A tandem rod or cable apparatus for bursting and replacing pipe, which includes
a frame, two sets of oppositely-disposed hydraulic cylinders having piston rods,
each of which pairs of piston rods are attached to a yoke, with a gripping element
provided in each yoke for independently gripping a rod or cable extending through
the aligned gripping elements. One end of the rod or cable is attached to a bursting
and stored energy head and the other end extends through the gripping elements,
typically to a reel (in the case of a cable) for taking up slack in the cable.
Advancement of the bursting and stored energy head through a defective pipe to
be burst and typical simultaneous replacement with an attached replacement pipe
is effected by operation of the two sets of hydraulic cylinders and the corresponding
gripping elements to push or pull the rod or pull the cable. In a preferred embodiment
a pneumatic hammer is typically seated in the bursting and stored energy head and
operates in cooperation with a pair of springs to optimize bursting of the defective
pipe as the pneumatic hammer repeatedly strikes the bursting and stored energy
head. The combined actions of the rod or cable operating hydraulic cylinders and
the hammer cause the bursting and stored energy head to progressively rupture the
defective pipe and typically draw the replacement pipe into position.