Exam 2 B

Automotive Engineering I

2nd semester of 1428-29

Student Name:                                                                        Student Class No.:

 

1) A- What are the functions and types of the following units of the transmission?

 

Functions

Types

Propeller shaft

-

-

-

-

Axle

-

-

-

-

 

1) B- If the input to gear A is equal to:

 Ninput = NA= 5000 rpm, Tinput = TA= 180 N.m, hg= 90%.

Find:

A) The 2nd gear ratio

B) The Toutput at 2nd gear

C) The Pin

2) A- What is the difference between the following:

- ¾ floating axle & fully floating axle

 

 

 

 

 

- Two speed axle & double reduction axle

 

 

 

 

 

 

2) B- A car has the following specifications

Ne (rpm)

2000

Find (at engine speed of 2000 rpm) the following:

a- axle shaft torque (Tw)dd at direct drive (1:1),

b- car speed (v)g2 on second gear,

c- car tractive effort (TE)dd at direct drive.

Te (Nm)

120

Gear box  ig

3.91, 2.17, 1.37, 1.00

hg

90%

Final drive if

3.46

hf

95%

rw (m)

0.32

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

           

 

 

3) A- What are the factors affecting the air drag coefficient (Cd)

 

 

 

 

 

3) B- i: In which case of the following would the car be faster? Case a or case b

Case (a)

Case (b)

with a final drive ratio (if) of 4.21

with a final drive ratio (if) of 3.85

with a velocity (v)of 30 m/s

with a velocity (v) of 30 km/h

ii- and why:

-

-

           

3) C- A car having the following characteristics:

- car mass (m) of 1200 kg.

- car frontal area (Af) 2.4 m2

- car coefficient of air resistance (Cd) (0.4).

- coefficient of wheel rolling resistance (fr) is 0.02

and the air density (r) is 1.2 kg/m3, Find:

a) the car air resistance (AR) at a car speed (v) of 120 km/h.

 

 

 

 

 

 

b) the car air resistance (AR) at a car speed (vcar) of 120 km/h and a tail wind speed (vair) of 30 km/h.

 

 

 

 

 

 

c) the rolling resistance (RR).