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Selecting secondary seals for low-emissions engines.

Article Excerpt
Heavy-duty diesel engines in virtually all applications and all markets face increasingly stringent emissions regulations. In 2007, new heavy-duty on-highway standards take effect, with another even tougher emissions hurdle ahead in 2010. Off-highway machinery faces its own emissions challenges with the implementation of Tier 3 and Tier 4 standards, which take effect on a staggered schedule based on engine horsepower.

In nearly every case, all major engine manufacturers are at the very least, in test with prototype engines and most have settled on gaskets for their primary joints (e.g., cylinder head and exhaust joints). What remains as potential problem areas, however, are secondary joints such as oil cooler, breather, oil pan and various connection gaskets.

While exhaust emissions regulations cover a number of different constituents, both the on- and off-road standards are primarily concerned with particulate matter (PM) and N[O.sub.x]. In some cases, emissions standards have required the application of advanced new technologies, including new turbocharger arrangements, closed crankcase ventilation systems and/or upgraded exhaust gas recirculation (EGR) systems.

In many instances, new flanged joints associated with these upgrades have been added to the engine assembly. Other secondary joints such as oil and...