Final Exam Paper
UNIVERSITI TUN HUSSEIN ONN MALAYSIA
FINAL EXAMINATION SEMESTER II SESSION 2011/2012
COURSE NAME COURSE CODE PROGRAMME EXAMINATION DATE DURATION INSTRUCTION
: : : : : :
MECHANICS OF MACHINES BDA20303 / BDA2033 2 BDD JUNE 2012 3 HOURS PART A: ANSWER ALL QUESTIONS PART B: ANSWER ONE (1) QUESTION ONLY
THIS PAPER CONTAINS SEVEN (7) PAGES
BDA20303 / BDA2033
PART A (COMPULSORY) Q1 (a) Indicate ‘True’ or ‘False’ for the following statements: The radial distance between pitch circle and root circle is called addendum. The common point of contact of the pitch circles of two meshing gears is called pitch point. (iii) Straight bevel gears are used to connect two intersecting co-planer shafts. (iv) In a reverted gear train, the axes of the first gear and last gear are parallel. (v) Train value of a gear train is equal to reciprocal of speed ratio of gear train. (vi) The angle of contact in cross belt drive is more than that for open belt drive. (vii) The ratio of tension of tight side to slack side in case of V-belt drive is e µθ sec β . (viii) In crossed belt drive, the directions of rotation of two pulleys connected by it are opposite. (ix) Because of slip of the belt, the velocity ratio of the belt drive is decreases. (x) If the initial tension in the belt is increased, the power transmitted by the belt increases. (10 marks) (b) A horizontal shaft running at 400 rpm is to drive a parallel shaft at 500 rpm. The diameter of the pulley on the driving shaft is 80 cm. If the belt is 8 mm thick, calculate the diameter of the driven pulley : (i) (ii) (iii) Neglecting belt thickness Taking belt thickness into account Assuming in the latter case a slip of 5% Given: N B DA = , N A DB (i) (ii)
N B DA + t = , N A DB + t
N B DA + t s = × 1 − N A DB + t 100
(6 marks)
(c)
What is velocity ratio? What is slip? Discuss the effect of belt thickness and slip on velocity ratio. (9 marks)
2
BDA20303 / BDA2033
Q2
(a)
FIQURE Q2 shows a
FINAL EXAMINATION SEMESTER II SESSION 2011/2012
COURSE NAME COURSE CODE PROGRAMME EXAMINATION DATE DURATION INSTRUCTION
: : : : : :
MECHANICS OF MACHINES BDA20303 / BDA2033 2 BDD JUNE 2012 3 HOURS PART A: ANSWER ALL QUESTIONS PART B: ANSWER ONE (1) QUESTION ONLY
THIS PAPER CONTAINS SEVEN (7) PAGES
BDA20303 / BDA2033
PART A (COMPULSORY) Q1 (a) Indicate ‘True’ or ‘False’ for the following statements: The radial distance between pitch circle and root circle is called addendum. The common point of contact of the pitch circles of two meshing gears is called pitch point. (iii) Straight bevel gears are used to connect two intersecting co-planer shafts. (iv) In a reverted gear train, the axes of the first gear and last gear are parallel. (v) Train value of a gear train is equal to reciprocal of speed ratio of gear train. (vi) The angle of contact in cross belt drive is more than that for open belt drive. (vii) The ratio of tension of tight side to slack side in case of V-belt drive is e µθ sec β . (viii) In crossed belt drive, the directions of rotation of two pulleys connected by it are opposite. (ix) Because of slip of the belt, the velocity ratio of the belt drive is decreases. (x) If the initial tension in the belt is increased, the power transmitted by the belt increases. (10 marks) (b) A horizontal shaft running at 400 rpm is to drive a parallel shaft at 500 rpm. The diameter of the pulley on the driving shaft is 80 cm. If the belt is 8 mm thick, calculate the diameter of the driven pulley : (i) (ii) (iii) Neglecting belt thickness Taking belt thickness into account Assuming in the latter case a slip of 5% Given: N B DA = , N A DB (i) (ii)
N B DA + t = , N A DB + t
N B DA + t s = × 1 − N A DB + t 100
(6 marks)
(c)
What is velocity ratio? What is slip? Discuss the effect of belt thickness and slip on velocity ratio. (9 marks)
2
BDA20303 / BDA2033
Q2
(a)
FIQURE Q2 shows a