Double Acting Hydraulic Cylinder
A double acting hydraulic cylinder has oil ports on both sides of the piston, so it produces controlled force in both directions: pushing when the rod extends and pulling when it retracts. It is the most widely used cylinder type in construction equipment, agricultural machinery and industrial automation.
Fenitsa builds double acting cylinders in standard FDH, KHS and THS series and to customer drawings.
How a Double Acting Cylinder Works
A 4/3 directional valve sends pump flow to the cap end to extend the rod while oil from the rod end returns to tank; switching the valve reverses the flow and the rod retracts. In the centre position the ports can be blocked to hold the load.
F_extend = P × π × D² / 4F_retract = P × π × (D² − d²) / 4v = Q / APush and Pull Force at 160 bar
Common bore/rod combinations; φ = area ratio (retract speed ÷ extend speed).
| Bore / rod | Push | Pull | φ |
|---|---|---|---|
| 40 / 22 mm | 20.1 kN | 14.0 kN | 1.43 |
| 50 / 28 mm | 31.4 kN | 21.6 kN | 1.46 |
| 63 / 36 mm | 49.9 kN | 33.6 kN | 1.48 |
| 80 / 45 mm | 80.4 kN | 55.0 kN | 1.46 |
| 100 / 56 mm | 125.7 kN | 86.3 kN | 1.46 |
| 125 / 70 mm | 196.3 kN | 134.8 kN | 1.46 |
| 160 / 90 mm | 321.7 kN | 219.9 kN | 1.46 |
| 200 / 110 mm | 502.7 kN | 350.6 kN | 1.43 |
Construction Types
Tie-rod
Heads clamped by tie rods; standard ISO dimensions, easy to service. See tie-rod cylinders.
Welded body
Cap welded to the barrel; compact and robust for mobile equipment. See welded cylinders.
Threaded / bolted head
Removable head for maintenance in industrial and mobile use.
Double rod
Rod on both ends; equal force and speed in both directions.
Applications
Construction equipment
Boom, arm and bucket cylinders.
Agriculture
Loaders, implements and trailers.
Presses
Forming and assembly presses needing return force.
Industrial machinery
Injection moulding, steel, recycling and handling equipment.
What to Specify
- Bore and rodOr the required push and pull forces.
- Stroke and closed lengthInstallation dimensions.
- PressureWorking and peak pressure.
- MountingsRod end and cap end mounting types and pin sizes.
- OptionsCushioning, position sensing, special seals or coatings.
Quote for a Double Acting Cylinder
Send your drawing or the key values; we reply with a technical proposal and lead time.
Double Acting Cylinder FAQ
How does a double acting hydraulic cylinder work?
Oil is supplied alternately to both sides of the piston. Pressure on the cap side extends the rod; pressure on the rod side retracts it, so the cylinder produces controlled force in both directions.
Why is the retract force lower?
On retraction oil acts on the annulus around the rod, which is smaller than the full piston area. Retract force = P × π × (D² − d²) / 4.
Why does it retract faster than it extends?
The same flow fills the smaller rod-side volume faster. The ratio of piston area to annulus area (φ) equals the speed ratio.
What pressure ratings do you offer?
Standard designs cover 160 bar (ISO 6020/2 type) and 250 bar (ISO 6022 type); mobile and custom designs are available for higher pressures on request.
Can I get double acting cylinders with cushioning and position sensing?
Yes. Adjustable end-of-stroke cushioning and magnetic or linear transducer position sensing can be specified.