Abstract:
A weighing system for material suspended from a rail or trolley. The system includes a transition track between the regular track and the weighing track to avoid oscillation of pressure on the weighing track which causes difficulty in rapidly arriving at a proper weight. The transition track is biassed away from the weighing track so as not to cause a false weight reading. It also includes a novel trolley moving mechanism for moving the trolley as it passes over the weighing mechanism.

Description:
BACKGROUND AND SUMMARY OF THE INVENTION 
     This invention pertains to a weighing mechanism designed to provide a more accurate weight in less time than present systems. This application is a continuation-in-part of a previous application by the same inventor, Ser. No. 08/334,957, filed Nov. 7, 1994 and now specifically abandoned. 
     Weighing systems for material suspended from a trolley rolling on a standing rail are fairly common. That material consists usually of meat carcasses, but may also include some other types of material. The purpose is to roll the trolley along the rail by the operation of a chain having a dog to engage the trolley to pull it over a short section of suspended track separated from the rest of the rail. The live track—that free section—is supported by weighing cells of various types. These cells may be strain gage type devices, thus a type of spring device, which provide for a measured displacement of measurable displacement to indicate the weight. 
     There are a number of problems with such a system. One of the chief of these problems is the oscillation of the free track caused by sudden loading of the spring-like devices which support that part of the track. The carrying trolley typically has only a single load-carrying wheel having linear contact with the track. Thus, any transition from one part of the rail to another is very quick, going from no load to full load almost instantaneously. Such a quick bounce creates an oscillation in the weighing cells making necessary an appreciable time for damping before the weight can be accurately measured. 
     There is another factor entering into the same problem. That factor is the motor force moving the trolley along the rail. In most instances that force is provided by a chain pulling the trolley along the rail through a dog on the chain engaging, either directly or indirectly through an arm, the top of the trolley. This engagement, particularly when the transition between the regular rail and the live rail is reached, is somewhat jerky resulting in a swinging load on the trolley. Such swinging also contributes to objectionable oscillation in the scale. The contact with the chain may also create a small component of vertical force creating a false reading of the scale. 
     The swinging problem is worsened by another system sometimes used to advance the trolley. This other system utilizes a downward slope on the live track to cause the trolley to roll. Trolleys in such a system must be freely rolling (well lubricated). Here again, the transition from regular to live rail is very quick so that the bouncing oscillation is enlarged. Swinging may also be encouraged by the slight bump between the two portions of the rails. 
     It should also be noted that flat or out-of-round wheels can also contribute to a bouncing oscillation. 
     It is the purpose of the present invention to avoid, so far as possible, any bouncing or swinging of the load as it passes over the live track. This is accomplished by use of a transitional rail to load the live rail more gradually and a unique separate transporting system to move the trolley on the live track. Thus, the bouncing is virtually eliminated and the swinging is reduced. To avoid an uncertain tare weight, the transitional rail is normally kept out of contact with the live rail. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a front elevational view of the system at the region of the live track, 
     FIG. 2 is a rear elevational view of the system, 
     FIG. 3 is an elevational view axially of the track showing the end of the system, 
     FIG. 4 is a plan view from line  4 — 4  of FIG. 2, 
     FIG. 5 is a detailed elevational view to an enlarged scale of the transition rail and its surrounding parts. 
     FIG. 6 is a top plan view of the parts shown in FIG. 5, 
     FIG. 7 is a sectional view from line  7 — 7  of FIG. 5, and 
     FIG. 8 is a view similar to FIG. 5 showing the parts just before the trolley is weighed. 
    
    
     DESCRIPTION 
     Briefly, this invention comprises a unique system of transmitting a trolley-suspended load from a fixed track to a live track for weighing the load. More specifically and referring to the drawings, the system includes a customary, basic, fixed track  10  on which trolleys  11  run. The trolleys normally include a single wheel  12  journalled to a hanging strap  13  and ending in a hook  14  from which the load is hung. The wheel  12  is grooved so that it will stay on the track  10 . 
     The trolley  11  is moved along the track  10  by a moving chain  15  linked to a series of arms  16 . The arms  16  carry wheels  17  adapted to roll on a second track  18  parallel to but disposed above the carrying track  10 . To maintain flexibility of use and free rolling for the trolleys  11 , each arm  16  carries an engagement dog  19  at its lower end in position to engage each single trolley  11 . The arm  16  by engagement between the dog  19  and the trolley  11  pushes the trolley along its track as required, but leaves the trolley to roll freely where the push is not required. This feature makes possible a feature of this invention which will be described later. 
     The weighing mechanism, for weighing each trolley and its load as the trolley moves along the track, ordinarily includes a scale mechanism  20  mounted on a beam  23 . The beam  23  is fixed to the track  10  so that a cut track will still have both ends supported. The weighing mechanism is arranged to support a short section  25  of the track  10  which is cut from the track. The support is from supports in the weighing mechanism which are carried by springs or strain gage devices of various kinds well known in the art. 
     Normally, the section  25  is simply cut from the track and catches the trolley wheel  12  from the fixed track  10  as the trolley rolls past. The section  25  thus actuates the weighing mechanism. However, the actuation is sudden and causes oscillating fluctuation of readings of weight. The present invention provides a vast improvement by alleviating that problem. Instead of a simple cut in the track  10 , a transitional piece  30  (FIGS. 1 and 2) is fastened to the fixed track near the entry side of the split track piece  25  at a pivot line. The pivot  31  is formed simply by use of a spherical surface on top of a block  37  fixed to the track  10 . The transition rail  30  rests on the spherical surface of the pivot line  31  and thus is free to rock on that surface. Opposite the pivot line  31  on the transitional rail  30 , a projection  32  is arranged to engage an opposite projection  33  on the weighing track section  25 . Thus, any vertical pressure on the transitional rail  30  will be shared between the pivot line  31  and the projection  32  and  33 . A bolt  34  extending through an enlarged hole  35  may be used to keep the transitional piece from tipping laterally. However, the piece must be free to tilt about the pivot line  31 . 
     It may be noted that the pivot line  31  is always spaced longitudinally under the entry side of the track  10 , and below that track so that the pivot line  31  is always beneath the solid part of the track  10  and not the downward side of the space between the track  10  and the transition piece  30 . This is done with the purpose of avoiding an upward tilt of the transition piece  30  as the trolley first rolls onto it from the fixed track  10 . Because there will always be a downward moment of the weight of the trolley onto the transition piece  30  there will not be a reversal of rotation of that transition piece tending to cause a “hammering” effect as the transition piece moves from upward to downward. Such a “hammering” effect causes undesirable fluctuations on any scale reading as can readily be seen. 
     It will now be apparent that as the wheel  12  of a trolley transitions from the track  10  onto the transitional track  30 , the weight on that wheel will shift from being largely supported at the pivot line  31  of the transitional track to being almost totally supported by the projections  32  and  33 . This is true because of the leverage caused by pivoting one end of the transitional track  30 . Because of this relatively gradual shift of weight rather than the nearly instantaneous change, the oscillation is greatly reduced, and becomes nearly non-existent, with the result of much easier and quicker weighing which is also much more accurate. 
     Although it is not essential to the operation of the weighing, a modification shown in FIGS. 5-8 is desirable for the sake of accuracy. Because the pivot line  31  is located either directly below or to the permanent track side of the division between the permanent track  10  and the transitional piece  30 , there is a small component of the weight of that transitional piece which will normally press onto the projection  33  of the weighing section  25 . To avoid what amounts to added tare weight on the scale, and because that weight might be somewhat variable, a way has been devised to keep that weight off the projection  33  of the weighing section  25 . 
     To accomplish the relief, the plate  36  which also supports the pivot piece  37  includes a small shelf  38 . The transition piece  30  also carries a corresponding shelf  39 . A compression spring  50  which may be relatively soft extends between these shelves. The spring must be strong enough to raise the transition piece  30  from the projection  33  on the weighing section  25  but should not be much stronger than that. For example, it should not be strong enough to interfere more than minimally with the pressing down of the press  30  as it is loaded by the wheel  12  of the trolley. 
     In this way, any adjustment of the tare weight because of the weight of the transition piece  30  is avoided. Also, the weight on the scale will not be interfered with as the wheel  12  runs onto the weight section. Any effect on the effectiveness of the transition piece in the gradual transition of weight onto the weighing section  25  of the track will be reduced to a minimum because of the proportions of the spring  50 . 
     Additional advantages in accuracy may be gained from an auxiliary transport system adapted to move the trolleys  11  over the weighing section  25  of track. The transit means includes a motor  40  which runs continuously. An electrically operated clutch  41  controls the engagement between the motor  40  and an operating shaft  42 . The engagement of the normally disengaged clutch may be controlled by any well known means for triggering an electrical device. That trigger might be a contact device arranged to be contacted by a strap  13  or an arm  16 , or it could be pressure switch triggered by the weight of the wheel  12 . The preferred device may be an electric eye switch actuated by the straps  13  breaking a beam in passing. The switch when actuated operates to engage the clutch to drive the shaft  42 . 
     A sprocket  43  on the shaft  42  drives an auxiliary chain  44  (FIG. 3) which in turn drives a finger chain  45  in a horizontal plane. This chain follows an elongated path between a driven sprocket at one end and an idler sprocket at the other end of the path, leaving a relatively straight run parallel to and relatively close to the underside of the weighing section  25  of the track  10 . In the preferred embodiment, the chain carries two fingers  46  equally spaced on the finger chain  45 . These fingers are adapted to engage the strap  13  of the trolley to move it along the weighing section  25  of the track  10 , thus providing an auxiliary drive mechanism at this stage of the movement of the trolley. It will be noted that at any instant, the auxiliary drive will be engaged with only a single trolley. 
     In operation, as the trolley  11  approaches the scale mechanism along the track  10 , it first triggers the electric engagement of the clutch drive  41  to cause the motor  40  to drive the finger chains  45 . The proportions of the gears and sprockets is such that the lineal speed of the finger chain  45  is slightly greater than that of the main chain  15  so that upon engagement of a finger  46  with the strap  13 , the trolley is advanced ahead of and out of contact with the dog  19  that had been providing propulsion. Because the finger  46  is supported by the chain  45  and indirectly, therefore, by the rail  25  and is far closer to the wheel  12  than is the main chain  15 , there is no chance that there will be any resultant vertical component of force on the trolley  11 , transmitted to the sides. Therefore, there is less opportunity for the introduction of error into the individual weight on the scales. Also the auxiliary device will be more steady because only a single trolley is propelled instead of the multiplicity of trolleys being moved by the main chain. This added steadiness helps also to avoid the swinging and related oscillating movement existing in prior scale systems. 
     As the trolley  11  passes over the weighing section  25 , it is released by the finger  46  to coast a short way down the track  10  and then is again picked up by the dog  19  to be moved to the unloading area. 
     Thus, this invention provides a comparatively highly accurate and relatively fast system of weighing the moving trolleys and their load.