New inner housing concept reduces losses and oil consumption in turbo gears, Voith says The new BHS AeroMaXX solution for turbo parallel-shaft gears by Voith: the cooling oil flows separately from the lube oil in a special inner casing. BY ROBERTA PRANDI Voith said its new BHS AeroMaXX solution for turbo parallel-shaft gears is designed to increase the efficiency of the gear by up to 0.5 percentage points and reduce oil consumption in the gear unit by more than 30%. The BHS AeroMaXX technology is based on a special inner housing and optimized sleeve bearings, the company said. “A special inner housing is added in the direct vicinity of the gear set, thanks to which cooling oil flows separately from the lube oil. The cooling oil absorbs heat from the external surface on the inner housing and dissipates it into the bottom area,” said Yvonne von Struensee-Binzer, global key account manager at Voith in Sonthofen, Germany. The high pitch line velocities—up to 200 m/s—in high-speed turbo gear units cause oil swirling and oil squeezing in the gear mesh, which accounts for a substantial part of the power loss in these units. With the BHS AeroMaXX technology, lubrication and cooling oil are separated and thus losses are reduced as is the overall oil consumption. In fact, with this solution a much smaller volume of oil is required for the actual lubrication of the teeth contact surfaces and the swirling of the oil and air mixture is minimized, the company said. A recent test carried out by Voith on a 60 MW turbo gear between a gas turbine and generator in a power generation application showed a power loss with the BHS AeroMaXX of 470 kW, against a standard power loss of 700 kW. In terms of oil consumption, the test showed a consumption of 560 l/min with BHS AeroMaXX, in comparison with a standard 860 l/min. In terms of oil flow, a reduction of 30% was reported, while the power saving indicated an increase in efficiency of 30%. Von Struensee-Binzer said the BHS Aero MaXX solution has a passive-mechanical character and does not require any additional accessories. “The design standards of the turbo unit remain the same, as well as the overall operating behavior and the unit’s reliability,” she said. “ For these reasons, the BHS AeroMaXX solution is recommended also for retrofit projects.” She said Voith offers a 36-month warranty for both new systems and retrofits, even when integrated into turbo gears of other manufacturers. “The possibility of retrofitting an existing turbo gear is independent of its original manufacturer,” von Struensee-Binzer said. “With Voith gears as well as pre-designed further types, retrofits can be carried out during the standard maintenance of the driveline.” BHS AeroMaXX is designed for high pitch line velocities in connection with medium to high powers that occur, for example, in the driveline of power plants with compressors and generators. For such applications, the retrofit with the BHS AeroMaXX technology without additional downtime is a very attractive option. In addition to the inner housing, the BHS AeroMaXX technology includes the new BHS EcoMax sleeve bearings on the pinion shaft. These hydrodynamic bearings are optimized specifically for the application and guarantee high energy efficiency with significant oil savings, said Voith. As far as maintenance and service of the gears with BHS AeroMaXX, von Struensee-Binzer said that an inspection window in the inner housing allows operators to continue checking the condition of the tooth set without opening the top portion of the gear housing.