STUPIDSID
1 (a)
Explain Pitting and Scoring for gear tooth failure.
4 M
1 (b)
A spur gear having 22 teeth to be made of plain carbon steel 40C8 (Sut=580N/mm ) is to be mesh with a gear having 88 teeth to be made of grey cast iron FG260(Sut=260N/mm 2 ).The pinion shaft is connected to 12KW,1440 rpm electric motor. The starting torque of the motor is approximately twice the rated torque. The tooth system is 20° full depth involute. The face width is 10 times module for which the load distribution factor is 1.4. The gear are to be machined to met the specifications of grade 7 for which deformation factor is 240 N/mm.
i) If factor of safety require against bending failure 1.0,design the gear pair by using velocity factor Velocity factor = 6/6+v and Buckingham's equation for dynamic load.
ii) if the factor of safety required against pitting failure is 1.5 , specify surface hardness. Y= 0.484 - 2.87/Z
Buckingham's equation \[ Fd=Ft+ \dfrac {(21v (bC+Ft\max))}{(21v+\sqrt{bC+Ft\max})} \] K=0.18(BHN/100)2 for steel pinion and cast iron
Standard module are 4,5,6,8,10,12,16, Service factor =2, Load concentration factor =1.4
i) If factor of safety require against bending failure 1.0,design the gear pair by using velocity factor Velocity factor = 6/6+v and Buckingham's equation for dynamic load.
ii) if the factor of safety required against pitting failure is 1.5 , specify surface hardness. Y= 0.484 - 2.87/Z
Buckingham's equation \[ Fd=Ft+ \dfrac {(21v (bC+Ft\max))}{(21v+\sqrt{bC+Ft\max})} \] K=0.18(BHN/100)2 for steel pinion and cast iron
Standard module are 4,5,6,8,10,12,16, Service factor =2, Load concentration factor =1.4
10 M
2 (a)
A elevator is designed to carry workers and materials to height of 40 meter. It is estimated that at least 10 workers with material load of 12 KN should be hoisted at a speed of 0.5m/sec which should be attained in the first 0.4s. The recommended steel wire rope is 6x19 with wire diameter 2.5mm. Determine factor of safety. Assume E = 84GPa, for 6x19 rope wire diameter dw=0.063d, cross sectional area =0.38d2, ultimate tensile strength for the wire rope is 435d2.
7 M
Answer any two question from Q2 (b) or Q2 (c)
2 (b)
Design a crane hook for lifting capacity of 5 tones. Take permissible tensile stress 80N/mm2 for forged steel. Assume a triangular section for hook design \[ Rn= \dfrac {\frac {((b1+b0)/2)}{H}}{\frac {(biRo-boRt)}{H} \left ( ln \left (\frac {Ro}{Rt} \right ) \right )-(bi-bo)} \] R=Ri+H(bi+2bo)/3(bi+bo)
7 M
2 (c)
Explain deign procedure for 6 speed reduction gear box.
7 M
Answer any two question from Q3 (a), (b) or Q3 (c), (d)
3 (a)
What is formative number of teeth in helical gear? Derive the expression for formative number of teeth in helical gears.
4 M
3 (b)
Design a gear pair of helical gear
Assume service factor 1.5 and factor of safety 3. Check wear and dynamic strength of gear.
Helix angle is 25o, speed of pinion is 720 rpm.
\[ Velocit \ factor = \dfrac {6}{6+v}, \ \ Fw = DpbQK/COS^2 \psi \\ K=((\sigma es)^2 \sin (\phi n)/1.4) (1/Ep+1/Eg), \ \ \sigma es = 2.75 (BHN)-70 \\ Fd = Ft + \dfrac {(21 v ( b C \cos \psi \cos \psi + Ft\max)\cos \psi)}{(21v+ \sqrt{bC \cos \psi \cos \psi + Ft\max})} \]
Design a gear pair of helical gear
| Gear | Pinion | |
| Material | 50C4 | 60C4 |
| Ultimate strength MPa | 660 | 750 |
| BHN | 241 | 255 |
| Pressure Angle in degree | 20o | 20o |
| Number of teeth | 70 | 35 |
| Normal module in mm | 5 | 5 |
| Face width in normal plane, mm | 50 | 50 |
| Module of elasticity GPa | 205 | 200 |
Assume service factor 1.5 and factor of safety 3. Check wear and dynamic strength of gear.
Helix angle is 25o, speed of pinion is 720 rpm.
| Material | Error 0.02 | Error 0.04 |
| Steel steel 20 degree involute | 228 | 456 |
\[ Velocit \ factor = \dfrac {6}{6+v}, \ \ Fw = DpbQK/COS^2 \psi \\ K=((\sigma es)^2 \sin (\phi n)/1.4) (1/Ep+1/Eg), \ \ \sigma es = 2.75 (BHN)-70 \\ Fd = Ft + \dfrac {(21 v ( b C \cos \psi \cos \psi + Ft\max)\cos \psi)}{(21v+ \sqrt{bC \cos \psi \cos \psi + Ft\max})} \]
10 M
3 (c)
Explain thermal consideration while designing worm and worm wheel drive.
4 M
3 (d)
A pair of high grade cast iron bevel gears having shaft at right angle are to have an angular velocity ratio of driver to driven of 2 to3. The driver is to rotate at 175 rev/min and is to transmit 10 KW. It is 0.4 meter in pitch diameter. Take the width of face as about one third of the length of pitch element and determine the pitch of the gear. Assume 24 hr/day operation. Velocity factor = 3/3+v, Levis factor=π(0.154- (0.921/no. of teeth))
Beam strength= fefm Y(1-F/L)
High grade cast iron Fef=84MPa, fes for cast iron=630 Mpa, Ep=Eg=105 Mpa.
Beam strength= fefm Y(1-F/L)
High grade cast iron Fef=84MPa, fes for cast iron=630 Mpa, Ep=Eg=105 Mpa.
10 M
Answer any two question from Q4 (a), (b) or Q4 (c), (d)
4 (a)
Discuss about various section of connecting rod.
4 M
4 (b)
Design a cast iron piston for single acting four stroke engine for following specification Cylinder Bore = 110 mm, Stroke = 130 mm, Maximum gas pressure = 5N/mm2 Brake mean effective pressure = 0.5 N/mm2, Fuel consumption = 0.2 kg/kw/hr, speed =2000rev/min. Assume suitable data for C.I permissible tensile stress is 40 N/mm2, HCV=41870 KJ/kg, K for C.I. = 46.6 Permissible tensile stress or piston ring is 100 N/mm2, permissible tensile stress for pin is 150 N/mm2.
10 M
4 (c)
Explain about material for piston.
4 M
4 (d)
Design a connecting rod for four stroke petrol engine for following data.
Piston diameter =0.1 m
Stroke=0.14 m,
Length of C.R. =0.315 m
Weight of reciprocating part =18.2 N
Speed = 1500 rpm with over speed 2500
Compression ratio 4:1
Maximum explosion pressure = 2.45 Mpa.
F.O.S. =5 , For connecting rod σ yield 380 N/mm2, σ ultimate= 580 N/mm2.
Piston diameter =0.1 m
Stroke=0.14 m,
Length of C.R. =0.315 m
Weight of reciprocating part =18.2 N
Speed = 1500 rpm with over speed 2500
Compression ratio 4:1
Maximum explosion pressure = 2.45 Mpa.
F.O.S. =5 , For connecting rod σ yield 380 N/mm2, σ ultimate= 580 N/mm2.
10 M
Answer any two question from Q5 (a), (b) or Q5 (c), (d)
5 (a)
Explain the design procedure of screw conveyor.
7 M
5 (b)
Explain design of flat belt conveyor.
7 M
5 (c)
Explain design procedure of wire rope drum.
7 M
5 (d)
What do you understand by 6×37 ropes? Explain with neat sketch the different rope section.
7 M
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