Hydraulic Cylinders — validation & limitations

What it calculates

• Hydraulic cylinder force and flow for the ISO 6020/6022 bore and rod series
• Piston rod buckling safety factor — Euler (long rod) and Johnson (short rod) column theory with selectable end conditions
• End-of-stroke cushioning and deceleration estimate — kinetic energy plus supply drive work, a mean cushion-chamber pressure and g-force
• Flow rate, hydraulic power, and speed vs pressure charts for extend and retract strokes
• Bore size selection chart for a target force across the supply pressure range
• Speed and cycle-time analysis with differential area speed ratio

Standards this tool applies

• ISO 1219 — Size and verify the hydraulic cylinders placed in the schematic — extension force, retraction force, rod buckling safety factor, and cushioning analysis (classical force and column theory; ISO 6020 / ISO 6022 dimensions are not checked).

Related standards — reference only, not implemented

• ISO 6020reference only — Extension and retraction force, rod buckling safety factor (Euler/Johnson), flow rate, hydraulic power, and end-of-stroke cushioning for the bore, rod and pressure you enter (classical force and column theory; ISO 6020/6022 dimensions are NOT checked). Note ISO 6020 and ISO 6022 are HYDRAULIC standards — pneumatic cylinder mounting dimensions are ISO 15552 and ISO 6432, which these parts do not cover.

Validation evidence — independent reference cases (2)

Each case runs the tool's engine on a worked example whose values come from a published source or a hand derivation from the cited equations, and an automated regression test asserts the engine against those values within the stated tolerance. "Conservative" means the engine is known to sit on the safe side of the reference and the test asserts that side. Sources are cited; their text is not reproduced.

• Hydraulic cylinder force, flow and power

  Agrees

  Source: Esposito, Fluid Power with Applications (7th ed.), Ch. 6; ISO 3320 / ISO 3322 bore-rod series; hand derivation from F = p·A, Q = A·v, P = p·Q

  Inputs: Bore 100 mm, rod 56 mm, 160 bar, eta_mech 95 %, 200 mm/s

  Quantity	Reference value	Tolerance
  Extend force	119 380.5 N	1e-6 relative
  Retract force	81 942.8 N	1e-6 relative
  Extend flow	94.248 L/min	1e-6 relative
  Hydraulic power	25.133 kW	1e-6 relative

  tests/golden/REF-cylinders-force-flow.golden.test.ts

• Rod buckling safety factor, pinned-pinned Euler regime

  Agrees

  Source: Shigley's Mechanical Engineering Design, 10th ed., §4-12 and §4-13 (Euler and J.B. Johnson column relations); buckling load = gross bore thrust p·A_bore (hydraulic-cylinder catalogue practice)

  Inputs: bore 63 mm, rod 40 mm, 160 bar, stroke 1500 mm, pinned-pinned K 1.0, E 210000 MPa, Sy 350 MPa

  Quantity	Reference value	Tolerance
  Critical load P_cr (column 1500 mm)	115 756.77 N	1e-6 relative
  Buckling SF (column 1500 mm)	2.320895 (CHECK)	1e-6 relative
  Critical load P_cr (L_pp 1800 mm)	80 386.65 N	1e-6 relative
  Buckling SF (L_pp 1800 mm)	1.611730 (FAIL)	1e-5 relative

  tests/golden/REF-cylinders-rod-buckling-euler.golden.test.ts

Limitations

Not checked by this tool

• Barrel (tube) pressure rating and wall stress — Rate the barrel with /pressure and the cylinder maker's pressure rating
• Rod tensile stress on the pull stroke — Only rod buckling is checked; check the rod section (thread root) for the pull force or use the maker's data
• Rod-end thread and rod-eye strength — Use the cylinder maker's data for the rod end
• Side loads and rod-eye bending on the rod and guide — Not included; keep side loads off the rod or use the maker's side-load / stop-tube data
• Pressure transients and rod-side pressure intensification — Steady flow only; check pressure peaks and meter-out intensification against the cylinder rating
• Mounting and pivot pin strength (trunnion, clevis, flange) — Check with the maker's mounting ratings