Spring Semester, 2003-2004 (031)
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:
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.