Valve for hydraulic braking of work machines or the like

A valve for the hydraulic braking of work machines, comprising:

• an outer casing provided with a longitudinal seat and with at least one first port for connection of said seat to a pumping assembly for feeding pressurized fluid, with at least one second port for connecting said seat to a fluid discharge and recovery tank, and with at least one third port for connecting said seat to a braking system of a work machine;
• a slider which is slidable along said seat and is provided with a contoured portion, which is suitable to allow or prevent passage of the fluid through said connecting ports, and with a reaction surface which faces said third connecting port and is sensitive to pressure of a pressurized fluid in a braking system of a work machine;
• actuation means for actuating sliding of said slider in said seat in contrast with the pressurized fluid that contacts said reaction surface, said actuation means comprising first elastic means and second elastic means, said second elastic means being arrangeable interposed, in a condition of preloading, between a first abutment element associated with a first end of said slider and a second abutment element arranged inside said casing;
• and
• manual actuation means for manually actuating loading and unloading of said second elastic means,
• wherein said first elastic means are arranged interposed between said casing and an abutment provided at a second end of said slider so as to directly contrast a thrust of the pressurized fluid against said reaction surface, said second elastic means being adapted to contrast a thrust of said first elastic means by a thrust value equal to that of said preloading.