Design problem Design problem

1. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
1 | P a g e
Machinery parts design
University of Baghdad
Name: - Saif Al-din Ali -B-
s.madi1603@coeng.uobaghdad.edu.iq
The fourth stage

2. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
2 | P a g e
Design Problem
For the shaft shown in Figure below, in which pulley B receives a power
from pulley K downward at an angle 45°. Gear C delivers 65% of the power
downward to the right at an angle of 20° with vertical axis. Gear E delivers
the remaining power upward the right at an angle of 30° with vertical axis.
The allowable shear stress of shaft is 42 N/mm2. Take Kn = 1.3 & Ks = 1.6
Hint:
1- The pulley K receives the power directly from a motor with 25 Kw at 850
rpm.
2- The pair of steel spur gears C and G has 14.5° full-depth teeth involute
profiles with velocity ratio 3:1 and center distance 500 mm.
3- The pair of helical gears has 20° stub teeth involute profiles with helix
angle 19°. The steel pinion E has 20 teeth and cast iron gear H has 50 teeth.
4- For steel material: modulus of elasticity 210 × 103 N/mm2, allowable
flexural stress 160 × 103 N/mm2, and σes = 630 × 103 N/mm2.
5- For cast iron material: modulus of elasticity 190 × 103 N/mm2, allowable
flexural stress 110 × 103 N/mm2, and σes = 590 × 103 N/mm2.
6- The slip between the belt and pulley K is 5% and between the belt and
pulley B is 0%. The coefficient of friction between the pulleys and the belt is
0.3. The speed ratio between pulley B and K is 3:1. Take the contact angle
as 190° and the central distance as 1 m. Take the effect of centrifugal force
on the belt where ρ = 1100 kg/m3 and σmax = 2.6 MPa. The maximum
allowable tensile stress in the belt is 3 MPa. The thickness of the belt should
be chosen for the range of width between eg. 250-600 mm.
7- The bearings to be chosen should be ball bearings that last for no less
than twenty million cycles with reliability of 90%. Assume light shock.
8- Neglect the effect of end thrust force (axial force) for the helical gears in
the design of shaft and bearings.
Put a full design for:
1- The pulleys B and K with its belt.
2- The pair of spur gears C and G. Check the design using Buckingham
equation and check the design for wear.
3- The pair of helical gears E and H. Check the design using Buckingham
equation and check the design for wear.
4- The shaft.
5- The bearings A and D.

3. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
3 | P a g e

4. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
4 | P a g e

5. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
5 | P a g e

6. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
6 | P a g e

7. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
7 | P a g e

8. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
8 | P a g e

9. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
9 | P a g e

10. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
10 | P a g e

11. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
11 | P a g e

12. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
12 | P a g e

13. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
13 | P a g e

14. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
14 | P a g e

15. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
15 | P a g e

16. Saif Al-Din Ail Madhi
Department of Mechanical Engineering/ College of Engineering/ University of Baghdad
16 | P a g e