For the problem specified in the table, build upon the results of the original problem to obtain a preliminary design of the shaft by performing the following tasks.

(a) Sketch a general shaft layout, including means to locate the components and to transmit the torque. Estimates for the component widths are acceptable at this point.

(b) Specify a suitable material for the shaft.

(c) Determine critical diameters of the shaft based on infinite fatigue life with a design factor of 1.5. Check for yielding.

(d) Make any other dimensional decisions necessary to specify all diameters and axial dimensions. Sketch the shaft to scale, showing all proposed dimensions.

(e) Check the deflections at the gears, and the slopes at the gears and the bearings for satisfaction of the recommended limits in Table 7–2. Assume the deflections for any pulleys are not likely to be critical. If any of the deflections exceed the recommended limits, make appropriate changes to bring them all within the limits.

Problem 3-77, A torque T = 100 N · m is applied to the shaft EFG, which is running at constant speed and contains gear F. Gear F transmits torque to shaft ABCD through gear C, which drives the chain sprocket at B, transmitting a force P as shown. Sprocket B, gear C, and gear F have pitch diameters of a = 150, b = 250, and c = 125 mm, respectively. The contact force between the gears is transmitted through the pressure angle φ = 20°. Assuming no frictional losses and considering the bearings at A, D, E, and G to be simple supports, locate the point on shaft ABCD that contains the maximum tensile bending and maximum torsional shear stresses.

Combine these stresses and determine the maximum principal normal and shear stresses in the shaft.

Transcribed Image Text:

aA E N ::100 N-Im d 30 mm f-250 mm 8125 mm e=75 mm c = 125 mm b=250 mm a=150mm View a-a