ENGINEERING GUIDE · SIZING & SELECTION · HYDRAULIC LIFT CYLINDERS
Lift Cylinder Sizing
& Selection Guide
Force · Bore · Stroke Calculation
Selecting the wrong bore size is the most expensive lift cylinder specification error — a cylinder that is too small fails to generate required force; one that is too large wastes energy and demands a larger, more expensive hydraulic power unit. This guide walks through the complete sizing methodology: load analysis, force calculation, bore selection, stroke determination, and pressure rating — with worked examples for the most common application types.
Bore Selection
Safety Factors
LIFT CYLINDERS · SIZING ENGINEERING · JULY 2026
REFERENCE · KEY SIZING FORMULAS AT A GLANCE
FUERZA DE EXTENSIÓN
F = P × π/4 × D²
F = force (N), P = pressure (Pa), D = bore diameter (m)
FUERZA DE RETRACCIÓN
F = P × π/4 × (D²−d²)
d = rod diameter — annular area is less than bore area
REQUIRED BORE
D = √(4F / π×P)
Solve for minimum bore — round up to next standard size
FLOW RATE
Q = A × v
Q = flow (m³/s), A = bore area (m²), v = rod velocity (m/s)
SECCIÓN 01
The Four-Step Lift Cylinder Sizing Process
Lift cylinder sizing is a sequential process — each step builds on the previous one, and an error at any stage propagates through the remaining lift cylinder calculations. The four steps must be completed in order:
1
Load Analysis
Identify all forces acting on the cylinder
2
Bore Selection
Calculate minimum bore for required force at system pressure
3
Stroke & Rod
Determine travel length and rod diameter for buckling
4
Pressure & Safety
Verify burst pressure, safety factors, test requirements
The most common sizing errors occur at Step 1 — engineers underestimate the actual working load — they use the nominal load rather than the total dynamic force the lift cylinder must generate, which includes acceleration forces, friction, pressure losses, and safety factors. A lift cylinder sized only for the nominal load without these additions will fail in service when the system experiences its actual worst-case operating conditions.
SECCIÓN 02
Step 1 — Load Analysis and Force Calculation
The total force a lift cylinder must generate is rarely the same as the weight being lifted. Five load components must be identified and summed for the worst-case operating condition:
Total design force: F_design = (F₁ + F₂ + F₃ + F₄) × safety factor. This is the force the lift cylinder must generate at the specified system pressure. All subsequent bore calculations use F_design, not F₁.
SECCIÓN 03
Step 2 — Bore Diameter Selection
With F_design known, the minimum bore diameter of the selected lift cylinder is calculated from the system operating pressure. Standard industrial hydraulic systems operate at 14–25 MPa; the chosen pressure directly determines the bore size — lower pressure requires larger bore, higher pressure allows smaller bore. The formula is:
BORE CALCULATION — EXTENSION STROKE
D_min = √( 4 × F_design / (π × P_system) )
Where D_min is in metres, F_design in Newtons, P_system in Pascals. Convert to mm and round up to the next standard bore size.
| BORE Ø (mm) | AREA (cm²) | FORCE @ 16 MPa | FORCE @ 20 MPa | FORCE @ 25 MPa | TYPICAL USE |
|---|---|---|---|---|---|
| 50 | 19.6 | 31 kN | 39 kN | 49 kN | Light platforms, dock lips, small agri |
| 63 | 31.2 | 50 kN | 62 kN | 78 kN | Tractor rear hitch, forklift tilt |
| 80 | 50.3 | 80 kN | 100 kN | 126 kN | Scissor lifts, combine header, dock platform |
| 100 | 78.5 | 126 kN | 157 kN | 196 kN | Seeder frame lift, aerial work platform mast |
| 125 | 122.7 | 196 kN | 245 kN | 307 kN | Heavy scissor tables, front-top tipper (light) |
| 150 | 176.7 | 283 kN | 353 kN | 442 kN | Front-top tipper 40–60 t, dump truck hoist |
| 180 | 254.5 | 407 kN | 509 kN | 636 kN | Front-top tipper 60–100 t, heavy industrial |
El cilindro de elevación range covers bore sizes from 32 mm through 200 mm. Always select the next standard bore size above the calculated minimum lift cylinder bore — never specify a bore exactly equal to the theoretical minimum, as this leaves no margin for pressure variations or oil temperature changes that affect delivered force.
SECCIÓN 04
Step 3 — Stroke and Rod Diameter Determination
Stroke of a lift cylinder is the linear distance the rod travels from fully retracted to fully extended. For direct-acting vertical cylinders (where the rod pushes the load directly), stroke equals the required height change. For lever, scissor, or angled mounting configurations, the required stroke must be calculated from the geometry of the mechanism — and is almost always longer than the height change suggests.
ROD DIAMETER — BUCKLING CONSTRAINT
WHAT IS BUCKLING?
When a lift cylinder rod is extended and loaded in compression, it can buckle sideways if the compressive load exceeds the Euler critical buckling force for the rod diameter and unsupported length. Buckling is a sudden, catastrophic failure mode — the rod bends sideways and the cylinder is destroyed in a single event. Rod diameter must be sized to prevent buckling at the maximum extended position under full design load.
STANDARD ROD-TO-BORE RATIOS
Standard rod-to-bore ratios (d/D) for all lift cylinder applications: 0.5–0.6× bore for short-stroke, moderate-load applications; 0.6–0.7× for medium-stroke; 0.7–0.8× for long-stroke heavy-load cylinders. For high-side-load applications, the rod diameter is sized upward regardless of the stroke-to-bore ratio. A minimum rod diameter of D/2 is the standard starting point; verify with Euler column analysis for any stroke exceeding 10× the rod diameter.
SECCIÓN 05
Step 4 — Pressure Rating and Safety Factors
The pressure rating of a lift cylinder has three distinct parameters — working pressure, test pressure, and burst pressure — and each has a defined relationship to the others:
WORKING PRESSURE
1.0×
Maximum continuous operating pressure. The pressure at which the cylinder delivers its rated force. Typically 16–25 MPa for industrial lift cylinders.
TEST PRESSURE
1.5×
Factory hydrostatic test pressure. Applied for a minimum of 30 seconds with no leakage at any seal or joint — mandatory for all lift cylinders before delivery.
BURST PRESSURE
4.0×
Minimum design burst margin for ISO-compliant cylinders. The barrel and end-caps must withstand 4× working pressure before failure — providing a design safety factor of 4:1 on structural integrity.
Application note: For personnel-carrying lift cylinders — vehicle hoists, scissor tables with workers on them, aerial work platforms — most regional safety regulations require additional certification beyond the standard 4:1 structural safety factor. Verify the applicable standards for your market before specifying. For a comprehensive range of industrial and heavy equipment lift cylinders rated for these requirements, see the Cilindro hidráulico de ingeniería industrial category which covers cylinders with documented certification trails for safety-critical applications.
SECCIÓN 06
Worked Examples by Application Type
Two worked examples showing the complete sizing process from load to specification:
EXAMPLE 1
Scissor lift table — 3 000 kg capacity, 800 mm travel
LOAD ANALYSIS
F₁ = 3 000 × 9.81 = 29 430 N. Scissor geometry factor at lowest position = 4.2×. Effective cylinder force needed = 29 430 × 4.2 = 123 600 N. Add 8% friction (F₃) = +9 900 N. Safety factor 1.5× = F_design = 200 250 N ≈ 200 kN.
BORE SELECTION
At 20 MPa system pressure: D = √(4 × 200 000 / (π × 20 000 000)) = 0.113 m = 113 mm. Next standard bore: Ø 125 mm (delivers 245 kN at 20 MPa — 22% margin).
STROKE & ROD
Scissor table 800 mm travel with horizontal cylinder requires approximately 600 mm lift cylinder stroke (calculated from scissor geometry). Rod diameter: 125 × 0.6 = 75 mm → standard 80 mm rod.
EXAMPLE 2
Front-top tipper — 60 t payload, 52° tip angle, 6.5 m body
LOAD ANALYSIS
Payload 60 t + body tare 12 t = 72 t total. Tipping moment at start of lift: approximately 45% of total weight acts against the cylinder (A-frame geometry). Required force at cylinder = 72 000 × 9.81 × 0.45 = 318 000 N. Safety factor 1.3× = F_design = 413 kN.
BORE SELECTION
At 20 MPa: D = √(4 × 413 000 / (π × 20 000 000)) = 0.162 m = 162 mm. Next standard bore: Ø 180 mm (delivers 509 kN — 23% margin above design force).
STROKE & ROD
6.5 m body at 52° tip with 1 000 mm A-frame height → stroke approximately 4 320 mm (from stroke table). 3–4 stage telescopic. Rod/stage wall thickness sized for column buckling at full extension.
PREGUNTAS FRECUENTES SOBRE LA SOLICITUD
Lift Cylinder Sizing and Selection Questions
P 01
What system pressure should I use for lift cylinder sizing if I am designing a new circuit?
For most new hydraulic circuit designs, 20 MPa (200 bar) is the recommended starting design pressure for mobile equipment lift cylinder circuits and 16–18 MPa for fixed industrial systems. Designing at 20 MPa gives a practical balance: pump and HPU costs are reasonable, hose and component ratings are standard, and the bore sizes produced are neither excessively large nor excessively small. Higher pressures (25 MPa) allow smaller bores but require more expensive components throughout — this is only worthwhile when bore size is constrained by the installation envelope. Lower pressures (12–16 MPa) produce larger, more forgiving cylinders at lower component cost, but are less commonly used in modern high-density mobile equipment.
P 02
How do I size a lift cylinder when the load changes significantly during the stroke (e.g. a dump body tipping)?
Size for the worst-case position across the entire stroke — which is typically the position where the combination of load and geometry produces the highest required cylinder force. For a dump body, this is usually near the beginning of the tip cycle when the cylinder must overcome static friction and the full body weight is resolved against the tipping mechanism at its worst geometric disadvantage. For a scissor table, it is at the lowest arm angle. Calculate the required force at multiple positions across the stroke (at least at 10%, 25%, 50%, 75%, and 100% of travel) and size the lift cylinder bore for the maximum value found across all positions.
P 03
Can I use a higher-pressure rating than my system pressure to get a smaller bore cylinder?
Yes — a lift cylinder rated for a higher pressure than the system will operate at is safe (the cylinder is over-built relative to its operating conditions), but it does not allow you to deliver more force from the same bore unless you also increase the system pressure to match the cylinder’s rating. The force produced is determined by the actual operating pressure in the circuit, not the cylinder’s rated maximum. Specifying a higher-pressure-rated cylinder at a lower system pressure gives you greater safety margin (the ratio between burst pressure and operating pressure increases), which can be valuable for shock-load applications where peak pressures briefly exceed steady-state system pressure.
P 04
What is the correct flow rate for a lift cylinder to achieve the target extension speed?
Flow rate required (litres/min) = bore area (cm²) × rod extension velocity (mm/s) × 0.006. For example, an 80 mm bore lift cylinder at 100 mm/s extension speed requires: 50.3 cm² × 100 mm/s × 0.006 = 30.2 litres/min. The hydraulic pump in the circuit must deliver at least this flow at the operating pressure — at higher pressure, pump volumetric efficiency decreases and actual flow drops, meaning the pump must be sized at 10–15% above the theoretical flow requirement to achieve the target extension speed under load.
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Editor: Cxm
