Caterpillar Performance Handbook, January 2017, SEBD0351-47

Engine Selection

On-Highway Trucks

Air Resistance: The HP required to overcome wind resis- tance. This starts becoming significant above 30 MPH. Over 65 MPH it can be the largest single load.

Cd = Aerodynamic Drag Coefficient. See table below. FA = Frontal Area of the Truck (sq ft) + Area of the body or trailer that is wider or taller than the Truck. If the trailer is more than eight feet behind the Truck, FA = the Frontal Area of the Truck + the Total Frontal area of the Trailer. See illustra- tion below. 156,000 = Constant. MPH = Desired Cruise Speed (not maximum speed).

FA × Cd × MPH 3 156,000

Pa =

Aerodynamic Drag Coefficients Configuration HD Tractor — Full Aero/Van Trailer Full Aero HD Tractor — Full Aero/Van Trailer Typical

Factor

0.42 0.48 0.50 0.54 0.55 0.55 0.80 0.80 0.80 0.80 0.80 0.90 0.90 1.00 1.00

73 sq ft

MD Van Truck — Full Aero

HD Tractor — Full Aero/Van Trailer some Aero HD Tractor — Full Aero/Tank Trailer Insulated

8.7 ft

HD Tractor — Full Aero/Flat Trailer some Aero (Smooth Load)

HD Tractor — Full Aero/Van Trailer no Aero

HD Tractor — Full Aero/Flat Trailer some Aero (Rough Load) HD Tractor — Full Aero/Tank Trailer Non Insulated

HD Tractor — No Aero/Van Trailer no Aero

MD Van Truck — No Aero

HD Dump

MD Dump — No Aero HD Tractor — Car Hauler

8.4 ft

HD Tractor — No Aero/Flat Trailer some Aero

CT660

Aero refers to side panels and deflectors to make the Truck more aerodynamic.

Gradeability: The reserve HP required to operate indefi- nitely (without downshifting) at the desired cruise speed on a small grade between 0.5% – 1% Grade.

G = Grade Percent (Typically 0.5 or 1). GW = Desired Gross Vehicle Weight or Gross Combi- nation Weight. 37,500 = Constant. MPH = Desired Cruise Speed (not maximum speed).

G × GW × MPH 37,500

Pg =

12-20 Edition 47