Power and free conveyor system

A power and free conveyor system comprising a power track, a power conveyor movable along the track, the conveyor having a plurality of depending pusher dogs thereon, a free track extending along the power track, and a plurality of carriers movable along the free track. Each carrier has at least one trolley with a pusher normally in the path of the depending pusher and holdback dogs. Each pusher and holdback dog is deflectable laterally into and out of the path of the pushers on the trolleys. A combined cam and stop member is provided with means for moving the cam and stop into the path of the pusher on the carrier. The cam and stop member includes a cam portion operable to depress the pusher dog and a cam portion operable to deflect the depending pusher and holdback dogs out of the normal path of the pusher. Stops are provided in advance of and to the rear of the carrier and are operable to maintain the carrier in stopped position.

This invention relates to power and free conveyor systems. 
BACKGROUND OF THE INVENTION 
In one type of power and free conveyor system, a power track is provided 
with a conveyor having downwardly depending pusher and holdback dogs which 
are laterally deflectable. The carriers which move along the associated 
free track have at least one trolley with an upwardly extending pusher 
which may be rigid or retractable which becomes entrapped by the depending 
pusher and holdback dogs to move the carrier along the track. 
Conventionally, in order to stop the carriers, it has been necessary to 
move the carriers out of the path of the depending pushers or to stop the 
conveyor. 
Among the objects of the invention are to provide a combined cam and stop 
member which not only stops the carrier but also deflects the depending 
pusher and holdback dogs laterally out of the path wherein they would 
normally engage the pushers on the carriers. 
SUMMARY OF THE INVENTION 
In accordance with the invention, the power and free conveyor system 
comprises a combined cam and stop member and means for moving the cam and 
stop member into the path of the pusher and holdback dogs on the carrier. 
The cam and stop member includes a cam portion operable to deflect the 
depending pusher and holdback dogs out of the path of the pushers and a 
stop portion operable to stop the pusher and, in turn, the carrier.

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. 3,060,866 and 3,094,943. 
The rear trolley comprises an upper body portion 31 on which wheels 26, 27 
are mounted and a lower body portion 32 pivoted about a horizontal axis to 
the upper body portion by a pin 33. A tie bar 35, in the form of an 
inverted U-shaped channel, is pivoted on trolleys 24, 25 about vertical 
axes. A rectangular paddle-shaped front bumper 37 is pivoted on the front 
end of tie bar 35. A pusher rod assembly 38 is pivoted to the upper ends 
of arms movable with front bumper 37. 
The pusher rod assembly 38 is connected to an actuator 39 pivoted to lower 
body portion 32 and connected to pusher 28 by linkage to lower pusher 28 
when bumper 37 encounters a preceding carrier or an obstacle. This 
construction is more completely shown in United States application Ser. 
No. 696,576, filed June 16, 1976, now U.S. Pat. No. 4,073,238, having a 
common assignee with the present application. 
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 37 pivots upwardly moving 
pusher rod assembly 38 rearwardly to pivot actuator 39, drawing the pusher 
28 out of engagement with the pusher dog 29, thereby stopping the carrier. 
In order to stop the carrier at a desired position along the track even 
though it has not encountered an obstacle or a preceding carrier, a 
combined cam and stop assembly 40 is provided and includes a bracket 41 
mounted on the top of the free track 21. A cam lever 42 is pivoted to the 
bracket 41. The cam lever 42 includes a pair of arms 43 mounted on a shaft 
44 that is rotatable between portions 45 of the bracket 41. The lever 42 
further includes a portion 46 extending generally downwardly from the arms 
43 and a portion 47 at a right angle to the portion 46. 
The cam lever 42 is movable from the broken line position shown in FIG. 6 
to the solid line position and back through an opening 48 in the free 
track wall by a mechanism which includes a link 49 fixed to shaft 44 and a 
fluid motor 50 which has a shaft 51 pivoted to the link and a cylinder 52 
pivoted to the bracket 41. 
As shown in FIG. 3, the portion 47 of the cam lever 42 supports a cam and 
stop member 53. The cam and stop member 53 comprises an elongated body 
which in plan view (FIG. 8) has a rounded leading end 54 and a tapered 
side 55. The cam and stop member 53 is positioned so that when it is in 
the path of the conveyor dogs 29 and 30, the side 55 deflects the holdback 
and pusher dogs 30, 29 out of the path of a pusher 28 on the oncoming 
carrier. The cam and stop member 53 also includes an inclined undersurface 
56 (FIG. 7) which tapers downwardly from the leading end 54 and functions 
to depress the pusher 28 of an oncoming carrier before the side 55 engages 
the pusher dog 29. Prior to this, the holdback dog 30 is cammed by the 
side 55. In this manner, any tendency of pusher 28 to lock the pusher dog 
29 and prevent it from being laterally deflected is eliminated. The 
underside of cam and stop member 53 includes a flat surface 57 extending 
rearwardly from inclined surface 56 and terminating at a rearwardly facing 
notch 58. As the carrier is carried forward and the side 55 engages the 
dogs 30, 29, the pusher 28 rides along the inclined surface 56 and flat 
surface 57 until it reaches notch 58 at which time it moves upwardly under 
the yielding force that normally urges it upwardly. The trailing trolley 
25 comes into contact with stop 100 stopping the forward motion of the 
carrier. 
When it is desired to stop the carrier, the motor 50 is activated to move 
the cam and stop member 53 so that cam and stop member 53 depresses pusher 
28 and deflects the dogs 29, 30 outwardly to interrupt movement of the 
carrier. Successive dogs 29, 30 are cammed outwardly by side 55 of cam 53. 
When it is desired to release the carrier, the motor 50 is actuated to 
retract the cam and stop member 53 and stop 100 to the broken line 
position permitting the next pusher dog 29 on the conveyor 22 to engage 
the carrier and move it along the track, 
Anti-backup members 60 and stop 100 are provided in advance of and beyond 
the combined cam and stop assembly and each is movable into positions to 
engage the trolley body 31 and prevent forward or rearward movement of the 
trolley. Each anti-backup member 60 and stop 100 is pivoted as at 62 to 
the free track and includes a downwardly extending arm 63 and a 
transversely extending arm 64. Each member 60, 100 is counterweighted so 
that arm 64 is urged by gravity so that it is always in the path of the 
trolley bodies. An inclined surface 65 on anti-backup member 60 and stop 
100 engages each successive trolley body to cam member 60 outwardly and 
permit the trolley bodies to normally move forwardly. Anti-backup member 
60 is deflected out of the path and then back into the path of the trolley 
bodies so that it is in position to perform its function when the carrier 
is stopped. Anti-backup member 60 is used to insure that the trolley body 
31 cannot rebound out of the cam and stop member 53 when the dog 28 is on 
the flat portion 57 of cam and stop member 53. Stop 100 operates with the 
cam and stop member 53 as shown on FIG. 6. When the cam and stop member 53 
is moved out of the path of the dogs, a portion of cam and stop member 53 
engages stop 100 to also move stop 100 out of the path of the dogs.