- General Layout Of Compound Reverted Gear Frain Not To Scale Required Countershaft Dimensions Fillet Radius At Bearin 1 (37.52 KiB) Viewed 40 times
- General Layout Of Compound Reverted Gear Frain Not To Scale Required Countershaft Dimensions Fillet Radius At Bearin 2 (85.54 KiB) Viewed 40 times
You work for a gearbox company and have been charged with helping to design a geared countershaft for a speed reducing gearbox. The gearbox consists of a compound reverted gear train as shown below and is to be designed for an exact 16:1 speed reduction ratio. The input motor provides 10-horsepower which is carried through the gear train and operates at a speed of 2,000rpm. You are asked to consider spur gears with a 20∘ pressure angle and 4teeth/ in diametral pitch for this project. 1. Determine the number of teeth and pitch diameters for each of the gears to minimize the gearbox size while avoiding gear tooth interference. 2. Calculate the rotational speed of the countershaft (i.e. intermediate shaft) and the output shaft. 3. Calculate the pitch line velocities and the radial and tangential loads acting at the two sets of gears. 4. Calculate the reaction loads at the proposed bearing locations. Using Table 11-2, specify a single ball-bearing that will work for both sides of the shaft. The bearing should be chosen to allow for 2 years of continuous operation. 5. Use the bore diameter of the chosen bearing to set d1. Calculate d2 and d3 using the approximations shown and rounding up to the nearest 1/8 ". Assume a fillet radius of 0.035 " at the bearing shoulders and 1/16" at the gear shoulders. 6. Draw all appropriate shear, moment, and torque diagrams for the shaft. 7. At the point of maximum stress, determine the bending and torsional shear stresses. 8. Using Table A-20, specify a material for the shaft that will allow for infinite life. Provide the factors of safety against both first cycle yielding and fatigue using the ASME-Elliptic criterion. 9. Specify the tolerances on both the ID of the bearings and OD of the bearing lands for a locational interference fit.