Device for the injection of fluids such as cement, resins and oxidizing agents, in particular for making special foundations and for soil consolidation and reclamation, characterized in that it comprises: - at least one electric motor of the brushless or stepping type; - at least one fluid-dynamic cylinder for the injection of fluids; - motion transmission means suited to transmit motion between said at least one electric motor and the piston of said at least one fluid-dynamic cylinder, and wherein said transmission means in turn comprise: - at least one threaded shaft; - connection means for connection between said electric motor and said threaded shaft; - at least one lead screw nut with recirculating balls coupled with said threaded shaft and suited to transform the rotary motion of said threaded shaft into a linear motion; - means for transmitting said linear motion between said at least one lead screw nut with recirculating balls and said at least one fluid-dynamic cylinder, and wherein said means for transmitting said linear motion between said at least one lead screw nut with recirculating balls and said at least one fluid-dynamic cylinder comprise a hollow transmission cylinder having: - one seat for the at least partial insertion of said threaded shaft, - a first end directly or indirectly constrained to said lead screw nut with recirculating balls; - a second opposite end directly or indirectly constrained to said piston, and wherein said lead screw nut with recirculating balls has a linear motion in both directions according to the rotation direction of said threaded shaft, and wherein the dimensions of said seat of said hollow transmission cylinder are such that it can contain the entirety or part of said threaded shaft when said cylinder is in an upper end-of-stroke position. - at least one electric motor of the brushless or stepping type; - at least one fluid-dynamic cylinder for the injection of fluids; - motion transmission means suited to transmit motion between said at least one electric motor and the piston of said at least one fluid-dynamic cylinder, and wherein said transmission means in turn comprise: - at least one threaded shaft; - connection means for connection between said electric motor and said threaded shaft; - at least one lead screw nut with recirculating balls coupled with said threaded shaft and suited to transform the rotary motion of said threaded shaft into a linear motion; - means for transmitting said linear motion between said at least one lead screw nut with recirculating balls and said at least one fluid-dynamic cylinder, - at least one threaded shaft; - connection means for connection between said electric motor and said threaded shaft; - at least one lead screw nut with recirculating balls coupled with said threaded shaft and suited to transform the rotary motion of said threaded shaft into a linear motion; - means for transmitting said linear motion between said at least one lead screw nut with recirculating balls and said at least one fluid-dynamic cylinder, and wherein said means for transmitting said linear motion between said at least one lead screw nut with recirculating balls and said at least one fluid-dynamic cylinder comprise a hollow transmission cylinder having: - one seat for the at least partial insertion of said threaded shaft, - a first end directly or indirectly constrained to said lead screw nut with recirculating balls; - a second opposite end directly or indirectly constrained to said piston, - one seat for the at least partial insertion of said threaded shaft, - a first end directly or indirectly constrained to said lead screw nut with recirculating balls; - a second opposite end directly or indirectly constrained to said piston, and wherein said lead screw nut with recirculating balls has a linear motion in both directions according to the rotation direction of said threaded shaft, and wherein the dimensions of said seat of said hollow transmission cylinder are such that it can contain the entirety or part of said threaded shaft when said cylinder is in an upper end-of-stroke position.