A power and free conveying system includes a track assembly having a power track and a free track spaced vertically from the power track, a power trolley supported on the power track for movement therealong and a free trolley supported on the free track for movement therealong. The free trolley includes a moveable holdback dog engageable and disengageable with the power trolley. The free trolley includes a retractable dog having a first position engageable with the power trolley and a second position disengageable with the power trolley and engageable with the holdback dog to completely disengage the free trolley from the power trolley upon engaging another one of the free trolley. The track assembly includes a C-shaped first side support member having an upper transverse end connected to the power track and a lower transverse end connected to the free track and a C-shaped second side support member opposite and spaced from the first side support member having an upper transverse end connected to the power track and a lower transverse end connected to the free track.
A cam bar assembly for transferring a trolley from driving engagement with a first chain to driving engagement with a second chain wherein the cam bar assembly includes a cam bar having a first longitudinal axis, a cam surface centered about the first longitudinal axis, a second longitudinal axis, and a cam face centered about the second longitudinal axis. The second longitudinal axis is offset from the first longitudinal axis. The present invention is also directed to a power and free conveyor having the cam bar assembly as well as a drive trolley disposed within a free track for movement in a driven direction and having a retractable surface movable between an engaging position and a retracted position. The power and free conveyor also includes a first drive chain, a second drive chain, and a transfer zone having an entrance and an exit. The first drive chain is positioned to drivably engage the drive trolley at the entrance and the second drive chain is positioned to drivably engage the drive trolley at the exit. The cam bar is positioned in the transfer zone to engage the drive trolley and move the retractable surface from its engaging position to its retracted position.
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).
