Abstract: An electromagnetic pile driver has an elongated guide in which a magnetic core is permitted to fall by gravity to impact against an anvil transmitting the impact energy to the pile. The core is raised by a coil in a ferromagnetic sheath disposed at an upper portion of the guide and an upper anvil can be provided and coupled to the pile when the apparatus is used for withdrawing piling. The coil is energized by the control discharge of a capacitor.

Abstract: An electromagnet hammer of the type described in U.S. Pat. No. 4,215,297 is autosynchronized by triggering the discharge thyristor in response to the detection of the position of the armature by a proximity detector, or by direct detection of the zero passage of the negative amplitude of the discharge current, or at a reference point representing the position of the armature, with a delay equal to at least half the period of the natural period of oscillation of the armature/plunger and its elastic suspension.

Abstract: A two-directional percussion implement selectively adaptable both for driving in and for extracting, e.g. piles, from the ground, includes two coaxial electromagnetic coils whose movable armatures are represented by extremities of a reciprocable ram. Opposite anvils, one of which is adapted to be coupled with a driven element, are interlinked by a non-magnetic shaft traversing the ram. When the implement is intended for drilling operations, a rotary drive imparts rotation to one of the anvils via a connection permitting independent rotation and reciprocation. The shaft in this case has a central channel for taking samples or for conducting drilling fluids. When adapted only for axial percussions, the implement is vertically suspended on a cable via a shock absorber.

Abstract: An electromagnetic hammer has a coil coacting with an axially reciprocable armature including a ferromagnetic core traversed by an elongate nonmagnetic ram which carries at one end a spring-loaded piston head forming part of a pneumatic damping device, its other end co-operating with a working tool. The coil is intermittently energizable by a control system including a capacitor chargeable from an electric power supply by way of a first thyristor and dischargeable through the coil by way of a second thyristor, the two thyristors being sequentially triggered in response to a control pulse applied to a transformer with two secondaries generating staggered firing pulses with the aid of a delay network in the output circuit of one of these secondaries.