Safety rope pulley type extension-and-retraction device

The invention relates to the technical field of liquid filtration, and specifically discloses a safety rope pulley type extension-and-retraction device. The safety rope pulley type extension-and-retraction device comprises an L-shaped seat, pulley frames, adjusting bolts and groove pulleys on the pulley frames. The groove pulleys are separately welded to two sides of a right angle of the L-shapedseat, and a plurality of equally spaced connection holes are formed in the end, away from the pulley frames, of the L-shaped seat. In the installation process, the appropriate connection holes are selected according to the actual size of the site, and the adjustment bolts penetrate through the connection holes and are tightly attached to the side surface of a parapet wall through nut connection, so that the device is firmly fixed. The safety rope pulley type extension-and-retraction device is extremely simple in method; materials are common, and the safety rope pulley type extension-and-retraction device is convenient