Power and free conveyor system with spaced apart actuation and engagement means
This is a continuation of application Ser. No. 593,650, filed July 7, 1975 now abandoned. 
    
    
     This invention relates to conveyor systems and particularly to power and free conveyor systems. 
     BACKGROUND OF THE INVENTION 
     In power and free conveyor systems, it has long been known that the carriers which are movable along a carrier or free track can be disconnected from driving engagement with the conveyor that is movable on the conveyor track by various means. Where the pusher dog is on the carriers and the pusher is on the conveyor, means may be provided on the carrier such that when the carrier engages an obstacle or a preceding carrier, the pusher dog on the carrier is moved out of the path of the pusher on the conveyor. Where the holdback and pusher dogs are pivoted about longitudinally extending axes on the conveyor and the pusher is on the carrier, the problem of accumulation has been approached by providing means long the track for deflecting the pusher and holdback dogs out of the path of the pusher on the carrier. It has also been heretofore suggested that a cam on the carrier be provided for moving the dogs on the conveyor so that they do not engage the pusher on the carrier. However, where the carrier comprises a plurality of trolleys and the pusher is on a trailing trolley, such an arrangement is not suitable. 
     Accordingly, among the objects of the invention are to provide a system wherein a carrier having a plurality of trolleys with the pusher on a trailing trolley be readily disconnectable from driving engagement with the conveyor upon engagement with an obstacle or a preceding carrier; which system is dependable and which will function effectively upon straight or curved track sections. 
     SUMMARY OF THE INVENTION 
     In accordance with the invention, the conveyor system comprises a conveyor track, a conveyor movable along said track, a free track, a plurality of carriers movable along the free track. The conveyor has longitudinally spaced pusher dogs mounted thereon. Each carrier comprises spaced trolleys and means interconnecting the trolleys. A trailing trolley has said pusher movably mounted thereon for movement into and out of the path of the pusher dogs. A bumper is mounted on said carrier at the front end thereof and is adapted to engage a preceding carrier or an obstacle, and means interconnect the bumper and the retractable pusher such that upon engagement of the bumper with the preceding carrier or obstacle the pusher is retracted out of the path of the pusher and holdback dogs. 
    
    
     DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a fragmentary part sectional side elevational view of a conveyor system embodying the invention. 
     FIG. 2 is a fragmentary sectional view on an enlarged scale taken along the line 2--2 in FIG. 1. 
     FIG. 3 is a fragmentary plan view showing the parts in a different operative position. 
     FIG. 4 is a fragmentary part sectional view on an enlarged scale of a portion of the system shown in FIG. 1. 
     FIG. 5 is a fragmentary view taken along the line 5--5 in FIG. 4. 
     FIG. 6 is a fragmentary sectional view taken along the line 6--6 in FIG. 4. 
     FIG. 7 is a view taken in the direction of the arrow 7 in FIG. 4. 
     FIG. 8 is a fragmentary sectional view taken along the line 8--8 in FIG. 4. 
     FIG. 9 is a fragmentary part sectional elevational view of a modified form of the invention. 
     FIG. 10 is a fragmentary sectional view taken along the line 10--10 in FIG. 9. 
     FIG. 11 is a fragmentary part sectional view of a portion of the system shown in FIG. 9 on an enlarged scale. 
     FIG. 12 is a fragmentary sectional view on an enlarged scale taken along the line 12--12 in FIG. 9. 
    
    
     DESCRIPTION 
     Referring to FIG. 1, the invention relates to a power and free conveyor system comprising a power or conveyor track 20 and a free or carrier track 21, herein shown as two tubular sections, one mounted within the other. A chain conveyor 22 having rollers thereon is movable along the carrier track 20. A plurality of carriers 23 are movable along the carrier track 21. 
     Each carrier 23 comprises a leading trolley 24 and a trailing trolley 25, each of which has spaced rollers 26, 27 that engage the carrier track 21. A pusher 28 is provided on the trailing trolley 25 and is adapted to be engaged by a pusher dog 29 on the conveyor 22 to move the carrier along the carrier track. A holdback dog 30 is provided in advance of each pusher dog 29 and serves the function of controlling the movement of the carrier since the pusher 28 is normally positioned between the holdback dog 30 and pusher dog 29. A plurality of holdback and pusher dogs 30, 29 are provided at longitudinally spaced points along the conveyor 22 and are pivoted about longitudinal axes extending in the path of movement of the conveyor, in accordance with conventional practice. If a carrier is stopped in any position, as the holdback dog 30 approaches, a cam surface thereon causes the holdback dog to be deflected by the pusher 28 bringing the pusher dog 29 into engagement with the pusher 28 so that the carrier is then advanced along the track by the conveyor. 
     Such a construction of power and free conveyor systems is old and well known, for example, in U.S. Pat. Nos. 3,060,886, issued Oct. 30, 1962, and 3,094,943, issued June 25, 1963. 
     In accordance with the invention, front and rear brackets 35, 36 are pivoted about vertical axes to the lower ends of the leading and trailing trolleys 24, 25, respectively. A tie bar 37 in the form of a tube is fixed to downwardly extending flanges 38, 39, respectively, of the brackets 35, 36. A bumper 40 in the form of a sphere is fixed to the front end of a rod 41 that extends within tube 37 and is yieldingly urged forwardly by a spring 42 interposed between the bumper 40 and flange 38 of bracket 35. 
     The rear end of rod 41 contacts a cam plate 43 that is pivoted about a horizontal axis by a pin 44 so that the cam plate extends downwardly and rearwardly in its normal position. A core wire 45 has one end fastened to the cam plate and the other end extends through a flexible housing 46 and is fastened to a bar 45a which engages a bracket 47 fixed to the pusher 28. The pusher 28 is mounted for vertical reciprocating movement in a tubular bracket 48 and is yieldingly urged upwardly by a spring 49 interposed between a fixed plate 49a held in a position by pin 49b and a pin 49c extending through the pusher 28. 
     A deflector 50 provides an arcuate surface 51 that has its center of radius extending vertically not only to protect the plate 43 but to serve as a fixed point of contact with the pumper 40. 
     In operation, the carriers are moved along by entrapment of the pusher 28 between pusher and holdback dogs 29, 30. When the carrier encounters an obstacle or a preceding carrier, the bumper 40 and rod 41 move rearwardly pivoting the cam plate 43 and drawing the pusher 28 out of engagement with the pusher dog 29, thereby stopping the carrier. When the obstacle is removed, the springs 41, 49 permit the return of the plunger to its initial position for engagement with the pusher dog 29. 
     Since the brackets 38, 39 are pivoted about vertical axes to the trolley bodies, the carrier can readily move about horizontal curves in the track as shown in FIG. 3. 
     In the form of the invention shown in FIGS. 9-12, the trolleys are substantially identical to the previous form of the invention except that each trolley includes two pairs of rollers 26&#39;, 27&#39;. In this form, the tie bar 55 comprises an inverted U-shaped cross section and the bumper 56 comprises an arcuate plate having a vertical center of curvature. Bumper 56 is mounted on a cross plate 57 which is fastened to a pair of rods 58 that are reciprocably mounted in openings in cross members 59, 60 and are yieldingly urged forwardly by springs 61 interposed between cross members 59 and washers 62 on the rods. 
     In this form of the invention, the cam plate 63 is pivoted at its lower end and normally extends upwardly and forwardly. Core wire 64 is connected to the plate and extends through a flexible housing 65 to the bracket 47 as in the previous form of the invention. 
     In addition, in this form of the invention, the trolley has longitudinally spaced wheels as contrasted to a single wheel as shown in the previous form. 
     The operation of the device is substantially the same as in the previous form of the invention. 
     A fixed vertically extending deflector 66 is provided at the rear end of the tie bar which projects beyond the rear trolley 25&#39;.