PNUEMATIC ACTUATOR

PURPOSE:To improve the durability of a pneumatic actuator which comprises an internal cylinder made of an elastic material and a braided body covering the outside of the internal cylinder, by arranging a middle layer formed by braiding a fiber having a prescribed streching modulus between the internal cylinder and a braided body. CONSTITUTION:Air-back type pneumatic actuator which works mainly as the operational force of a robot has an internal cylinder 1 made of rubber or rubber- like elastic material and a braided body 2 covering the outside of the internal cylinder 1. Then a middle layer 14 which is formed by braiding a fiber and has a stretching modulus per unit width of 1-5X10 g/cm when it is stretched by 50% is fixed between the internal cylinder 1 and the braided body 2. The tensile elongation of the middle layer 14 when fractured is set at a value larger than 55%. Thus by protecting the internal cylinder 1 from the braided body 2 using the middle layer 14, the expansion and bending life of the internal cylinder 1 is improved and as a result, the life of the actuator is improved.