Abstract:
A mobile screening machine with a frame on tracks, having a hopper and a main conveyor mounted to a frame. The main conveyor conveys particulate matter from the hopper to a screening device positioned beneath the upper end of the main conveyor. The particulate is screened into three grades of coarseness, with the coarsest falling into a chute, the middle coarseness falling onto one lateral conveyor and the finest falling onto an underscreen conveyor, which preferably is driven downhill onto another lateral conveyor. The tracks permit the machine to be driven around the work site and onto and off of a trailer, and the entire machine can be remotely controlled. The downhill conveyor permits loading of the hopper from both sides of the frame.

Description:
BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     This invention relates generally to machines used for separating particulate of various sizes into separate piles of particulate of like size, and more particularly to an improved mobile machine that has a plurality of vibrating screens and conveyors for accomplishing particulate separation. 
     2. Description of the Related Art 
     It is well known to pour mixed particulate matter onto a vibrating screen to separate the particulate into matter with dimensions greater than the openings in the screen and matter with dimensions less than the openings in the screen. The matter with dimensions less than the openings in the screen falls by gravity through the screen openings and is collected beneath the screen. Alternatively, the particulate matter that falls through the screen can be directed onto a conventional conveyor that conveys the particulate away from the screening part of the machine and discharges it on a pile or in a container. 
     Many machines having such screens and conveyors are designed to be portable and have various combinations of vibrating screens and conveyors. Many are able to be towed on the road by a large vehicle, such as a tractor-trailer type tractor. As such, these machines ordinarily have hitches, legs and wheels conventional for towed vehicles. Alternatively, such machines can be towed onto a trailer and hauled by trailer. However, this can be difficult if the machine is the same size as the trailer. 
     The benefits of being roadworthy are significant, and often are a limiting factor in the design of these machines. For example, virtually every machine is restricted in width, length and height to maximum dimensions that enable the machine to be hauled on the highway. 
     One conventional machine is shown in U.S. Pat. No. 5,234,564 to Smith, in which a plurality of conveyors convey particulate from a hopper to a screening apparatus, and then into separate piles. Although this machine has advantages over the prior art, it also has disadvantages. 
     Therefore, the need exists for a screening machine that overcomes the disadvantages of the prior art. 
     BRIEF SUMMARY OF THE INVENTION 
     The invention is a portable machine for screening particulate. The preferred machine has an elongated frame, and the frame has a hopper end and an opposite, discharge end. A hopper is mounted to the hopper end of the frame and configured to receive particulate matter poured into the top of the hopper. A main conveyor is also mounted to the frame. The main conveyor has a receiving end beneath the hopper, and extends uphill toward a main conveyor rejecting end. 
     A screening device, preferably a vibrating screen driven by a rotary motor driving eccentric weights, has an upper screen and a lower screen. The screens have openings of different size, and the screening device is drivably mounted to the frame beneath the rejecting end of the main conveyor. The screening device extends from an upper end that is closer to the hopper end of the frame to a lower end that is closer to the discharge end of the frame. Thus, the screening device goes downhill away from the main conveyor. 
     An underscreen conveyor is mounted to the frame and is disposed beneath the screening device for catching particulate that passes through the screening device. The underscreen conveyor has an upper end near the upper end of the screening device and a lower end near the lower end of the screening device, and in a preferred embodiment the underscreen conveyor is substantially parallel to the screening device&#39;s screens. 
     A first lateral conveyor is mounted to the frame with an inboard end near one of the ends of the underscreen conveyor. The first lateral conveyor extends laterally outward from the frame for conveying particulate that falls onto the underscreen conveyor laterally of the frame. A second lateral conveyor is mounted to the frame with an inboard end near the lower end of the screening device. The second lateral conveyor extends laterally outwardly of the frame for conveying particulate that fails to pass through the lower screen of the screening device laterally of the frame. 
     A chute is connected to the frame at the lower end of the screening device and extends downhill from it for directing material that fails to pass through the upper screen off of the machine. A pair of endless tracks is mounted to the frame substantially intermediate the frame&#39;s length. The tracks are drivingly linked to a prime mover for driving the tracks, thereby moving the machine. 
     In a preferred embodiment the underscreen conveyor is only drivable in a downhill direction from the upper end to the lower end. Furthermore, the first lateral conveyor mounts near the lower end of the underscreen conveyor. This provides the advantage that the piles of material are both as close to the discharge end of the frame as possible, thereby permitting loading of the hopper from both sides without interference from the piles of particulate. 
    
    
     BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS 
     FIG. 1 is a view in perspective illustrating the preferred embodiment of the present invention in an operable position. 
     FIG. 2 is a side view illustrating the preferred embodiment of the present invention in an operable position. 
     FIG. 3 is a side view illustrating the preferred embodiment of the present invention in an operable position. 
     FIG. 4 is a view in perspective illustrating the preferred embodiment of the present invention in an operable position and showing the piles of particulate material. 
     FIG. 5 is a top view illustrating the preferred embodiment of the present invention. 
     FIG. 6 is an end view illustrating the preferred machine. 
     FIG. 7 is a top view illustrating the preferred machine. 
     FIG. 8 is a view in perspective illustrating the preferred embodiment of the present invention in a position suitable for transport. 
     FIG. 9 is a side view illustrating an alternative embodiment of the present invention. 
     FIG. 10 is a side view illustrating an alternative embodiment of the present invention. 
     FIG. 11 is a top view illustrating an alternative embodiment of the present invention. 
     FIG. 12 is a side view illustrating the preferred tracks apparatus used on the present invention. 
    
    
     In describing the preferred embodiment of the invention which is illustrated in the drawings, specific terminology will be resorted to for the sake of clarity. However, it is not intended that the invention be limited to the specific term so selected and it is to be understood that each specific term includes all technical equivalents which operate in a similar manner to accomplish a similar purpose. For example, the word connected or term similar thereto are often used. They are not limited to direct connection, but include connection through other elements where such connection is recognized as being equivalent by those skilled in the art. 
     DETAILED DESCRIPTION OF THE INVENTION 
     The machine  10  is shown in FIGS. 1 and 2 in an operable position set up and ready to receive particulate material. The particulate is loaded into the machine  10  at the top side of the hopper  12 . The hopper is mounted to the frame  14  of the machine  10 , and the frame is an elongated, rigid, preferably steel structure to which essentially all of the components of the invention are mounted or connected to through other structures. The frame has a hopper end  16  and a discharge end  18 , and particulate material moves, as it is processed, from the hopper end  16  toward the discharge end  18 . 
     A main conveyor  20  is mounted to the frame  14  with its receiving end  22  beneath the lower end of the hopper  12 . The main conveyor  20  extends longitudinally uphill toward the discharge end  18  of the frame  14  and terminates in a rejecting end  24  of the conveyor  20 . The main conveyor  20  receives particulate poured into the hopper  12  and conveys it uphill toward its rejecting end  24 . 
     The main conveyor  20  and other conveyors discussed below are conventional in their structure, inasmuch as they all have a pair of elongated, parallel arms held rigidly relative to one another, between which are rotatably mounted wheels, drums or other round-surfaced objects. A continuous loop belt extends between the parallel arms and substantially tightly around the wheels or drums. At least one of the wheels or drums is driven, such as by an electric or hydraulic motor, which drives the belt to revolve around the wheels lengthwise of the parallel arms. 
     With particular reference to FIGS. 2 and 3, a screening device  30 , which preferably has a pair of screens  32  and  34 , is mounted to the frame  14  beneath the rejecting end  24  of the main conveyor  20 . A vibratory prime mover  36 , such as a rotary hydraulic motor drivingly linked to eccentric weights, is drivingly linked to the screening device  30 . Upon actuation of the motor, the eccentric weights are rotatably driven, causing the screening device  30  to vibrate rapidly. When particulate matter falls onto the screens  32  and  34 , it is vibrated rapidly, thereby causing particulate to fall through the openings of the screens, and causing matter which fails to fall through the openings to be displaced in a downhill direction from the upper end  37  to the lower end  38  of the screening device  30 . 
     Particulate matter that does not fall through the upper screen  32  is displaced downhill onto a chute  40  (see FIG. 1) that is mounted with its upper end near the lower end  38  of the screening device, and substantially in, or close below, the plane of the upper screen  32 . Thus, the chute  40  guides the largest particulate off of the discharge end of the machine and away from the machine by gravity. The term “chute” includes an extension of the lower end of the upper screen  32  beyond the lower end of the lower screen  34 , and other structures by which material is guided to the ground from the upper screen. 
     At the lower end of the lower screen  34 , the lower end of a lateral conveyor  50  is mounted to the frame  14 . The lower end  52  of the lateral conveyor  50  is positioned just below the plane of the lower screen  34  in order to receive particulate that is displaced downwardly over the lower screen  34 . That particulate that falls onto the lateral conveyor  50  is conveyed uphill toward the upper end  54  of the lateral conveyer  50 , which is positioned laterally outwardly of the frame  14  from the lower end  52 , and the particulate is dropped. The lateral conveyor  50  forms an angle with the ground of about 24 degrees (see FIG.  6 ). 
     An underscreen conveyor  60  is mounted to the frame  14  beneath the screening device  30  in a substantially parallel relationship. An upper end  62  and a lower end  64  of the underscreen conveyor  60  are positioned directly beneath the upper and lower ends of the lower screen  34 , for receiving particulate matter that falls through the lower screen  34 . This particulate matter will be the finest particulate that was in the mixture poured originally in the hopper  12 , because the coarsest material fails to pass through the upper screen  32 , and the next finer material passes through the upper screen  32 , but not the lower screen  34 . These separated materials are conveyed away from the machine  10  by the chute  40  and the lateral conveyor  50 , respectively. 
     The material that falls onto the underscreen conveyor  60  is conveyed, in the preferred embodiment, downhill to the lower end  64  of the underscreen conveyor, which is above the lower end  72  of another lateral conveyor  70 . The underscreen conveyor  60  drives its conveyor belt in a direction that conveys all particulate that falls onto the underscreen conveyor  60  downhill toward the lower end  64 . 
     At the lower end of the underscreen conveyor  60 , the lower end of the lateral conveyor  70  is mounted to the frame  14 . The lower end  72  of the lateral conveyor  70  is positioned just below the lower end  64  of the underscreen conveyor  60  in order to receive particulate that is displaced downwardly by the underscreen conveyor  60 . That particulate that falls onto the lateral conveyor  70  is conveyed uphill toward the upper end  72  of the lateral conveyer  70 , and is positioned laterally outwardly of the frame  14  from the lower end  74 , and the particulate is dropped. The lateral conveyor  70  forms an angle with the ground of about 24 degrees (see FIG.  6 ). 
     The machine shown and described functions as follows and with reference to FIGS. 1 through 5. Particulate matter is poured into the hopper  12  by one or more loaders. The hopper directs the material onto the main conveyor  20 , which conveys the mixed particulate from the hopper  12  to the screening device  30 . The vibrating screens of the screening device separate the mixed particulate into three sizes. The coarsest size falls off of the upper screen  32  onto the chute  40  and onto the ground in a pile  75  near the machine  10 . The next coarsest matter falls through the upper screen  32 , but not through the lower screen  34 . This matter is driven downwardly onto the lateral conveyor  50 , which conveys the matter outwardly of the machine  10  into a pile  80 . The finest matter falls through the upper screen  32  and the lower screen  34  onto the underscreen conveyor  60 . The underscreen conveyor  60  conveys the particulate matter downhill to the lateral conveyor  70 , which conveys the matter outwardly of the machine  10  into a pile  90 . In this manner, the machine  10  separates mixed particulate matter into three separate piles. 
     It will be appreciated from FIGS. 4 and 5 that the piles  80  and  90  are on opposite sides of the machine  10 , and are both near the discharge end  19  of the frame  14 . This permits loaders that pour particulate matter into the hopper  12  to approach and pour from both sides of the hopper  12 , and from the rear side of the hopper  12 . The ability to load the hopper  12  from any or multiple of these sides is a result of the lateral conveyors  50  and  70  being as close to the discharge end  18  of the frame as possible, which means the edges of the piles  80  and  90  are spaced distances d 1  and d 2  (see FIG. 5) from the closest end of the hopper  12 . This is only possible when the underscreen conveyor is driven downhill, as in the preferred embodiment, because only when the underscreen conveyor is driven downhill can both lateral conveyors be at the same end of the screening device, and therefore as far from the hopper as possible. And the advantage of this structure is that two or more loaders can load the hopper  12 , greatly speeding up the screening time. 
     Another advantage to the downhill underscreen conveyor  60  is that the particulate matter is always moving in the same direction; it never has to double-back as it does on some prior art machines. The advantage of this is that long objects do not get caught or thrown out at the turn-around point. They simply tumble down the screening device and off of the machine at the pile  75  where they should end up. 
     When it is time to move the machine  10 , this is easily accomplished with the endless tracks apparatus  100 . The endless tracks apparatus  100  includes a pair of endless tracks  102  and  104 , similar to those found on bulldozers, military vehicles, etc. The operation of the tracks  102  and  104  is similar on the machine  10  as on the conventional machines, inasmuch as each of the tracks  102  and  104  extend around a driven sprocket or gear. The sprocket drives the tracks, and a plurality of idler wheels keep the tracks  102  and  104  in place and support the tracks  102  and  104  and therefore the machine  10 . The driven sprockets are drivingly linked to a prime mover, preferably a hydraulic motor or a internal combustion engine mounted to the frame  14 . The sprockets and idler wheels are rotatably mounted to the frame  14 , or a member that is rigidly mounted to the frame  14 . The endless tracks apparatus  100  is preferably mounted substantially intermediate the frame  14  to balance the machine  10 . In order to balance the machine  10  under certain circumstances, such as when it is not moving, the legs  92  and  94  that are rigidly mounted to the frame  14  near the hopper end  16  can be lowered, for example by prime movers such as hydraulic rams, to seat against the ground for greater stability if necessary. The preferred legs pivot downwardly from a horizontal position to a vertical position by the action of the hydraulic rams that cause the pivoting. 
     Upon actuation, the sprockets are driven either both forward, both backward or one forward and one backward (in order to rotate the machine  10 ), as controlled by a remote control apparatus. The remote control apparatus includes a transmitter  120  either held by the operator or mounted in the vehicle loading the hopper  12 , and a receiver  122  mounted on the machine  10  and connected to the controls for the machine  10 . Thus, the operator actuates the machine  10  into operation by transmitting control signals to the receiver  122  from the transmitter  120 , and the receiver  122  actuates the prime movers of the machine  10 . 
     Another advantage to the present invention is that the machine can be moved short distances, such as less than the diameter of a pile of particulate, between times the particulate is dropped onto piles. This permits the formation of elongated piles of particulate, rather than just circular piles, thereby more efficiently storing the particulate matter. 
     The lateral conveyors  50  and  70  can be folded inwardly for transportation (see FIG. 8) due to a hinge and support mechanism. The hinge and support mechanism for the conveyor  70 , shown in FIGS. 1,  2  and  3  (FIG. 3 shows the conveyor  70  removed) includes a first pair  126  and a second pair  128  of nested tubes. The tubes  126  and  128  are mounted to the frame  14  at their lower ends and to the conveyor&#39;s  70  parallel arms at joints that pivot. A hydraulic ram within the tubes  126  is actuated when it is time to fold the conveyor  70  in, causing the conveyor to hinge along an arcuate path to the position shown in FIG.  8 . The tubes  128  are free to move relative to one another longitudinally. This structure provides substantial support to the conveyors  50  and  70  during use, and allows them to fold up easily for transport. 
     Although the underscreen conveyor that is driven only downhill is preferred, it is possible to have an uphill driven underscreen conveyor on the present invention. This is shown in FIGS. 9-11. These Figures show the machine  210  having a frame  214 , a hopper  212 , a main conveyor  220 , a screening device  230 , a tracks apparatus  300  and a lateral conveyor  250  essentially identical to the embodiment shown in FIG.  1 . Two significant differences are the fact that the underscreen conveyor  260  is driven uphill and the lateral conveyor  270  is positioned at the uphill end of the underscreen conveyor  260  to receive the particulate that falls off of the upper end thereof. These differences result in a different machine  210 , but one that has advantages over the prior art, nonetheless. 
     While certain preferred embodiments of the present invention have been disclosed in detail, it is to be understood that various modifications may be adopted without departing from the spirit of the invention or scope of the following claims.