between the snap switch module case side and the pocket walls. A corresponding unique feature of this design is the ability to easily supply a different degree of rotation either side of the center position. For example, the rotation to the left could be 45° while the rotation to the right was 90°. The advantage to users is that it enables them to have greater flexibility in coding many different degrees of rotation to different control output functions as may be desired. After assembly to the switch module and insertion of the module  4  in the pocket  76 , the drivers  66 ,  70  are held in position by the main shaft  8 . The entire control of the switch assembly  2  can be mounted in any rotational position in the panel without affecting its mechanical operation. 
     These unique drivers  66 ,  70  effectively transfer rotary motion into linear motion. As shown in FIG. 1, modules  4   a - 4   d  are slidably mounted within pockets  76   a - 76   d  which are formed as an integral part of the housing  6 . No other types of controls that employ these precision snap switch modules  4  actually move the entire switch to activate them. Because the snap switch modules  4  require precise travel ranges for their operating button  82 , in the prior art modules are typically fixed in rigid positions usually on posts, pins, rivets, eyelets, or screws when mounted in their respective frame assemblies. A cam is then typically used to operate the button within prescribed limits. 
     Allowing these switch modules  4  to float would normally present major problems in operating these switches without damage to their mechanisms. The constant operation of the button  82  to its maximum travel point or beyond would either cause them to totally fail due to button or internal switch module spring breakage or would significantly reduce their mechanical operating life due to overstressing the switching module  4 . However, the present invention including the switch module retaining pockets  76  in the embodiment herein described, prevents this from happening. Means to control the amount of movement of the switch modules  4  activated by the long key  46  during shaft rotation is provided. The drivers  66 ,  70  are designed to bottom out in the slots  78  (FIG. 7, Part A) in the inside walls of the pockets  76 , absorbing the primary force of the rotational pressure. In addition, the bottom of the pocket  76  has been designed as a second safety backup stop. The external case of the switch module  4  will bottom out on raised portion of the pocket floor  80  before the module operating button  82  exceeds its travel limits. 
     Also, as mentioned earlier, the third button-over-travel backup is supplied by the index pin  32  in the main shaft  8  that travels in the slots  30  in the rear shaft bearing  28 . This pin  32  stops the rotational movement by engaging the slot wall before the operating button  82  on the module  4  reaches its maximum travel. 
     The switch assembly  2  allows the internal module button spring forces in the switch modules  4  to return each left and right switch module ( 4   a ,  4   b , and  4   c ,  4   d ) to their neutral position  3  once the main shaft  8  is released from a turn mode. A depressed button  82  unloads, pushing the module  4  until the button reaches an unloaded state. Because the button  82  in the switch module  4  is off-set from center of the module  4 , the addition of a second compression spring  84  (FIG. 7, Part A) in the bottom of the pockets  76  provides a counter balance force to the switch module  4 . This reduces the possibility of a module  4  cocking during its travel, facilitates smoother module movement, and minimizes mechanical wear between the switch module case and pocket side walls. While this second compression spring  84  is designed to match the forces of the switch button  82  in this specific switch module  4 , by increasing or reducing the depth of this pocket  76 , spring forces can be easily adjusted to match snap switch module button forces of a number of different manufacturers of these devices. This counter balance of spring  84  will also return the module  4  to its at rest state should the switch module internal button spring fail for any reason. 
     The pull snap switch modules  4   e - 4   h  have special mounting pins  86  (FIG. 7, Part B) inserted into the module mounting holes. These pins drop into press-fit slots  88  (FIG. 1) in the housing  6 , retaining the modules  4   e - 4   h  in the desired location to insure their operating buttons  82  engage the operating disk  90  (FIG. 1) secured to the main shaft  8 . These switching modules  4   e - 4   h  do not move and are supported by walls on both sides. Because the heads of the mounting pins have an interference fit to the slot walls, they can&#39;t fall out of the switch modules. 
     The pins  91  used to nest the push switch modules (e.g. pin  91  of FIG. 1) are sized to fit between interior enclosure walls (e.g. walls  93   a  and  93   b  of FIG. 1) of the switch assembly housing  6  and have an interference fit in a rear cover point mounting slot (e.g. slot  95  of FIG.  1 ), of the assembly. FIG. 7A includes several views of push switch modules and pins for the purpose of showing how the push modules and pins are integrated into the assembly. Switch modules  4   f  and  4   h  and pin  91  of FIG. 1 are reproduced in FIG. 7A view A. As can be see from view B, pin  91  includes reduced diameters  91   a , and  91   b  on both of its ends, the reduced diameters being sized so as to fit into the mounting holes of switch modules  4   f  and  4   h . In a preferred embodiment shown in view C, an additional pin  97  is used to more securely anchor the modules. In view D, a side view of switch  4   f  by way of example is provided to show exemplary mounting holes  99   a  and  99   b  for pins  91  and  97 . With the switching modules  4   f ,  4   h  properly positioned in a horizontal plane, the pins can easily be inserted into the slot, providing exact positioning of the push switch module operating buttons. Should one of the push switch modules  4   f  be eliminated, the position of the one module  4   h  on the other side (e.g.,  4   f  v.  4   h ) will not change as the pins  91  are of sufficient length to engage the enclosure ( 93   a ,  93   b ) walls on the other side before coming free from the mounting holes in the other switch module. 
     The lid  13  (FIG. 2A) provides an additional retention of all switch modules  4 . In addition, circuit wires  92  (FIG. 8) passing through channels along the inside walls of the housing  6  will inhibit any outward motion of the pins  91 , securing the pull switch modules  4   e - 4   h . The position of the slots in the housing  6  that accept these pin heads is critical to proper positioning of the modules. Their position is timed to the total pull stroke to insure the buttons on the snap switch modules operate within their design parameters. The primary stop control to prevent overdriving these module buttons  82  is the button operating disk  90  or disks mounted along or on the rear of the main shaft  8 . As a primary safety stop, this disk  90  is designed to bottom out on internal housing walls  94  (FIG. 1) and supports prior to reaching a position that will bottom out the buttons in the push or pull modes. A second safety stop to the pull motion of the main shaft  8  is the index/slot pin  32  in the slot  30  in the rear main shaft bearing  28 . It will bottom out in the slot  30  it travels in before the push switch module button  82  exceeds its travel limits for  4   e - 4   h.    
     The unique operating disks  90  can be supplied with no breaks in their circumference. These disks  90  will operate all push-pull switch modules  4   e - 4   h  when the main shaft  8  is operated in the center or any left-right turn position of any degree angle of rotation. Conversely, by selectively removing small portions of the circumference of the disks  90  at specific locations on the perimeter of the disks, selective push-pull circuits can be activated or not activated at specific degrees of rotation of the main shaft. Some representative disks  90  are shown in FIGS. 9 a - 9   e . Referring to FIG. 9 a , disk  96  is a non-indexing disk, FIG. 9 b  disk  98  is a 30° disk, FIG. 9 c  disk  100  is a 45° disk, FIG. 9 d  disk  102  is a 90° disk and FIG. 9 e  disk  105  is an alternate 30° disk. Arrow  104  is indicative of the rotary position of the shaft  8  and points to the bottom of the assembly enclosure when the shaft  8  is in the neutral position. 
     Additional flexibility of circuit selection is possible because the present invention permits mounting of the push-pull switch modules  4   e - 4   h  in their respective slot positions with the module operating buttons  82  either up or down. This provides a variety of combinations of which push-pull switches selectively operate at various degrees of left-right main shaft rotation. The practical advantage of being able to mix and match specific switch module operation to different degrees of shaft rotation is that it allows the system circuit designer a much greater latitude when designing system control functions. With this design, the designer can now provide a much higher density of control function per square area within an envelope of panel space than can be obtained with switches of other designs. 
     This basic design intentionally provided for linear separation of the left-right turn functions from the push-pull functions. This would enable shortening the length of the housing  6  for switch assembly  56  to eliminate either the push-pull switch modules  58   a - 58   d , as illustrated with reference to FIGS. 5 and 6 of the left-right turn switch modules  54   a - 54   d  (see FIG. 6) when supplying only the push-pull version of switch assembly  56  on the shorter housing  6 , as illustrated with reference to FIGS. 5 and 6. Both bearing points for the main shaft are located in the front drop-in bushing when building the shorter enclosure version of this family. In the case of an 8 switch module push-pull device (assembly  106 , FIG.  10 ), a second drop-in rear bearing  108  is provided. 
     Referring now to FIGS. 11A-11D, the LED illumination aspects of the invention will be discussed. The methods of LED illumination for the variety of panel types and thickness&#39;, or grid and tile systems available, required a new but flexible approach to be able to mount in the remaining available space. Prior to this invention, incandescent or LED indicators were mounted to the grid by snap-in modules that typically occupied a complete tile space. In the case of metal or phenolic panels, lamp carriers have to be attached by screws or clip assemblies screwed to the back of the panel. These methods occupied valuable panel space and did not permit maximizing the use of available front panel space. Indicator lamps, in the case of LEDs, were wired as permanent assemblies requiring the replacement of the entire module if an LED burned out. In other cases, the LED or incandescent lamp assemblies were available in telephone slide bases, but could only be replaced from behind the panel. An aspect of this invention will show three LED mounting assembly embodiment, by way of example, that provide for front panel replacement of individual LEDs. 
     As illustrated with reference to FIGS. 11A and 11B, one embodiment includes a special adjustable low profile LED carrier  110  that will accept 1, 2 or 3 LEDs  112   a - 112   c  either of the Ti or Ti ¾ size. The carrier  110  is designed to nest a particular manufacturer&#39;s connector but could be easily altered to use connectors from several other manufacturers. The carrier has two slots  114   a ,  114   b  on either side that allow linear adjustment. This permits either use with panels  111  of various thickness&#39; and the option of front or rear panel LED replacement. The carrier  110  has a vertical section  116  with 1, 2 or 3 threaded holes  118   a - 118   c , positioned side by side, that will accept up to three cylindrical threaded plastic bases  120   a - 120   c . Each base  120  has two metal sockets  122   a - 122   c  positioned to accept the LED leads. The side of the base  120  has a polarity indicator to identify which socket  122  is to be used for the cathode lead. The base position can be adjusted by how far the base  120  is screwed into the carrier  110 . A portion of the threaded base is left exposed so a cap  119  can be assembled after the. LED is inserted in the base. The base  120  has a nut  124  threaded down to the carrier  110  or plates  111  to insure the base stays in the proper position and resists any base movement when the cap is unscrewed. The cap secures the LED to the base. 
     In panel mounted devices the hole  118  for the indicator light  112  can be large enough to allow the cap  119  to partially extend through the panel  111  (this is the case in FIG.  11 B), allowing enough finger access to unscrew it. Thus, by adjustment of the carrier  110  or plate position, and the threaded base position, the LED assembly can be moved to account for a range of panel thicknes&#39;and also allow for easy front panel or behind panel LED positioning and replacement. To illustrate examples of LED assemblies having alternative carrier and/or base positioning, FIGS. 11C and 11D are provided. For purposes of description, the FIGS. 11C and 11D embodiments are taken to be three LED assembly embodiments like that of FIGS. 11A and 11B. However, it should be noted that the invention is not limited to the three LED type embodiments, and embodiments such as those including 1 or 4 LEDs may be constructed in accordance with the invention. 
     In the FIG. 11C configuration, carrier  110  and/or bases  120   a-c  have been positioned such that LEDs  112   a-c  are located behind the front panel  111 . In addition, in the FIG. 11C configuration rectangular press in lenses (e.g. lens  121 ) are installed in the panel  111  to operate in conjunction with the LEDs  112 . The FIG. 11D configuration is similar to the FIG. 11C configuration with the exception that round lenses (e.g. lens  123 ) are installed in the panel  111  to operate in conjunction with the LEDs  112 . 
     Illumination with respect to grid and tile systems  130  will now be discussed with reference to FIGS. 12A and 12B; wherein FIG. 12A depicts three different types  132 ,  134  and  136  of switch assemblies installed within a single grid system  130 , and FIG. 12B shows a detailed section of a grid mounted assembly  138  with a protruding LED  140 . In the case of grid and tile systems  130 , the base and socket assembly instead of the carrier assembly is used. However, two different plates are used to position the LEDs depending on the total thickness of the particular grid system being used and whether the LED is to protrude through the tile or remain behind the tile and illuminate a lens (e.g. lens  126  or  128  of FIG.  12 A). If the LEDs are to protrude through the tile which allows the tips of the LEDs to be uncovered, a threaded bracket  131  is used to mount up to three T 1  or T 1  {fraction (2/4)} size LEDs. The bracket  131  is designed to properly position the LEDs to fit within one typically 24-25 mm grid space. It is designed to have the LEDs positioned at the factory specifically for the particular manufacturer&#39;s grid  130  and the indicator appearance specified by the customer. 
     After the switch assembly is mounted and secured to the grid  130  with grid plates  145 , a nut and lockwasher, the plate  146  is slid over the shaft and bushing and secured in position with another nut  142 . The insulated leads  144  (FIG. 12B) attached to each base have been terminated with male connector pins. The leads fit through holes provided in the back grid plate  146  (FIG. 12A) that secures the controller switch to the grid assembly. The lid  13  or cover of the switch assembly has a narrow channel  148  cut in its surface to accept the LED connector  150  and align it to the switch assembly. The connector  150  is further secured to the switch lid  13  with a small screw  152  that prevents any movement. The lead wires from the LEDs are inserted in the proper holes in the male connector side and the connector is then secured to the switch lid  13 . The wire harness with the mating female connector  154  can then be connected to the male, completing the wiring connections. Finally, the front tile is assembled, completing the system graphics. 
     LEDs and tiles are generally replaced only if graphics and panel functions are changed or LEDs burn out. In either case, it is a simple matter to remove the tile  130 , unscrew the LED cap  119  and replace the LED  112  without having to access the rear of the grid/tile  130 . Should a section of grid  130  be re-configured to the extent that both switch assembly and LED assembly are not required, again they are easily moved. The o tile is removed, the nut holding the LED plate is removed. The screw holding the connector to the lid is removed and the connector slides forward enough for the LED plate to clear the front of the operating shaft. The switch mounting nut is removed, allowing the switch to be pulled out from the rear of the grid. The LED plate or LED grid plate can then be removed through the rear of the grid assembly. All parts can then be reused in another section of the grid. 
     In an alternate embodiment herein discussed in connection with FIGS. 13A-13D a replaceable LED is carried directly in the end of the operating shaft. Earlier controller switches could only offer a permanent LED which was epoxied into place. When the LED burned out, the entire switch had to be replaced. They had to be returned to the factory and the repair was very expensive. 
     By providing a screw-in base with sockets that can fit within the controller switch operational shaft customers can now easily change illumination colors or replace damaged or burned out indicators. Referring to FIGS. 13A, two set screws (only one set screw,  156 , is shown) holding the knob to the shaft are loosened and the operating knob  158  is removed. The screw on cap  160  that holds the LED to the base is removed and the LED is replaced. The entire operation can be done in seconds from the front of the panel or grid and tile, a major advancement that allowing designers unmatched maximization of panel density. As an alternative, knobs can be supplied with the LED slightly recessed (as in FIG. 13B) so that a lens may be used to cover the tip of the LED, or with just the tip of the LED protruding (as in FIG.  13 C). 
     FIG. 13D details an exemplary embodiment of a shaft mounted replaceable LED in accordance with the invention. Part A of FIG. 13C shows a completed shaft/LED sub-assembly. As can be seen from part A, the sub-assembly includes an LED  162 , an LED base  164 , screw on cap  160 , socket pins  166   a  and  166   b , LED wire leads  168 , insulation  170   a  and  170   b  for the LED leads and shaft  8 . The LED base can be threaded as shown, or can be formed with a partially smooth outer surface to allow for a “press-fit” connection with shaft. As can be seen from Part B, the shaft includes an interior-threaded end  172  to accommodate base  164  and includes an opening  174  along its length to allow the LED leads to pass from the shaft&#39;s interior to its exterior where they can be more readily accessed. If a press-fit LED base is used, the shaft end  172  would be smooth to accommodate the smooth portion of the base. Part C shows front and side views of screw in base  164 , and part D shows front and side views of screw on cap  160 . As can be seen from part C, the screw in base includes two holes  164   a  and  164   b  to accommodate the socket pins and a notch  165  which serves as an LED polarity indicator. As can be seen from part D, the screw on cap includes a through hole  161  to accommodate LED  162 . Part E shows how the LED, socket pins, base, leads and insulation fit together. As can be seen from part E, the socket pins are inserted into the base and the LED is, in turn, inserted into the socket pins. Electrical coupling to the LED is achieved through the socket pins by connecting the LED leads to the pins, the leads and pins being joined, for example, by heat shrink insulation tubing  170   a  and  170   b.    
     When designers only need a single LED indicator, a completely enclosed switch assembly with a front panel replaceable indicator and totally enclosed wiring allows stacking and front panel savings of up to 70% over other products. When they need multiple indication capability, they can use the light in the knob plus the 3 light array on top of the enclosure. All of this indication can be done within a 0.950 inch square area. 
     FIGS. 14A and 14B show various types of illumination layouts which can be achieved with the present invention, as well as showing how switches incorporating such layouts can be incorporated into grid and tile systems. FIG. 14A shows a 4×2 grid of switch assemblies, wherein each assembly occupies a 0.950 inch square area of the grid (the knobs of the switches are not shown for clarity of presentation). Assemblies  172   a  and  172   b  each have three LEDs, and are of the type where the tips of the LEDs protrude from the grid panel (see e.g. FIG. 12A, assembly  132 ). Assemblies  174   a  and  174   b  each have one LED, and are of the type where the tip of the LED is positioned behind the panel and the panel includes a rectangular lens for operation with the LED (see e.g. FIG. 12A, assembly  134 ). Assemblies  176   a  and  176   b  each have one LED, and are of the type where the tip of the LED is positioned behind the panel and the panel includes a round lens for operation with the LED (see e.g. FIG. 12A, assembly  136 ). Assemblies  178   a  and  178   b  each have one LED, and are of the type where the tip of the LED protrudes from the grid panel and the LED is front panel replaceable (see e.g. FIG.  11 B). 
     FIG. 14B illustrates a 3×2 grid of switch assemblies wherein the switch knobs are shown. As can be seen from FIG. 14B, assembly  180  includes two protruding type LEDs mounted above an “arrow” knob. Assembly  182  includes a protruding LED mounted above a round knob. Assembly  184  includes a first LED mounted above a round knob and behind the front panel, and a second LED mounted in the center of the knob and behind the knob face, a rectangular lens being positioned in the panel for operation with the first LED and a round lens being positioned in the knob face for operation with the second LED (see e.g. FIG.  13 B). Assembly  186  includes an LED mounted above a round knob and behind the front panel with a round lens being positioned in the panel for operation with the LED. Assembly  188  includes a first LED mounted above a round knob and behind the front panel, and a second LED mounted in the center of the knob and protruding from the knob face (see e.g. FIG.  13 C), a rectangular lens being positioned in the panel for operation with the first LED. Assembly  190  includes a first LED mounted above a round knob and behind the front panel, and a second LED mounted in the center of the knob, a round lens being positioned in the panel for operation with the first LED and the second LED being positioned for easy front panel replacement (see e.g. FIG.  13 A). 
     FIG. 15 shows an additional switch assembly  192  suitable for use in a grid system according to the present invention. The assembly of FIG. 15 includes an LED mounted in the center of an arrow knob and protruding from the knob face. 
     FIG. 16 shows an exemplary grid plate  194  which can be used in a grid system such as that depicted in FIG.  14 B. The depicted grid plate includes a through hole  196  for a switch assembly shaft, and two through holes  198   a  and  198   b  to accommodate LEDs protruding from a front panel. The grid plate of FIG. 16 can be used, for example, with switch assembly  180  of FIG.  14 B. 
     FIG. 17 is a top view of switch assembly  180  as the assembly is mounted in a grid  200 . As shown in FIG. 17, and as mentioned above in relation to FIG. 16, grid plate  194  is suitable for mounting assembly  180  in the grid. The knob of assembly  180  is not shown in FIG.  17 . 
     Two of many possible methods of connecting the switch assemblies of the present invention to various control equipment are shown in part X of FIG.  4 . The design is flexible to allow for a male/female connector assembly  162 , single cable or double cable connections. In the case of the plug and receptacle connector assembly, the rear of the enclosure is designed to accept up to 15 pins of #22 GA. Wire. With reduced current requirements and/or smaller gauge wire, we can increase the number of pins (circuits ) to 24 for an integral connector within the 0.950″ wide × 0.640″ high foot print. The female portion of the connector is designed to “drop-in” to a nest in the rear of the housing. With the final assembly of the lid, the connector is fully trapped and cannot be pulled out. 
     When cables or individual wires are used, the bottom rear of the housing is designed to nest either one  164  or two grommets  166  that are sized to the diameter of the cable/cables being brought into the rear of the switch. A single  168  or double  170  clamping bar is then tightened using two screws  172  for the single and one screw  174  for the double. The screws thread into the base, compressing the grommet/grommets for secure wire retention. The switch lid is then assembled. The lid covers the clamping plate screws preventing any possibility of a “backing out” situation due to vibration inherent in many locations using these switches. The end of the cable not connected directly to the switch can then be terminated with another connector or at a terminal junction strip located somewhere else in the control console. 
     Another feature of our wire termination design is that we retain the ability to easily manufacture the enclosures out of various materials and process. As mentioned earlier, the enclosures can be machined out of metal or plastic. With simple inserts in the tooling for the rear cable/connector section, the parts can be either injection molded of metal or plastic, or fabricated using a zinc diecast method. Inserts can also be used for alterations in the push-pull or turn switch pockets to accommodate a variety of snap-switch modules available from different manufacturers. These features prevent being locked into a position of having to rely on a sole supplier for critical functional components used in these switch assemblies. 
     The designs of other manufacturers using cams to operate switch modules, generally have mechanisms that constantly force the operating button to “bottom out” at the maximum of the travel limit and manufacturers of snap-switch modules advise this will reduce the mechanical operating life of their products. Our invention insures that we get the maximum mechanical life these products were designed to provide. In addition, the nature of the basic enclosure design of other manufacturers allows them to easily twist or distort after being mounted in a panel or grid and tile system. This is generally caused by the forces exerted by cables or bundles of cables attached to groups of controls mounted in close proximity. The distortion due to these forces can inhibit operating shaft motion and, therefore, affect switch performance. The invention&#39;s controller switch case design is significantly more durable and capable of much harsher handling without loss in performance. 
     While the present invention has been particularly shown and described in conjunction with preferred embodiments thereof, it will be readily appreciated by those of ordinary skill in the art that various changes may be made without departing from the spirit and scope of the invention. Therefore, it is intended that the appended claims be interpreted as including the embodiments described herein as well as all equivalents thereto.