Apparatus for guiding and steering earth boring casing

摘要

Apparatus for guiding and steering pipe casing bored and pushed underground by an earth boring machine is disclosed which includes hinge assemblies pivotally connecting a steering head to a front casing. Each hinge assembly includes two pivots. A first pivot has a horizontal pivot axis and a second pivot has a vertical pivot axis. Preferably, the hinge assemblies are compound hinges so that the pivots are carried by a unitary hinge assembly. Actuators are provided which impart an actuation force on the steering head to rotate the steering head about the first and second pivot axes. One of the actuators is provided by slidably mounting one of the hinge assemblies so that the first and second pivot axes of that hinge assembly are compounded and moved unitarily. A second actuator is connected to the steering head to move the steering head about the first pivot axis while the hinge assembly slides to pivot the steering head about the second axis.