Mechanical timber grab is equipped according to the characteristic of crane, which could be divided into three species, that is single rope, double rope, and four rope. The kind of grab is simple structure, convenient operation, and single rope grab has novel opening and closing mechanism, reliable action, which is a kind of efficient tool for loading and unloading bulk log, and which is suitable to be used on the working site such as port, forestry centre , woodyard. The lifting capacity of crane is normally 5t~25t.