A double blade bar for pruning and pollarding of olive tree groves, citrus groves, hedges, timber trees and similar trees, comprising: - a support framework for a cutting blade and a counter-chop blade extending along a cutting direction, interconnected and arranged to be operated in alternating rectilinear movement, in opposite sense to one another, along said cutting direction, from an open configuration of the bar in which the cutting teeth of said cutting blade overlap the counter-chop teeth of said counter- chop blade, to a closed configuration of the bar in which each of said cutting teeth is in a substantially intermediate position with respect to the span defined by two successive teeth of said counter-chop teeth, and vice versa, - movement transmission means having a series of double racks, comprising a plurality of upper racks which face on as many lower racks, each element of said plurality of upper and lower racks being respectfully integrally associated with different portions of said cutting blade and of said counter-chop blade, each upper rack being arranged to be engaged with a corresponding lower rack by means of a respective cogwheel interposed between said upper rack and said lower rack, arranged to be pivoted on a corresponding support rod around a pivoting axis and arranged to be driven by motor means, so that in said open configuration of the bar each of said cogwheels engages, on one hand, with a substantially median portion of said respective upper rack and, on the other side, with a substantially median portion of said corresponding lower rack, so that, in said closed configuration of the bar, said cogwheel engages with a first peripheral portion of said respective upper rack and, simultaneously, with a second peripheral portion of said corresponding lower rack, said second peripheral portion being anti-symmetric to said first portion with respect to said pivoting axis wherein for each displacement of one of said racks (6, 8) an identical feed of said cutting blade along said cutting direction occurs and simultaneously, but in the opposite direction, a similar advancement along said cutting direction of said counter-chop blade occurs, said similar advancement being caused by the displacement of the other of said racks (6, 8), such that the alternating movement of said upper racks and said lower racks cause the cutting. - a support framework for a cutting blade and a counter-chop blade extending along a cutting direction, interconnected and arranged to be operated in alternating rectilinear movement, in opposite sense to one another, along said cutting direction, from an open configuration of the bar in which the cutting teeth of said cutting blade overlap the counter-chop teeth of said counter- chop blade, to a closed configuration of the bar in which each of said cutting teeth is in a substantially intermediate position with respect to the span defined by two successive teeth of said counter-chop teeth, and vice versa, - movement transmission means having a series of double racks, comprising a plurality of upper racks which face on as many lower racks, each element of said plurality of upper and lower racks being respectfully integrally associated with different portions of said cutting blade and of said counter-chop blade, each upper rack being arranged to be engaged with a corresponding lower rack by means of a respective cogwheel interposed between said upper rack and said lower rack, arranged to be pivoted on a corresponding support rod around a pivoting axis and arranged to be driven by motor means, so that in said open configuration of the bar each of said cogwheels engages, on one hand, with a substantially median portion of said respective upper rack and, on the other side, with a substantially median portion of said corresponding lower rack, so that, in said closed configuration of the bar, said cogwheel engages with a first peripheral portion of said respective upper rack and, simultaneously, with a second peripheral portion of said corresponding lower rack, said second peripheral portion being anti-symmetric to said first portion with respect to said pivoting axis wherein for each displacement of one of said racks (6, 8) an identical feed of said cutting blade along said cutting direction occurs and simultaneously, but in the opposite direction, a similar advancement along said cutting direction of said counter-chop blade occurs, said similar advancement being caused by the displacement of the other of said racks (6, 8), such that the alternating movement of said upper racks and said lower racks cause the cutting.