Conical driving head for pneumatic thrust borer - enlarges pilot bore, has liner plates welded to radial plates from core sleeve (OE151276)

A pneumatic earth boring tool has a conical driving head of simple welded plate construction. It can be used to enlarge a pilot bore by compaction of soil substrate. Thrust boring may be used to install service cables under highways without trench excavation. The head has a core sleeve (5) which fits onto a hammer nose (1). Triangular web plates (4) radiate from the core sleeve to receive the outer lining plates (3). The web plates (4) may be fixed to the core sleeve (5) by continuous longitudinal welds. Each outer lining plates (3) is of truncated pyramid shape, spans between successive radial web plates (4), and may be fixed to the free-edges of the web plates by intermittent longitudinal welds. The rear of the cone may be formed by a polygonal ring plate (6).