Redesign of PPU Highlights April 2015 25 years down the line and FLSmidth MAAG Gear has revamped a classic and created a state-of-the-art gearbox: the PPU gearbox for roller presses and other applications. Roller presses in cement plants are used for the primary reduction of the grinding stock. For this application, FLSmidth MAAG Gear offers a special series of gearboxes for roller presses (read more about FLSmidth's new roller press concept on pages 34-37). The gearboxes are always used in pairs for the drive of the two grinding rollers. They can be used in both directions of rotation. The gearboxes for roller presses have been designed as two-stage planetary reducers with spur pre-stages. This ensures optimal design of the planetary stages with good load distribution and adaptation to the required gearbox ratio. The new version Experience gained over the last 25 years was analysed in order to fully redesign the PPU gearbox. The following objectives were met: • Weight reduction of 25% • 15% smaller outer diameter • Diversity of parts reduced by 20% The main focus of the redesign was in the toothing and the bearing system of the individual components. The choice of an

optimum bearing system and good sizing has resulted in a high level of reliability. With a bearing lifetime in excess of 100.000 hours, the PPU is like a marathon runner who leaves the competition way behind. Compared with other gearboxes in the same application class, the new PPU uses just five different types of antifriction bearings instead of up to eight, which simplifies the management of spare parts. Operating costs are reduced thanks to efficiency and optimised maintenance intervals. Lubrication oil consumption has been optimised. The ideal oil level reduces churning losses and improves...