Federal-Mogul Powertrain, a division of Federal-Mogul Holdings Corporation (NASDAQ: FDML) has an unparallelled range of piston rings for both two-stroke and four-stroke large bore engines (LBE). The ability to offer rings for every type of engine and every fuel used across a multitude of industry sectors gives Federal-Mogul Powertrain market leadership in the LBE arena.
Federal-Mogul Powertrain is represented in the LBE market by the well-known and respected GOETZE® and DAROS® brands; the GOETZE products fit bores from 145mm to 640mm and the DAROS brand spans bores between 260mm and 980mm. "Large bore engines of this size can have operating speeds as low as 60rpm and piston stroke exceeding 2m in cross head engines," commented Gian Maria Olivetti, chief technology officer, Federal-Mogul Powertrain.
"LBEs are in use globally in the marine, power generation, railway, construction and defence industries and the wide range of engine types and applications makes ring design extremely challenging; with our exceptional breadth of technological expertise, Federal-Mogul Powertrain is ideally positioned to deliver the solutions that customers demand."
Designing piston rings to minimise environmental impact and reduce operating costs Ring design for LBEs is increasingly driven by the desire to minimise environmental impact through reduced oil consumption and pressure to cut operating costs by improving fuel economy and extending time between overhauls (TBO). Federal-Mogul Powertrain satisfies these demands with ring geometries that optimise contact conditions with the cylinder bore, and through the use of wear-resistant materials and coatings that promote longer life.
The rings must also function reliably when facing rising combustion temperatures and pressures as engine manufacturers increase efficiency and specific power output, as well as resist the corrosion that can occur because many of the engines operate with heavy fuel oil.
Federal-Mogul Powertrain is also the world’s leading company in the field of negative ovality piston rings, with more than 40 years experience of the technology. Difficult to achieve but highly beneficial, negative ovality reduces the radial ring pressure at the ends of the ring, next to the ring gap. "This is the region most at risk of scuffing due to locally high temperatures from blow-by gases," said Peter Schmidt, head of application engineering, large bore engine piston rings, Federal-Mogul Powertrain. "Negative ovality helps the ring conform evenly to the deformed shape of the hot cylinder liner, reducing oil consumption and wear, in both two-stroke and four-stroke engines."
Technologies for a range of applications or a specific sector requirement Federal-Mogul Powertrain’s galvanic coatings, such as GDC® (chrome diamond coating) and CKS® (chrome ceramic coating) may reduce the wear rate of both ring and liner and can be applied in different thicknesses, to match the life required. The company’s range of thermal spray coatings includes plasma; high-velocity oxy-fuel (HVOF); and electric arc processes, which gives the company the ability to select the optimum coating for each individual application.
Some of the technologies developed, including many of Federal-Mogul Powertrain’s proprietary galvanic and thermal spray coatings, are appropriate for a wide range of applications; others are directed at specific sectors, such as eWAVE® for two-stroke marine vessels and the LKZ® oilcontrol ring for four-stroke engines.
Two-stroke engines, which can suffer from uneven distribution of lubricating oil on the cylinder bore surface, necessitating a copious oil supply, much of which is ineffective and contributes to pollution, can benefit from eWAVE technology. The geometry of the WAVE piston ring creates a circumferential pressure difference that generates controlled oil flow around the bore as the piston reciprocates; this improves the uniformity of the oil film, enabling less oil to provide greater protection. Tests have shown that the eWAVE ring distributes oil over an area ten times the size of that achieved by conventional ring profiles, reducing wear and brings oil consumption benefits in the region of 20%.
Federal-Mogul Powertrain’s patented LKZ oil control ring, for four-stroke engines, uses a stepped and tapered profile to provide optimal downward scraping action with minimal upward scraping. This allows the ring tension to be reduced, which cuts friction while minimising oil consumption, as Schmidt explained: "Typical piston rings apply equal pressure to the cylinder bore on the downstroke and the upstroke; by providing a greater effect during the downstroke, our LKZ ring is so effective in pulling oil away from the combustion chamber that we are able to reduce ring tension and friction, so improving the fuel efficiency of the engine and at the same time, improving oil consumption."
Federal-Mogul Powertrain will be showcasing its range of large piston rings for marine engines at SMM, the Shipbuilding, Machinery and Marine technology trade show that will take place in Hamburg, from 6-9 September 2016. The company is at Booth 205, in Hall A3.