Abstract: Expandable tubular mandrels have lengthwise sections the upper ends of which are joined by a head. Hydraulically operated piston-cylinder units within the mandrel are spaced apart lengthwise of the sections and connected to the mandrel in a manner such that the axis of each unit extends lengthwise of the mandrel and expanding and contracting forces are applied to the mandrel sections when the units are operated to vary their overall length, to effect mandrel expansion when their overall lengths are changed in one direction and mandrel retraction when changed in the opposite direction.

Abstract: A composite pile includes a tubular pile and a tapered, reinforced concrete tip having a central passage opening through its larger upper end and a seat exposed in its bottom. The passage is of a cross sectional area greater than that of the pile and freely receives the boot end thereof. With the boot end of the pile in engagement with the seat the pile is secured thereto in a centered position once the space between the pile and the wall of the passage is filled with a suitable packing.

Abstract: An expansible mandrel, for use in driving a tubular pile, has the pile-entering relationship of its lengthwise arcuate sections established by cable actuated means with separate cable actuated means operable to effect the pile-gripping relationship of the mandrel sections. One of the cables, in the disclosed embodiment, the retraction cable, is operated by a winch mounted on the outside of the mandrel at its upper end and driven in a winding direction by a motor, in the disclosed embodiment, an hydraulically operated motor.

Abstract: An expansible mandrel operated by fluid pressure has its head end encircled by a fluid supply joint having inner and outer rings, the outer ring supported by the hoist ring of a pile driver and held against turning by the guide rails thereof. The inner ring is supported by the outer ring for rotation independently thereof and is connected to the mandrel to turn therewith. Each ring has a pair of conduits with the corresponding conduits of the two rings in communication. Each of the conduits of the outer ring is connected to a hose extending to the ground and each of the two conduits of the inner ring is connected by a hose to the appropriate one of the conduits that are in communication with the fluid pressure operated means.

Abstract: A composite pile includes a tubular pile and a reinforced tapered concrete tip having an axial core opening through its larger upper end and of a diameter less than that of the tubular pile and seats at the upper and lower ends of the core. An expansible mandrel for use in driving such tips and the tubular pile connected thereto has a main portion dimensioned for driving engagement with the tubular pile, a tip portion dimensioned for driving engagement with the core of such a tip with its boot end engageable with the lower seat and an intermediate shoulder engageable with the upper seat.

Abstract: An expansible mandrel for use in driving or withdrawing tubular piles has fluid pressure operated means both to effect the pile-gripping relationship of its sections and their retracted, pile-entering relationship, each including a plurality of sets of sheaves spaced lengthwise of the mandrel and from the sets of the other with a cable in such trained engagement therewith that a pull thereon by fluid pressure operated means effects the appropriate relationship of the mandrel sections.

Abstract: A tapered pile tip has a welded core assembly within its reinforced concrete body, the assembly having a tubular, mandrel-receiving core including a tubular member exposed at the larger end of the tip to which a length of corrugated tubing is to be welded and a member welded to the reinforcements of the body, one member including a seat engageable by the mandrel and a tubular portion receiving an end of the core.