A rodless cylinder from Airtec Pneumatics, Addison, Ill. (www.airtec.se), uses a patented cylinder tube with two chambers to minimize leakage and improve flexural and torsional stiffness. Inside, a toothed belt turns a pulley that moves the shaft with no slippage. Common driveshafts can link and synchronously operate several cylinders. The cylinders can also be supplied with a brake mounted on the drive shaft without using a transmission chain or mechanical linkage. Combining a cylinder with a brake and encoder results in an inexpensive positioning system. Cylinder rods are available in 25 and 40-mm diameters.