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Deck Machinery & Planetary Gearboxes

15 March 2013

Marine deck machinery has to work in harsh environmental operating conditions, and take up the least amount of space. Ships work in many varied locations during their life and equipment, including the gear units, must be able to withstand the extremes of temperature and salt water

Rossi Gearmotors UK has supplied many planetary units for marine deck applications. Planetary gearboxes are selected because of the arduous application’s requirement for low speed and the space constraints.

One such application is for unwinding and rewinding of cables from reels. These are mounted on the decks of ships, for laying cables and pipes in the petrochemical and communication industries. Under roller reel drive systems (also known as dolly bases) are used to wind the reel, which contain the cables. They are often used in multiple arrangements and in a typical application Rossi has supplied 32 units (four units per reel), synchronised with the pay in or pay out of the eight cables. Each reel, when full with cable, has a weight of 350t, and 50t when empty. Rather than being mechanically linked, the units are electronically coupled, which provides the speed variation as well as allowing for free access below the reels for the passage of the product.

The low maintenance of the gearbox is an important requirement. Most manufacturers have a "running in period” for their planetary products, which can be as low as 100 hours. At this point the lubrication needs to be flushed and changed. In many circumstances this is difficult to perform effectively, particularly when the units are integrated within the machinery. Rossi planetary gearboxes require the first oil change at 12500 hours, due to the use of standard specification quality ground gearsand high performance synthetic lubricant.

With the high amount of torque transmitted within a relatively small gearbox, the thermal rating for planetaries has to be frequently verified. Rossi planetary gearboxes lower running temperatures are achieved by the use of ground gears, improved oil circulation with superior internal geometry and the use of caged roller bearings. With the dolly base application the thermal consideration is vital as the gearbox is enclosed in the reel support structure. From working with the customer, the design of the application incorporating the Rossi planetary gearbox was refined to take into account the high torque and arduous environment. To withstand these extreme conditions the units used a Rossi optional paint system for the marine industry.