RTA68TB Diesel Engine

　

■Introduction

Attractive features and qualitative requirements of marine diesel engines have changed over time. During the years shortly after the oil crisis, low fuel consumption used to be a major criterion for selection of a diesel engine, and engine builders concentrated on reducing fuel consumption with great success. More recently, emphasis has shifted to high reliability and environmental friendliness. Pursuit of ever higher reliability is an eternal challenge, and a low NOx emission level to meet the IMO's requirement is another priority objective of developmental efforts. In response to these requirements, Wartsila NSD Corp. (WNSD) has developed the RTA68TB marine diesel as a model of the RTA-TB series, an more powerful version of the earlier RTA48T and RTA58T series.

Features of the RTA68TB diesel engine will be described below.

　

■Comparison of RTA72 and RTA68TB Diesel Engines

The new model is compared below in main particulars with the RTA72 engines developed as part of the RTA-2 series, of which many units have been manufactured.

　

　

Compared with the RTA72 engine, though the power output is increased by more than 7%, the weight, 593 tons for an eight-cylinder unit, is reduced by about 19%. While the new diesel is built more compactly, it embodies a number of design features for increased reliability.

　

■Features of RTA68TB Diesel Engine

The RTA68TB diesel engine is assured of increased reliability by inheriting proven techniques incorporated into earlier products and applying state-of-the-art technical features as described in more detail below.

　

　

・Inheritance of Proven Techniques

- Shaker jet cooling, which excels in cooling efficiency, is applied to pistons.

- Cylinder liners are honed 100% deep to secure high scuffing immunity.

- A high-efficiency water separator is used to clear the supercharging air intake of condensate water.

- NIMONIC-80A heat-resistant alloy is used for exhaust valves.

・Use of State-of-the-Art Technical Features

- Machining method for main bearings

To improve the roundness of the main bearings, the main bearing caps are machined after they are fitted to the bed plate. This technique is also applied to the main bearings of the RTA48TB engine.

- Anti-polishing ring (APR)

To further reduce ring liner trouble, APRS are provided to prevent combustion residue from easily sticking to the top lands of piston crowns.

- New type stuffing box

A stuffing box improved in oil scraping and sealing performance is used with a view to saving the consumption of system oil.

　

　

Diesel United, Ltd.

8th Floor, Prime Kanda Building, 8, Kanda Suda-cho 2-chome, Chiyoda-ku, Tokyo 101-0041

Tel: +81-3-8257-8222　Fax: +81-3-3257-8220

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