Importance

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Abstract

The invention relates to an improved rod pushing and pulling machine suited for use in underground pipe bursting and replacement with a rod string wherein each rod has at least one radially enlarged upset thereon. The machine includes a housing or frame having a pair of side walls and a front wall with an access opening therein through which a rod string can extend. At least one main thrust cylinder is mounted on the housing. A ratchet block mechanism driven by the main thrust cylinder includes a pivoting pawl and a reversible stop mechanism that permits the pawl to swing out of the way of an upset on a rod as the ratchet block mechanism moves along the rod in one direction, but forces the pawl to engage the upset to drive the rod string when the ratchet block mechanism moves along the rod in the other direction. A bungee vise is mounted on the housing behind the ratchet block mechanism, the bungee vise having a pair of jaws and an actuator that causes the jaws to engage the rod string and hold it against longitudinal movement when the rod string is not engaged by the ratchet block mechanism, and disengage when the rod string is engaged by the ratchet block mechanism.

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First Claim