This section describes how to use the Greenhouse gas Emissions Model (GEM) simulation tool (incorporated by reference in Sec. 1037.810) to show compliance with the CO2 standards of Sec. Sec. 1037.105 and 1037.106. Use good engineering judgment when demonstrating compliance using the GEM.
(a) General modeling provisions. To run the GEM, enter all applicable inputs as specified by the model. All seven of the following inputs apply for sleeper cab tractors, while some do not apply for other regulatory subcategories:
(1) Regulatory subcategory (such as ``Class 8 Combination--Sleeper Cab--High Roof'').
(2) Coefficient of aerodynamic drag, as described in paragraph (b) of this section. Leave this field blank for vocational vehicles.
(3) Steer tire rolling resistance, as described in paragraph (c) of this section.
(4) Drive tire rolling resistance, as described in paragraph (c) of this section.
(5) Vehicle speed limit, as described in paragraph (d) of this section. Leave this field blank for vocational vehicles.
(6) Vehicle weight reduction, as described in paragraph (e) of this section. Leave this field blank for vocational vehicles.
(7) Extended idle reduction credit, as described in paragraph (f) of this section. Leave this field blank for vehicles other than Class 8 sleeper cabs.
(b) Coefficient of aerodynamic drag and drag area. Determine the appropriate drag area as follows:
(1) Use the recommended method or an alternate method to establish a value for the vehicle's drag area, expressed in m\2\ and rounded to two decimal places. Where we allow you to group multiple configurations together, measure the drag area of the worst-case configuration. Measure drag areas specified in Sec. 1037.521.
(2) Determine the bin level for your vehicle based on the drag area from paragraph (b)(1) of this section as shown in the following tables:
Table 1 to Sec. 1037.520--High-Roof Day and Sleeper Cabs------------------------------------------------------------------------
If your
measured CDA Then your CD
Bin level (m\2\) is . . input is . . .
.------------------------------------------------------------------------
High-Roof Day Cabs------------------------------------------------------------------------Bin I................................... =8. 0.79
0Bin II.................................. 7.1-7.9 0.72Bin III................................. 6.2-7.0 0.63Bin IV.................................. 5.6-6.1 0.56Bin V................................... <=5.5 0.51------------------------------------------------------------------------
High-Roof Sleeper Cabs------------------------------------------------------------------------Bin I................................... =7. 0.75
6Bin II.................................. 6.8-7.5 0.68Bin III................................. 6.3-6.7 0.60Bin IV.................................. 5.6-6.2 0.52Bin V................................... <=5.5 0.47------------------------------------------------------------------------
Table 2 to Sec. 1037.520-- Low-Roof Day and Sleeper Cabs----------------------------------------------------------------------------------------------------------------
If your measured CDA Then your CD input is . .
Bin level (m\2\) is . . . .----------------------------------------------------------------------------------------------------------------
Low-Roof Day and Sleeper Cabs----------------------------------------------------------------------------------------------------------------Bin I..................................................... =5.1 0.77Bin II.................................................... <=5.0 0.71----------------------------------------------------------------------------------------------------------------
Mid-Roof Day and Sleeper Cabs----------------------------------------------------------------------------------------------------------------Bin I..................................................... =5.6 0.87Bin II.................................................... <=5.5 0.82----------------------------------------------------------------------------------------------------------------
(3) For low- and mid-roof tractors, you may determine your drag area bin based on the drag area bin of an equivalent high-roof tractor. If the high-roof tractor is in Bin I or Bin II, then you may assume your equivalent low- and mid-roof tractors are in Bin I. If the high-roof tractor is in Bin III, Bin IV, or Bin V, then you may assume your equivalent low- and mid-roof tractors are in Bin II.
(c) Steer and drive tire rolling resistance. You must have a tire rolling resistance level (TRRL) for each tire configuration. For purposes of this section, you may consider tires with the same SKU number to be the same configuration.
(1) Measure tire rolling resistance in kg per metric ton as specified in ISO 28580 (incorporated by reference in Sec. 1037.810), except as specified in this paragraph (c). Use good engineering judgment to ensure that your test results are not biased low. You may ask us to identify a reference test laboratory to which you may correlate your test results. Prior to beginning the test procedure in Section 7 of ISO 28580 for a new bias-ply tire, perform a break-in procedure by running the tire at the specified test speed, load, and pressure for 602 minutes.
(2) For each tire design tested, measure rolling resistance of at least three different tires of that specific design and size. Perform the test at least once for each tire. Use the arithmetic mean of these results as your test result. You may use this value as your GEM input or select a higher TRRL. You must test at least one tire size for each tire model, and may use engineering analysis to determine the rolling resistance of other tire sizes of that model. Note that for tire sizes that you do not test, we will treat your analytically derived rolling resistances the same as test results, and we may perform our own testing to verify your values. We may require you to test a small sub-sample of untested tire sizes that we select.
(3) If you obtain your test results from the tire manufacturer or another third party, you must obtain a signed statement from them verifying the tests were conducted according to the requirements of this part. Such statements are deemed to be submissions to EPA.
(4) For tires marketed as light truck tires and that have load ranges C, D, or E, use as the GEM input TRRL at or above the measured rolling resistance multiplied by 0.87.
(d) Vehicle speed limit. If the vehicles will be equipped with a vehicle speed limiter, input the maximum vehicle speed to which the vehicle will be limited (in miles per hour rounded to the nearest 0.1 mile per hour) as specified in Sec. 1037.640. Otherwise leave this field blank. Use good engineering judgment to ensure the limiter is tamper resistant. We may require you to obtain preliminary approval for your designs.
(e) Vehicle weight reduction. For purposes of this paragraph (e), high-strength steel is steel with tensile strength at or above 350 MPa.
(1) Vehicle weight reduction inputs for wheels are specified relative to dual-wide tires with conventional steel wheels. For purposes of this paragraph (e)(1), a light-weight aluminum wheel is one that weighs at least 21 pounds less than a comparable conventional steel wheel. The inputs are listed in Table 3 to this section. For example, a tractor with aluminum steer wheels and eight (4 x 2) dual-wide aluminum drive wheels would have an input of 210 pounds (2 x 21 + 8 x 21).
Table 3 to Sec. 1037.520--Wheel-Related Weight Reductions------------------------------------------------------------------------
Weight
reduction (lb
Weight reduction technology per tire or
wheel)------------------------------------------------------------------------Single-Wide Drive Tire with
Steel Wheel......................................... 84
Aluminum Wheel...................................... 139
Light-Weight Aluminum Wheel......................... 147Steer Tire or Dual-wide Drive Tire with . . .
High-Strength Steel Wheel........................... 8
Aluminum Wheel...................................... 21
Light-Weight Aluminum Wheel......................... 30------------------------------------------------------------------------
(2) Vehicle weight reduction inputs for components other than wheels are specified relative to mild steel components as specified in the following table:
Table 4 to Sec. 1037.520--Nonwheel-Related Weight Reductions------------------------------------------------------------------------
High-strength
Weight reduction technologies Aluminum weight steel weight
reduction (lb) reduction (lb)------------------------------------------------------------------------Door............................ 20 6Roof............................ 60 18Cab rear wall................... 49 16Cab floor....................... 56 18Hood Support Structure System... 15 3Fairing Support Structure System 35 6Instrument Panel Support 5 1
Structure......................Brake Drums--Drive (4).......... 140 11Brake Drums--Non Drive (2)...... 60 8Frame Rails..................... 440 87Crossmember--Cab................ 15 5Crossmember--Suspension......... 25 6Crossmember--Non Suspension (3). 15 5Fifth Wheel..................... 100 25Radiator Support................ 20 6Fuel Tank Support Structure..... 40 12Steps........................... 35 6Bumper.......................... 33 10Shackles........................ 10 3Front Axle...................... 60 15Suspension Brackets, Hangers.... 100 30Transmission Case............... 50 12Clutch Housing.................. 40 10Drive Axle Hubs (8)............. 160 4Non Drive Front Hubs (2)........ 40 5Driveshaft...................... 20 5Transmission/Clutch Shift Levers 20 4------------------------------------------------------------------------
(3) You may ask to apply the innovative technology provisions of Sec. 1037.610 for weight reductions not covered by this paragraph (e).
(f) Extended idle reduction credit. If your tractor is equipped with idle reduction technology meeting the requirements of Sec. 1037.660 that will automatically shut off the main engine after 300 seconds or less, use 5.0 g/ton-mile as the input (or a lesser value specified in Sec. 1037.660). Otherwise leave this field blank. [76 FR 57398, Sept. 15, 2011, as amended at 78 FR 36392, June 17, 2013]