Revolvo’s SRB split roller bearings have been specified as part of the diesel electric propulsion system for a refurbished icebreaker that has recently been re-engineered in the Ukraine. The SRB split roller bearings were specified due to their ability to be quickly changed in-situ, preventing unplanned layovers or dry docking, in the event of a bearing replacement being required whilst the vessel is in service. The SRB split bearing design – totally split to the shaft – allows simple and fast installation and easy replacement – up to 90% faster than solid roller bearings used on marine drive propulsion systems.
The SRB split bearings are being employed as support bearings for the intermediate shaft between the icebreakers diesel engines and the generator units. In contrast to conventional vessels with fore or amidships mounted main engines, and long propulsion shafts connected via couplings to propellers, the diesel-electric propulsion system uses several medium speed diesel engines to drive generator units providing electrical power for the vessels electric motors that drive the ship’s propellers.
Over the last few years the move to diesel-electric propulsion systems has accelerated as the benefits of the system have been proven. It is now estimated that the utilization of diesel electric marine propulsion systems has doubled over the past 3 years. The benefits include reducing the overall size of the drive system, with smaller engine rooms as it’s possible to replace large slow speed engines with multiple smaller generators; reduced noise and vibration as there is no need for long fixed drivelines; increased efficiency reducing fuel consumption; and increased flexibility as power can be shared with multiple devices such as bow thrusters, pumps etc, along with the main propellers.
The specification of Revolvo’s SRB split bearings on the icebreaker is the latest in a long line of successful installations for these bearings in the arduous marine operating sector. The SRB split roller bearings offer proven reliability and a number of key operating benefits. First, easier bearing fitting: typically fitting a split roller bearing takes only about 10% of the time taken to fit an equivalent solid bearing in a trapped location. Second, the ability to inspect the bearing in situ without any major disassembly. Third, the ease and speed with which the bearing housing of a SRB split roller bearings can be replaced if it’s required. Fourth, the ability of SRB split bearings to perform reliably in aggressive environments, due to the performance of the sealing systems available to protect the bearing units.
The design of Revolvo’s SRB split bearing allows the shaft to be supported by the lower section of the bearing; whilst the upper section can be removed, allowing simple inspection or servicing without drive or shaft removal. This intrinsic feature is extremely valuable, generally, but especially regarding large machines, where sheer weight and size can be a barrier to fast and effective servicing. It also allows for faster bearing replacement, which can save continuous-type applications such as Marine propulsion systems a lot of costly downtime.
Revolvo manufactures its SRB split bearing housings, and support pedestals in tough 250-grade grey cast iron to ensure maximum strength and durability of the product. In addition, as part of its specialized service for SRB, the company manufactures corrosion resistant stainless steel housings, where conventional materials do not offer sufficient corrosion resistance. The latest in this series was produced for an underwater application, where the split roller bearings have to operate totally submerged in clean water without any risk of corrosion contamination. This design is a synergy of stainless steel and specialized sealing, the latter, being Revolvo’s special split and sprung garter seal, has been well proven over many years in submerged applications.
For further information, please contact Adrian Menzies
Source: Process and Control Today