A vehicle comprising - a frame; - a suspension seat installed so as to be capable of moving vertically relative to the vehicle frame in response to the vehicle movements, the suspension seat including a first and a second lower belt attachment points (14, 19); - and a seat belt arrangement comprising: - a seat belt having a first end portion secured to the seat at a first lower attachment point, and a second end portion mounted on a reel secured to the vehicle frame; - a lower deflection member slidably attached to the seat belt between said first end portion and said second end portion and equipped with a locking element removably locked in a second lower attachment point on the seat such that, when the lower deflection member is locked in said second lower attachment point, the direction of the seat belt is modified by the lower deflection member; - an upper deflection system to deviate the seat belt between the lower deflection member and the reel, and in or on which the seat belt may slide; - a pivotable arm in or on which the upper deflection system is arranged and which is mounted on the vehicle frame through a pivot axis wherein said pivotable arm comprises braking means capable of restraining or blocking the movement of the seat belt relative to the upper deflection system when the seat moves vertically. - a frame; - a suspension seat installed so as to be capable of moving vertically relative to the vehicle frame in response to the vehicle movements, the suspension seat including a first and a second lower belt attachment points (14, 19); - and a seat belt arrangement comprising: - a seat belt having a first end portion secured to the seat at a first lower attachment point, and a second end portion mounted on a reel secured to the vehicle frame; - a lower deflection member slidably attached to the seat belt between said first end portion and said second end portion and equipped with a locking element removably locked in a second lower attachment point on the seat such that, when the lower deflection member is locked in said second lower attachment point, the direction of the seat belt is modified by the lower deflection member; - an upper deflection system to deviate the seat belt between the lower deflection member and the reel, and in or on which the seat belt may slide; - a pivotable arm in or on which the upper deflection system is arranged and which is mounted on the vehicle frame through a pivot axis - a seat belt having a first end portion secured to the seat at a first lower attachment point, and a second end portion mounted on a reel secured to the vehicle frame; - a lower deflection member slidably attached to the seat belt between said first end portion and said second end portion and equipped with a locking element removably locked in a second lower attachment point on the seat such that, when the lower deflection member is locked in said second lower attachment point, the direction of the seat belt is modified by the lower deflection member; - an upper deflection system to deviate the seat belt between the lower deflection member and the reel, and in or on which the seat belt may slide; - a pivotable arm in or on which the upper deflection system is arranged and which is mounted on the vehicle frame through a pivot axis