A shut-off valve comprising: a housing including a bore, a master cylinder port (40, 40a, 40b), a pressure supply port, a system pressure port, and a return port, wherein each port connects with the bore and the bore includes a valve seat section and a piston receiving section, wherein the valve seat section is connected with the system pressure port, wherein the piston receiving section is connected with the return port; a first valve seat disposed in the valve seat section of the bore between the pressure supply port and the system pressure port; a second valve seat disposed in the valve seat section of the bore between the system pressure port and the master cylinder port (40, 40a, 40b); a spool disposed in the bore; a poppet on the spool, wherein the poppet moves with the spool and is disposed in the valve seat section for movement between the first valve seat and the second valve seat; a first piston disposed in the piston receiving section of the bore and connected with the spool for movement with the spool; and a first spring disposed in the piston receiving section of the bore and biasing the first piston and the poppet in a first direction towards the first valve seat, wherein when pressure at the master cylinder port (40, 40a, 40b) overcomes a biasing force of the first spring and pressure at the return port the first piston and the poppet travel in a second direction; and characterized by a second piston and a second spring each disposed in the piston receiving section of the bore and, the second piston including a second piston passage that receives the first piston, the second spring biasing the second piston in the first direction, the second piston travels with the first piston and the spool toward the second direction when the pressure at the master cylinder port (40, 40a, 40b) is larger than a total force of the first spring, the second spring and pressure at the return port. a housing including a bore, a master cylinder port (40, 40a, 40b), a pressure supply port, a system pressure port, and a return port, wherein each port connects with the bore and the bore includes a valve seat section and a piston receiving section, wherein the valve seat section is connected with the system pressure port, wherein the piston receiving section is connected with the return port; a first valve seat disposed in the valve seat section of the bore between the pressure supply port and the system pressure port; a second valve seat disposed in the valve seat section of the bore between the system pressure port and the master cylinder port (40, 40a, 40b); a spool disposed in the bore; a poppet on the spool, wherein the poppet moves with the spool and is disposed in the valve seat section for movement between the first valve seat and the second valve seat; a first piston disposed in the piston receiving section of the bore and connected with the spool for movement with the spool; and a first spring disposed in the piston receiving section of the bore and biasing the first piston and the poppet in a first direction towards the first valve seat, wherein when pressure at the master cylinder port (40, 40a, 40b) overcomes a biasing force of the first spring and pressure at the return port the first piston and the poppet travel in a second direction; and a second piston and a second spring each disposed in the piston receiving section of the bore and, the second piston including a second piston passage that receives the first piston, the second spring biasing the second piston in the first direction, the second piston travels with the first piston and the spool toward the second direction when the pressure at the master cylinder port (40, 40a, 40b) is larger than a total force of the first spring, the second spring and pressure at the return port.