{"data":{"id":"us/40-cfr-appendix-ii-to-part-1039","jurisdiction":"us","citation":"40 CFR Appendix II to Part 1039","heading":"Appendix II to Part 1039—Steady-State Duty Cycles","body":"(a) The following duty cycles apply for constant-speed engines:\n(1) The following duty cycle applies for discrete-mode testing:\nD2 mode number Engine speed Torque (percent) 1 Weighting factors\n1 Engine governed 100 0.05\n2 Engine governed 75 0.25\n3 Engine governed 50 0.30\n4 Engine governed 25 0.30\n5 Engine governed 10 0.10\n1 The percent torque is relative to maximum test torque.\n(2) The following duty cycle applies for ramped-modal testing:\nRMC mode Time in mode (seconds) Engine speed Torque (percent) 1 2\n1a Steady-state 53 Engine governed 100.\n1b Transition 20 Engine governed Linear transition.\n2a Steady-state 101 Engine governed 10.\n2b Transition 20 Engine governed Linear transition.\n3a Steady-state 277 Engine governed 75.\n3b Transition 20 Engine governed Linear transition.\n4a Steady-state 339 Engine governed 25.\n4b Transition 20 Engine governed Linear transition.\n5 Steady-state 350 Engine governed 50.\n1 The percent torque is relative to maximum test torque.\n2 Advance from one mode to the next within a 20-second transition phase. During the transition phase, command a linear progression from the torque setting of the current mode to the torque setting of the next mode.\n(b) The following duty cycles apply for variable-speed engines with maximum engine power below 19 kW:\n(1) The following duty cycle applies for discrete-mode testing:\nG2 mode number Engine speed 1 Torque (percent) 2 Weighting factors\n1 Maximum test speed 100 0.09\n2 Maximum test speed 75 0.20\n3 Maximum test speed 50 0.29\n4 Maximum test speed 25 0.30\n5 Maximum test speed 10 0.07\n6 Warm idle 0 0.05\n1 Speed terms are defined in 40 CFR part 1065.\n2 The percent torque is relative to the maximum torque at the commanded test speed.\n(2) The following duty cycle applies for ramped-modal testing:\nRMC mode Time in mode (seconds) Engine speed 1 3 Torque (percent) 2 3\n1a Steady-state 41 Warm idle 0.\n1b Transition 20 Linear transition Linear transition.\n2a Steady-state 135 Maximum test speed 100.\n2b Transition 20 Maximum test speed Linear transition.\n3a Steady-state 112 Maximum test speed 10.\n3b Transition 20 Maximum test speed Linear transition.\n4a Steady-state 337 Maximum test speed 75.\n4b Transition 20 Maximum test speed Linear transition.\n5a Steady-state 518 Maximum test speed 25.\n5b Transition 20 Maximum test speed Linear transition.\n6a Steady-state 494 Maximum test speed 50.\n6b Transition 20 Linear transition Linear transition.\n7 Steady-state 43 Warm idle 0.\n1 Speed terms are defined in 40 CFR part 1065.\n2 The percent torque is relative to the maximum torque at the commanded engine speed.\n3 Advance from one mode to the next within a 20-second transition phase. During the transition phase, command a linear progression from the torque setting of the current mode to the torque setting of the next mode, and simultaneously command a similar linear progression for engine speed if there is a change in speed setting.\n(c) The following duty cycles apply for variable-speed engines with maximum engine power at or above 19 kW:\n(1) The following duty cycle applies for discrete-mode testing:\nC1 mode number Engine speed 1 Torque (percent) 2 Weighting factors\n1 Maximum test speed 100 0.15\n2 Maximum test speed 75 0.15\n3 Maximum test speed 50 0.15\n4 Maximum test speed 10 0.10\n5 Intermediate test speed 100 0.10\n6 Intermediate test speed 75 0.10\n7 Intermediate test speed 50 0.10\n8 Warm idle 0 0.15\n1 Speed terms are defined in 40 CFR part 1065.\n2 The percent torque is relative to the maximum torque at the commanded test speed.\n(2) The following duty cycle applies for ramped-modal testing:\nRMC mode Time in mode (seconds) Engine speed 1 3 Torque (percent) 2 3\n1a Steady-state 126 Warm Idle 0.\n1b Transition 20 Linear Transition Linear Transition.\n2a Steady-state 159 Intermediate Speed 100.\n2b Transition 20 Intermediate Speed Linear Transition.\n3a Steady-state 160 Intermediate Speed 50.\n3b Transition 20 Intermediate Speed Linear Transition.\n4a Steady-state 162 Intermediate Speed 75.\n4b Transition 20 Linear Transition Linear Transition.\n5a Steady-state 246 Maximum Test Speed 100.\n5b Transition 20 Maximum Test Speed Linear Transition.\n6a Steady-state 164 Maximum Test Speed 10.\n6b Transition 20 Maximum Test Speed Linear Transition.\n7a Steady-state 248 Maximum Test Speed 75.\n7b Transition 20 Maximum Test Speed Linear Transition.\n8a Steady-state 247 Maximum Test Speed 50.\n8b Transition 20 Linear Transition Linear Transition.\n9 Steady-state 128 Warm Idle 0.\n1 Speed terms are defined in 40 CFR part 1065.\n2 The percent torque is relative to the maximum torque at the commanded engine speed.\n3 Advance from one mode to the next within a 20-second transition phase. During the transition phase, command a linear progression from the torque setting of the current mode to the torque setting of the next mode, and simultaneously command a similar linear progression for engine speed if there is a change in speed setting.","path":["Title 40—Protection of Environment","CHAPTER I—ENVIRONMENTAL PROTECTION AGENCY","SUBCHAPTER U—AIR POLLUTION CONTROLS","PART 1039—CONTROL OF EMISSIONS FROM NEW AND IN-USE NONROAD COMPRESSION-IGNITION 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":"24ad90a59df61e57dafb78a36084144b17d4b0dd6c0e96f35a8a5e4916cbdcb4","source_id":"us-cfr","stale":true,"prev":"us/40-cfr-appendix-i-to-part-1039","next":"us/40-cfr-appendixes-iii-v-to-part-1039"},"notice":"GroundRules: Original legal text. Not legal advice."}