1. Limited time only! Sign up for a free 30min personal tutor trial with Chegg Tutors
    Dismiss Notice
Dismiss Notice
Join Physics Forums Today!
The friendliest, high quality science and math community on the planet! Everyone who loves science is here!

Elevator vs. Piston/Cylinder

  1. Apr 30, 2008 #1
    [SOLVED] Elevator vs. Piston/Cylinder

    In designing a reciprocating linear motion force, I have two approaches to the problem using a standard 1 horsepower motor. The travel is 2 feet forward and 2 feet backwords with a minimum force of 200lbs.

    From calculations, each cycle of the reciprocating motion will generate at minimum:
    2(200LBS x 2FT) = 800 FT LBS per cycle.

    Theoretical maximum with 100% efficiency will yield:
    (33,000FT LBS) / (800 FT LBS/cycle) = 41.25 Cycles/Minute

    If I had a choice between designing a system where the 1HP motor will power a system much like a car's piston/cylinder approach, or one where the 1HP motor will power a cable-system-powered-elevator, which would be a better approach to attain the highest cycles per minute?

    The elevator approach would have counterweights to balance the system in order to conserve energy since if it's balanced, it'll require only a little bit of force to tip the balance to move the counterweight down and the elevator up.

    I am not asking for calculations, but just opinions on which would be the better route to take in terms of output cycles per minute.

  2. jcsd
  3. Apr 30, 2008 #2


    User Avatar
    Gold Member

    Welcome to PF, Bananabrownin.
    It seems to me that the crank system is inherently capable of much higher cyclic rates than the cable, and is probably more reliable as well.
  4. May 1, 2008 #3
    I like the elevator idea. The only problem might be that your speed would be determined by the amount of passengers/load the elevator would lifting. No load, all the speed you need.
  5. May 2, 2008 #4
    For an application that requires 200 FT LBS, would a camshaft suffice?

    My idea was connecting a 1HP motor to a reducer to obtain ~35RPM and attaching a camshaft to the output shaft. Then mounted above the camshaft will be a cam follower that will travel up and down as the camshaft rotates.

    Example picture is g.photos.cx/CAM-95.jpg

    Would a camshaft be able to support torques of that amount or will 200 FT LBS exceed the inherently simple design of linear reciprocating motion?
Share this great discussion with others via Reddit, Google+, Twitter, or Facebook