These needs ruled out the standard pulley with external drive arrangement used in other applications. The Interroll motorized pulley, he says, solved these problems. Key components of the unit are a heavy-duty motor, gearbox, and two shafts joined together to form a rigid shaft around which the shell rotates. Additionally, all internal components are immersed in an oil bath that lubricates and cools. Double-lipped oil seals at either end of the drum prevent oil leakage while excluding dust and moisture.
Power leads pass from the motor through the hollow shaft to the terminal box.
The pulleys come crowned, which helps eliminate belt tracking problems. Motor and gearing is housed inside the pulley shell. As a result, the fully rated horsepower of the drive is available at the surface of the pulley. No motorized pulley failures have yet been experienced. This durability is particularly impressive, he adds, because the systems operate in excess of 320 days per year.