Download Tutorial 1 (Automobile Engineering) and more Exercises Automobile Engineering in PDF only on Docsity!
3.1 3.2 Tutorial 1 A vehicle weighs 20.02 KN (4500 Ib) and has a wheelbase of 279.4 cm (110 in.). The center of gravity is 127 cm (50 in.) behind the front, axle and 50.8 cm (20 in.) above ground level, The frontal area of the vehicle is 2.32 m? (25 ft” ) and the aerodynamic drag coefficient is 0.45. The cocfficient of rolling resistance is given by f-=0.013640.4x10" V*, where ’ is the speed of the vehicle in kilometers per hour. The rolling radius of the tires is 33 cm (13 in.). The cocfficient of road adhesion is 0.8. Estimate the possible maximum speed of the vehicle on level ground and on a grade of 25% as determined by the maximum tractive effort that the tire-road contact can support, if the vehicle is (a) tear-wheel-drive, and (b) front-wheel-drive. Plot the resultant resistance versus vehicle speed, and show the maximum: thrust of the vehicle with the two types of drive. The vehicle described in Problem 3.1 is equipped with an engine having torque-speed characteristics as shown in the following table. The gear ratios of the gearbox are: first, 4,03; second, 2.16; third. 1.37: and fourth, 1.0. The gear ratio of the drive axle is 3.54. The transmission efficiency is 88%. Estimate the maximum speed of the vehicle on lovel ground and on a grade of 25%, as determined by the tractive effort that the engine torque with the given transmission can provide, if the vehicle is rear-wheel-drive. Plot the vehicle thrust in various gears versus vehicle speed. Engine Characteristics . Engine speed, rpm_ 500 :1000__1750_ 2500 3000 3500 4000 4500 5000 Engine torque, N-m 339 379.7 406.8 393.2 363.4 325.4 284.8 233.2 1808
