PNEUMATIC ACTUATOR

PURPOSE:To improve the bending strength in an air-back type pneumatic actuator which expands and contracts as a result of supply and exhaust of the pressurized air by constructing its main body from an internal cylinder made of an elastic material, a cushioning layer a middle layer of a braided fiber, and a braided body on the outermost side. CONSTITUTION:In an air-back type pneumatic actuator, controlling pressure is supplied from the connecting hole 11 into the internal hollow space 10 of a tube- shaped body 1 made of rubber or rubber-like elastic material to expand the tube- shaped body 1 in the diameter direction. As a result, the braided angle theta0 of a braided body 2 covering the outside of the tube-shaped body 1 is enlarged into the angle thetax. This pantagraph motion of the braided body 2 contracts the tube- shaped body 1 in the axial direction, and the distance between the linked pin holes of closing members 3 on both ends of the actuator main body. Eurthermore, a cushioning layer 14 made of a gum material which has a specific dynamic shearing storing elastic modulus and a middle layer 15 formed by braiding a fiber having a specific stretching strength are placed between the tube-shaped body 1 which is the internal cylinder of the actuator and the braided body 2, in order to improve the bending strength of the actuator.