Apron feeder machines can be used in mining operations to carry rocks and minerals such as coal for crushing or further processing.

For optimum performance, this combination has the advantage of a high torque ratio of up to 1000:1 as well as a good thermal rating.

The company’s business development manager Kris Jaryn said the power of such combinations was further extended recently with two new gear unit sizes that increased the torque capacity of the range up to an impressive 1,100,000 Nm.

The input stage box not only reduces the input speed to the planetary head – which operates best with lower input speeds – but it can also be fitted with a shaft cooling fan to increase the allowable installed power.

The drives can either have a hollow output shaft with a shrink disc, or a solid output shaft with a rigid coupling.

“Bonfiglioli can cater the design of the drives to suit individual needs,” he said.

“In most cases the motors are flange mounted in the horizontal position. If there is not enough room around the drive, the motor can be mounted vertically.

“In these cases, the drive is supplied with a motorised oil pump, which lubricates the top bearing of the box. In some cases, when really big motors are required – over 200 kW – which are too heavy to be flange mounted, the drives can be supplied with locally designed baseplate attached to the gear units, thus still offering a relatively compact drive.

All drives are shaft mounted and are fitted with a torque arm, which in most cases is attached to the outside of the planetary box.

Generally the motors are controlled using a variable frequency drive (VFD), which allows smooth speed changes and control as well as limiting the motor starting torque, usually to about 150% of the full load torque.

Bonfiglioli’s VFDs range from 0.25-400 kW and can practically supply the complete drive solution for any apron feeder application, designed, engineered and built locally at their Glendenning facility in NSW, Jaryn said.

“Bonfiglioli can ensure the best drive is selected for the optimal price by using their calculations software from their Italian headquarters,” he said.

“This software checks and calculates bearing life and gear strength so that the customer is getting the drive best for the job, at the best price.”

“Gear boxes are basically torque multipliers, so the bigger the ratio the bigger the output torque of the machine [but the lower the speed].

“So, when a relatively small motor is used with high ratio box a high torque can be created to move a large or heavy load. Using a combination of a planetary gear head with a bevel helical input gear unit allows us to build big ratios in a relatively small package.”