Abstract: This traction apparatus for hauling in and out a rope, of the type comprising a linkage mechanism adapted to actuate by turns two self-clamping pairs of jaws performing alternate to-and-fro movements, comprises a safety release device coupled to one of the levers of the mechanism, this device comprising essentially a push knob for releasing a two-armed strap normally held in locking engagement with the edges of apertures formed in the half-casings of the apparatus, push members associated with the outer bent arms of this strap and a U-shaped rod surrounded by pre-clamping springs and operatively connected to the strap, so that the rope cannot be released by the clamping jaws unless the operator pushes with both hands the push members subsequent to the depression of the push knob.