Well not sure of the ins and outs of your game, but is one
conveyor made of a single graphic or a line of tile blocks?
If the answer is the latter you could write your own routine
to test if two rectangles overlap, and you would only need a single collision check between each movable object and each straight segment of conveyor. If it's the latter, then you could only check for collisions if the object moved in the last game loop. If neither, sorry I don't have any ideas.
conveyor made of a single graphic or a line of tile blocks?
If the answer is the latter you could write your own routine
to test if two rectangles overlap, and you would only need a single collision check between each movable object and each straight segment of conveyor. If it's the latter, then you could only check for collisions if the object moved in the last game loop. If neither, sorry I don't have any ideas.