BIZOMAT 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. |
What each input means
Open an input to see what it is, its units, the worked example and the common mistakes, with a small diagram.
What this means: Bore
- What it is
- The inside diameter of the cylinder barrel, which sets the cap-side area the supply pressure acts on.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 63 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
What this means: Rod diameter
- What it is
- The diameter of the piston rod. The annulus area on the rod side is the bore area less the rod area.
- Units and format
- Enter a number in mm: millimetres. The form accepts 0.000001 mm to 1000 mm. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 36 mm as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A larger rod shrinks the annulus and raises rod-side pressure (intensification).
- Get it right
- It must be smaller than the bore, or the tool stops.
What this means: Supply (relief) pressure
- What it is
- The pressure held on the cap side during extension. With meter-out control the relief valve holds the supply at its setting.
- Units and format
- Enter a number in bar: bar (1 bar = 100 kPa). The form accepts 0.000001 bar to 700 bar. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 100 bar as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher supply pressure raises the rod-side pressure and the heat over the relief.
- Get it right
- Enter gauge pressure at the cylinder port.
What this means: Load (positive resists, negative overruns)
- What it is
- The external load on the rod during extension. Positive when it resists the motion, negative when it pulls the rod out (an overrunning load).
- Units and format
- Enter a number in kN: kilonewtons (1 kN = 1000 N). The form accepts -10000 kN to 10000 kN. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 15 kN as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Each extra kN of resisting load lowers the rod-side pressure.
- Get it right
- An overrunning load must be entered as negative; it raises the rod-side pressure.
What this means: Extend speed wanted
- What it is
- The speed you want the rod to extend at, controlled by the meter-out orifice on the rod side.
- Units and format
- Enter a number in m/s: metres per second. The form accepts 0.000001 m/s to 10 m/s. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.1 m/s as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Flows rise in proportion; the orifice area needed grows in proportion too.
- Get it right
- Metres per second: 100 mm/s is 0.1 m/s.
What this means: Pump flow
- What it is
- The flow the pump delivers. Any flow beyond what the cap side takes passes over the relief valve as heat.
- Units and format
- Enter a number in L/min: litres per minute. The form accepts 0.000001 L/min to 10000 L/min. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 25 L/min as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- Extra pump flow above the cylinder’s need adds relief heat in proportion.
- Get it right
- Use the delivered flow at working pressure, not the nameplate displacement.
What this means: Orifice discharge coefficient
- What it is
- The discharge coefficient of the control orifice or flow valve: the ratio of real to ideal flow through it, from the valve maker or orifice data.
- Units and format
- Enter a plain number with no unit. The form accepts 0.3 to 1. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 0.62 as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Effect on the result
- A higher coefficient lets a smaller orifice pass the same flow.
- Get it right
- It is a dimensionless ratio, not a flow or a size.
What this means: Oil density
- What it is
- The density of the hydraulic oil at operating temperature, from the oil data sheet.
- Units and format
- Enter a number in kg/m³: kilograms per cubic metre. The form accepts 0.000001 kg/m³ to 1500 kg/m³. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 870 kg/m³ as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Enter kilograms per cubic metre, not kilograms per litre.
What this means: Rod-side pressure rating
- What it is
- The lowest pressure rating among the rod-side seals, cylinder and meter-out valve. The intensified rod-side pressure is checked against it.
- Units and format
- Enter a number in bar: bar (1 bar = 100 kPa). The form accepts 0.000001 bar to 1000 bar. Required: the tool does not calculate until every input is valid.
- Example
- The form opens with 250 bar as a worked example. It is an illustration, not a recommended value: replace it with your own figure.
- Get it right
- Take the rating from the maker of each component and use the lowest.
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