ISO 6020 Hydraulic Cylinder Standard — Bore Sizes, Mounting & Force Calculator
ISO 6020 — Hydraulic fluid power — Single rod cylinders, 16 MPa (160 bar) series — Mounting dimensions
ISO 6020 is the international standard that defines the preferred bore diameters, rod diameters, mounting dimensions, and dimensional accessories for single-rod hydraulic cylinders. Part 1 covers the 16 MPa (160 bar) series and Part 2 extends the specification to the 25 MPa (250 bar) series. By standardising the bore series (25, 32, 40, 50, 63, 80, 100, 125, 160, 200 mm), the mounting interfaces (flange, foot, trunnion, clevis), and the rod-end thread geometries, ISO 6020 allows cylinders from different manufacturers to be interchangeable — critical for machine builders and system integrators selecting off-the-shelf actuators.
While ISO 6020 itself governs dimensions rather than design-pressure calculations, the standard pairs naturally with the fundamental fluid-power force equations (force equals pressure times piston area) and with Euler/Johnson column theory for piston-rod buckling. The MechanixCalc hydraulic cylinders calculator uses the ISO 6020/6022 preferred bore and rod series as its selection chart reference and applies the full force, flow, speed, and rod-buckling methodology in a single auditable pass, delivering a shareable PDF engineering report with the governing equations shown.
Calculators that implement ISO 6020
What ISO 6020 covers
- Preferred bore diameter series for single-rod hydraulic cylinders: 25, 32, 40, 50, 63, 80, 100, 125, 160, 200 mm (ISO 6020-1/-2)
- Standard rod diameters matched to each bore — typically 0.5 × to 0.7 × bore diameter — and the associated rod-end thread sizes per ISO 6020
- Mounting interface dimensions for the most common attachment types: front- and rear-flange mounts, foot (side-lug) mounts, trunnion mounts, clevis mounts, and the eye-bracket accessories
- Operating pressure ratings: 16 MPa (160 bar) in Part 1 and 25 MPa (250 bar) in Part 2 — the maximum allowable working pressure the cylinder body and seals are designed to sustain
- Stroke increments and overall envelope dimensions so that a standard-bore cylinder from any conforming manufacturer can be swapped without re-engineering the machine frame
- Relationship to ISO 6022 (200 bar heavy-duty series) which extends the same dimensional philosophy to larger bore sizes and higher proof pressures
Parts of the standard
- ISO 6020-1Hydraulic fluid power — Single rod cylinders, 16 MPa (160 bar) series — Mounting dimensions
- ISO 6020-2Hydraulic fluid power — Single rod cylinders, 25 MPa (250 bar) series — Mounting dimensions
Governing formulas
F_ext = P · A_bore − P_back · A_ann − F_frictionwhere F_ext = net extension force (N); P = supply pressure (Pa); A_bore = π/4 · D² = full bore area (m²); P_back = back-pressure on rod side (Pa); A_ann = π/4 · (D² − d²) = annular rod-side area (m²); F_friction = seal friction allowance (N). Bore diameter D and rod diameter d selected from the ISO 6020 preferred series.
F_ret = P · A_ann − P_back · A_bore − F_frictionwhere F_ret = net retraction force (N); A_ann = π/4 · (D² − d²) (m²). Retraction force is always lower than extension force for the same supply pressure because A_ann < A_bore. The deficit grows as the rod diameter increases relative to the bore.
Euler: F_cr = π² · E · I / Le² ; Johnson: F_cr = A · Sy · [1 − Sy · Le² / (4π² · E · r²)]where F_cr = critical buckling load (N); E = elastic modulus (Pa); I = π/64 · d⁴ (m⁴, solid round rod); Le = K · L = effective length (m); K = end-condition factor (2.0 fixed-free, 1.0 pin-pin, 0.7 fixed-pin, 0.5 fixed-fixed); A = rod cross-section area (m²); Sy = yield strength (Pa); r = d/4 = radius of gyration (m). Johnson formula governs when slenderness λ = Le/r < λ_c = π · √(2E/Sy).
Frequently asked questions
What is ISO 6020 used for?
ISO 6020 standardises the bore diameter series, rod diameters, mounting interface dimensions, and pressure ratings for single-rod hydraulic cylinders. Part 1 covers the 16 MPa (160 bar) series and Part 2 the 25 MPa (250 bar) series. The standard ensures dimensional interchangeability between cylinders from different manufacturers, so machine builders can source replacements without re-engineering the mounting structure.
What are the standard bore sizes defined by ISO 6020?
The ISO 6020 preferred bore series is: 25, 32, 40, 50, 63, 80, 100, 125, 160, and 200 mm. Each bore is paired with one or more standardised rod diameters (typically 0.5 × to 0.7 × bore) and defined mounting-face dimensions. The MechanixCalc cylinder calculator uses this series as the reference for its bore selection chart.
Does ISO 6020 define the force calculations for hydraulic cylinders?
No — ISO 6020 is a dimensional standard for mounting interfaces and bore/rod series, not a design-calculation standard. The force equations (F = P × A_bore for extension; F = P × A_annular for retraction) and the rod buckling check (Euler/Johnson column theory) are classical fluid-power engineering applied within the ISO 6020 dimensional framework. The MechanixCalc calculator applies both the standard bore series and the governing force and buckling equations together.
How does ISO 6020 relate to ISO 6022?
ISO 6022 covers the 200 bar (20 MPa) heavy-duty series, defining mounting dimensions for larger and higher-rated cylinders that extend beyond the ISO 6020-1 range. The two standards use compatible dimensional conventions and bore-series logic; the MechanixCalc calculator supports both. ISO 6022 cylinders are common in heavy mobile and industrial machinery where higher force density or larger bores are required.
Is the ISO 6020 hydraulic cylinder calculator free?
You can run it during a free 30-minute preview with no sign-up required, and a free 14-day account trial unlocks every MechanixCalc calculator with no credit card. The branded PDF engineering report and saved calculations are part of a paid plan.
Related standards
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