Single acting air cylinders are pneumatic devices used for the unidirectional extension or retraction of a rod or piston through the introduction of varied amounts of compressed air into a closed cylinder system. Also known as single action air cylinders, these devices serve a number of mechanical applications by converting the power of compressed air into mechanical energy.
Because single acting cylinders operate using only compressed air, they offer an economical and environmentally friendly source of mechanical power that is popular in a wide range of industrial, commercial and even domestic applications. Automotive, food processing and packaging, metal working, mining, construction, textile and forestry industries all utilize air cylinder systems to open, close, push, pull and lift products as well as equipment and building components.
While double acting cylinders are also common in these environments and have the added benefit of multidirectional movement, single action cylinders operate on approximately 50% less compressed air than the equivalent double system, allowing for smaller compression systems that are often more easily installed and integrated into pre-existing workspaces. A number of different designs and housings are also available to ensure that a single acting cylinder system can be easily fitted and incorporated.
Tie rod, smooth body, pancake, rectangular, rotating and multiple bore are just a few of the options widely available in both custom and standard sizes to meet the needs of any application. While body type is important, additional considerations for air cylinders include mounting options, bore size, connectors, port size, load, velocity and air pressure.
Although there are several variable options regarding single acting cylinders, the basic construction and process remains relatively uniform. The cylinder itself is a round or rectangular tube shaped device that contains a shaft, piston rod and plunger. Additionally, a port is located at one end of the cylinder. Compressed air is forced through the port and into the enclosed shaft.
The air acts upon the plunger, or piston face, and forces it towards the opposite end. This creates the linear energy needed to push the piston towards the opposing end of the shaft. The attached rod is pushed out of the shaft, where it fulfills its mechanical purpose. The rod is retracted when pressure is released and the piston moves back toward its withdrawn position within the cylinder. In some instances gravity or the opposing force load of the involved mechanical processes themselves are responsible for the retraction.
Some single action cylinders, however, have an additional implement housed within the shaft: a spring. The spring is compressed between the rod side of the piston and the end of the cylinder during extension, but returns to the starting position when compressed air is released. As this spring and all other components receive a great deal of wear, the body and internal mechanisms of single acting cylinders are most often made of durable materials such as aluminum, steel, stainless steel and thermoplastics.