Abstract:
The present invention discloses a hand brake mechanism having a gravity based release hold mechanism with a visual indicator to prevent unwanted application of the railcar brakes and indicate such release hold condition. The release hold mechanism comprises a gravity based member pivotally linked to a release shaft preventing reverse rotation of the release shaft causing an unintended take-up of the chain. A detent retaining device disposed within the railcar hand brake housing further provides improve reliability of the operation. The gravity based member incorporates an indicator portion having a reflective coating to indicate such release hold position of the railcar hand brake.

Description:
FIELD OF THE INVENTION 
   The present invention relates, in general, to hand brake assemblies for use on railcars and, more particularly, this invention relates to a hand brake assembly equipped with a quick release mechanism. 
   BACKGROUND OF THE INVENTION 
   Railway car hand brake mechanisms are well known in the art. They usually include a relatively large, rotatable hand wheel disposed in a vertical plane and mounted on a shaft which, through a gear train, can rotate a chain drum to wind up a chain that is secured at its end remote from the chain drum to the brake rigging of the railway car. As the hand wheel is rotated in one direction, the brakes are applied and rotation of the hand wheel shaft in the opposite direction is prevented by a pawl which engages a detent wheel on the hand wheel shaft. 
   These hand brake mechanisms further include a clutch mechanism for facilitating gradual release of the brake. When a hand wheel is rotated clockwise (as viewed from the front of the unit), such rotation is transmitted directly through a drive shaft, a pinion, a gear, and a winding drum to take up slack of a chain connected to the brake rigging. When resistance is offered by the chain to further rotation of the hand wheel, such resistance, acting back through the drum, the gear, and pinion, causes a nut to be advanced on a threaded portion of the drive shaft to move against a ratchet member which is clamped between respective friction surfaces on the nut and on the drive shaft, thus causing the drive shaft, ratchet, and the nut to rotate as a unit. A pawl prevents rotation of the ratchet in the opposite direction. The hand wheel torque is increased until a state of static equilibrium is reached, or at the point at which the brakes are fully applied, whereupon rotation of the hand wheel is terminated, and the clamped ratchet, by means of the holding pawl, prevents the chain from unwinding. 
   The clutch mechanism also provides for quick release of the brakes by operating a release handle which effects disengagement of the normally engaged clutch and thereby allows free rotation of the pinion and gear to release the chain load while the nut and ratchet are held stationary by the holding pawl. The brakes may also be released by disengaging the pawl from the detent wheel but this causes rapid rotation of the hand wheel and the gears of the gear train. 
   To avoid rapid rotation of the hand wheel, hand brake mechanisms have been devised which are known as “quick release” mechanisms. U.S. Pat. No. 4,368,648 titled Hand Brake for Railroad Car teaches such a hand brake having a quick release mechanism. The quick release mechanism includes a releasable connecting means between the hand wheel shaft and the gear train. When the connecting means is released, the gears of the gear train rotate rapidly, without constraint by the pawl and detent wheel, but the hand wheel remains stationary. The teachings of U.S. Pat. No. 4,368,648 are hereby incorporated in present application by reference thereto. 
   It has been found that when a hand brake is quick released using the handle, the chain may not be fully expelled from the hand brake, thus maintaining residual tension due to lack of sufficient slack. This residual tension may set the hand brake, especially as the railcar travels around a curve. As a result the brakes may be applied unintentionally during railcar motion. As can be seen, it is desired to incorporate a positive means assuring that the brake is in a released and hold position and that the chain is fully released and provides sufficient slack to avoid unintentional setting of the hand brake. 
   Another long felt need in present hand brakes is related to their not having a positive visual indication of the hand brake being in the released hold position as viewed from the outside by railcar operating personnel and, particularly, providing such indication during darkness of nightfall. One of the challenges that must be overcome is the fact that railcars are painted in many different colors and may be contained within the same train consist. 
   SUMMARY OF THE INVENTION 
   A hand wheel in a handbrake mechanism for a railway car is used to rotate a gear wheel to apply the brakes. Such handbrake having a housing with a back wall and a front wall. There is a chain winding drum and a main gear wheel rotatably mounted on a drum shaft thereon disposed within such housing. The hand wheel having a shaft rotatably mounted on such housing having a bearing section at a first end and a hand wheel receiving section on a second end external to the housing. A ratchet wheel is mounted on the hand wheel shaft and rotatable with such hand wheel shaft intermediate the first and second ends thereof. A holding pawl in such housing cooperates with the ratchet wheel so as to prevent reverse rotation thereof. Additionally, a freely rotatable pinion on the hand wheel shaft engages the main gear wheel, such pinion having a radially extending flange cooperating therewith. A quick release mechanism cooperates with the holding pawl to allow reverse rotation of the ratchet wheel for releasing the chain. The hand brake incorporates a release hold mechanism having a release shaft attached to a quick release handle at one end. The release shaft also has a pivot portion engaging a fork-like portion of the movable cam to enable brake application. The release hold mechanism further includes a release bias means comprising a gravity based bias member substantially attached to one end of the bias shaft. The bias member is of a predetermined configuration and weight to rotate into an overcenter condition under its own weight due to gravity and restrict rotation of the release shaft after the release hold condition has been achieved. The bias shaft is journaled within a front and rear bushing and has a pivot portion for pivotal coupling to a link. A link pivotally connects the bias shaft with the release shaft. The bias member further incorporates an indicator portion having a reflective coating for visual identification of the hand brake in such release hold position, especially during darkness and nightfall. The release hold mechanism may also include at least one detent disposed within the hand brake housing and engaging the detent portion of the release shaft to improve reliability of hand brake operation. 
   OBJECTS OF THE INVENTION 
   It is therefore a primary object of the present invention to provide a hand brake having a means to substantially maintain the hand brake in the release hold position. 
   A further object of the present invention is to provide a hand brake assembly which substantially prevents unintentional application of the braking apparatus during the railcar motion around a curve. 
   Yet a further object of the present invention is to provide a hand brake which provides a more reliable operation. 
   It is another object of the present invention to provide a hand brake having a visual indication means when the hand brake is in the released hold position. 
   Still yet another object of the present invention is to provide a hand brake having a visual indication means independent from the quick release handle. 
   It is still another object of the present invention to provide a hand brake having a visual indication means employable with railcars painted in different colors. 
   An additional object of the present invention is to provide a hand brake having a visual indication means easily seen during darkness or nightfall. 
   These and various other objects and advantages to the present invention will become more readily apparent to those persons skilled in the relevant art from the following more detailed description, particularly, when such description is taken in conjunction with the attached drawing Figures and with the appended claims. 

   
     BRIEF DESCRIPTION OF THE DRAWINGS 
       FIG. 1  is a rear planar view of a hand brake assembly of a presently preferred embodiment of the invention with the rear plate partially cut-out to expose internal components. 
       FIG. 2  is a cross-sectional view of the hand brake assembly, taken along the lines  2 — 2  of  FIG. 1  also showing the chain component. 
       FIG. 3  is a cut-away partial rear perspective view of a hand brake assembly of the present invention, particularly showing the release hold mechanism when the hand brake is in an applied position. 
       FIG. 4  is a cut-away partial front perspective view of a hand brake assembly of the present invention, particularly showing the release hold mechanism when the hand brake is in such applied position. 
       FIG. 5  is a cut-away partial rear perspective view of a hand brake assembly of the present invention, particularly showing the release hold mechanism when the hand brake is in released and hold position. 
       FIG. 6  is a cut-away partial front perspective view of a hand brake assembly of the present invention, particularly showing the release hold mechanism when the hand brake is in released and hold position. 
       FIG. 7  is a partial perspective view of the release hold mechanism of the present invention. 
       FIG. 8  is a perspective view of the holding pawl of the present invention. 
   

   DETAILED DESCRIPTION OF THE INVENTION 
   The following background information is provided to assist the reader to understand the environment in which the invention will typically be used. The terms used herein are not intended to be limited to any particular narrow interpretation unless specifically stated otherwise in this document. 
   Prior to proceeding to the more detailed description of the various embodiments of the present invention, for the sake of clarity and understanding of such invention, it should be noted that identical components having identical functions have been identified with identical reference numerals throughout each of the figures illustrated herein. 
   A hand brake, generally designated  10 , for a railcar embodying the invention is shown in  FIGS. 1 and 2 . Such hand brake  10  includes a housing, generally designated  14 , having a front plate  16  and a back plate  18 . A driving mechanism, generally designated  20 , is disposed in the upper portion of housing  14 , such driving mechanism includes a hand wheel  22  secured to a drive shaft  24 . Such drive shaft  24  is journaled for rotation in bearings  26  and  28  secured in front plate  16  and back plate  18 , respectively. 
   Drive shaft  24  has secured thereon for rotation therewith, at the end adjacent bearing  28 , a pinion  30  which substantially engages with a gear  32  for rotating a chain drum  34  journaled for rotation in bearings  36  and  38  secured on front plate  16  and back plate  18 , respectively, in the lower portion of housing  14 . Chain drum  34  engages alternate links of a chain  37  for either taking-up or letting-out the chain. 
   Also disposed in the upper portion of housing  14  and associated with the driving mechanism  20 , is a clutch and quick release mechanism, generally designated  40 , which may best be seen in  FIGS. 2 ,  3  and  5 . The clutch and quick release mechanism  40  comprises an annular stationary cam member  42  restrained from both axial and rotational movement, and a movable cam member, generally designated  44 , rotatably disposed concentrically within such stationary cam  42 , the movable cam  44  being rotatable relative to the stationary cam member  42  by means of complementary fast pitch threads  43  formed thereon. 
   An internally splined annular clutch collar  48  is provided with an annular flange (not shown) which concentrically surrounds the drive shaft  24 , such collar  48  engaging with an externally splined nut, generally designated  52 , attached to a threaded portion (not shown) of drive shaft  24 . 
   The improvement to a hand brake  10  comprises a release hold mechanism, generally designated  68 , of the present invention having a release shaft, generally designated  70 , best seen in  FIGS. 3 ,  5 , and  7 . The release shaft  70  has a first shaft portion  72  preferably journaled in a first release shaft bushing  73  perpendicularly secured in housing front plate  16  above the driving mechanism  20 . Preferably, the release shaft  70  has a second shaft portion  80  journaled in a second release shaft bushing  82  perpendicularly secured in the rear plate  18  of the housing  14 . The second shaft portion  80  is disposed substantially concentric to the first shaft portion  72 . 
   A holding pawl, generally designated  90 , best shown in  FIG. 8 , has a substantially cylindrical cavity  94  rotatably coupled to the first release shaft bushing  73  and a ratchet engaging portion  96  engaging ratchet wheel  58 . The holding pawl  90  is free to ratchet thereon upon rotation of said ratchet wheel  58  in a counterclockwise direction, as viewed in  FIGS. 3 and 5 . A force receiving portion  86  of the release shaft  70  cooperates with the force transmitting portion  98  of said holding pawl  90  and is engaged by said force transmitting portion  98  during brake application cycle. 
   A release handle  120  is keyed at the external end of the first shaft portion  72  enabling rotation thereof in a clockwise direction, as viewed in  FIG. 1 , after the quick release without disengaging detent portion  74  of the release shaft  70 . 
   There is a release bias means, generally designated  128 , disposed within the hand brake  10  for biasing the release shaft  70  in the release and hold position and, more particularly, biasing the chain  37  from achieving tension. In the preferred embodiment the release bias means  128  comprises a bias member  130  of a predetermined configuration and of a predetermined weight, disposed adjacent the release handle  120 . It is preferred that the bias member  130  is biased to the right of the vertical center line under its own weight, as viewed in  FIG. 6 , to gravity bias the release shaft  70  in the release hold position. 
   It is further preferred that such bias member  130  further includes an indicator portion  132  having a coating  134  easily recognizable from a distance. It is additionally preferred that the color of such coating  134  will differ from the color of the railcar (not shown). In the most preferred embodiment, a reflective coating is applied to such indicator portion  132  for ease of identification during the darkness or nightfall, with the use of a flashlight like device. 
   The bias member  130  is substantially attached to the first end of the bias shaft  138  by any suitable means such as welding, pinning, use of fasteners, use of adhesives and other well known methods. The first end of the bias shaft  138  is preferably pivotably journaled within a third bushing  140  perpendicularly secured within the front plate  16  of the brake housing  14 . Preferably, the second end of the bias shaft  138  is pivotably journaled within a forth bushing  142  perpendicularly secured within the rear plate  18  of the brake housing  14 . It is further preferred that such third bushing  140  and such forth bushing  142  are of substantially identical size. 
   A pivot portion  146  having a pivot cavity  148  is disposed substantially perpendicular to the bias shaft  138  adjacent its second end. A connecting link  150  is pivotally coupled to the pivot portion  146  with a first pivot retaining means  156  at one end and pivotally coupled to a pivot portion  76  of the release shaft  70  at the distal end with the second pivot retaining means  78 . The second pivot retaining means  78  can be of any well known type, but preferably a threaded fastener type engaging a threaded cavity (not shown) of a predetermined diameter and a predetermined depth axially disposed within the pivot portion  76 . 
   The bias means  128  further includes at least one detent retaining means, generally designated  100 , attached to housing  14 . The at least one detent retaining means  100  has a detent  102  preferably engaging a detent portion  74  of the release shaft  70  with the brake in the released and hold condition. In the preferred embodiment, the at least one detent retaining means  100  includes a detent housing  104  substantially attached to housing  14 . A detent  102  is movably disposed within the housing  104 , protruding beyond the housing  104  and is biased by the bias spring (not shown) toward the detent position. It is further preferred that adjustment means  108  disposed adjacent bias spring are provided to very the protrusion of the detent  102  and, more particularly, set the predetermined force of the at least one detent retaining means  100  to allow for component wear and overall tolerances of the hand brake and to provide substantial engagement of the release shaft  70  while the brakes are in a released and hold condition while allowing release of such release shaft  70  to apply such brakes. 
   Alternatively such at least one detent means  100  can be of the variety of mechanical, pneumatic, hydraulic or electrical detent means mounted internally or externally said hand brake housing  14 . For example, such at least one detent means  100  can comprise a cylinder having a detent portion disposed at the end of the cylinder rod and receiving a fluid pressure signal to extend the rod in order to positively retain such release shaft  70  and receiving yet another fluid pressure signal to retract such rod at the beginning of the brake application cycle. Yet alternatively, such cylinder can be an electrical solenoid having similar interfaces. 
   Yet additionally, a leaf spring (not shown) of a predetermined strength can be attached at a predetermined position within the housing  14  engaging the detent portion  74  of the release shaft  70  to exert a predetermined force onto the release shaft  70 . 
   In operation, in order to apply the brakes, hand wheel  22  is rotated counterclockwise, as viewed in  FIG. 1 , such rotation being transmitted through drive shaft  24 , and pinion  30  to cause rotation of gear  32  in a counterclockwise rotation and thereby take-up slack of chain  37 . Until such time that tension starts to build up in chain  37 , shaft  24 , pinion  30 , nut  52 , and clutch collar  48  all rotate as a unit during rotation of hand wheel  22 . When tension begins to build up in the chain  37 , such tension is reflected in gear  32  and transmitted back through pinion  30  to clutch collar  48 . 
   Resistance to rotation by clutch collar  48 , which is splined to nut  52 , causes the nut  52  to advance on threads  25  and thereby clamp ratchet member  58  between friction surfaces (not shown). With ratchet  58  so clamped, continued rotation of wheel  22  causes drive shaft  24 , the ratchet member  58 , and nuts  52  to rotate as a single unit until the desired tension is attained on chain  37 , while holding pawl  90  ratchets on such ratchet member  58 . When the desired tension has been achieved on chain  37 , rotation or application of torque on wheel  22  is terminated, and the holding pawl  90  engaged on clamped ratchet member  58  prevents the chain from unwinding, since such pawl permits only counter-clockwise rotation of the ratchet member  58 . 
   Once applied, the brakes may be released either gradually or quickly. 
   For providing a gradual release of the brakes, hand wheel  22  is turned counterclockwise slightly to partially loosen nut  52  and thereby reduce the clamping force on ratchet member  58 , which is restrained from rotation by holding pawl  90 . The initial counterclockwise rotation of hand wheel  22  effects a corresponding rotation of the pinion  30  and gear  32 , thereby easing tension on chain  37 . Continued counterclockwise rotation of hand wheel  22  effects complete release of the load on chain  37  with gear  32  continuing to rotate until winding drum  34  has taken up all chain slack, that is, the amount of chain that had been taken up during the brake-applying phase of operation. When all chain slack has been taken up, further rotation of gear  32 , pinion  30  and nut  52  is terminated with the brakes fully released. Clockwise rotation of hand wheel  22  is limited by a drive shaft pin (not shown) which projects into a slot (not shown) formed in nut  52 . 
   A quick release of the brake application is caused by rotating release handle  120  (which is normally in an applied position) in a counter-clockwise direction, as viewed in  FIG. 1 . As shown in  FIGS. 4 and 6 , such release lever  120  is keyed onto a first end of the first shaft portion  72  by having a force transmitting portion  124  for engagement with a force receiving portion  88  disposed within the second end of the release shaft  72  for rotation of the release shaft  70  in a counter-clockwise direction, as viewed in  FIG. 1 . 
   Subsequent engagement of pivot portion  76  with a second fork portion  49  of movable cam  44 , causes clockwise rotation of such movable cam  44 . As was hereinbefore noted, the stationary cam  42  and movable cam  44  are provided with complementary fast-pitch threads  43 , so that as movable cam  44  rotates clockwise, it moves axially outwardly of the stationary cam  42 , in a right hand direction as viewed in  FIG. 2 , and carries with it clutch collar  48  by engagement of a flange (not shown) thereof. A groove (not shown) in movable cam  44  serves to constrain the collar flange (not shown) from relative axial and lateral movement with respect to movable cam  44  but does allow free clutch collar  48  rotation. Stationary cam  42  is restrained against both rotational and axial movement by engagement of lugs  62  formed on the periphery thereof and engaged in respective T-shaped elements  63  fixed to the inside surface of housing  14  (see  FIG. 3 ). Thus, axial movement of movable cam  44  causes axial disengagement of external splines (not shown) formed on clutch collar  48  from internal splines (not shown) formed on pinion  30 , thereby allowing such pinion  30  and gear  32  to rotate freely for releasing the load on chain  37 , while drive shaft  24 , nut  52 , collar  48 , and ratchet  58  are all held stationary by holding pawl  90 . 
   Rotation of the release handle  120  in the counter-clockwise direction as viewed in  FIGS. 1 ,  3 , and  5 , causes rotation of the release shaft  70  and, more particularly, causes the rotation of the bias member  130  in a counter-clockwise direction through the movement of the connecting link  150  causing rotation of the bias shaft  138  into an “overcenter” condition due to gravity of such bias member  130  assuring retention of the release shaft  70  in the release hold position. 
   The resulting retention of the release shaft  70  prevents such release shaft  70  rotation in a clockwise direction toward the applied position, further preventing rotation of the gear  32  and, more particularly, preventing partial release of the chain  37  so that motion around the curve will not cause unintended brake application due to the partially released chain  37  not having enough slack to withstand said railcar motion. 
   The resulting vertical orientation of indicator portion  132  provides a visual indication that the hand brake  10  is in the release hold position. 
   Engagement of the detent portion  74  of the release shaft  70  with the detent  102  of the detent means  100  further improves reliability of he hand brake operation. 
   When the brakes are fully released, the operator allows release handle  120  to return by gravity to the “applied” position from which the brakes may again be applied if desired. 
   For brake application, the clockwise rotation of the wheel  20  as viewed in  FIGS. 4 and 6 , rotates the holding pawl  90  in a counter-clockwise direction, causing counter-clockwise rotation of the release shaft  70  through the action of force transmitting portion  98  of the holding pawl  90  onto a force receiving portion  86  of the release shaft  70  and further causing disengagement of the detent portion  74  from the at least one detent means  100 . 
   Thus, the present invention has been described in such full, clear, concise and exact terms as to enable any person skilled in the art to which it pertains to make and use the same. It will be understood that variations, modifications, equivalents and substitutions for components of the specifically described embodiments of the invention may be made by those skilled in the art without departing from the spirit and scope of the invention as set forth in the appended claims.