A hydraulic cylinder is a key component of a hydraulic system, converting fluid energy into mechanical motion. Proper selection of a hydraulic cylinder determines not only the efficiency of the equipment but also its operational safety. In this article, we'll take a detailed look at How to choose the right hydraulic cylinder, what parameters need to be taken into account, what types there are and mistakes when choosing.
🔧 What is a hydraulic cylinder and what is it used for?
A hydraulic cylinder is linear actuator, which creates force and movement through the pressure of a working fluid (oil or emulsion). It is used in industry, construction, agriculture, transport systems, lifting mechanisms, and presses.
The main functions of the hydraulic cylinder:
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lifting, lowering and moving loads;
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control of working parts of machines (booms, buckets, platforms);
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fixing parts under pressure;
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regulation of technological processes.
⚙️ Hydraulic cylinder design
To understand how to select a cylinder, you need to know its structure:
| Element | Purpose |
|---|---|
| Case (sleeve) | Contains liquid and directs the movement of the piston |
| Piston | Divides the internal space into cavities and transmits force |
| Stock | Connects the piston to the actuator |
| Seals | Prevent oil leaks |
| Covers and guides | Provides sealing and guides the movement of the rod |
| Fitting | Connect the hydraulic cylinder to the hydraulic system |
🧩 Steps to selecting a hydraulic cylinder
Selecting a cylinder isn't just a matter of choosing the right size. It requires considering a combination of technical parameters, operating conditions, and the type of mechanism.
1. Determining the purpose and type of movement
The first thing you need to understand is what the cylinder is used for:
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Raise/lower - a one-sided cylinder is used.
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Pushing and pulling - double-sided cylinder.
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Rotate or lock - telescopic or rotary.
Types of hydraulic cylinders:
| Type | Peculiarities | Application |
|---|---|---|
| Single-acting | Works only in one direction, return by spring or weight | Lifts, press molds |
| Double-acting | Bidirectional movement, fluid flow control | Construction and road equipment |
| Telescopic | Multiple sections, extended stroke | Dump trucks, lifting platforms |
| Plunger | Without a piston, movement is due to pressure on the rod | Hydraulic lifts, jacks |
2. Calculation of force and pressure
Formula for calculating the force on the rod:
F = (P × S) / 10,
Where
F — force (kN),
P — pressure (bar),
S is the piston area (cm²).
The piston area is calculated:
S = (π × D²) / 4,
where D is the piston diameter.
💡 Example:
If the pressure in the system is 160 bar and the piston diameter is 80 mm,
That
S = (3.14 × 8²) / 4 = 50.24 cm²,
F = (160 × 50.24) / 10 = 803.8 kN ≈ 80 tf.
3. Determining the working stroke
The piston stroke depends on the required amplitude of movement.
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For dump trucks - from 600 to 1500 mm.
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For lifts - from 200 to 800 mm.
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For agricultural machinery – up to 400 mm.
The cylinder stroke should always have a reserve of 10–15% to avoid running “at a standstill”.
4. Selecting the rod diameter
The stem must be strong enough to not deform under load. Typically, the stem diameter is from 0.7 to 0.9 of the piston diameter.
| Piston diameter, mm | Rod diameter, mm |
|---|---|
| 40 | 25–30 |
| 63 | 36–45 |
| 80 | 50–56 |
| 100 | 63–70 |
| 125 | 80–90 |
5. Taking into account operating conditions
It is important to consider:
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Temperature of the environment (standard - from -30 to +80 °C);
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Liquid type (mineral or synthetic oil);
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Installation position (horizontal, vertical, inclined);
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Impact of external factors (dirt, moisture, vibrations).
For aggressive environments it is recommended to use stainless steel And Viton, NBR or PTFE seals.
6. Selecting the type of fastening
The type of fastening affects the kinematics of movement and the reliability of the structure.
| Type of fastening | Description | Application |
|---|---|---|
| On the lugs | Universal, allows for a small turning angle | Hydraulic lifts, excavators |
| Flanged | Rigid connection to the body | Machine tools, presses |
| On spherical bearings | To compensate for distortions | Mobile equipment |
| With threaded stem | For precise installation | Industrial installations |
7. Determining the speed and oil consumption
The speed of the rod movement depends on the fluid supply:
V = Q / S,
Where
V — speed (m/s),
Q — oil flow rate (l/min),
S is the piston area (cm²).
For the cylinder to operate smoothly, the oil supply must correspond to the volume of the cavity and not cause cavitation.
8. Selection of material and seals
The hydraulic cylinder body is usually made of steel 20, 35, 45, the sleeve is honed.
Stock - made of chrome-plated steel to protect against corrosion.
Types of seals:
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NBR (nitrile) — for standard conditions;
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Viton - at elevated temperatures;
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PTFE (Teflon) - under high pressure and friction.
🧰 Calculation example
| Parameter | Meaning |
|---|---|
| System pressure | 160 bar |
| Required effort | 50 kN |
| Piston stroke | 500 mm |
| Piston diameter (calculation) | 63 mm |
| Rod diameter | 40 mm |
| Oil consumption | 12 l/min |
| Mounting type | On the lugs |
| Body material | Steel 45 |
| Type of seals | NBR |
⚠️ Common mistakes when selecting a hydraulic cylinder
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Underestimating pressure and effort - leads to piston failure or oil leakage.
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Incorrect choice of move - limits the operation of the mechanism.
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Lack of consideration of temperature and environment - destroys seals.
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Incorrect choice of fastening - causes distortion and wear of the rod.
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Driving speed too high — leads to water hammer.
🧠 Recommendations from experts
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Use hydraulic system passport for accurate calculation.
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Check it out tightness of seals every 500 engine hours.
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Use if necessary hydraulic cylinders with damping - they reduce impact loads.
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If the equipment operates outdoors, choose anti-corrosion coating and anthers.
✅ Conclusion
Selection of hydraulic cylinder — is a complex engineering challenge that requires consideration of forces, pressure, speed, mounting type, and operating conditions. A properly selected cylinder ensures stable, safe, and durable operation of the entire hydraulic system.
Company Art-Metal offers manufacturing hydraulic cylinders to order tailored to your parameters and design requirements. All products are manufactured from high-quality materials and undergo leak testing and pressure testing.
💬 Contact us — we will select the optimal hydraulic cylinder for any equipment: from mini-hydraulic power plants to heavy industrial installations.
