Abstract: Apparatus for forming cast-in-place caseless concrete piles wherein an elongated mandrel having a driving tip or foot releasably coupled on its lower end to be driven into the ground and form a pile-forming hole. The mandrel passes through the lower discharge opening of a fill hopper at ground level containing a supply of flowable concrete which flows by gravity into the pile-forming hole as it is being formed. The fill hopper has a self-sealing rigid cylindrical skirt extending downwardly from the discharge opening, and the driving tip or foot has an enlarged circular portion of slightly larger diameter than the skirt and axially alined vertically below the skirt to form the pile hole of such size and shape that the skirt advances into the pile hole during initial soil penetration of the tip to seal against loss of concrete along the ground.

Abstract: Driving tips for forming cast-in-place caseless piles by driving a vertically elongated mandrel having one of the driving tips releasably fitted on the bottom of the mandrel, to thereby produce the pile-forming hole in the earth to be filled with flowable concrete or other fill material. The driving tips have a lower leading end plate of circular cross-section of larger diameter than the mandrel, and include straight parallel rod members rising perpendicularly from the end plate paralleling the center axis of the end plate and located at circumferentially spaced locations along a circular path having a diameter slightly smaller than the inner diameter of the mandrel and concentric with said center axis, rods or cylindrical members to interfit in the hollow interior bore in the mandrel and thereby center the tip relative thereto.