60,000 Hours service of Rotary Vane Steering in Royal Canadian Naval Frigates
Port Moody, BC, Canada: The first generation of the Autonav Rotary Vane steering systems were put into service over 20 years ago in the RCN Halifax Class Frigates and since then have undergone over 60,000 hours of service with minimal maintenance. On recently inspecting one of these early systems the seals and bearings were confirmed to have zero measurable wear due to the unique bearing and seal design. While rotary vane steering actuators are much more compact and lower weight than traditional Ram systems, their internal sealing has frequently been a problem which caused rudder drift under load. In addition the internal bearings would score and wear, requiring expensive and troublesome rebuilding. Such past problems have been eliminated in the Autonav design, resulting in these long operational periods with minimal wear or servicing. In addition, the internal and self lubricating radial and carrier bearings provide greatly reduced rudder friction and a very compact installation envelope. Such long maintenance free service makes the rotary vane ideal for high duty cycle Rudder Roll Stabilization, a technique which uses the steering gear and rudder to counter roll and eliminate the need for expensive, acoustically noisy and vulnerable anti-roll fins. All control piping is automatically isolated by directly manifolded lock valves which hold the rudder in position in case of damaged piping or pumpsets. This allows immediate continued control with the separately connected standby pumpset. There is only one internal moving part which is protected from external mechanical damage by the pressure housing and from corrosion and wear due to automatic internal lubrication from the hydraulic fluid.
The reliability and low maintenance of such a design was confirmed in a paper presented to ASNE (American Society of Naval Engineers) which used NAVSEA Reliability and Maintainability data to calculate that this rotary vane, when compared to the standard NAVSEA Ram design, was 235% more reliable and required only 9.6% of the maintenance, a calculation verified by over 60,000 hours of service to date with no seal or bearing replacement required. The current second generation rotary vane as now manufactured by Autonav is even more compact and lighter weight. This proven performance makes the Autonav rotary vane steering ideally suited to modern combatant vessels while being economical for commercial vessels as well. www.autonav.ca