Valve for disconnecting the front braking and/or the trailer braking, for a farm tractor or a similar vehicle

A valve (VD) intended to disconnect, in specific circumstances, the braking of the front wheels (RAS1RAD), and/or of the trailer (RI) when a braking system thereof is connected through a trailer brake valve (VFR), for a braking system of a vehicle having two pair of wheels all provided with braking devices, or of a vehicle having at least a pair of wheels provided with braking devices and having a trailer brake valve, the braking system comprising two master cylinders (CMS, CMD) operating as pumps, each master cylinder (CMS1CMD) being operated by a separate braking pedal (PS1PD), directly controlling the braking of one rear wheel (RPS1RPD), and controlling the braking of the front wheels (RAS1RAD) and/or the braking device of the trailer (RI), if present, through a disconnection valve (VD) intended for disconnecting the braking of the front wheels and/or of the trailer when only one braking pedal (PS1PD) is operated, said disconnection valve including a body (21), a first (25) and a second (24) inlet connections intended to be connected to the two master cylinders(CMS,CMD), and a delivery connection (29) intended to be connected to a braking circuit of the front wheels (RAS1RAD) and/or to the trailer brake valve (VFR)1 characterized in that:

• said body (21) has a first bore (38) wherein is installed one movable piston (23) subjected to the action of the pressure applied to said first inlet connection (25);
• said body (21) comprises a normally closed interception valve (26) closing a communication between said second inlet connection (24) and said delivery connection (29);—and said movable piston (23) has a member (28) suitable for operating said interception valve (26) in order to open the same when said movable piston (23) is displaced by the pressure applied to said first inlet connection (25), then allowing communication between said second inlet connection (24) and said delivery connection (29), and therefore allowing the application to said delivery connection (29) of the pressure present in said second inlet connection (24).