A pre-fabricated tourniquet that is easy to apply, that ensures consistent and even circumferential pressure, that is light weight, that provides standard life saving operation, and that can be utilized in any setting or situation, and related methods are provided. Mechanically constricting tourniquet apparatus and related methods are provided that are comprised of a tourniquet body, a carriage, a torsion bar, a receiver and a slider. The tourniquet is long enough to encircle a human limb, for example, an arm or leg.