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Urgent calculation: design a construction lift

  1. Apr 26, 2009 #1
    Urgent calculation: design a construction lift....

    the construction lift is used in a building construction project. the construction will raise building materials from ground level to any height up to 12.2m. The life will be at the top of a rigid scaffold that is not a part of the design project. it will raise a load up to 3kN at the rate of about 20cm/s. the load will be on a pallet (1m x 1.5m) the construction site is powered by 3 phase AC current , 460 voltage with 60 hertz electrical power supply. the construction lift is used for 12 hour per day. the structure to support the life is considered to be rigid.... Question 1: motor selection, speed at sychronous speed and no. of pole, power rating of motor. Question 2 Narrow section V-belts recommended to use in this design! its service factor, design power. selected output speed, belt selection, driving sheave size and driven sheave size, actual output speed , center distance , belt length , no. of belt require. Question3: a speed reducer using spur gear by using 4 gear... the gears have a 20 degree pressure angle.... find the no of teeth,size of teeth as indicated by the pitches, force and torque act on teeth, velocity ratio and train value ,speed of driving gear and driven gear, center distance. Question 4: chain drive (single strand roller chain is recommended) finf its service factor,design power ,velocity ratio,required no. of teeth on each sprocket, actual output speed, chain lenth,center distance, chain no and type of lubrication.... plz help me slove this problem.... Thx a lot~


    actually this is nt my homework...
    i juz do it for my extra knowledge only.....
    my lecture never ask us to do homework de...cos i think he also dun know how to do...-.-!
    when i take this question to ask him, he juz say exam will nt come out this type of question...so no need to do it.... >.<
    i have try it by using my text book.
    but those question in my text book always got sufficient information to solve those calculation.....
    In the 1st question....
    i had choose 3phase AC motor with NEMA design D due to the information state at my book... but my book din say how to find what power rating that need to use..
    beside the speed of synchronous speed is calulate by (120f/p).
    the p=no. of pole of the motor...
    so how many pole should i choose....
    for the other question,
    because the given output speed in question is 20cm/s and the text book that i read use the output speed in the unit (rad/s)
    so how should i convert it??
    i hope got ppl can help me solve this problem at here....
    because i dun know where can help me if find the solution from net also cant solve...
     
  2. jcsd
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