an agricultural vehicle is disclosed having ancillary equipment that may be raised and lowered relative to the ground with consequential changing of the position of the center of gravity of the vehicle and having a hydraulic braking system comprising a master cylinder and a slave cylinder . the braking system further includes a pressure relief valve for limiting the hydraulic pressure applied to the slave cylinder only when the vehicle is in road mode . this ensures that the braking force does not exceed a safe limit below which the vehicle does not risk toppling forwards when braking .