Patent Grant
7093694
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.
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.
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.
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.
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
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
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
A holding pawl, generally designated 90, best shown in
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
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
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
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
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
Rotation of the release handle 120 in the counter-clockwise direction as viewed in
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
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.
| Number | Name | Date | Kind |
|---|---|---|---|
| 3176539 | Mersereau | Apr 1965 | A |
| 3668944 | Natschke | Jun 1972 | A |
| 3822669 | Schrag | Jul 1974 | A |
| 3854417 | MacDonnell et al. | Dec 1974 | A |
| 4291793 | Klasing | Sep 1981 | A |
| 4368648 | Housman et al. | Jan 1983 | A |
| Number | Date | Country | |
|---|---|---|---|
| 20040183368 A1 | Sep 2004 | US |
