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Altra Industrial Motion has produced a package of electromechanical power transmission products designed for use in critical, safety-related nuclear power applications.

At the core of Altra’s offering are high-speed gear increaser and reducer drives from Nuttall Gear (formerly Westinghouse Gearing Division).

The Nuttall SU high-speed gear design offers the key advantage to nuclear operators of proven operation over millions of hours in approximately 50 per cent of the nuclear power plants built by Westinghouse.

The SU gear drives in these existing facilities continue to be supported through new units, replacement gearing and parts, and Nuttall Gear also offers a full rebuild service to original OEM specifications.

In new applications, Nuttall gear excels in designing, to AGMA standards, high-speed drives for custom applications such as compressors, fans, pumps and turbines.

These drives offer proven reliability with features such as rigid cast-iron or welded-steel housings; dynamically balanced precision double-helical gearing for uniform load distribution and quiet running; oversized split-sleeve bearings for smooth, efficient running; split-labyrinth non-contact oil seals for longer life; and self-contained forced oil-lubricated gears and bearings.

Crucially for use in nuclear facilities, the Nuttall gear units are supported by options such as monitoring systems to measure temperature, pressure and vibration; remote-mounted lubrication consoles; and multi-speed shifters.

Also employing designs that deliver long life in critical applications are Altra’s Bibby and Ameridrives ranges of disc and diaphragm couplings.

Designed and manufactured in compliance with API-671 and rated for operation up to 677,400Nm, these non-lube, maintenance-free couplings offer high reliability in the power-generation market, particularly in critical applications such as boiler feed pumps, generator sets and gas compression.

Bibby’s latest HS series of disc couplings are manufactured from alloy steel that is fully traceable.

They have a design that effectively drives in friction, rather than shear, to the disc assembly joint.

This eliminates the potential for fretting during normal operation and prolongs the life of the coupling.

The HS series also offers the benefit of a plug-in design that allows easy installation.

This enables the couplings to be installed and the flexible elements (disc packs) changed, without disturbing adjacent machinery.

In addition, disc couplings are torsionally stiff and backlash free.

They will also accept high levels of angular, radial and axial misalignment without any loss of operating performance.

The Ameriflex range of diaphragm couplings offers features such as: 15-5 PH shot-peened stainless steel diaphragms, for improved fatigue strength and stress corrosion resistance; multiple separated diaphragms to provide power transmission redundancy and design flexibility; and field-replaceable flex elements.

The ‘fitness for purpose’ of the Ameridrives diaphragm couplings for nuclear applications is ably illustrated by the use of 80in coupling, to provide power transmission in the propulsion system of a nuclear submarine.

The coupling is designed to deliver infinite life.

The third key element in Altra’s nuclear power package is the Centrifugally Disengaged Vertical Backstop Anti-Rotation Device (ARD) from Formsprag-Stieber.

This Altra group company was instrumental in the development of the long-life Anti-Rotation Device (ARD) for the reactor coolant pumps of pressure water reactors’ and continues to support the installed base of these devices by offering field inspections, factory rebuilding and new ARDs with improved bearing performance.

In addition to coolant pumps, Formsprag-Stieber ARDs are also used in other nuclear applications: as backstops for various pumping systems, cooling tower fan backstops and overrunning clutches in rotating gear drives.

According to Altra, the ARDs’ design offers virtually unlimited speed capability and torque-holding facility (56,450Nm).

The ARDs feature lift-off sprags for no-contact running, no heat generation and long-life, exceeding 10-year maintenance-free operation between recommended inspections.

They have balanced torque arms to prevent reverse rotation and use dynamically balanced hydrodynamic babbitted bearings and races, for minimal wear and heat generation.

For nuclear use the ARDs offer the facility to ensure performance compliance, with pressurised oil flow and monitoring systems to measure temperature, pressure and vibration.

They are all 100 per cent factory tested before despatch in an ISO 9001:2000- and AS9100-rated facility.

Altra Industrial Motion

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