More or Less – Compact Air Cylinders are a Big Deal! “Less is more” seems to be the trend in the pneumatic actuator market. Real estate on OEM equipment is at a premium today more than ever before! This just confirms that Alfred W. Schmidt (the founder of Fabco-Air, Inc.) was well ahead of the curve when he designed the original Pancake® (a registered trademark of Fabco-Air, Inc.) air cylinder in the late 1950’s. This particular type of pneumatic actuator was designed to satisfy the need for short stroke, low profile, compact air cylinders that were required to fit in very tight spaces. In fact, this cylinder type provides the longest stroke possible in the smallest overall envelope size. Approximately 6 decades later, compact air cylinders are still a big deal!
Today, compact cylinders using compressed air are most often the primary solution when space is limited and mechanical actuation is desired. A typical compact air cylinder is between the bore size range of ½” (12mm) to 4” (100mm) with standard strokes ranging from 1/16” (1.5mm) to 4” (100mm). With the typical maximum standard stroke of 4” (100mm), these cylinders are also frequently referenced as short stroke cylinders.
The original Pancake® is a bored body design. In addition to the bored body design, compact cylinders are now offered in a conventional tie-rod/spacer configuration in both a round and square design as well as an extruded body designs.
Compact air cylinders have a piston rod configuration (as opposed to a rodless cylinder). Piston rod cylinders function in two ways: double-acting and single-acting. Double-acting cylinders use compressed air to power both the extend and the retract stroke (moving the rod back and forth). This arrangement makes double-acting cylinders ideal for pushing and pulling loads. Here are some common double-acting, compact air cylinder application functions:
Single-acting cylinders have compressed air supplied to only one side of the piston; the other side vents to atmosphere. Depending on whether air is routed to the cap or rod end determines whether the rod extends or retracts. The most common type is pressure-extended with an internal spring returning the piston to its original position when air exhausts. This is typically called spring return.
Spring extend is when air pressure retracts the rod and the spring force causes the rod to extend when pressure is removed. This makes single-acting cylinders ideal when a force is needed in one direction only and where the return stroke is unimpeded and unloaded. These are also popular in areas where, for safety reasons, a defined position must be taken in the event of a power failure. Here are some typical single-acting, compact air cylinder application functions:
- Actuating of Flaps and Levers