hey mechanical engineering people i hope i can find someone to help me in just explain the plan of how to design this project .......i just need the steps should be taken generally
especially what should i suppose it and what for example is fixed and if some one will give me how the safety factor values should be i need this help as soon as possible if someone can help and thanks for all
the question :
A mechanical engineer has proposed the design of the power lift shown in the figure below, you are kindly asked to help in designing this lift by answering the questions (A) to (G). The lift is required to raise a maximum load of 3000 lb a distance of 7 ft in 2 min at constant speed. Other specifications of the lift are given in the figure. The speed ratios are indicated in the figure. Assume uniform operation and self-locking power screw. (A)The system has estimated efficiency of 75%, find the power of the required motor in units of hp. (B) Find the magnitude and direction of the rotational speed of shaft a when viewed from right while the lift is raising the load. (C) Due to space limitations, select a suitable V-belt drive to transmit motion between shafts a and b. Identify belt section, a reasonable central distance between the two shafts, the diameter of each pulley. Make any necessary assumption (D) Calculate the torque in shaft b. You may benefit from knowing belt tensions. (E) Find the tangential and radial components of the force between gears 2 and 3. Make any necessary assumption. (Specify central distance between shafts b and c, specify number of teeth on each gear, and identify the diametral pitch.) (F) Find an appropriate face width of gear 2; identify suitable material specifications and working conditions (use AGMA method). Make any necessary assumption. (G) Calculate the radial reactions with which bearings B and C push against the shaft b. Assume belt tensile forces vertical. You need to specify reasonable shaft length and bearing locations. (H) Consider static stress analysis of shaft b, use maximum shear stress theory to determine a suitable shaft diameter with a reasonable factor of safety; select suitable steel for the shaft material. (I ) Use the diameter found in part (H) to calculate first estimate for the fatigue factor of safety of shaft b using the Goodman method. Make any necessary assumption. (J) Select a suitable deep groove ball bearing to be located at C and D, assume uniform load, 90% reliability and desired life of 13000 hours. (K) Find an appropriate face width of the bevel gears; identify suitable material specifications and working conditions (use AGMA method). Assume 15 teeth and 20o pressure angel. Make any necessary assumptions. (L) Due to distance constraints, select a suitable sprocket-chain drive to transmit motion between shafts c and d. Make any necessary assumption. Identify chain number, length of the chain in number of pitches, number of teeth on the small and large sprockets. (M) Consider static force analysis of shaft d, calculate the bearing reactions at bearings G and H. Assume the tension in the chain is perpendicular to shaft
d and parallel to shaft c. You need to specify suitable shaft length and bearing locations.