Methods and mechanism for providing variable torque with variable torque resolution to rotation of a web roll

Mechanism for controlling rotation comprising, in combination:

• means for receiving a variable pilot signal, with the variable pilot signal adapted to cause a pilot torque to the rotation in direct proportion to the variable pilot signal;
• a first relay receiving the variable pilot signal and creating a first relay signal in direct proportion to a first difference between the variable pilot signal and a first level, with the first relay signal adapted to cause a first relay torque to the rotation in addition to the pilot torque, with the first relay torque being in direct proportion to the first difference;
• and
• a first amplifier amplifying the first relay signal.

Method for tensioning a web comprising:

• rotating a roll of the web;
• applying a pilot torque to the rotation of the roll in direct proportion to a variable pilot signal to create tension in the web extending from the roll;
• and
• applying a first torque to the rotation of the roll in addition to the pilot torque, with the first torque being in direct proportion to a first difference between the variable pilot signal and a first level, with the first level being greater than zero, with applying the first torque comprising automatically applying the first torque to the rotation of the roll whenever the variable pilot signal is greater than the first level, with the tension in the web extending from the roll being the combination of the pilot torque and the first torque.