Hydraulic accumulator (hydropneumatic suspension)

  1. OCTOBOX New Member

    Messages:
    12
    Location:
    Uk
    hi there i am new to this forum. I am building hydropneumatic suspension on to my 4x4 i have mounted 2 hydraulic rams on the front. And am now trying to calculate what size accumulators are required. My rams hold 750ml each and i have roughly worked out it will take 400psi on either side to lift the truck. In an ideal world i need to be able to bottom out the rams till the axle hits the bump stops without blowing anything. Am i right in thinking if you halved the size of a area the pressure would double? Any input would be much appreciated.

    Cheers
     
  2. pressbrake1

    pressbrake1 Member

    Messages:
    1,584
    essex england
    That is correct. I assume you meant area and not aria cos singing won’t help:D
     
  3. Gareth0123

    Gareth0123 You'll need 16 pigs to do the job in one sitting!

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    1,367
    Location:
    Norwich, Norfolk, UK
    OCTOBOX likes this.
  4. OCTOBOX New Member

    Messages:
    12
    Location:
    Uk
    Wow thanks for that ill give them a bell.
     
  5. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    Welcome to the forum.

    Pressure = force/area, so if you halve the area of a ram you'll need twice the pressure to generate the same force.
     
  6. OCTOBOX New Member

    Messages:
    12
    Location:
    Uk
    Thanks for the reply please could you elaborate as I don’t understand. My ram is roughly 700mm long and has a internal bore of 40mm and is rated at 750ml full. The truck weighs 1.7 ton so i was working on roughly 2 thirds of that as it is for the front.

    Cheers octobox
     
  7. rtbcomp

    rtbcomp Moderator Staff Member

    Messages:
    18,615
    Location:
    Sheffield UK
    Your original question was

    Basically physics says yes you'd need to double the pressure to get the same force from your ram if you halve the area of the piston.

    Throwing arbitrary values at the formula P= F/A (and ignoring units) for a force of 8 with an area of 2, P = 8/2 = 4, if you halve the area to 1 then to generate a force of 8 P = 8/1 = 8, ie you need to double the pressure.

    Of you're talking about a piston used to generate pressure (such as in a pump):

    Lets say an area of 8 and an applied force of 16, P = 16/8 = 2. If you halve the area of the piston to 4 and keep the same force of 16, P = 16/4 = 4, ie the pressure generated would double


    The whole application is more complicated as you have to take into account the displacement of the pistons, so really you need to speak to experts in this particular field.
     
    OCTOBOX likes this.
  8. OCTOBOX New Member

    Messages:
    12
    Location:
    Uk
    Thanks for the reply i see what you are getting at now. I had already calculated the pressure reqired to lift the truck. I cheated and used a online hydraulic ram calculator. Thanks for the info though its always good to know the maths behind the madness.

    Cheers octobox
     
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