Single Acting Hydraulic Cylinder
A single acting hydraulic cylinder uses oil pressure in one direction only: the rod extends under pressure and returns by the weight of the load or by an internal spring. With a single hydraulic line, it is the simplest, most economical and most robust cylinder design.
Typical applications are jacks, dump bodies, lifting platforms, forklift masts and presses where the load returns on its own.
Types of Single Acting Cylinders
Load (gravity) return
The load pushes the rod back; used for vertical lifting.
Spring return
An internal spring retracts the rod; ideal for short-stroke clamping.
Ram / plunger
No piston; the rod is the working area. High load capacity and simple construction.
Telescopic single acting
Multi-stage design for long strokes from a short body. See telescopic cylinders.
How It Works
When the directional valve opens the pressure line, oil fills the cap end and the rod extends. When the valve switches to tank, pressure drops and the load or spring pushes the rod back while oil returns to the reservoir. The opposite chamber breathes through a filter.
Return speed depends on the load and on any restriction in the return line. For vertical loads a flow control or counterbalance valve prevents uncontrolled lowering. Push force follows the usual formula F = P × A.
Single Acting vs Double Acting
| Feature | Single acting | Double acting |
|---|---|---|
| Force direction | One (push) | Both (push and pull) |
| Hydraulic lines | 1 | 2 |
| Return | Load or spring | Oil pressure |
| Speed control | Limited on return | Full in both directions |
| Cost | Lower | Higher |
| Typical use | Jacks, dump bodies, presses, lifts | Construction machinery, automation |
Lifting Force by Bore
Theoretical push force.
| Bore / ram | 160 bar (2,320 psi) – metric t | 160 bar – US tons | 250 bar (3,625 psi) – metric t |
|---|---|---|---|
| 40 mm | 2.1 t | 2.3 US tons | 3.2 t |
| 50 mm | 3.2 t | 3.5 US tons | 5.0 t |
| 63 mm | 5.1 t | 5.6 US tons | 7.9 t |
| 80 mm | 8.2 t | 9.0 US tons | 12.8 t |
| 100 mm | 12.8 t | 14.1 US tons | 20.0 t |
| 125 mm | 20.0 t | 22.1 US tons | 31.3 t |
| 160 mm | 32.8 t | 36.2 US tons | 51.3 t |
| 200 mm | 51.3 t | 56.5 US tons | 80.1 t |
How to Specify
- 1
Load
Maximum load plus safety margin.
- 2
Pressure
Working pressure of the power unit.
- 3
Bore
Required area from F = P × A; choose the next standard bore.
- 4
Stroke and return
Stroke length and whether the return is by load or spring.
- 5
Mounting
Eye, clevis, flange or trunnion.
Quote for a Single Acting Cylinder
Send load, stroke and pressure; we will recommend bore and return type.
Single Acting Cylinder FAQ
What is a single acting hydraulic cylinder?
A cylinder in which oil pressure works in one direction only. The rod extends under pressure and retracts by the load’s weight, a spring or an external force.
Single acting vs double acting: which do I need?
If the load returns by gravity and no pulling force is needed, a single acting cylinder is simpler and cheaper. If you need controlled force or speed in both directions, choose a double acting cylinder.
What is a ram (plunger) cylinder?
A single acting cylinder without a separate piston: the rod itself is the working area. It is rugged and carries high loads, which is why it is used in lifts, jacks and presses.
How many hydraulic lines does it need?
One. The other side of the cylinder is vented to atmosphere through a breather filter.
Can you build single acting cylinders to order?
Yes. We build spring-return, load-return, ram and telescopic single acting cylinders to your bore, stroke and mounting requirements.