{"data":{"id":"us/40-cfr-1037.320","jurisdiction":"us","citation":"40 CFR 1037.320","heading":"Audit procedures for axles and transmissions.","body":"Selective enforcement audit provisions apply for axles and transmissions relative to the efficiency demonstrations of §§ 1037.560 and 1037.565 as specified in this section. The following provisions apply instead of 40 CFR 1068.415 through 1068.445 for the selective enforcement audit.\n(a) A selective enforcement audit for axles or transmissions would consist of performing measurements with a production axle or transmission to determine mean power loss values as declared for GEM simulations, and running GEM over one or more applicable duty cycles based on those measured values. The axle or transmission is considered passing for a given configuration if the new modeled emission result for every applicable duty cycle is at or below the modeled emission result corresponding to the declared GEM inputs.\n(b) Run GEM with the define vehicles to determine whether the transmission or axle family passes the audit.\n(1) For transmission audits, run GEM for each applicable vehicle configuration and GEM regulatory subcategory identified in 40 CFR 1036.540 and for each vehicle class as defined in § 1037.140(g) using the applicable default engine map in appendix C of 40 CFR part 1036, the cycle-average fuel map in Table 1 of this section, the torque curve in Table 2 of this section for both the engine full-load torque curve and parent engine full-load torque curve, the motoring torque curve in Table 3 of this section, the idle fuel map in Table 4 of this section. For transmission testing, use the test transmission's gear ratios in place of the gear ratios defined in 40 CFR 1036.540. Table 1 through Table 4 follow:\nTable 1 to Paragraph (b)(1) of § 1037.320—Transient Cycle-Average Fuel Map by Vehicle Class\nLight HDV and medium HDV—spark-ignition Light HDV and medium HDV—compression-ignition Heavy HDV\nEngine cycle work (kW·hr) N/V (r/min) Fuel mass (g) Idle speed (r/min) Idle torque (N·m) Engine cycle work (kW·hr) N/V (r/min) Fuel mass (g) Idle speed (r/min) Idle torque (N·m) Engine cycle work (kW·hr) N/V (r/min) Fuel mass (g) Idle speed (r/min) Idle torque (N·m)\n3.5404 2.8739 1109.31 600.5 37.997 3.3057 2.3317 919.01 750.3 36.347 11.4255 2.3972 2579.58 600.7 89.658\n3.6574 3.0198 1153.35 600.4 37.951 3.3822 2.5075 982.53 750.2 36.461 11.6112 2.2432 2591.08 601.2 90.428\n3.8119 3.0370 1188.66 600.2 37.956 3.4917 2.5320 998.64 750.2 36.608 12.5052 2.1620 2763.28 602.4 92.014\n4.0121 3.1983 1250.76 600.1 38.153 3.6087 2.6181 1036.34 750.2 36.734 17.7747 2.5195 3835.77 602.2 91.780\n5.5567 3.1325 1585.32 604.6 56.535 5.2397 2.5050 1354.33 753.0 51.992 18.4901 2.4155 3994.29 603.5 93.724\n5.6814 3.2956 1639.08 604.0 56.549 5.3153 2.7289 1417.20 751.9 51.488 20.1904 2.3800 4374.06 605.1 96.340\n5.8720 3.3255 1686.14 602.5 56.234 5.4112 2.6689 1416.75 751.3 51.280\n6.1774 3.4848 1773.39 601.7 56.038 5.5590 2.7231 1450.67 751.0 51.254\nTable 2 to Paragraph (b)(1) of § 1037.320—Full-Load Torque Curves by Vehicle Class\nLight HDV and medium HDV— spark-ignition Light HDV and medium HDV— compression-ignition Heavy HDV\nEngine speed (r/min) Engine torque (N·m) Engine speed (r/min) Engine torque (N·m) Engine speed (r/min) Engine torque (N·m)\n600 433 750 470 600 1200\n700 436 907 579 750 1320\n800 445 1055 721 850 1490\n900 473 1208 850 950 1700\n1000 492 1358 876 1050 1950\n1100 515 1507 866 1100 2090\n1200 526 1660 870 1200 2100\n1300 541 1809 868 1250 2100\n1400 542 1954 869 1300 2093\n1500 542 2105 878 1400 2092\n1600 542 2258 850 1500 2085\n1700 547 2405 800 1520 2075\n1800 550 2556 734 1600 2010\n1900 551 2600 0 1700 1910\n2000 554 1800 1801\n2100 553 1900 1640\n2200 558 2000 1350\n2300 558 2100 910\n2400 566 2250 0\n2500 571\n2600 572\n2700 581\n2800 586\n2900 587\n3000 590\n3100 591\n3200 589\n3300 585\n3400 584\n3500 582\n3600 573\n3700 562\n3800 555\n3900 544\n4000 534\n4100 517\n4200 473\n4291 442\n4500 150\nTable 3 to Paragraph (b)(1) of § 1037.320—Motoring Torque Curves by Vehicle Class\nLight HDV and medium HDV— spark-ignition Light HDV and medium HDV— compression-ignition Heavy HDV\nEngine speed (r/min) Engine torque (N·m) Engine speed (r/min) Engine torque (N·m) Engine speed (r/min) Engine torque (N·m)\n700 −41 750 −129 600 −98\n800 −42 907 −129 750 −121\n900 −43 1055 −130 850 −138\n1000 −45 1208 −132 950 −155\n1100 −48 1358 −135 1050 −174\n1200 −49 1507 −138 1100 −184\n1300 −50 1660 −143 1200 −204\n1411 −51 1809 −148 1250 −214\n1511 −52 1954 −155 1300 −225\n1611 −53 2105 −162 1400 −247\n1711 −56 2258 −170 1500 −270\n1811 −56 2405 −179 1520 −275\n1911 −57 2556 −189 1600 −294\n2011 −57 1700 −319\n2111 −58 1800 −345\n2211 −60 1900 −372\n2311 −65 2000 −400\n2411 −81 2100 −429\n2511 −85\n2611 −87\n2711 −88\n2811 −89\n2911 −91\n3011 −91\n3111 −96\n3211 −96\n3311 −97\n3411 −98\n3511 −99\n3611 −104\n3711 −105\n3811 −108\n3911 −108\n4011 −111\n4111 −111\n4211 −115\n4291 −112\nTable 4 to Paragraph (b)(1) of § 1037.320—Engine Idle Fuel Maps by Vehicle Class\nLight HDV and medium HDV—spark-ignition Light HDV and medium HDV—compression-ignition Heavy HDV\nEngine speed (r/min) Engine torque (N·m) Fuel mass rate (g/s) Engine speed (r/min) Engine torque (N·m) Fuel mass rate (g/s) Engine speed (r/min) Engine torque (N·m) Fuel mass rate (g/s)\n600 0 0.4010 750 0 0.2595 600 0 0.3501\n700 0 0.4725 850 0 0.2626 700 0 0.4745\n600 100 0.6637 750 100 0.6931 600 100 0.6547\n700 100 0.7524 850 100 0.7306 700 100 0.8304\n(2) Follow the procedure in paragraph (b)(1) of this section for axle audits, but cover the range of tire sizes by using good engineering judgment to select three representative tire sizes for each axle ratio for each vehicle configuration instead of using the tire size determined in 40 CFR 1036.540.\n(3) The GEM “Default FEL CO2 Emissions” result for each vehicle configuration counts as a separate test for determining whether the family passes the audit. For vocational vehicles, use the GEM “Default FEL CO2 Emissions” result for the Regional subcategory.\n(c) If the initial axle or transmission passes, the family passes and no further testing is required. If the initial axle or transmission does not pass, select two additional production axles or transmissions, as applicable, to perform additional tests. Note that these could be different axle and transmission configurations within the family. These become official test results for the family. Use good engineering judgment to use the results of these tests to update the declared maps for the axle or transmission family. For example, if you fail the audit test for any of the axles or transmissions tested, the audit result becomes the declared map. This may also require revising any analytically derived maps.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER U—AIR POLLUTION CONTROLS","PART 1037—CONTROL OF EMISSIONS FROM NEW HEAVY-DUTY MOTOR VEHICLES","Subpart D—Testing Production Vehicles and Engines"],"source_url":"https://www.ecfr.gov/api/versioner/v1/full/2026-08-25/title-40.xml","current_through":"2026-08-25","vintage":"","retrieved_at":"2026-08-27T02:26:04Z","sha256":"a940db5b71a191e18d7968a710237dc472b4391ae85d3b7a2132f3f36a79c2d8","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-1037.315","next":"us/40-cfr-1037.401"},"notice":"GroundRules: Original legal text. Not legal advice."}