Abstract: An apparatus for the tensioning and relaxing of a safety belt including an elongated housing, a tensioning piston, and a tie rod for connection with the safety belt and arranged for retraction relative to the housing in response to pressure on the tensioning piston as well as being arranged thereafter for extension relative to the housing with a delay in response to tensile stress on the safety belt. A hydraulic damping arrangement including a damping cylinder containing a liquid and damping piston coupled with the tensioning piston is provided for forming a telescopic arrangement such that after the tensioning piston effects the retraction of the tie rod and reaches an arrested retracted position thereof, the hydraulic damping arrangement enables damped extension of the tie rod relative to the housing by displacement of the damping piston which in turn displaces liquid in the damping cylinder in response to tensile stress on the safety belt.

Abstract: Device for tensioning safety belts in vehicles in which one end of the safety belt is securable to the vehicle and the other end of the belt is securable to the tensioning device. The device includes a cylinder having a piston with a piston rod extending from one side of the piston out of the cylinder to which the safety belt is securable. The piston is provided with a recess receiving an electrically ignitable propellant charge cartridge such that upon ignition of the cartridge propellant gases are generated which flow into the cylinder at the piston rod side of the piston for causing the piston and piston rod to be displaced into the cylinder to effect a tensioning of the safety belt.

Abstract: A rotary power device for use in conjunction with tensioning mechanism of safety devices for the protection of passengers in vehicles and the like. The preferred embodiment disclosed is used for tensioning safety belts of a vehicle passenger restraint system in response to predetermined experienced deceleration such as occur in an accident situation. The rotary power device includes a rotary piston guided in a helically wound guide track such that the piston moves both rotatably and axially in response to compressed gas forces against a pressure face which extends in a plane containing the axis of rotation of the piston. A coupling bushing arrangement is interposed between the piston and the rotating shaft accommodating the safety belt, with axial movement of the piston with respect to the bushing and shaft, and with rotatable locking of the piston and shaft.