3.3.1 Speeds and gradeability. High and low speed requirements shall be met with the vehicle
loaded to the specified GCW.
184.108.40.206 High speed gradeabilitiy. The vehicle shall ascend a continuous grade of 0.22 percent
at 50 mph. Gradeability requirements shall be met with the main transmission in direct drive, and
with the axles in high speed range. Gradeability shall be verified with calculations in accordance
with SAE J688 (see 6.3).
220.127.116.11 Low speed gradeability. The vehicle shall ascend a continuous grade of 7.0 percent at
5 mph. The vehicle shall be capable of making a complete stop while ascending a 7.0 percent
grade and accelerating from stopped position to 5 mph up the 7.0 percent grade. Gradeability
requirements shall be met with the transmission and axle in low speed range. Gradeability shall be
verified with calculations in accordance with SAE J688.
18.104.22.168 Low speed. Low speed shall be calculated in forward and in reverse with the engine
operating at not less than 35 percent of recommended governed speed, and shall provide a vehicle
speed of not more than 10 feet per minute. In lieu of calculations, low speed requirement may be
demonstrated with driver assistance. The vehicle shall be capable of sustaining a load of 87,000
pounds at the fifth wheel, gradually reducing to 54,200 pounds at the fifth wheel while the
tractor-semitrailer combination is moving at 10 feet per minute over a distance of 40 feet. Loads
shall be sustained without the permanent deformation or failure of any part and without excessive
22.214.171.124 Maximum geared speed. The maximum geared speed at engine governed speed shall
be not less than 55 mph. Conformance to geared speed specified shall be determined by
calculating in accordance with the following formula:
Maximum geared speed (mph) =
Governed speed (rpm)
Total gear reduction x tire factor (see 6.3).
3.3.2 Service brakes. The service brakes shall control and hold the vehicle, when loaded to
its specified GVW, on a 30 percent grade. The service brakes shall stop the tractor-semitrailer
combination, loaded to specified GCW, within the stopping distance requirements of Federal
Motor Carrier Safety Regulation 393.52.
* 126.96.36.199 Emergency brakes. The emergency brakes shall stop the tractor-semitrailer
combination, loaded to specify GCW, within the stopping distance requirements of Federal Motor
Carrier Safety Regulation 393.52(b).