Until now, only PM and NOx were considered, but carbon dioxide (CO2) was omitted from the calculations. The newest emission requirements, or GHG 2014, involve CO2 and fuel efficiency.
The new metrics will be based on work done, not just power produced. CO2 emissions will be measured in grams per ton mile. Fuel economy will also be measured per ton mile. The goal is to reduce CO2 and diesel consumed by 20% from 2014-17. More reductions will take effect for model years 2018 and beyond.
Vehicle and engine builders have had typical on-highway and vocational truck configurations benchmarked to account for varying marketplace needs. It would be improper and inaccurate to use one set of ton-mile figures for on-highway and all the variations and sizes of vocational trucks.
Even using the National Highway Traffic Safety Administration’s established weight classes would fail to account for application differences in Class 8 (33,000 pounds and greater gross vehicle weight rating/gross trailer weight rating) trucks alone. Freight trailers and dump trailers differ widely, as do tanks and equipment haulers. Not only are they configured differently with different aerodynamics and other characteristics; their operating profiles vary widely.
With EPA 2004, 2007, and 2010 regulations, emissions could be measured at the tailpipe. There were absolute limits. But GHG 2014 regulations allow for vocational variations. It would be unfair to measure a tractor pulling a van trailer with the same yardstick as a ready-mix truck. That is why truck builders and engine makers average their results.
The vehicle classes for EPA/NHTSA 2014 regulations differ from standard Classes 1 through 8. They account for truck configurations and applications as well as weight.Five of the 10 new classes involve Class 8 (by weight) vehicles, varying by cab configurations. Only one of those five should concern us: the EPA Class 8, defined as (weight) Class 8 vocational trucks. EPA Class 9 includes (weight) Class 6 and 7 vocational trucks, while the new Class 10 includes (weight) Classes 2b through 5 vocational trucks.Vocational, or work trucks are considered “heavy heavy-duty,” “medium heavy-duty,” or “light heavy-duty.” (Most ready-mix trucks will be heavy heavy-duty trucks.) Virtually every diesel-powered vehicle we use, from service vehicles based on pickup trucks to heavy dump trucks, prime movers and ready-mix trucks, is covered.GHG-certified vehicles will have compliance stickers on the door, showing the GHG technologies delivered with the particular truck. The sticker and the listed technologies must remain on the truck throughout its useful life, defined as 10 years for all, and 110,000 miles for light heavy-duty trucks, 185,000 miles for medium heavy-duty trucks and 435,000 miles for heavy heavy-duty trucks.
EPA states, “Not every truck has to be compliant, but every truck has to be certified. It’s up to the OEM to ensure they have enough adoption of those [advanced] technologies across the fleet.” Technologies available to users run from low rolling resistance and wide base single tires to natural gas or hybrid power.
The OEM must demonstrate the value of various technologies to the buyer. Then the OEM can average the mileage improvements and CO2 reduction over the entire range of trucks sold. Not all trucks sold as certified may meet GHG 2014 reduction targets, but they will be averaged with those that do.
Technologies will be grouped according to application, as engine- or vehicle-related. For example, biofuels, alternative fuels, and fuel management technologies will be measured according to use-specific test cycles. Those results will determine an engine’s certification of meeting its CO2 standard.
Using results of coast-down and other forms of testing, EPA assigned baseline values to trucks and efficiency values for devices to be added or removed from trucks. These could include weight reduction, fuel-efficient tires, idle timers, and vehicle speed limiters.
It will be up to vehicle operators to maintain each vehicle in its as-purchased condition. On-board diagnostics assure against malfunctions in vehicle operations compared to its original condition.
Any malfunction or variance in any of 38 systems being monitored will be recorded in the engine computer. It could violate federal regulations if not addressed in a timely manner. Transient malfunctions such as temporary stoppage of diesel exhaust fluid flow at start-up if the fluid is frozen will be recorded and stored, even if the malfunction indicator light goes out when the fluid thaws. When the malfunction indicator or check-engine light stays on, the truck should be taken to the shop.
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