Problem 1

A gear reduction uses a countershaft shown in the figure. Gear A receives power from another gear with the transmitted load force FA applied at the 20degree pressure angle as shown below. The power is transmitted through the shaft and delivered through gear B through a transmitted load FB at the pressure angle shown below. The transmitted steady torque is 2819 lbf in. Show a preliminary design of the shaft by performing the following task. a)Sketch a general shaft layout including means to locate the components. b)Determine critical diameter of the shaft based on infinite fatigue life with a design factor of 1.5.Check for yielding. c)Make any other dimensional decision necessary to specify all diameters.

Problem 2

Design the shaft shown in the figure below. It is to be machined from a SAE 1144 OQT 1000 steel. The shaft is part of the drive for a large blower system supplying air to a furnace. Gear A receives 200 hp from gear P. Gear C delivers the power to gear Q. the shaft rotates at 600 rpm. Consider the Sy = 83000 psi and Sut = 118000 psi. The tangential and radial forces for gears A and C are given below: Gear A: WtA = 2100 lbf WrA = 764 lbf Gear C: Wtc = 4200 lbf Wrc = -1529 lbf Hint: Torque can be calculated by using the following relation: Torque (lbf in.)= 63000 (power in hp)/shaft speed in rpm Steady torque acts along the length from gear A to gear C.