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Hydraulic force

  1. Oct 21, 2015 #1
    Most examples of hydraulic mechanical advantage display a little force on a small piston traveling a long distance to move a bigger piston a short distance with a lot of force.

    With the inverse, if we have an input of:
    100 lbs of force on a 3" diameter piston traveling 1"
    the output would be
    33 lbs of force on a 1" diameter piston traveling 3"
    and this is true for single pistons.

    What happens if the output is forked into 2 or more pistons as my illustration shows?
    To have the same travel & force on the small diameter output pistons, would the travel & force on the input piston need to change at all? Or will it stay the same (as with a single output cylinder)?
    Thanks in advance.

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  2. jcsd
  3. Oct 21, 2015 #2


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    I might be a bit rusty but are you sure about this example?

    100lbs on a 3" diameter piston is 14psi
    33lbs on a 1" diameter piston is 38psi
  4. Oct 21, 2015 #3
    You can't use just the diameter of the pistons. You have to calculate the area of each piston.

    Piston A = 3 square inches
    Piston B = 1 square inch

    Applying force to Piston A to move it 1 inch will move Piston B 3 inches, with 1/3rd the output force.
    Applying force to Piston B to move it 3 inches will move Piston A 1 inch, with 3 times the output force.
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