Air Rams: Single Acting vs Double Acting Pneumatic or Hydraulic Cylinders

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If you need power from compressed air pressure to be used for industrial machinery, pneumatic cylinders or air rams can deliver the big punch. On the other hand, if you need power for heavy machinery such as heavy lifters, movers, bulldozers, dump trucks, and the like, hydraulic cylinders are the standard mobile applications. 

Both pneumatic cylinders and hydraulic cylinders are either in single acting or double acting form.

Single Acting Cylinders

Single acting cylinders, whether pneumatic or hydraulic, only extends the pressure from a pump and then retracts it using a built-in spring. You can tell a single acting cylinder because it will only have one port (hence, “single” acting) for the connection of a hydraulic cylinder or hydraulic hose fitting.


  • Its simple design is easy to install.
  • Its purchase price is low cost or at least affordable.
  • A single port means it has a small housing.
  • It reduces valve and piping cost compared to double acting cylinders.

Although being less costly, single acting cylinders carry more disadvantages than their double acting counterparts:

  • Compressed air pressure requires more complicated preparation.
  • The spring can take up too much space and limits the working area.
  • There is reduced thrust due to the opposing spring force.
  • When the spring is under prolonged usage, the piston strokes can become inconsistent.

Double Acting Cylinders

Double acting cylinders need hydraulic power to both extend and retract pressure from a pump. It also has two ports (hence, “double” acting), one port is for the advanced or extended hydraulic hose fitting, and the other port is for the retracted hydraulic hose fitting.


  • There is more control over movement since pressurised air or fluids move both ways.
  • Power provided is faster and stronger, but uses less energy.
  • It offers more design variation in terms of stroke and bore sizes.
  • Many double acting pneumatic cylinders are ISO compliant, as opposed to single acting cylinders.

The two main disadvantages of double acting cylinders are their high cost and requirement for a larger housing, especially if the feed cylinder needs to be coupled with another machine system. 

Master Mac 2000

Master Mac 2000 P/L was established in 1989 and has grown to become one of Australia’s largest privately-owned process valves, air rams, and pneumatic component distributors. This also includes the distribution of quality local and international brands such as Mack, Univer, Piab, Tolomatic, and Bimba. Contact Master Mac 2000 for more information as they are sure to have the stocks and solutions you need at their Brisbane office and warehouse. You can call them at 07 3344 4711 or visit their website at

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