For the past 30 years aggregate plants have been adapting the drum motor or motorized pulley to drive their belt conveyors. Although the drive of choice for quarry conveyors has been the external mounted motor and gear box, the drum motor has been gaining popularity due to the all enclosed design that protects all vital components such as the electric motor, gear reducer and bearings, from the environment.
Any mechanical equipment that is used in a quarry has to withstand harsh, abrasive and dusty conditions. Abrasive dust ultimately finds its way into the air ducts of the electric motor, cutting the airflow substantially, which causes the motor to overheat resulting in a complete motor failure. It also penetrates the bearing, seals, couplings and other mechanical conveyor components, creating conveyor failure, which results in loss of production.
The Van der Graaf motorized drum is designed to address all the above points of failure. The extreme duty series drum motor for aggregate use features an all-enclosed design. Bearings, electric motor and all gear reducer components are inside the drive drum (head pulley) working in an oil bath that ensures optimum lubrication and longevity that averages four times the life of a standard external motor/gear box drive arrangement.
Since all bearings are housed inside the drum there is no need for maintenance, such as re-greasing the bearings, noted the company. The Van der Graaf drum motor features standard class “H” inverter duty motor windings for extreme duty applications, and the VPI (Vacuum Pressure Impregnation) process protects the motor under high vibration conditions.
The inline design of the motor and gear reducer results in a 96 percent mechanically efficient conveyor drive that saves an average of 30 percent on the electrical consumption.
Van der Graaf, www.vandergraaf.com