KEVOS® MAKEOS · Hydraulics
Cylinder Meter-Out Speed Control (Orifice, Intensification, Heat)
What meter-out orifice sets this cylinder to the speed I want under its load, how high does the rod-side pressure rise, and how much heat does the control make?
Meter-out flow control of a double-acting cylinder extending against a resisting or overrunning load: cap-side and annulus areas, cap-side flow for the speed against pump flow, rod-side (back) pressure from the force balance including intensification, the orifice diameter that passes the rod-side flow at that pressure drop (as the orifice flow tool), heat generated in the orifice and over the relief valve, and the rod-side pressure against its rating.
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How this tool works
Inputs, units and where to find them
| Input | Unit | Typical source |
|---|---|---|
| Bore | mm | Cylinder bore. |
| Rod diameter | mm | Rod diameter. |
| Supply (relief) pressure | bar | Pressure on the cap side (the relief setting holds it there with meter-out control). |
| Load (positive resists, negative overruns) | kN | Load on the rod: positive when it resists extension, negative when it pulls the rod out. |
| Extend speed wanted | m/s | Extension speed wanted. |
| Pump flow | L/min | Pump flow available. |
| Orifice discharge coefficient | Discharge coefficient of the orifice or valve (about 0.6–0.7). | |
| Oil density | kg/m³ | Oil density. |
| Rod-side pressure rating | bar | Pressure rating of the rod-side seals, cylinder and valve. |
Method and formulas
- A₁ = π D² ÷ 4, A₂ = A₁ − π d² ÷ 4; Q₁ = A₁ v, Q₂ = A₂ v.
- Force balance p₁ A₁ = F + p₂ A₂, so p₂ = (p₁ A₁ − F) ÷ A₂ (an overrunning load raises it above p₁ A₁ ÷ A₂).
- Orifice area A₀ = Q₂ ÷ [C_d √(2 p₂ ÷ ρ)] with the tank at zero pressure (as the orifice flow tool).
- Heat = p₂ Q₂ (orifice) + p₁ (Q_p − Q₁) (relief).
- Example: 0.1 m/s against 15 kN needs a 1.7999 mm orifice; the rod side runs at 77.035 bar and the circuit makes 2.6667 kW of heat.
Limitations
- Sharp-edged orifice, turbulent flow; a pressure-compensated flow control holds speed as the load changes.
- Line and valve losses are not included.
- Example values are illustrations. Replace them with values for your actual task.
Typical uses
- Size a fixed orifice or set a flow control for a cylinder speed
- Check rod-side pressure with a meter-out circuit
- Estimate heat from speed control
Who it is for
- Hydraulic engineers
- Machine designers
- Maintenance engineers
What you get
- Areas, flows and pump check
- Rod-side pressure and intensification
- Orifice diameter and heat
Interpreting the result
- Meter-out holds overrunning loads but intensifies rod-side pressure: check the rod seals when the load reverses.
References
- Machinery’s Handbook, 29th edition (Industrial Press, 2012), printed pp. 3024–3027, 352–368. Topic reference; no source tables or recommended settings are reproduced.
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Open the Cylinder Meter-Out Speed Control (Orifice, Intensification, Heat) calculator
