Abstract:
A railroad brake sensing apparatus particularly suitable for handbrake sensing has a sheave wheel/bellcrank bracket which is slotted to allow the wheel/crank axle to move from a first position when the chain is under tension and the brake is applied; to a second position when the chain is slack and the brake is off. A sensor is placed to detect when the wheel/crank is in the second position. The brake sensing apparatus is easily adapted to be used with other forms of brake actuating force and placed with other moving members of the brake rigging.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates to sensors capable of distinguishing when the manual hand brake setting apparatus of a railroad car is in the “Off” or “Brake Release” position. 
     2. Description of the Related Art 
     The rail industry has a very high maintenance cost related to wheel damage. The majority of this damage is the result of handbrakes being left on prior to a train departing the rail yard. If a car has the handbrake left on when the train begins to move, the wheels of that car will not turn, resulting in a worn, flat spot on the wheel. The handbrake being left on can also result in a derailment if not detected prior to the train leaving the rail yard. For these reasons it is desirable to provide the manual handbrake setting apparatus of a railcar with a sensor having an indication means whereby the railroad operator is able to determine that the manual setting of the brakes is placed in the “off” position before moving the train. 
     It is well known in the art of railroad car building to equip railcars with a manual brake system which is actuated by a manually turned wheel generally located on the front, or back, of said car. In one common application the wheel is attached through gearing to an axle which is attached to a chain running down the front of the car and generally to the undercarriage of said car where the chain is linked to the brake rigging. Turning of the wheel gathers the chain, putting it in tension, whereby the brakes, i.e. brake pads, are pulled into the wheel assembly. Release of the chain to sufficient slack where it will not tighten and engage the brakes under any conditions, such as the rail car tilting when going around curves, etc., is accomplished by turning the wheel in the opposite direction, or pulling a release arm, to unwind chain from the main axle. 
     Because the railroad car will often be subject to extremes of environment including temperature, dirt, water, and the like it is further very desirable that the sensor have a rugged construction unlikely to be susceptible to environmental degradation. It is further desirable that the sensor be located on the railroad car where it is least likely to be susceptible to such environmental degradation or contamination. 
     SUMMARY OF THE INVENTION 
     A railroad brake sensor according to the present invention operates on a railroad brake system at points where the brake actuating force is translated or transfered creating an opportunity to sense the brake position through the orientation or position of the force translating/transfer members of the brake rigging or apparatus. For example a handbrake system which uses a sheave wheel or bellcrank to guide a handbrake chain from its vertical position, at the front of the car, to a horizontal position running under the car where it connects with the brake rigging, provides many such opportunities. 
     For example, the sheave wheel can be mounted in a bracket by its axle. The mounting of the bracket is slotted to allow the wheel and its axle to move from a first or upper position when the chain is under tension and the brake is applied; to a second, lower position when the chain is slack and the brake is off. A sensor is placed to detect when the axle is in the second position. The sensor may be placed near the lower position to detect the axle or may be placed on the axle in order to detect a target feature located near the second position. The type of sensor is preferably a magnetically sensitive sensor such as a Hall effect or magnetoresistive sensor. It could also be a suitably selected proximity sensor, mechanical switch, force sensor or other suitable sensing means. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     The present invention will be more fully and completely understood from a reading of the Description of the Preferred Embodiment in conjunction with the drawings, in which: 
     FIG. 1 is a schematic of a railroad car with the handbrake sense of the present invention installed thereon. 
     FIG. 2 is a top view of an embodiment of the present invention utilizing a sheave wheel. 
     FIG. 3 is a side view of the sheave wheel and sensor mechanism along lines III—III of FIG.  2 . 
     FIG. 4 is an alternative embodiment of the present invention shown generally along lines IV—IV of FIG.  2 . 
     FIG. 5 is a detailed view of the present invention in situ. 
     FIG. 6 shows a variant of FIG. 5 wherein the axle is not directly sensed. 
     FIG. 7 is an alternative embodiment of the present invention utilizing a bellcrank instead of a sheave wheel and showing the bell crank with chain tension applied. 
     FIG. 8 shows the bell crank in the slack chain position. 
     FIG. 9 shows an alternative guide plate taking the place of the bracket slot. 
    
    
     DESCRIPTION OF THE PREFERRED EMBODIMENT 
     Throughout the Description of the Preferred Embodiment, like components will be identified by like reference numerals. 
     As seen in FIG. 1, a railcar  11  (front end) has a body  13  mounted on a carriage assembly, or trucks (not shown) which carry the wheels  15  and the brake linkage  17 . A manual system for engaging the brake linkage  17 , simplified to its main components, includes a chain  19  which is attached to a main shaft  21  which is rotatably affixed to the car body  13  by a bearing  23  near the car body  13 . At the outboard end of the main shaft  21  is located a hand wheel  27  for manual rotation of the main shaft  21  in order to put the chain  19  in tension or slack. When hand wheel  27  is turned to gather chain  19  about the main shaft  21 , chain  19  is put in tension thereby engaging the brake linkage  17  to set the brake pads  28  against the wheels  15 . Normally a cover  29  is provided for the journaled end of the main shaft  21  and the gathered chain  19  to provide some environmental protection therefor. 
     According to the present invention, as shown highly schematically in FIG. 1, a means for translating the orientation or motion of chain  19  from vertical to horizontal such as a sheave wheel  51 , bellcrank, or the like, is attached to the car  13  by a bracket  55 . A sensing element  57  is located near the axle  53  of the sheave wheel, which acts as a target for the sensing element  57 . When the target is placed within the sensitivity range of the sensing element  57  the position of the brake chain  19  is therefore determined. Normally the most critical piece of information for the railroad operator is that the brakes are off when the train is placed under motive force. Therefore it is this condition which is most preferably sensed. The sensor  57  is then connected to suitable output electronics and operator interface indication means schematically illustrated by LED  37  although many forms of operator interface will be apparent to the ordinarily skilled artisan in the sensing arts. 
     Some common parts of the brake mechanism and railroad car assembly have been left out for purposes of clarity of explanation but will be recognized by the ordinary artisan of railroad construction and are not deemed necessary to a further exposition of the present invention. 
     Referencing FIG. 2, a top view of a sheave wheel and sensor assembly according to the present invention, a sheave wheel  51  with an axle  53  is contained within a mounting bracket  55 . Sheave wheel  51  is one embodiment of a means for directing a brake actuation force from a first orientation to a second orientation. A magnetically sensitive sensor  57  is placed on the outside of the bracket near axle  53 , as further explained below. A magnetically sensitive sensor such as a Hall effect element or magneto-resistive sensor is preferred due to its ruggedness and resistance to environmental degradation. However, it will be apparent to the ordinarily skilled artisan upon further exposition of the invention that any of a variety of suitably rugged sensors may be utilized including proximity sensors, forces sensors, or mechanically actuated switches for example. It will further be understood that the sensing element  57  may be placed either on the inside or the outside of the bracket  55  in order to accomplish its intended purpose. 
     Also as seen in FIG. 2, a sensing element  59  may likewise be located upon the axle to travel therewith in order to detect a feature  61  placed within the range of the travel of axle  53 . Should the sensing element  59  be magnetically sensitive, the feature may be either a magnet or a ferromagnetic structure. In the case of a non magnetically sensitive sensing element, the feature may merely be a mechanical stop affixed to the bracket  55 . 
     Referencing FIG. 3, the bracket  55  is shown as having a slot  63  for containing the axle  53  of the sheave wheel  51  (in phantom). A slot  63  is cut at an approximately 45° angle at such a length as to allow the axle  53  to move therein from an at rest position, or brake-off position  65  when the handbrake chain is not applied, to an upward or brake-on position  67  when tension is applied to the handbrake chain (not shown) to set the brakes thereby lifting sheave wheel  51  within the slot  63  and moving the axle  53 , as shown in phantom at brake-on position  67 , to a point (brake-off position  65 ) where the axle  53  can not be sensed by the sensing element  57 . Thus, slot  63  is one embodiment of a means for allowing the above described means for directing to travel from a first position when the brake is on, to a second position when the brake is off. In addition, sensing element  57  is one embodiment of a means for detecting when the means for directing is in one of the first or second positions. The chain force when chain  19  is under tension to apply the handbrakes is indicated by force lines  68  and  69 . Chain force  68  is the tension in chain  19  between sheave wheel  51  and the brake rigging, e.g. brake linkage  17 . Similarly, Chain force  69  is the tension in chain  19  between sheave wheel  51  and the handbrake, e.g. hand wheel  27  and main shaft  21 . When axle  53  is in the brake off position  65 , sheave wheel  51  is in position  62 , typically with no load on chain  19 . On the other hand, when axle  53  is in the brake-on position  67 , sheave wheel  51  is in position  64 , typically with force  68  and  69  in chain  19 . Care should be taken that the desired slack in chain  19  amount of travel  66  allows axle  53  to be sensed by sensing element  57  only when there is enough slack in the chain to prevent unintended application of the brakes such as during railroad car (railcar  11 ) travel around a curve where the car and its trucks are pivoting in opposite directions. The sensing element  57  is equipped with suitable electrical or other communication cabling  71  in order to communicate the data of the sensing element  57  to an operator interface or the like which utilizes the sensor data. 
     Although not shown, a spring or springs may be placed on the axle of the sheave wheel in order to bias it toward the slack or “brake off” position  65  in order to prevent environmental contamination from preventing the sheave wheel axle  53  from moving to the brake-off position  65  in order to be sensed. 
     As seen in FIG. 4, the sensing element  59  may be placed inside the bracket  55  and mounted to the sheave wheel axle  53 . When the sheave wheel (not shown) is at the brake-off position  65  resting at the lower end of slot  63 , the sensing element  59  is placed in close proximity to a target feature  61 . The axle  53  should have a fixed end which does not rotate for this embodiment. Where the sensing element  59  is a magnetically sensitive sensor, such as a Hall element or the like, the target  61  may be a simple steel plate or the like welded to the bracket  55 . Alternatively it may be a magnet mounted such as by expoxying to the side of the bracket  55 . 
     As seen in FIG. 5, the chain  19  is shown in its slack position (brake-off position  65 ) wherein it places no force on the sheave wheel  51  (in phantom) thereby allowing the axle  53  to rest at the lower portion of the slot  63  in proximity to the sensing element  59 . 
     As shown in FIG. 6, an arrangement similar to FIG. 5, the slot  63  contains the sheave wheel axle  53 . Helping to retain the axle  53 , and serving as an alternative target for sensing element  59 , is a collar ring  73  to illustrate the principle that the axle need not be directly sensed, but rather may have features applied thereto. 
     In FIG. 7, a bellcrank  75  is shown with chain  19  in tension, placing the bellcrank  75  in the brake-on position. Bell crank  75  is an alternate embodiment of a means for directing a brake actuation force from a first orientation to a second orientation. When the chain is placed in slack, as in FIG. 8, the axle  77  of the bellcrank  75  moves to a lower position, wherein it is placed in a position to be sensed by the sensing element  59  thereby indicating that the manual handbrakes are not applied to the railroad car. The bellcrank is a well known alternative to the sheave wheel of FIGS. 2-6. Since it is a moving apparatus in and of itself, it is conceivable that no special slot needs to be cut in the mounting bracket for its axle. Instead it could be directly sensed. Such an arrangement is an embodiment of a means for allowing the above described means for directing to travel from a first position when the brake is on, to a second position when the brake is off. In addition, sensing element  59  is an embodiment of a means for detecting when the means for directing is in one of the first or second positions. Such a bellcrank embodiment may call for a mechanical stop to be placed to limit the travel of the bellcrank towards the sensing element should construction and arrangement of the parts so require. 
     In FIG. 9, an alternative embodiment is shown wherein a guide plate  81  with a slot  83  therein is fitted over the axle hole  85  of the mounting bracket  55 , and a smaller axle  87  is substituted therefore, thereby allowing axle  87  to move to and away from the sensor. With this alternative, the existing brackets  55  need merely be fitted with guide plates  81 , rather than being replaced or remachined with slots (e.g. slot  63  shown on FIG.  3 ). Thus, slot  83  is another embodiment of a means for allowing the above described means for directing to travel from a first position when the brake is on, to a second position when the brake is off. It will be appreciated that either embodiment may be suitably utilized in various types of brake mechanisms and in various locations thereon, according to the teachings of the present invention. 
     While the present invention has been shown and described with reference to preferred embodiments, many alternatives will become apparent to the ordinarily skilled artisan upon disclosure of the present invention. Therefore the present invention is only to be limited by the claims appended hereto.