# AT6503 Vehicle Design and Data Characteristics Nov Dec 2016 Important Questions

Important questions for Nov Dec 2016 AT6503 Vehicle Design and Data Characteristics examinations conducting by Anna University Chennai
B.E./ B.Tech. DEGREE EXAMINATION Nov Dec 2016
05th Semester / III Year
Computer Science Engineering
AT6503 Vehicle Design and Data Characteristics
(Regulation 2013)
Nov Dec 2016 Important Questions

Important 02 Marks Questions with answers (All five units) are listed for AT6503 Vehicle Design and Data Characteristics subject

1. (i) Discuss about the design variables which are affecting performance of a vehicle. (8)
(ii) Determine the brake thermal efficiency, indicated thermal efficiency and overall efficiency of a four stroke four cylinder inline engine with the following specifications. Bore = 101 mm, Stroke =
114mm, Speed = 1600 rpm , Fuel consumption = 0.204 kg/mm, Heating value of the fuel = 41800 kJ
/kg, Difference in tension on either side of brake pulley = 380 N, Brake circumference = 3.35 m and
mechanical efficiency = 83 %. (Jun 2013)

2. Briefly explain the following
(i) Various operating parameters affecting the performance of an engine.
(ii) Factors influencing various resistances to motion

3. (i) What are the effects of over cooling and overheating of engine? (6)
(ii) Show the valve timing diagram for inlet and exhaust valve. (4)
(iii) On what factors, the volumetric efficiency is depending on supercharger engine? (6)

4. Derive the Velocity and Acceleration of a piston. Also sketch the diagram of Velocity and Acceleration Vs Crank angle for a piston of typical 4-stroke petrol engine

5. Briefly explain about the following:
(i) System modeling.
(ii) Vehicle body design consideration

6. A truck weighing 59 kN has a frontal area of 5.6 m2.The overall top gear ratio and the second gear ratio are 6.2:1 and 15:1 respectively. The transmission efficiency at top gear is 90 % and that in second gear is 80 %. The rolling resistance is 17.7 N per 1000 N of truck weight and the wind resistance coefficient is 0.027. If the truck is running on a level road at a maximum speed of 88 km/h, find the following:
(i) The engine BP required at the maximum truck speed
(ii) The engine rpm at the maximum truck speed if the driving wheels have an effective diameter of 0.81m.
(iii) The maximum grade the truck can negotiate at the above engine speed in the second gear and
(iv) The maximum draw bar pull available on level at the above engine speed in the second gear. (Jun
2013)

7. A fully loaded car weighs 19.9 kN and gives 88 % transmission efficiency in top speed. The road
resistance and air resistance are 23 N per 1000 N and 0.0827 V2 (The resistance being in N and V the speed in km/h) respectively. Calculate; .
(i) the brake power required for a top speed of 144 km/h
(ii) the acceleration in m/s² at 48 km/h, assuming the torque at 48 km/h in the top gear 25 % more than at 144 km/h
(iii) the brake power required to drive the car up a gradient of 1 in 5at 48 km/h, transmission efficiency is 80 % in bottom gear. (Jun 2013)

8. The coefficient of rolling resistance for a truck weighing 62 kN is 0.018 and the coefficient of air resistance is 0.0276 in the formula R = KW + KaAV² ,N, where A is m² of frontal area and V the speed in km/h. The transmission efficiency in top gear of 6.2 : 1 is 90 % and that in the second gear of 15 : 1 is 80 % . The frontal area is 5.6 m². If the truck has to have a maximum speed of 88 km/h in top gear,calculate:
(i) The engine BP required
(ii) The engine speed if the driving wheels have an effective diameter of 0.8 m
(iii) The maximum grade the truck can negotiate at the above engine Speed in second gear.
(iv) The maximum draw bar pull available on level at the above engine speed in second gear

9. The coefficient of rolling resistance for a truck weighting 62293.5 N is 0.018 and the coefficient of air resistance is 0.0276 in the formula R = KW + KaAV², N, where A is m2 of frontal area and V the speed in Km/hr. The transmission efficiency in top gear of6.2:1 is 90% and that in the second gear of 15:1 is 80%. The frontal area is 5.574m². If the truck has to have a maximum speed of 88 km/hr in top gear, calculate:
(i) The engine b.p require;
(ii) The engine speed if the driving wheels have an effective diameter of 0.8125m;
(iii) The maximum grade the truck can negotiate at the above engine speed in second gear; and
(iv) The maximum drawbar pull available on level at the above engine speed in second gear

10. (i) Explain the variables that affects the vehicle speed. (10)
(ii) Explain combustion process in engine. (6)

11. Draw the performance curves for the following characteristics of an automotive diesel engine.
Variations of BP, FP, IP,· torque, BMEP, mechanical efficiency and fuel consumption against speed in
rpm. Calculate the cylinder dimensions of a Six cylinder engine for the conditions given below:
Thermal efficiency = 22%
Volumetric efficiency= 80%
Mechanical efficiency= 82%
Heating value of petrol= 46400 kJ/kg
Theoretical air required per kg petrol 14.5
Excess of air = 25 %

12. (i) Plot typical performance curve for diesel and petrol engines. (8)
(ii) Brief about the heat transfer, residual gas, valve resistance and valve timing factors that affect the
performance of an engine. (8)

13. The indicated horsepower of an eight cylinder engine of capacity 4736 CC is 159 kw at 4400 rpm and indicated mean effective pressure is 8.6 bars. Brake power can be assumed as 154 kW after deduction of friction power. Calculate the torque produced by the engine for brake power of 154 kW at 4400 rpm.

14. (a) The coefficient of rolling resistance for a truck weighing 62293.5 N is 0.0 18 and the Coefficient of air resistance is 0.0276 in the formula R= KW+ Ka AV², N, where A is m² of frontal area and V the speed in km / hr. The transmission efficiency in top gear of 6,2: 1 is 90% and that in the second gear of 15:1 is 80%. The frontal area is 5.574 m². If the truck has to have a maximum speed of 88 km / hr in top gear calculate,
( i) The engine b.p required.
(ii) The engine speed if the driving wheels have an effective diameter of 0.8125 m
(iii) The maximum grade the track can negotiate at the above engine speed in second gear.

15. Write short notes on
(i) Rolling Resistance
Also write the procedure to draw Driving Force Curve from the Acceleration Curve

16. Derive the equations for calculating the displacement, velocity and acceleration of piston and
connecting rod of an IC engine.

17. A petrol engine is of 100 mm diameter and 125 mm stroke has a connecting rod 250 mm long. The piston has a mass of 1.15 kg. The engine speed is 2000 rpm. On explosion stroke with the crank 20° from The TDC the gas pressure is 0.7 MPa. Determine,
(i) Net force on piston
(ii) The resultant load on gudgeon pin
(iii) The thrust on the cylinder walls
(iv) The speed above which the gudgeon pin load would be reversed in direction, the other things remaining the same. (Jun 2013)

18. The following details are given for the piston, during expansion stroke. Find the gas force, inertia force and resultant force. Assume Bore area as 49 cm
19. Write the procedure to find the Gas force, Inertia force and Resultant force of a piston for all the
crank angles

20. The following details are given for the piston during expansion stroke. Find the Resultant force. Assume the bore area as 49 cm'' and stroke length as 7.9 cm.

21. A four speed gear box is to be constructed for providing the ratios of 1.0, 1.46, 2.28 and 3.93 to 1 as nearly as possible. The diametrical pitch of each gear is 3.25 mm and the smallest pinion is to have at least 15 teeth. Determine the suitable number of teeth of the different gears and the distance between the main and lay shaft. Also sketch the layout of a typical constant mesh gear box for these conditions. (Jun 2013)

22. How is the vehicle speed related to engine rotation? For typical motor car, the road resistance is
given by 23 N per 1000 N, the air resistance by the expression 0.0827 V², transmission efficiency 88 % in top speed; car weight 20 kN when fully loaded. Calculate
(i) The brake power required for a top speed of 144 km/h
(ii) The acceleration in m/s² at 48 km/h, assuming. the torque at 48 km/h, in the top gear 25% more
than at 144 km/h
(iii) The brake power required to drive the car up a gradient of 1 in 5 at 48 km/h, transmission efficiency 80% in bottom gear. The resistance being in N and V the speed in km/h and g = acceleration due to gravity = 9.81 m/s².
23. Explain the need for a gear box in the automobile. Briefly explain the procedure of calculation of gear ratios for a small car.
24. An automotive gear box gives three forward speeds and reverses with a top gear of unity and bottom and reverse gear ratio of approximately 3.3:1. The centre distance between the shafts is to be 110 mm approximately. Gear teeth of module 3.25 mm are to be employed. Sketch the layout of a typical constant mesh gear box for these conditions giving the number of teeth for the various gear wheels and showing closely how the different ratios are obtained. Since the pitch is same for all wheels and the centre distance is the same for all pair of mating wheels, the total number of teeth must be same for each pair.
25. A vehicle with normal laden weight of 1000 kgf gives the following acceleration in top gear. When the vehicle is running at 110 KMPH the engine develops 35.6 GHP. The vehicle tyres were
changed and the new tyres have their rolling radius 0.9 times the rolling radius of old tyres. Find the
gradability of the vehicle in top gear with the new tyres,