pneumatic actuators main drawback is that certain response or deviate from the resistance will be lost, this is because the compressibility of the gas, especially with large area of elastomer ( The diaphragm, for example) The actuators. But it's not - A problem, because does not require a high degree of response of many conditions and ability to resist deviation. For larger actuators speed is a problem, because the actuator volume must be filled with pressure and/or air emissions into the atmosphere. For this reason, the larger actuators by all shrink the time spent on their trip to total elongation than small spend the time of the actuator, such as in table 5. 1. Pneumatic actuators must be close to the air source and rely on the continuous operation of air compressor, but also has a separate or set volume pot except for auxiliary system.

although some structure is better than others, but pneumatic actuators also limits the amount of available thrust, make some structure in large size pipeline of high pressure condition selection is unlikely. Diaphragm actuators are usually have low thrust, because the diaphragm can only absorb a certain amount of air pressure and not failure, thus limiting the ability of thrust.

in the past 40 years is the most commonly used pneumatic actuators diaphragm actuator ( Figure 5. 8) 。 Most of the diaphragm actuators are designed into linear motion, but also has the structure of the rotary motion. Typical diaphragm actuators are, by definition, unidirectional actuator, it provide the air pressure to the idols of the elastomer ( Is called diaphragm) To stretch or shrink on only one side of actuator rod, the rod connected to the closed element. Diaphragm clamping between the upper and lower casing, depending on the type of the actuator, both one of the casing to withstand air pressure.