The procedures in this part generally follow either the International System of Units (SI) or the United States customary units, as detailed in NIST Special Publication 811 (incorporated by reference, see § 1037.810 ). See 40 CFR 1065.20 for specific provisions related to these conventions. This section summarizes the way we use symbols, units of measure, and other abbreviations.
Table 1 to Paragraph (a) of § 1037.805 -Symbols for Chemical Species and Exhaust Constituents
Symbol | Species |
C | carbon. |
CH4 | methane. |
CO | carbon monoxide. |
CO2 | carbon dioxide. |
H2 O | water. |
HC | hydrocarbon. |
NMHC | nonmethane hydrocarbon. |
NMHCE | nonmethane hydrocarbon equivalent. |
NO | nitric oxide. |
NO2 | nitrogen dioxide. |
NOX | oxides of nitrogen. |
N2 O | nitrous oxide. |
PM | particulate matter. |
THC | total hydrocarbon. |
THCE | total hydrocarbon equivalent. |
Table 2 to Paragraph (b) of § 1037.805 -Symbols for Quantities
Symbol | Quantity | Unit | Unit symbol | Unit in terms of SI base units |
A | vehicle frictional load | pound force or newton | lbf or N | kg·m·s-2. |
a | axle position regression coefficient | |||
[ALPHA] | atomic hydrogen-to-carbon ratio | mole per mole | mol/mol | 1. |
[ALPHA] | axle position regression coefficient | |||
[ALPHA]0 | intercept of air speed correction | |||
[ALPHA]1 | slope of air speed correction | |||
ag | acceleration of Earth's gravity | meters per second squared | m/s2 | m·s-2. |
a0 | intercept of least squares regression | |||
a1 | slope of least squares regression | |||
B | vehicle load from drag and rolling resistance | pound force per mile per hour or newton second per meter | lbf/(mi/hr) or N·s/m | kg·s-1. |
b | axle position regression coefficient | |||
[BETA] | atomic oxygen-to-carbon ratio | mole per mole | mol/mol | 1. |
[BETA] | axle position regression coefficient | |||
[BETA]0 | intercept of air direction correction | |||
[BETA]1 | slope of air direction correction | |||
C | vehicle-specific aerodynamic effects | pound force per mile per hour squared or newton-second squared per meter squared | lbf/mph2 or N·s2/m2 | kg·m-1. |
c | axle position regression coefficient | |||
ci | axle test regression coefficients | |||
Ci | constant | |||
[DELTA]CdA | differential drag area | meter squared | m2 | m2. |
CdA | drag area | meter squared | m2 | m2. |
Cd | drag coefficient | |||
CF | correction factor | |||
Crr | coefficient of rolling resistance | newton per kilonewton | N/kN | 10-3. |
D | distance | miles or meters | mi or m | m. |
e | mass-weighted emission result | grams per ton-mile | g/ton-mi | g/kg-km. |
Eff | efficiency | |||
F | adjustment factor | |||
F | force | pound force or newton | lbf or N | kg·m·s-2. |
fn | angular speed (shaft) | revolutions per minute | r/min | [PI]·30·s-1. |
G | road grade | percent | % | 10-2. |
g | gravitational acceleration | meters per second squared | m/s2 | m·s-2. |
h | elevation or height | meters | m | m. |
i | indexing variable | |||
ka | drive axle ratio | 1. | ||
kd | transmission gear ratio | |||
ktopgear | highest available transmission gear | |||
L | load over axle | pound force or newton | lbf or N | kg·m·s-2. |
m | mass | pound mass or kilogram | lbm or kg | kg. |
M | molar mass | gram per mole | g/mol | 10-3·kg·mol-1. |
M | vehicle mass | kilogram | kg | kg. |
Me | vehicle effective mass | kilogram | kg | kg. |
Mrotating | inertial mass of rotating components | kilogram | kg | kg. |
N | total number in series | |||
n | number of tires | |||
n | amount of substance rate | mole per second | mol/s | mol·s-1. |
P | power | kilowatt | kW | 103·m2·kg·s- 3. |
p | pressure | pascal | Pa | kg·m-1·s-2. |
[RHO] | mass density | kilogram per cubic meter | kg/m3 | kg·m-3. |
PL | payload | tons | ton | kg. |
[PHI] | direction | degrees | ° | °. |
[PSI] | direction | degrees | ° | °. |
r | tire radius | meter | m | m. |
r2 | coefficient of determination | |||
Re# | Reynolds number | |||
SEE | standard error of the estimate | |||
A | standard deviation | |||
TRPM | tire revolutions per mile | revolutions per mile | r/mi | |
TRRL | tire rolling resistance level | newton per kilonewton | N/kN | 10-3. |
T | absolute temperature | kelvin | K | K. |
T | Celsius temperature | degree Celsius | °C | K-273.15. |
T | torque (moment of force) | newton meter | N·m | m2·kg·s-2. |
t | time | hour or second | hr or s | s. |
[DELTA]t | time interval, period, 1/frequency | second | s | s. |
UF | utility factor | |||
v | speed | miles per hour or meters per second | mi/hr or m/s | m·s-1. |
w | weighting factor | |||
w | wind speed | miles per hour | mi/hr | m·s-1. |
W | work | kilowatt-hour | kW·hr | 3.6·m2·kg·s-1. |
wC | carbon mass fraction | gram per gram | g/g | 1. |
WR | weight reduction | pound mass | lbm | kg. |
x | amount of substance mole fraction | mole per mole | mol/mol | 1. |
Table 3 to § 1037.805 -Superscripts
Superscript | Meaning |
overbar (such as y) | arithmetic mean. |
Double overbar (such as y) | arithmetic mean of arithmetic mean. |
overdot (such as y) | quantity per unit time. |
Table 4 to Paragraph (d) of § 1037.805 -Subscripts
Subscript | Meaning |
±6 | ±6° yaw angle sweep. |
A | A speed. |
air | air. |
aero | aerodynamic. |
alt | alternative. |
act | actual or measured condition. |
air | air. |
axle | axle. |
B | B speed. |
brake | brake. |
C | C speed. |
Ccombdry | carbon from fuel per mole of dry exhaust. |
CD | charge-depleting. |
circuit | circuit. |
CO2 DEF | CO2 resulting from diesel exhaust fluid decomposition. |
CO2 PTO | CO2 emissions for PTO cycle. |
coastdown | coastdown. |
comp | composite. |
CS | charge-sustaining. |
cycle | test cycle. |
drive | drive axle. |
drive-idle | idle with the transmission in drive. |
driver | driver. |
dyno | dynamometer. |
effective | effective. |
end | end. |
eng | engine. |
event | event. |
fuel | fuel. |
full | full. |
grade | grade. |
H2 Oexhaustdry | H2 O in exhaust per mole of exhaust. |
hi | high. |
i | an individual of a series. |
idle | idle. |
in | inlet. |
inc | increment. |
lo | low. |
loss | loss. |
max | maximum. |
meas | measured quantity. |
med | median. |
min | minimum. |
moving | moving. |
out | outlet. |
P | power. |
pair | pair of speed segments. |
parked-idle | idle with the transmission in park. |
partial | partial. |
ploss | power loss. |
plug-in | plug-in hybrid electric vehicle. |
powertrain | powertrain. |
PTO | power take-off. |
rated | rated speed. |
record | record. |
ref | reference quantity. |
RL | road load. |
rotating | rotating. |
seg | segment. |
speed | speed. |
spin | axle spin loss. |
start | start. |
steer | steer axle. |
t | tire. |
test | test. |
th | theoretical. |
total | total. |
trac | traction. |
trac10 | traction force at 10 mi/hr. |
trailer | trailer axle. |
transient | transient. |
TRR | tire rolling resistance. |
UF | utility factor. |
urea | urea. |
veh | vehicle. |
w | wind. |
wa | wind average. |
yaw | yaw angle. |
ys | yaw sweep. |
zero | zero quantity. |
Table 5 to Paragraph (e) of § 1037.805 -Other Acronyms and Abbreviations
Acronym | Meaning |
ABT | averaging, banking, and trading. |
AECD | auxiliary emission control device. |
AES | automatic engine shutdown. |
APU | auxiliary power unit. |
CD | charge-depleting. |
CFD | computational fluid dynamics. |
CFR | Code of Federal Regulations. |
CITT | curb idle transmission torque. |
CS | charge-sustaining. |
DOT | Department of Transportation. |
EPA | Environmental Protection Agency. |
FEL | Family Emission Limit. |
GAWR | gross axle weight rating. |
GCWR | gross combination weight rating. |
GEM | greenhouse gas emission model. |
GVWR | gross vehicle weight rating. |
Heavy HDE | heavy heavy-duty engine (see 40 CFR 1036.140 ). |
Heavy HDV | heavy heavy-duty vehicle (see § 1037.140 ). |
HVAC | heating, ventilating, and air conditioning. |
ISO | International Organization for Standardization. |
Light HDE | light heavy-duty engine (see 40 CFR 1036.140 ). |
Light HDV | light heavy-duty vehicle (see § 1037.140 ). |
Medium HDE | medium heavy-duty engine (see 40 CFR 1036.140 ). |
Medium HDV | medium heavy-duty vehicle (see § 1037.140 ). |
NARA | National Archives and Records Administration. |
NHTSA | National Highway Transportation Safety Administration. |
PTO | power take-off. |
RESS | rechargeable energy storage system. |
SAE | SAE International. |
SEE | standard error of the estimate. |
SKU | stock-keeping unit. |
Spark-ignition HDE | spark-ignition heavy-duty engine (see 40 CFR 1036.140 ). |
TRPM | tire revolutions per mile. |
TRRL | tire rolling resistance level. |
U.S.C | United States Code. |
VSL | vehicle speed limiter. |
Table 6 to Paragraph (f) of § 1037.805 -Constants
Symbol | Quantity | Value |
g | gravitational constant | 9.80665 m·-2. |
R | specific gas constant | 287.058 J/(kg·K). |
Table 7 to Paragraph (g) of § 1037.805 -Prefixes
Symbol | Quantity | Value |
[MICRO] | micro | 10-6 |
m | milli | 10-3 |
c | centi | 10-2 |
k | kilo | 103 |
M | mega | 106 |
40 C.F.R. §1037.805