Patent ID: 7603923

Claim:
A hydraulic servo ( 1 ) for a gear change provided with a control shaft ( 2 ); the servo ( 1 ) comprising: a frame ( 4 ) having a first plane connection wall ( 30 ); a first hydraulic actuator ( 5 ), which is carried by the frame ( 4 ) and comprises two first chambers ( 7 ), which are alternatively filled with a pressurized fluid for displacing the control shaft ( 2 ) axially in two directions; two first solenoid valves ( 26 ), which control filling of the two first chambers ( 7 ) of the first hydraulic actuator ( 5 ); a second hydraulic actuator ( 6 ), which is carried by the frame ( 4 ) and comprises at least one second chamber ( 14 ), which is filled with a pressurized fluid for rotating the control shaft ( 2 ) about a central axis ( 3 ); a second solenoid valve ( 27 ), which controls filling of the second chamber ( 14 ) of the second hydraulic actuator ( 6 ); and a supporting body ( 25 ), which is fixed to the frame ( 4 ), has a second plane connection wall ( 29 ) set in contact with the first connection wall ( 30 ) of the frame ( 4 ), houses the solenoid valves ( 26 , 27 ), and has inside it a series of hydraulic circuits ( 31 , 40 ) that connect the solenoid valves ( 26 , 27 ) themselves both to the chambers ( 7 , 14 ) of the actuators ( 5 , 6 ) and to a supply of the pressurized fluid; the servo ( 1 ) is characterized in that: passing through the second connection wall ( 29 ) of the supporting body ( 25 ) is a pair of actuation pipes ( 31 ), each of which connects a first solenoid valve ( 26 ) to a first chamber ( 7 ) of the first hydraulic actuator ( 5 ); in a position corresponding to the second connection wall ( 29 ) of the supporting body ( 25 ) there gives out a number of exhaust pipes ( 32 ), each of which originates in an exhaust manifold ( 33 ) of the fluid at ambient pressure; and made in a position corresponding to the second connection wall ( 29 ) is a recovery channel ( 34 ), which traverses and joins the exhaust pipes ( 32 ) and extends at least partially around the actuation pipes ( 31 ).