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Single-Acting vs Double-Acting vs Telescopic Cylinders: Selection Guide

The first decision in hydraulic cylinder specification is the type: single-acting, double-acting or telescopic. This guide compares the three families for engineers and buyers at the concept stage and gives clear selection criteria. HPS Hydraulic Power Systems manufactures all three types in Konya, Türkiye, with bores of Ø25-320 mm, industrial strokes up to 7,000 mm and telescopic strokes up to 12,600 mm.

The Three Families at a Glance

A single-acting cylinder generates hydraulic force in one direction; the return is driven by gravity or a spring. A double-acting cylinder generates controlled hydraulic force in both directions. A telescopic cylinder uses nested stages to reach a long stroke from a short closed length. HPS builds all three families with bores of Ø25-320 mm and rods of Ø15-250 mm. Rated working pressure is 200-250 bar, and every cylinder is factory-tested at 1.5 times rated pressure per ISO 10100.

Single-Acting: How It Works and Where It Wins

In a single-acting cylinder, pressure acts on one side of the piston and a single hydraulic line is sufficient. The return stroke is completed by the weight of the load or by a spring. This simplifies the circuit: fewer hoses, a simpler valve arrangement, lower cost. It wins in applications where the load lowers under its own weight, such as tippers and lifting platforms. If the return stroke must be hydraulically controlled, a double-acting type is required.

Double-Acting: Controlled Force in Both Directions

A double-acting cylinder has two ports, so pressure can be applied to either side of the piston. This gives controlled force and speed in both push and pull. Force follows F = P x A: a Ø100 mm bore at 200 bar delivers about 157 kN (about 16 tonnes) of push. Pull force is lower because the rod cross-section is subtracted from the effective area. It is the standard choice for construction machinery, presses and industrial machines that need control in both directions.

Telescopic: Long Stroke from a Short Closed Length

A telescopic cylinder consists of multiple nested stages, and the largest stage extends first. At constant flow, the effective area drops with each stage, so speed rises and force falls; the design must account for this. It is the answer where the installation length is limited but a long stroke is needed. Typical applications are tipper trucks, refuse vehicles and mobile platforms. HPS supplies telescopic cylinders with strokes up to 12,600 mm.

Decision Criteria: Stroke, Load Direction, Speed, Circuit

Stroke versus installation space: if the required stroke does not fit the available closed length, choose telescopic; HPS industrial strokes reach up to 7,000 mm depending on buckling analysis. Load direction: if the load works in one direction and returns under its own weight, single-acting is enough; force in both directions requires double-acting. Speed control: if both directions must be speed-controlled, choose double-acting. Circuit complexity: single-acting gives the simplest circuit, one line is sufficient. Long strokes always require a buckling check: Euler analysis applies (Pcr = pi^2 x E x I / Lk^2), and the free buckling length Lk depends on the mounting configuration.

When Standard Families Do Not Fit: Custom Design

Standard families do not cover every application: special mountings, tight envelope dimensions or special fluids may rule them out. HPS designs and manufactures custom cylinders from a customer drawing or a physical sample. Tubes are DIN 2391-2 ST52 or EN 10305-1 E355, honed to H8-H9; rods are CK45 or 42CrMo4 with about 30 um of hard chrome. The seal package (NBR, HNBR, PU, FKM, PTFE) is verified by engineering against temperature and fluid. All processes, including machining, welding, honing, chrome plating, assembly and testing, run in-house at the 20,000 m2 plant in Konya/Karatay. EN 10204 3.1 material certificates are available on request.

Selection Shortcuts and the Online Configurator

Quick rules: load returns under its own weight and the circuit should stay simple, single-acting; controlled force in both directions, double-acting; long stroke into a short installation length, telescopic. In borderline cases, force, buckling and sealing calculations decide. The online configurator on the HPS website runs live force, buckling, seal and port calculations. Before dispatch every cylinder passes internal and external leak checks, a full-stroke function test and a drift (holding) check. HPS exports to more than 35 countries and ships on EXW, FCA, CIP, CIF or DAP terms.

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