A glass manufacturing apparatus comprises a forming device configured to produce a glass ribbon and a control device configured to independently operate a first pull roll apparatus and a second pull roll apparatus such that the first pull roll apparatus rotates with a substantially constant torque the second pull roll apparatus rotates with a substantially constant angular velocity. The control device is further configured to adjust the substantially constant torque of the first pull roll apparatus based on an operating condition of at least one of the first pull roll apparatus and the second pull roll apparatus. In further examples, methods of manufacturing a glass ribbon are provided.