MAAG® GEAR WPU Gear Unit

Refined for coal mills

We developed the small series of MAAG® GEAR WPU Gear Units specifically for coal mills in cement, mineral and thermal power plants. The unique requirements of coal mills demand that the coal grinding system considers the heat sources used to dry raw coal, as well as the fire and explosion hazards of coal dust. To meet these demands, the entire grinding plant must be shock-resistant and have explosion relief valves.

If our MAAG® GEAR WPU Gearbox will be used in thermal power plant applications, we will follow the latest ATEX standards. We can also ensure that all electrical equipment installed on the WPU gear unit complies with anti-explosive requirements.

Our WPU Gear Units combine proven technology for driving vertical roller mills with the necessary adjustments to deliver high functionality for coal mills in cement plants and other applications. The standardised design of the WPU Gear Unit allows you to use it in many different types of mills and plant arrangements, while benefiting from the improvements to vibration dampening and ability to handle variable load operation.

Torque transmission that fits your mill

Our conventional two-stage gear unit, the MAAG® GEAR WPU, fits perfectly in the classic vertical roller mill drive arrangement, where a horizontally-oriented electrical motor provides the drive power and rotary motion. The first reduction stage in the gear unit, the bevel stage, redirects the horizontal rotation into the vertical axes of the mill and is followed by a planetary gear stage, according to your torque and ratio requirements.

We use the ring gear of the planetary stage directly as part of the casing in the larger series of our MAAG® GEAR gear units. This minimises the ratio in the bevel gear stage, increasing the transmittable torque to a maximum.

Components deliver endurance and ease

The profile and longitudinal modifications of the toothed flanks of the sun pinion fully compensate for deformations of the pinions, wheels and gears while under load. This method guarantees optimum tooth flank contact and combines with the high toothing quality in the MAAG® GEAR WPU to deliver efficient power output and smooth operation – and ensure gear unit longevity.

The thrust bearing, which supports the mill table of your vertical roller mill, absorbs the static and dynamic loads from the grinding process. Each bearing pad is lubricated with low-pressure oil and the pads are lined with Babbitt metal at the contact surface. Subject to your needs for the grinding process, our WPU Gear Units also include high-pressure lubrication for hydrostatic table support. Depending the size and application, we can supply both gear stages with slide bearings or roller bearings.

The gear casing for the MAAG® GEAR WPU Gearbox is robust welded or cast steel. Additionally, the casing’s even, circular shape guarantees an optimal force flow from the mill table into the foundation of your vertical roller mill.

Get the most from this effective gear unit with auxiliary system

A broad collection of auxiliary systems completes our MAAG® GEAR WPU Gear Unit. While the lubrication system and coupling are must-haves for operating the gear unit, we can supply auxiliary or maintenance drives according your plant arrangement and maintenance philosophy. Our comprehensive online monitoring system ensures you get the most out of your vertical roller mill – and lets you efficiently plan maintenance.

Lubrication keeps the gear unit running smoothly

The oil supply units for our MAAG® GEAR WPU Gear Unit include low-pressure pumps that supply filtered and cooled lubrication oil to the bearings and toothings. If required, high-pressure pumps deliver oil to the thrust bearing from a separate compartment of the tank, using filtered oil from the low-pressure section. Using only clean oil on the high-pressure side improves the lifespan of the pumps and decreases the frequency of required maintenance.

Low-maintenance, high-performance connections

The flexible coupling that comes standard with the WPU Gear Unit is almost maintenance free, as it requires no lubrication changes. It also has low vibratory loads in the drive train and relatively wide ranges for axial and radial misalignment. These features combine to give you reliable function, with low operating costs.

Bring it all together with an auxiliary or maintenance drive

A maintenance or auxiliary drive that is tailored to your requirements rounds out the scope of supply for your WPU gear unit. The maintenance drive is placed between the motor and gear unit and allows you to rotate the mill table very slowly. This simplifies maintenance work at your vertical roller mill, including replacing lining plates or rebuilding surfaces through welding.

The auxiliary unit is mostly used to start the mill when the breakaway torque is too substantial to start the motor directly. The fluid coupling of the auxiliary unit guarantees smooth acceleration and the overrunning clutch automatically disengages the auxiliary drive after the main motor starts.

Beyond a basic condition monitoring system

All of our gear units are equipped with unparalleled condition monitoring sensors. Normally, these types of sensors keep an eye on critical operating parameters like bearing temperatures, casing vibrations, etc. and trigger a mill shutdown in the case of exceedances.

Our condition monitoring system does much more. It lets you set up condition-based preventive maintenance that uses continuous monitoring and data analysis to detect wear and tear at an early stage. With this enhanced information, we help you plan maintenance and servicing in advance – reducing downtime and keeping your plant running smoothly.