Tandem cylinders use multiple pistons connected through a common rod to generate relatively high force from a low supply pressure and small bore.Like all cylinders, specialty cylinders use pressurized fluid (air, in this case) to produce linear motion-and force to move, position, or compress a load. They depart from convention in their configuration, design, construction, or even mode of operation.
For example, a tandem cylinder uses two or more pistons connected to a single piston rod to multiply force produced by a cylinder without increasing bore size. This makes tandem cylinders ideal for applications where high force must be generated from a slender profile.
A duplex cylinder, however, contains two pistons connected to a separate, coaxial piston rod. This configuration can produce motion with two different stroke lengths. With both pistons retracted, one stroke is accomplished by energizing the cylinder chamber opposite the rod end. A second stroke occurs by energizing the chamber closed to the rod end. The net result is a cylinder that produces three distinct positions with having to use complicated switching or external stops.
Spare the rod
Probably the widest variety of designs occurs with rodless cylinders. As their name implies, these do away with the piston rod that normally protrudes from a cylinder's end cap. Because of this, they can produce the same stroke of a conventional design, but in roughly half the retracted length.
