King Fahd University of Petroleum & Minerals

Department of Mechanical Engineering

ME 308 ( Machine Design - II ) Lab

Spring Semester, 2003-2004 (031)

 

 

Project # 2 Design of Double Reduction Unit.

 

The Fig. shows the layout of a countershaft used to transmit power to a blower from a pulley drive (4–5). Pulley 4 has a diameter of 125 mm and pulley 5 has a diameter of 75 mm. Pulley 5 is mounted vertically below pulley 4. Belt tension on the loose side is 20 % of the tension on the tight side. A power of 7.5 kW is transmitted via the pulley drive (4-5) from a motor rotating at 1800 rpm. Gear 3 is meshed with Gear 2. Both gears have a pressure angle of 25o and a module between 3 to 6. The location of the pulley, gears and bearings are as shown in the figure. The train value is 2.22.

 

 The following rigidity limitations have been imposed:

 

a)         The shaft at the gear shall not deflect more than 0.001"

b)         The slope of the shaft through the bearings shall not exceed 1O

 

The bearings are assumed to have a life of 25000 hours and a reliability between 90 and 95%.

 

Dimesion A = C = 100 mm

Dimension B = 200 mm.

 

You are required to do the following tasks:

 

  1. Calculate the bearing reactions in the horizontal and vertical directions on the counter shaft.

 

  1. Draw the shear and bending moment diagrams in the horizontal and vertical planes for the counter shaft. Also, draw the Resultant Bending Moment diagram (RBMD) and the torque diagram (TD).

 

  1. Determine the shaft dimensions at the different locations (Static and Fatigue analysis).

 

  1. Do the rigidity analysis of the counter shaft.

 

  1. Select appropriate bearings.

 

  1. Calculate the required dimensions of the square keys.

 

  1. Do the stress analysis for gears 2 and 3.

 

  1. Calculate dimensions for gear 3.

 

9. Make a complete detailed engineering drawing for the countershaft and Gear 3. The drawing should include full dimensions with surface finish, tolerances and proper fits between the components and detailed dimensions of all fillets and grooves.