AFWD vehicle has the following data:

Rear axle weight: 1200 lb

Wheelbase: 105 in.

Front axle weight: 1750 lb

Center of gravity height: 15 in.

Air drag coefficient: 0.30

Tire radius: 11.40 in.

Max. power @6000 RPM: 138 HP

Powertrain efficiency: 0.96

A six-speed manual transmission is used for the vehicle and the gear ratios from 1st to 4th gears are: 1st gear (3.92),

2nd gear (2.76), 3rd gear (1.85), 4th gear (1.35). The engine WOT output plot is as given in Elgure 1.3.

Frontal projected area: 22.0 square feet

Roll resistance coefficient: 0.02

Max. torque @4500 RPM: 132 ft.lb

Final drive ratio: 3.143

a. The vehicle runs in the 5th gear at a speed of 55 mph with the engine speed at 2450 RPM. The driver then makes

a 5-6 upshift and the engine RPM drops by 500 RPM Immediately after the shift. Determine the 5th and the 6th

gear ratios.

b. Determine the engine torque and work done by the engine when the vehicle cruises for 1.5 miles at a constant

speed of 65 mph on level ground in the 6th and 5th gears respectively.

c. The driver floors the gas pedal and simultaneously makes a 6-5 downshift when

a speed of 65 mph. Determine the vehicle acceleration immediately after the 6-5

the vehicle runs on a 3% slope at

downshift.

d. What is the steepest percentage slope the vehicle can negotiate at a speed of 70 mph?

COP

com