Machine Design - II (ME 308 Lab)

Shaft Design - Project # 1

Term 992

Steps # 1 & 2

1. Using the following equation, calculate input torque:
2.  lb.in.

Where:

P is power in HP

n is speed in rpm

3. Draw the torque diagram based upon this value of T

1. Solve for tensions T1 & T2 using the following relations
2.  Where:T is torque in lb.in. from above r is the radius of the pulley in inches

3. Calculate the radial and tangential forces on the gear
4.  Tangential force on the gear Ft = T1-T2 lb.Radial force on the gear Fr = Ft Tan f lb. Where:f is the pressure angle = 20°

5. Perform a complete force analysis on the shaft in the y and z directions to determine the resultant reactions at the bearing locations
6. Resultant reaction is given by

lb.

7. Using equation (11-9) from the text book, calculate the rated force for each bearing:
8.

………………. Eqn. (11-9)

Where:

FR is the Catalog Load Rating

LD is the Design Life in Hours = 25000 Hrs.

nD is the Design Speed (given in rpm)

LRnR is the Rated Life = 106 rev.

R is the Reliability = 95%

a for Ball Bearings = 3

* for the values of FD, use the values of the resultant reactions calculated for locations B & D in step 5 of the lab-sheet, i.e. RB & RD

9. To calculate C, use the following equation:
10. C=A.F. ´ FR

Where:

A.F. is the Load-Application Factor - use table (11-6)

11. Select Deep Groove Ball Bearings for the bearing locations B & D on the shaft using table (11-3). Use the value of C, calculated above to select the bearing and note down all bearing data

NOTE:

• Convert LDnD to rev. before solving the equation

1. Draw the shear force and bending moment diagrams in the y and z directions and the resultant bending moment diagram with a free hand sketch of the shaft