Roller conveyors are equipped with strong beams on both sides and connected with crossbeams everywhere. Many rollers are installed side by side on the ladder-shaped frame so that the rollers can rotate easily. The goods can be loaded on it, pushed by manpower, tilted to slide by gravity, or rotated by power, which can be used to transport products. * Linear roller conveyors are made of light channel iron in the shape of a ladder, and light and simple rollers are installed on it with a pitch of 100~150 mm. Handles are added to the frame for easy transportation, and connectors are added to the left and right ends of the frame so that no matter how many units can be connected, the required conveying route can be made. Rollers need to use thin-walled steel pipes to reduce weight. The shaft must not only be reduced to the limit that can withstand the conveyed goods, but also designed to be lightweight using a hollow shaft.