A strap buckle features first and second ratchet gears fixed at opposite ends of a slotted axle, for corotation with the axle, a drive gear engaging the first ratchet gear, and a rotationally fixed holding gear engaging the second ratchet gear. A handle is connected to the drive gear for toggle ratchet rotation of the ratchet gears and axle without rotation of the holding gear, to cinch a strap in the slot. Each gear is circular, with an annular series of teeth and with each tooth having a planar surface oriented obliquely to the winding axis, thereby defining low and high edges on each tooth. Springs are provided for imposing an adjustable axial biasing force to the drive gear and holding gear, for selective engagement or disengagement with the ratchet gears. A tourniquet buckle and an industrial buckle are disclosed.
