acrossthedock

Re: “Coming soon to a fleet near you: ultra-clean lifting machines,” September 2013

I think it [the effect of upcoming diesel emission regulations on lift truck fleets] is a very important topic to cover, but there are some points that could be clarified.

First is that there have been four main pollutants that have been regulated from the start and continue to be regulated. These are: HC (hydrocarbons), CO (carbon monoxide), NOx (nitrogen oxides), and PM (particulate matter). To state that only PM and NOx are currently regulated is simply not true. HC and CO are still regulated.

But to explain this further: The Environmental Protection Agency (EPA) and other regulators have focused on NOx and PM once HC and CO were brought to reasonable levels [as a result of] the early regulations. And it is for NOx and PM that total reductions of 90 percent or so will be achieved with Tier 4 final emissions restrictions.

The significance is that for Tier 4 interim requirements, a considerable decrease in PM was mandated and engine manufacturers used several techniques (as mentioned in the article) to achieve this. Now, for Tier 4 final standards, a significant decrease in NOx is mandated and some of the techniques for achieving this have changed from the interim requirements. The most dramatic variation is actually encouraging the engine combustion to be at higher temperatures—which minimizes the production of PM but results in more production of NOx—and then treating the exhaust gas by the SCR (selective catalytic reduction) process to break down the NOx into less-harmful chemicals. This is in effect a complete secondary chemical reaction process after the combustion chemical

More to compliance than meets the eye

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process and must be developed and tuned so that it is effective.
And it requires that a number of parts be fitted to the engine.

Your readers therefore might soon have an SCR system to maintain as well as a DEF (diesel exhaust fluid) supply to regularly replenish as this fluid is consumed.

A second point would be regarding “the containers required to hold and burn oxidation catalysts.” One would not “burn” an oxidation catalyst but might have one fitted, which would indeed take up precious space on a vehicle. The benefit of a catalyst, however, is that it does not require maintenance as does a particulate filter—which collects the particulates and in addition to the regeneration process (which burns off the accumulated particles) still needs to be removed at some point(s) for a more thorough cleaning.

Readers therefore might benefit if a particular unit does not have a particulate filter fitted.

A final point is regarding “the effect of overheating on the combustion process.” This [phrase] is puzzling. The combustion process itself is what generates the heat and as mentioned, some engines now conduct this process at a higher level and therefore, more heat is generated. So often there is more heat that must be dealt with. Some of this would be directed through the cooling system—with larger cooling systems now required—and some would be radiated from the various engine components—with more thermal shielding being used both to direct the heat and to minimize operator exposure.

Readers should generally be aware of this and continue with their diligent maintenance of the cooling system to ensure that it’s operating at its best.