Sheave: sheave wheel assembly. Countersunk rivets riveting rim protruding nail head, recessed deviation should be less than 0.5mm. Should close fit between the various parts of Shandong caulking fixed sheave, the extent of its close fit within the circumferential extent of twice the radius of the nail head gap should be less than 0.1mm, with a feeler. Replace the sheave job preparation work: Xintian wheel must be carefully checked prior to use for each site. Checked for the use of wire rope can be put into use after passing the wire rope used during operation must rope the new establishment. Lighting the main wellhead repair and overhaul heaven round lighting.