View A Video on Air Cylinders - A Quick Introduction
Air cylinders, which are also known as compressed air cylinders and
pneumatic cylinders, are pneumatic tools that use the force of
compressed air to move things. They are among the most common pneumatic
tools and are used in food processing and packaging, metal working,
automotive manufacturing, mining, textile production and many other
Every air cylinder is composed of a piston, end covers and a cylinder barrel with at least one air inlet. As compressed air is directed into the cylinder, it pushes the piston along the cylinder's length. The cylinder can be connected to a protruding rod or other structure, which is itself connected to the object that is intended to be moved. There are two categories into which all air cylinders fit. In single acting cylinders, a single inlet allows compressed air in, which moves the piston. A spring behind the piston pushes the piston back when the compressed air is evacuated. In double acting cylinders, two inlets, one on either side of the piston, allow compressed air in and out, pushing the piston back and forth. Valves control the flow of compressed air to the cylinder in both configurations. Other cylinder construction varieties include rotary cylinders, cable cylinders and rodless cylinders, all of which are alternatives to rod-equipped cylinders. Stainless steel and brass are among the most common cylinder construction materials. Compact cylinders, miniature air cylinders and small air cylinders are gaining prominence among manufacturers as microtechnology development operations require access to them; air cylinders are available in sizes as small as 2.5 mm in diameter to 1,000 mm in diameter.
Air cylinders function as actuators in pneumatic systems; an actuator is any mechanism that supplies or transmits controlled energy as part of a mechanical process. Many mechanical processes require access to an actuation method that is reliable, makes no use of harmful chemicals and that is available in many configurations. Different applications call for different air cylinder configurations. The single acting cylinder is able to perform an operating motion in one direction. Pressurized air is introduced on one side of a piston, which causes the piston to move. A spring on the other side of the piston supplies the return force after the pressurized air is released. Single acting cylinders require approximately half the amount of air used by a double acting cylinder for a single operating cycle. A double acting pneumatic cylinder is capable of powered motion in two directions. When a cylinder is pushed out in one direction, compressed air moves it back in the other direction. Air lines running into both ends of the cylinder supply the compressed air. Within these two main configuration categories, there are many specialized configurations available.
Cable cylinders have elongated housing, two rollers and a cable that extends from one end of the cylinder to the other. The yoke, which is the load-bearing surface, is suspended by the cable and moves its attached load as the cable moves back and forth. Rotary cylinders differ from typical air cylinders because they allow revolving motion instead of linear motion. They are typically housed in a circular enclosure in which impellers turn around an axis when pushed by a stream of compressed air. The load-bearing carriage is attached to the axis, which turns in circles both clockwise and counter clockwise. Rodless cylinders are made of long barrels formed with a vertical slot that allow the piston to connect to a load-bearing carriage. They can use mechanical or magnetic coupling to convey force, usually to a body that moves along the length of the cylinder. Each of these configurations varies in size and in load-bearing capacity. The smallest varieties are used in the processing of very small electronics, and the largest are used in heavy-duty industrial processes. A cylinder's composition also depends on its intended application. Stainless steel, for example, is chosen for cylinders that will sustain heavy loads and be subject to harsh conditions.
Choosing an air cylinder for a pneumatic system can be a difficult task. ISO 6432-compliant cylinders all conform to the same dimensions from manufacturer to manufacturer, but not all air cylinder producers make compliant cylinders. If two non-ISO-certified cylinders from different manufacturers are compared, they can have the same bore dimensions, but their stroke length and other dimensions may differ. Because so many of the processes in which air cylinders are used require extreme precision, every air cylinder must be carefully chosen to ensure proper and safe operation. Cylinders should be chosen for their ability to move the greatest load at the lowest acceptable velocity with the minimum available pressure. Cylinder mounting hardware, which includes noses, blocks, pivots and other equipment, is chosen based on the size, force and function of the cylinder. Optional components that help to improve cylinder performance or prevent problems include cushions, bumpers, stop tubes, dual pistons, flow controls, position-sensing switches and position feedback sensors. Carefully chosen air cylinders can be great assets to their users; they are effective, environmentally friendly and available in enough configurations to suit the needs of most industries.
Types of Air Cylinders
have adjustable stops at one or both ends to restrict the amount of
Brass cylinders are pneumatic actuators built of specific copper alloys that resist corrosion and wear and allow use in a number of harsh industrial environments.
Cable cylinders are pneumatic devices that utilize pressure differentials to convert compressed air energy into mechanical energy in order to facilitate lateral movement of a cable or wire and all attached loads.
are flat barrels with round edges and T-slots for sensors along the
entire length of the barrel on three sides. Clean profile cylinders
are used in applications that require ease of cleaning and good hygiene
as the clean, square line design prevents the collection of dust and
also called "short stroke cylinders," are cylinders whose
overall dimensions at zero stroke are minute compared to the typical
cushioned cylinders. These low-profile cylinders are used in applications
in which there is not enough space for a standard length cylinder, as
they can lock or move short distances, even in limited spaces.
power from compressed air into mechanical power.
Double acting cylindershave air lines that provide pressure to both ends of the cylinder,
supplying motion in two directions. The flow of compressed air is controlled
have one piston, and the piston rod extends from both ends of the cylinder.
also called "microcylinders," are small, rectangular, single-acting
air cylinders in which the springs are housed inside enlarged piston
rods. Miniature air cylinders operate in reverse motion and are easy to
install. They offer a range of interchangeable mounting brackets, which attach
to the cylinder ends to provide versatility and adaptability and can
be powered by plant air.
have two or more boxes and pistons combined or stacked in the
are double-acting cylinders that consist of two cylinders with the same
diameter. Multiple-position cylinders provide three or more end positions,
as opposed to the normal two provided by other double-acting cylinders.
are cylinders in which the piston rod, ram or plunger and the relative
rotation of the cylinder housing and piston are set.
have shorter lengths and larger diameters than other cylinders.
are comprised of a piston, a lower and upper port and an expansion chamber.
are similar to single acting air cylinders, but
the port is located on the opposite end in order to provide power on
the retraction (or "pull") stroke.
are encased in a rectangular, box-shaped frame.
Rodless cylinders have a barrel that is formed with a longitudinal
slot, permitting the connection of the piston to the mounting carriage.
A hardened band pneumatically seals the cylinder, while
a second band on the exterior closes the slot and prevents
contamination to the interior of the cylinder; a system of slide rails
divides the two bands in the pressure-free zone between the two piston
seals, which allows movement of the mounting carriage.
Rotary cylinders are pneumatic actuators that utilize pressure differentials, converting compressed air energy into mechanical energy, which is manipulated to facilitate rotational movement.
have only one piston, and the piston rod extends from only one end.
Single acting cylinders have air pressure that supplies motion and force from one side of the
piston flange and a spring that provides the return force after pressure
release. Single-acting air cylinders utilize about half the amount of
compressed air, which is controlled by valves, required by double-acting
air cylinders for a single operating motion.
Small air cylinders are compact pneumatic actuators precision-built to maximize productivity within a limited amount of space.
are cylinders in which the cylinder body encases the piston.
are suitable for harsh environments in which they will be rigorously
cleaned for hygienic reasons or exposed to corrosive forces. Stainless
steel cylinders are often referred to as "throwaway," as
they are irreparable, and therefore, the cheapest of all cylinders.
consist of two or more cylinders with linked piston assemblies.
are held together by exterior tie rods and are usually in a rectangular
consist of a series of twin-cylinder slide units and feature side-by-side
twin cylinders in one body and two piston rods connected with a mounting
plate. This design guarantees precise guiding compared to a typical
cylinder and applies double the force of a cylinder of the same height.
Air Cylinder Terms
A device that converts fluid power into mechanical power. An actuator
may be a cylinder or a fluid motor.
- The amount
of compressed air that is consumed by a pneumatic cylinder. The energy
of the air is converted into power output and exhausted into the atmosphere
on the reversal of the piston stroke.
- Device used
in a pneumatic power system to supply the compressed air.
- A circumferentially
corrugated cylinder that is flexible and thin-walled and may have integral
ends that axially contract or expand when under changing pressure.
- The inside diameter of
the cylinder tube.
- A term referring
to a tightly closing valve seat that prevents the leakage of visible gas
- On the working
side of the piston, the maximum volume of the cylinder from which the
piston displacement volume per stroke is subtracted. Typically, clearance
is expressed as a percentage of the displacement volume.
- A cylinder mounting
- Air that is
at any level of pressure greater than the prevailing atmospheric pressure.
- The connecting
assembly used to translate circular motion to linear motion from the crankcase
and connecting rod to the cylinder head and piston rod.
- A device
in a cylinder that enables the control of movement by restricting the
flow at the outlet, stopping the movement of the piston rod.
- Also referred to
as a "linear motor," it is a device that converts pneumatic
power into linear (in a line) or reciprocating (back-and-forth) motion.
- The driving
force (i.e. the piston power) generated in the cylinder that is a function
of the piston diameter, the working air pressure and resistance caused
A valve that controls the flow of air in a particular direction.
- A situation in which
the valve remains partially open after popping until the pressure further
- A device through which
air is passed in order to separate suspended contaminants. The life of
cylinders and valves is lengthened by using filters.
- A liquid or gas.
- Power conveyed
and maintained by the use of a pressurized fluid.
- A mounting device for
- A device that, when attached
to a safety or safety relief valve, prohibits its opening at the set pressure.
(http://www.iqsdirectory.com/linear-actuators) - A
device that creates mechanical force in a linear manner.
- A designation
describing the position of a valve when it is resting (non-activated).
- A designation
describing the resting position (non-activated) of a valve.
- The sliding piece that
is put into motion by pneumatic pressure. Typically, pistons consist of
a short cylinder fitted inside a cylindrical tube in which it moves in
by opposing forces, operating pressure, inside diameter, length of air
line between control valve and cylinder and size of control valve. The
piston velocity may also be affected by the installation of any quick-exhaust
or throttle valve.
- The use of
a gas, usually air, to transmit, convert or store power.
-The external or internal
terminus of the valve on an air cylinder.
- The relationship
between the surface area of a piston and air pressure of an air cylinder.
- The sum of gauge and atmospheric pressures, which will vary with
- A device that provides
control of the operating pressure of the compressed air system. Regulators
allow working pressure of the system to be adjusted from the minimum to
the maximum at the prop.
- A storage area for
air that, when located near the prop, prevents air starvation.
- A coil of wire, usually in cylindrical form, that is used as
a switch or control for the valve of an air cylinder. When solenoids
a current, they act like a magnet, drawing a moveable core into the coil
as the current flows.
- A device that controls
the flow of air in an air cylinder.