The bridge across the track or on the shelf, the best frame is bearing surface of leg link on the standard level measured at both ends of the bearing surface on the trolley track.

Representative nose width, 135 representatives of leg-length, 28 representatives of the lens height, the buyer can make reference to this data to select their own eyes Frame!

The problem of the effect of oblique tension link on the derricks' cross section frame in the front leg stability calculation of open front derricks remains unsolved.