Start from force and pressure
Cylinder force follows F = P x A, where P is system pressure and A is the effective piston area. A Ø100 mm bore at 200 bar delivers about 157 kN of push force, roughly 16 tonnes. Pull force is always lower, because the rod cross-section subtracts from the effective area. Fix the required force and the available pressure first; every other dimension follows from them.
Choosing the bore from force and pressure
With force and pressure fixed, the bore is the first dimension to calculate: select the smallest standard bore whose area delivers the required force at your working pressure. HPS manufactures bores from Ø25 to Ø320 mm. If the calculated bore lands between standard sizes, round up to keep a force margin. A larger bore also lowers the pressure needed for the same force, which relieves pump and valve selection.
Choosing the rod: pull force and buckling
Rod diameter, available from Ø15 to Ø250 mm at HPS, is set by two checks. First, pull force: the rod cross-section subtracts from the piston area, so a thicker rod reduces pulling capacity. Second, buckling: long push-loaded cylinders are checked with Euler analysis, using the critical load Pcr = pi^2 x E x I / Lk^2, where the free buckling length Lk depends on the mounting configuration. If buckling governs, the remedies are a thicker rod, a larger bore, a stop tube or a different mounting. HPS rods are CK45 or 42CrMo4, hard-chrome plated at about 30 um and salt-spray (NSS) tested.
Stroke limits: when stroke drives the design
HPS builds industrial cylinders with strokes up to 7,000 mm, subject to buckling analysis. When the required stroke exceeds what the installation length allows, a telescopic cylinder with multiple nested stages reaches up to 12,600 mm. Telescopics extend the largest stage first; per stage the effective area drops, so speed rises and force falls at constant flow. They suit tippers, refuse vehicles and mobile platforms where closed length is limited but a long stroke is needed. On very long strokes, stroke, not force, drives the whole design.
Pressure rating and the 1.5x test
HPS cylinders are rated for working pressures of 200 to 250 bar. Every cylinder is factory-tested at 1.5 times its rated pressure per ISO 10100; at a 250 bar rating that means a 375 bar test. The acceptance procedure covers internal and external leak checks, full-stroke function and a drift (holding) check on the test bench. A pressure test certificate is available on request. For high-pressure duty, dimensions follow the ISO 6020-2 and ISO 6022 series.
Ports and speed from flow
Cylinder speed is flow divided by effective area: at a given pump flow, a larger bore moves slower and a smaller bore faster. Size the ports so the required flow passes without excessive flow velocity, and check both directions; the rod side has a smaller annular area, so the same flow produces a higher speed there. The online configurator on the HPS site computes force, buckling, seal and port values live, so speed and port checks can be run before requesting a quote.
What to send HPS for a quote
A complete RFQ lets HPS engineering respond quickly. State the required force or bore, working pressure, stroke, rod diameter if known, mounting configuration (ISO 6099 or NFPA T3.6.7R designation), operating temperature, fluid and the expected duty. Note seal requirements: NBR is standard up to about 90 C, HNBR to about 120 C, FKM for high temperature and aggressive fluids, PU for heavy-duty wear, PTFE for low friction; final selection is verified by engineering. EN 10204 3.1 material certificates are available on request. The online configurator on the HPS site produces the same parameter set with live force, buckling, seal and port calculations; HPS exports from its 20,000 m2 Konya plant to 35+ countries under EXW, FCA, CIP, CIF or DAP terms.
- Euler Buckling in Hydraulic Cylinders: When Long Stroke Drives the Design →
- Telescopic Cylinder Staging: How Multi-Stage Hydraulic Cylinders Are Designed →
- Hydraulic Cylinder Pressure Testing: The 1.5x Factory Acceptance Test →
- Single-Acting vs Double-Acting vs Telescopic Cylinders: Selection Guide →
- Hydraulic Cylinder Troubleshooting: Drift, External Leakage, Noise and Slow Operation →