Compact cylinders have been shortened relative to standard pneumatic cylinders. They may take up to 50% less space than the normal, while still maintaining the capacity to exert the same force as their larger counterparts. Important parameters for the proper selection of a compact cylinder can be broken up into general, dimensional, performance, material, features.

The “Pancake cylinder” was the original compact pneumatic cylinder, invented by Al Schmidt in 1958, to fill a need for force in a tight, enclosed space. The basic intent was to get the most stroke in a short overall length using common machined parts and seals. Through the years, this design has been further developed, with many features and options to satisfy an extreme variety of customer applications. This round body cylinder has a smooth, clean outside diameter for ease of machinery cleaning. Even though initially used for strokes less than 1-in., manufacturing methods have allowed increased strokes to as much as 4-in. Non-metallic rod bushings and piston bearings can accommodate extreme or unforeseen loads to provide long term durability.

Other compact cylinders vary quite a bit. They can be square shaped, offer numerous mounting features and can be placed with adjacent cylinders at a close center-to-center dimension. Piston bearings, materials, hard anodized bore and chrome plated rods can enhance cylinder capability for unexpected side loads and long term durability. Up to 6-in. strokes can be accomplished with extruded body material. Other features may include metric dimensions, extruded sensor mounting, and non-rotating styles. FPH

Selecting a compact cylinder

Application data needed for sizing a compact cylinder and choosing the best component:

• Operating psi, force required (Force = Pressure x Piston Area)
• Stroke
• Preferred mounting, foot print
• Spring return or double acting

Other items to consider:

• Ambient temperature
• Media temperature
• Environment
• Excessive loads other than required axial force
• Load guiding (non-rotating) requirement