Additional device: according to user needs, various additional devices can be installed to meet different working needs. Ascending or descending valve (H, S, MS): adding the ascending valve "H" and the drop valve "HS", the rise drop time is not extended extremely, the adjustable minimum value can reach 10-20 times the rated value, the valve is adjusted outside, the valve's propeller (when the valve is fully open) its rise and fall time will be extended, the short stroke is extended for about 0.1-0.2 seconds. The long stroke is extended for about 0.2-0.4 seconds. Brake spring (C- spring): it produces braking force. The spring force value listed in Table 1 is the spring force of the 1/3 of ascending stroke (2/3 of descending stroke). Reset spring: working principle is similar to C- spring, but the spring force of reset is small, users need to contact with each other. Retarding spring (D- spring): adding a gentle spring (with the brake spring C- spring combined, and only used in short stroke propeller), mainly regulating the braking process: the non periodic transient process of the retarded brake, making the brake smooth, it is installed on the piston rod instead of the push rod connection block, and does not change the drive B. (Note: the propeller installed with D springs can not be fitted with a stroke switch). Travel switch: according to the needs of users, the propeller can be equipped with mechanical switches or inductive switches to indicate the piston position or the degree of wear of the brake pad. Heater: the heater can be installed according to the user's needs in the area where the ambient temperature is below -20 C. The heater is divided into two kinds of voltage, 110V or 220V. When ordering, it should be noted that the adjustment and control method of temperature is selected by users, and the inlet of the junction box is M22X1.5. Fast descending circuit: by adding capacitance to the motor, the drop time can be reduced by about 15%, and the user can install the suitable capacitance according to the need to shorten the time of reducing the action. High efficiency anticorrosion: application: it is used for corrosive medium and high relative humidity in air, and may cause condensation water. Motor: the stator of vacuum pressure injection. Paint: special anticorrosion paint. Products can provide anti-corrosion products, users need to contact with each other.