PURPOSE: To keep constant the tension of a carcass ply by a method wherein a stock roll is provided with a means for increasing a braking torque in response to a decrease in a roll diameter of the carcass ply, and a liner roll is driven by a torque motor.

CONSTITUTION: The material feeding device is comprised of the stock roll 11 and the liner roll 12. The stock roll 11 consists of a cylindrical barrel 11b, fixed to a shaft 11a rotatably supported by bearing disks 9, 9, flanges 11c, 11d and wheels 13, wherein a braking means consisting of a friction disk and a spring receiving plate pressed against the friction disk by the elastic force of a coil spring is provided in the interior of the right end of the barrel 11b. The liner roll 12 consists of a barrel 12b fixed to a shaft 12a rotatably supported by bearing disks 9, 9, flanges 12c, 12d and wheels 24 and is driven by the torque motor. When the carcass ply is let out from the stock roll 11 and is wound around a molding drum, the coil spring is compressed in response to the decrease in the roll diameter of the carcass ply so as to increase the braking torque, and on the other hand, the torque motor functions to keep constant the tension of the carcass ply.