Pressure limiting device, in particular for an assist system for vehicles

A pressure relief device suitable to be installed in a system comprising a first line and a second line wherein one of the first line and the second line comprises oil under pressure and comprising an auxiliary line forming a discharge line booster line, which device comprises a pressure selector in the form of a cage defining two seats and two pressure relief valves, wherein the device comprises a body comprising a casing which has a narrowed portion forming the two seats of the pressure selector on either side of a passage for connection to the auxiliary line, the pressure selector comprises a cage made by a diabolo formed from a central cylinder movable in regard of the narrowed portion of the casing, provided on two axial ends of said cylinder with respective protrusions protruding on an inner surface of said cylinder to define seats of pressure relief valves and on an outer surface of said cylinder to define selector shutters in regard of the two seats of the pressure selector formed on the narrowed portion of the casing, each pressure relief valve comprising a pressure relief shutter formed with a protrusion on one end of a rod in regard of a seat formed on a protrusion of the cage, the rods emerging, axially on each end of the pressure selector and each rod and each pressure relief shutter being biased toward a respective axial end of the device by a respective spring interspersed on the rod, between on one side a protrusion forming a selector shutter and on the other side a stop carried by the rods, and wherein said device further comprises at least one adjustment means of a pressure relief valve, disposed on the outside of an axial end of the pressure selector to allow adjustment of the calibration of the associated pressure relief valve.