Caterpillar has developed a proprietary advanced propulsion system for marine applications. The Cat® Marine Advanced Variable Drive™ (AVD™) is a patented system that leverages Caterpillar’s extensive experience with heavy duty continuously variable transmission (CVT) technology, advanced controls and power system integration knowledge. CAT AVD represents a fully integrated marine propulsion solution from the bridge interface down to the propellers and is applicable to a wide range of vessel types and missions.
The paper will present a historical perspective on the evolution of various marine propulsion solutions, before outlining the AVD operating principle and its applicability for tugs. The paper will present a 2 -3MW/ shaft system case study, and detailing operating modes and power flow for a typical tug or salvage vessel application, as well as the concept for scalability up to 20MW/ shaft. Differentiated advantages offered by the Cat AVD for a wide array of vessel types will also be discussed.
Attributes such as better controllability, higher operational efficiency, lower total cost of ownership (TCO), reduced greenhouse gas emissions, ease of serviceability and robustness are among the most common and important requirements for drive technology observed across multiple industry sectors. These requirements apply uniquely well to the tug and salvage industry. Superior controllability directly translates into safer operations, lower crew fatigue and better operational efficiency. While reduced emissions helps to lower the local and global environmental impact of vessel operations.
One key technology developed by Caterpillar, initially for land applications, has proven to be instrumental in satisfying the ambitious requirements cited above, as well as many other customer needs. Continuously variable transmission (CVT) machinery has been delivered over the years in various implementations and products, from purely diesel-electric D7E tractors to power-split hydro-mechanical 966XKE wheel loaders, to name just two.
Leveraging positive experience from these land products, the CVT principle has most recently been applied to the marine propulsion space. The resulting marine CVT configuration, the Advanced Variable Drive (AVD) is proving to be transformative in many ways, exceeding the challenging requirements of multiple types of vessels and applications.
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