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Cummins ISX

Emissions Control
The Cummins ISX diesel engine can be run in a dual fuel configuration, meaning it can properly operate on diesel fuel and natural gas. The burning of a natural gas alternative preserves diesel thermal efficiencies. The more efficient engine can produce less emissions in turn. The ISX can achieve this by altering ignition delay and injection timing. By examining the start of combustion (SOC), the engine’s computer is able to employ a predictive ignition delay correlation. The predictive characteristics of the engine maximize both efficiency and useful power for the given fuel source. Compensations are made for the natural gas so that the power band and operating range are still functional for customers, while reducing emissions. Testing has also been done with the Cummins ISX by the EPA for natural gas usage that yielded results of major NOx emissions reduction. The configuration boasts ninety percent lower NOx emissions than the current EPA standard. This makes the Cummins ISX that burns natural gas one of the cleanest running diesel engines in the world. The ISX also utilizes a DPF, or diesel particulate filter, required by the EPA. The DPF filters out the solid particles in the engine’s exhaust, reducing tailpipe emissions. The DPF does have to be regularly maintained, however, because of its intricate design. The emissions control system will institute a filter regeneration which burns off the particulates. Any in-combustibles found in lubrication additives will remain in the DPF, which can cause problems with back pressure and efficiency. This means the DPF needs to be regularly removed and cleaned for the Cummins ISX. An ash-less oil could mean that cleaning would be unnecessary, but can inhibit lubrication properties. A zero phosphorous oil has been studied and found to be ideal for DPF systems and lubrication. The oil displays passing results for both piston deposits and oil consumption, which means the DPF system would be optimized with use of zero phosphorus, ultra low sulfur oil. The Cummins ISX also utilized DEF, or diesel exhaust fluid, in later models when EPA requirements changed. DEF is system of injected urea that reduces the emissions of a diesel engine. The Cummins ISX is required to have inhibitors in place for certain failures of the DEF system. When the DEF tank is low or empty, the ISX cuts power by twenty five percent. Power cuts and driver warnings are also used when the DEF system has been tampered with or is not functioning properly. Cummins has corrected several malfunctions and conducted customer based research of several million miles of on road use of the Cummins ISX to make the DEF system as functional as possible. The system is also required to de-rate power given any problems in order to reduce emissions to an absolute minimum.

Technology
In early ISX engines an anti backlash gear train is used. The anti backlash gears allow the engine to operate with minimal gear rattle. Cummins uses a gear train in the front of the engine which is inherently noisy. The anti backlash gearing makes the engine less noisy due to the reduced rattle while in operation.The anti backlash gear train comes at a cost of efficiency. The Cummins ISX 15 model equipped with anti backlash gearing suffers a friction loss. The gears must overcome more friction throughout their moving range than a standard gear. A standard gear in a Cummins ISX 15 needs to overcome 0.75 Newton meters of force, while the anti backlash gearing needs to overcome approximately 5 Newton meters of force.