FEATURE GEARS & GEARBOXES MARINE SOLUTIONS
Needing a low maintenance yet high reliability gearbox/clutch power transmission combination, a Chinese roll-on-roll-off ferry OEM turned to Stromag for a solution
D
eveloping a suitable gearbox/clutch power transmission combination for a large ferry application was proving challenging
for one major Chinese marine propulsion system manufacturer. The roll-on-roll-off ferry is used to transport wheeled cargo/vehicles in an enclosed lower deck, while passengers travel on an upper deck. However, the size of the vessel demanded a high torque transmission but this had to be in a very compact package, which put high stresses on the clutch. The solution specified needed to be low
maintenance yet offer high reliability, as the ferries typically run to tight schedules and the cost of unplanned downtime would be high. Any failure within the propulsion system can impact on speed and manoeuvrability, disrupting the vessel’s schedule and leading to significant commercial losses. Large ferries commonly use a dual diesel- powered propeller shaft propulsion, with four
AN EXTENSIVE PORTFOLIO
2021 marks the 40th anniversary of the establishment of the first subsidiary of Italian drive specialist Bonfiglioli Riduttori in the UK. Here, all the business areas of the
Bonfiglioli Group are represented. The D&P business area offers solutions for almost all industrial applications. An extensive portfolio ranging fromprecision gearboxes to extremely powerful large planetary gearboxes is the basis for further growth. TheM&Wbusiness unit suppliesmany well-knownmanufacturers ofmobile constructionmachinery, cranes, and agricultural applications. In addition to hydraulic applications, Bonfiglioli helps in the electrification of thesemachines.
Bonfiglioli
www.bonfiglioli.com
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diesel engines driving two propeller shafts. In this arrangement, there are twin diesel engines connected to a common gearbox for each shaft. The gearboxes reduce the medium shaft
speed from the engine down to the low-speed drive required for the propeller. The two engines per gearbox are each connected via a clutch, which enables engagement/disengagement to allow either one or both engines to be run as needed, and facilitates reversing of the engine. The application is very demanding on the clutch, which must be compact enough to be integrated into the tight space yet still transmit the required high torques.
A PARTNER FOR MARINE GEAR MANUFACTURERS Having looked into a number of solutions, the OEM got in touch with Stromag. Renowned within the marine industry for extra heavy-duty clutches that are characterised by a high power
density in a small mounting space, the company is a leading engineering partner for marine gear manufacturers around the world. To meet the application demands, wet-
running multi-disc KMS clutches, which are designed for use in marine gearboxes, were specified. These oil-cooled, hydraulically- operated units are used where high torques must be transmitted reliably in tight engine room spaces. Additional features include an excellent torque-to-weight ratio and low mass moment of inertia, as well as a high thermal capacity since switching heat is dissipated by internal oil cooling. Stromag supplied Model KMS 18000/25
clutches which were integrated and adapted into the gearboxes. Each 635mm diameter clutch has a torque rating of 240,000Nm.
Stromag T: +49 2303 102239
www.stromag.com
GEARBOX BEARINGS WITHSTAND HARSH CONDITIONS
In the rail industry, gearbox bearings often have to withstand frequent shock and vibration. These arduous conditions necessitate regular bearingmaintenance – mounting andmaintaining tapered roller bearings, which are commonly used to support gears and pinion shafts, requires time-consuming end-play clearance adjustment by expertmaintenance engineers. In light of these challenges, and to meet
demand for even higher reliability solutions, NSK offers bearings that incorporate a suite of proprietary technologies, helping significantly enhance handling. A low-maintenance design is among the major features of the bearings for small gear shafts. The combination of the new cylindrical roller bearings and four-point- contact ball bearings eliminates the need for end-play clearance adjustment, simplifying both mounting and maintenance. Another enhancement relates to cage strength,
3 DESIGN SOLUTIONS NOVEMBER 2021
which is vital in applications where effects such as intense shock and vibration are commonplace. Here, NSK has developed a special ring-guided cage with optimised pockets employing ‘R- shaped’ corners. This reduces stress in the cage structure by 75%. The bearings also feature an inner ring that
is specially heat-treated to ensure dimensional stability, even under conditions of extended use at high temperatures. Extremely high dimensional stability delivers excellent creep suppression, preventing the bearing from shifting along the shaft. With the company’s high-reliability tapered
roller bearings for large gears shafts, it has added a number of standard new sizes in line with growing demand.
NSK Europe
www.nskeurope.com
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