A rod pushing and pulling machine includes at least one hydraulic cylinder
having a front end thereof engagable with a reaction surface at an entry
opening of a existing pipeline or borehole, a spindle assembly, and a
dual vise assembly. The spindle assembly includes a frame, a spindle
shaft rotatably mounted in the frame, a distal end of the spindle shaft
being threaded for engagement with a mating thread of a rod, a drive
system for rotating the spindle shaft in threading and unthreading
directions, the spindle frame being secured to a rear end of the
hydraulic cylinder for pushing or pulling of a rod string engaged to the
spindle shaft upon extension or retraction of the hydraulic cylinder, and
a support assembly for the spindle shaft. The support assembly includes a
set of roller bearings rotatably supporting the spindle shaft, a radial
flange on the spindle shaft, and a load flange secured to the spindle
frame positioned to engage the radial flange, whereby the radial flange
comes into engagement with the load flange during pulling operation to
prevent rotation of the spindle shaft during pulling operation, and
leaves engagement with the load flange during pushing operation so that
the spindle shaft may rotate during pushing operation supported by the
roller bearings. The dual vise assembly has two pairs of separately
actuable jaws positioned to grip a rod nearest the spindle shaft and a
rod adjacent the rod nearest the spindle shaft.