gears pulleys engaging members and the like such components and their respective functions are described in detail in u s pat no 6 490 979 in some embodiments the conveyor 10 is provided with a gate assembly 24 at entry and exit points of both the first track 14 and the second track 18 the gate assembly 24 illustrated in fig2 is entry gate and includes a door 28 that is movable between an open position allowing access to the track and a closed position inhibiting access to the track in the illustrated embodiment the gate assembly 24 includes two doors 28 the operation of one of the doors 28 will be described herein the door 28 is mounted for pivotal movement relative to the frame 32 the pivotal movement of the door 28 is only given as a single example the door 28 can include virtually any type of configuration that provides an open position and a closed position single or multiple doors 28 may be used with the invention and in some embodiments the gate assembly 24 includes a completely different configuration for selectively preventing entry of shopping carts other objects or beings to the tracks 14 18 of the conveyor 10 in the illustrated embodiment the door 28 is provided with a lock 36 the lock 36 allows the door 28 to be configurable in either a locked state or an unlocked state the lock 36 may consist of virtually.