Tag Archive: cylinder

Multi-Cylinders conduits calculation

Cylinders conduits flow

Cylinder’s flow

These calculations can help you to figure-out conduits (hoses, pipes or tubes) parameters (ID sizes, piston speed, flow velocity and cylinder’s force) for any qty of cylinders connected in parallel circuit.

Calculations Notes:

  • The recommended flow velocity in conduits you can find at the article Recommended flow velocity.
  • The assumption: if you use more than 1 cylinder in calculations, all cylinders have the same parameters (bore/rod diameters, stroke and friction)
  • The assumption: Pressure and Return lines conduits (flow source – flow divider and flow divider – tank) have the same ID size.
  • The assumption: the conduits between flow divider and cylinders have the same ID size.

Cylinder’s Area Ratio


  • Understanding the Cylinder Area Ratio

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By the definition, the “Cylinder Area Ratio” is the relation between the complete area of the bore and the same area minus the area of the rod:

 CR = \frac{A_b}{A_b - A_r}


For the ratio there is important a diameter of the rod (but not rod side annular area!) because when you choose the cylinders for your project in hydraulic catalogs you pick out them using Piston and Rod diameters.

This is why the area ratio CR is always >1.

Sometimes, you can meet records like:

 \frac{A_b}{A_b - A_r} : 1

For example, for cylinder 4″ bore diameter and 2.5″ rod diameter, the ratio is:


So, CR=1.64 or 1.64:1