MAAG™ CPU Central Mill Gear Unit

The MAAG™ CPU horizontal gear units are specially designed to drive ball mills. The design of the two-stage planetary gear unit guarantees optimum power transmission between 1,000 and 10,000 kW range.

CPU 2 Central Gear Unit Ball Mill Gear
  • Technical Description
  • Customer Benefits
  • Downloads

Technical Data

The gearbox comprises two co-axial planetary stages arranged one behind the other. Both stages of the central gear unit are straight-toothed planetary gears with fixed ring gear and rotating planet carrier. The drive is achieved through the sun pinion. The rotating planet carrier is, at the same time, also the output drive shaft of the first stage. The planetary gears are supported on planetary gear axles in the planet carrier.  

Gearing of the MAAG CPU central gear unit 
The spur teeth of the sun pinion and the planet wheels are case-hardened and grinded. The toothed flanks of the sun pinions have both profile and longitudinal corrections to fully compensate for deformations occuring under load. This method guarantees optimum tooth flank contact and very long life. The inner gear rings are heat treated.

Gear Unit Types
Types range from CPU-09 to CPU-83
Power range from 1'000 to 10'000 kW



Additional Components

Auxiliary Drive
The auxiliary drive facilitates maintenance operations by providing: interval mill turning, smooth start, position hold with brakes, automatic auxiliary drive disengagement at main motor start-up and level out function.

Coupling ZCF
The ZCF toothed coupling installed between the mill and the MAAG CPU central gear unit is a unique FLSmidth MAAG Gear design combining a high degree of freedom (alignement) with efficient torque transmission.

Coupling ZEXF
The gearbox to motor coupling ZEXF is a toothed coupling specially designed by FLSmidth MAAG Gear.  With this coupling the gearbox is electrically insulated from the motor.

Lubrication System
The gearbox is lubricated by a closed circuit oil system which is ideally located beneath the mill drive motor. The design of the lubricant system is standardised thus it is applicable for several gear unit types.

Your reasons to choose the MAAG CPU central gear unit by FLSmidth MAAG Gear

  • Customer specific design
  • Efficiency exceeds 98.9 %
  • Extremely compact construction
  • High reliability
  • Impeccable operation
  • High availability
  • Short installation time under good conditions
  • Low-cost maintenance
  • Gearing and journal bearings with a very long life
  • Only babbit slide bearings inside, no roller bearings used
  • Comprehensive service packages available to guarantee continued customer satisfaction
Brochure CPU
FLSmidth MAAG Gear CPU two-stage central gear unit
Watch a technical animation about MAAG CPU
cpu video
Overhaul of a MAAG CPU gearbox in India