A two-track conveyor system includes an I-beam-shaped power track and a channel-shaped free track, where the power track supports a heavy-duty chain drive having a pusher dog with a pivotal connector. By providing the pusher dog with the pivotal connector the pusher dog can be used with a load-bearing trolley, that rides within the free track, that has a fixed power dog at the front end of the leading trolley and that does not require a hold back dog.
CROSS-REFERENCE TO RELATED APPLICATION
This application claims priority from U.S. Provisional Application Ser. No. 60/160,039, filed Oct. 18, 1999, which application is incorporated herein by reference in its entirety.
The invention relates to a power & free conveyor which comprises a free rail (3) and a power chain (1) that follows said free rail (3), to a large extent, in a parallel manner. A transport carriage (4) provided with a front runner (5) and a rear runner (6) are arranged on the free rail (3). The front runner (5) and the rear runner (6) each comprise a carrier (11, 14) that can pivot between two positions. In an area of the movement path of the transport carriage (4), the course of the power chain (1) deviates from that of the free rail (3) so that the transport carriages (4) can no longer be moved via the front runner carrier (1) thereof. Instead, the transport carriage is pushed by the interaction between a chain carrier (2) and the rear runner carrier (14) that is swung out into a carrying position. The rear runner carrier (14) comprises two stabile positions which can be changed by overcoming a resistance. To this end switch-over devices (24, 22) are provided which are arranged at the necessary locations along the movement path of the transport carriages (4).
