Patent ID: 7438089

Claim:
A pilot control unit ( 1 ) having an oscillation damping system, which operates by damping an actuation stroke; comprising a casing ( 1 a ) having two chambers one above the other: a lower chamber ( 9 ), connected to a pressure line (LP), and an upper chamber ( 6 ), connected to a discharge line (LS); one or more spools ( 8 ) that slide within a body, to control pressures at control ports ( 12 ); coaxial and concentric springs ( 2 ) and ( 3 ) provided in the chamber ( 6 ), to press a poppet ( 7 ) upward against a push rod ( 4 ) and to transmit the pressing force applied from the poppet ( 7 ) to the spool ( 8 ) respectively, wherein, the upper chamber ( 6 ) is connected to a discharge port (T) through a discharge hole ( 11 ), which is situated in the upper portion of said upper chamber ( 6 ), above the poppet ( 7 ); upon actuation of a pilot mechanism ( 20 ), the poppet ( 7 ) pushes the fluid in the upper chamber ( 6 ) toward the discharge hole ( 11 ), through a clearance between the poppet ( 7 ) and a bore ( 13 ); the upper chamber ( 6 ) being always filled with oil, and allowing damping during the actuation stroke.