Pullback Cradle & Roller Support Spacing Analysis

On the pullback side of an HDD, the fabricated pipe string is supported on roller cradles as it is drawn toward the bore. If the cradles are too far apart, the pipe sags between them and picks up bending stress before it even enters the ground. This analysis sets the maximum cradle spacing that keeps sag and bending within allowable limits.

It complements the pull-force and installation-stress checks by controlling the loads the string sees on the surface.