MIL-T-62276 Truck Tractor: Diesel Engine Driven, 80,000 Pounds Gvw, 145,000 Pounds Gcw, 8X4, Modified CommercialThis specification covers a tilt cab, diesel engine driven, eight-wheel, four-wheel drive truck tractor having a minimum gross cehicle weight GVW of 80,000 pounds and a minimum gross combination wight GCW of 145,000 pounds, for normal operating conditions.

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MIL-T-62276C

3.3 Performance.

3.3.1 Speeds and gradeability. High and low speed requirements shall be met with the vehicle loaded to the specified GCW.

3.3.1.1 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).

3.3.1.2 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.

3.3.1.3 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 deflection.

3.3.1.4 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.

* 3.3.2.1 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).