A vehicle of the following data is equipped with a 4-speed AT. The ratios are: 2.84(1), 1.60(2nd), 1.0(3rd),

0.7(4th). The final drive ratio is 2.84. The torque converter has the characteristics as shown. The engine

WOT output torque is also shown. The vehicle is being driven at WOT on level ground in the first gear

with the torque converter unlocked.

a) Plot the engine torque capacity factor at WOT versus engine RPM.

b)

Suppose the vehicle is launched with WOT and the vehicle is braked until the engine and torque

converter reach dynamic balance in the joint operation, determine the vehicle acceleration at launch.

c) Determine the vehicle speed and acceleration when the torque converter speed ratio is 0.6.

d) What are the vehicle speed and acceleration when the torque converter becomes a fluid couple?

Vehicle Data

Vehicle weight: 3400 lbs

Center of gravity height: 16 inch

Air drag coefficient: 0.30

Tire radius: 12.0 in.

Powertrain efficiency: 0.86

Wheel base: 108 in.

Frontal projected area: 22 square feet

Roll resistance coefficient: 0.02/n(

Torque 250

(ft.lb)

200

150

100

50

0

1000

torque

2000

Max. Torque

Max. Power

3000 4000 5000

237.5 (HP)

190

6000 7000

Power

142.5

95

47.5

Max. Power:

200 нрат 5500 rpm

Mex. Torgne:

199 ft.bat 3850RPM

RPM/n3:0

40-

K: capacity)

10- factor

1: efficiting

2.0 100

1.8

go.

6

#

2.

1.0

8.8

08

Z

1. Togatio

175

~

e

R

8

3

9

8

3

O

Torque Ratio

www.pre

200

S

wpmengs

150

125-

100

FK

75-

50%

3

0.

unit fork.. Mini

IXI

N

Compting point

1

(minute), ft·lb

•Efficiency

pead ratio

0.2

LO

0.4

V 0.6

af

Torgne Converter Characteristic plot