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Couplings Pass 'Hell Hole' Test

Zero-Max Inc. , an ISO 9001-certified design and manufacturing company, introduces its composite disc couplings for the wind turbine industry.

Zero-Max Inc., an ISO 9001-certified design and manufacturing company, introduces its composite disc couplings for the wind turbine industry.

"These couplings withstand extreme misalignment while remaining torsionally stiff, and have passed the 'hell hole' test at Tehachapi [CA] Wind Farm," reports James Motz, member of the wind team at Zero-Max.

"The couplings were tested under conditions simulating a 20-year load spectrum of continuous operation," Motz adds. "Once fatigue tested, the 'hell hole' location was selected for field testing in a wind turbine whereby the coupling would experience wind conditions in excess of 80 MPH with continuous wind direction changes.

"The Zero-Max couplings survived these conditions that put [more than] 50 wind turbines not using our coupling out of commission. The Zero-Max coupling continues to operate uninterrupted at this writing."

These couplings are designed with composite disc packs at both ends of a center spacer. According to the company, these disc packs provide the coupling's strength and calculable flexibility, while also granting a distinct advantage over other coupling component designs by allowing a surplus of parallel and axial misalignment. The couplings do this while remaining torsionally stiff through all harmonic ranges of the wind turbine's oscillating load.

Depending on the application, the Zero-Max's center spacers can be machined out of steel, composite glass fiber or 6061-T6 aluminum. Through the use of finite element analysis, these center spacers can also be engineered to withstand in excess of 70,000 NM of torque (dependent on the material selection).

The company believes that its wind turbine couplings have many additional design advantages. The flex elements electrically insulate the turbine's generator from the gear box, thereby eliminating amperage leak across the coupling and preventing gear box damage. Moreover, the coupling protects the generator by transferring lower reaction loads to the generator bearings.

Also, the coupling's composite material withstands all types of environmental elements, including temperature extremes from -57° to 121°C, as well as moisture and chemicals native to wind turbines.

"Zero-Max has been a leader in the design and engineering of wind turbine couplings that outlast the life of any wind turbine built for more than 50 years," reports Motz. "Today's Zero-Max's wind turbine coupling technology and facilities have advanced and expanded to serve leading wind turbine manufacturers worldwide with designs that exceed any OEM turbine coupling life requirements."