Tensioning apparatus and method of applying tension to a tendon

• US 4,192,215 A
• Filed: 08/28/1978
• Issued: 03/11/1980
• Est. Priority Date: 05/05/1975
• Status: Expired due to Term

• Current Assignee: Nelson J. Hymans
• Original Assignee: Nelson J. Hymans
• Inventors: Hymans, Nelson J.
• Primary Examiner(s): Britts, Ramon S.
• Application Number:
  US05/937,377
• Time in Patent Office: 561 Days
• Field of Search: 85/36, 85/33, 85/1 T, 151/19 R, 254/29 A, 52/223 L, 52/223 R, 52/230, 24/122.6, 24/263 D, 24/136 R, 24/115 M, 403/374, 403/369
• US Class Current: 411/548
• CPC Class Codes: E04C 5/122 the tensile members are anchored by wedge-action
• CPC Class Codes: E04C 5/125 the tensile members are profiled to ensure the anchorage, e.g. when provided with screw-thread, bulges, corrugations
• CPC Class Codes: Y10T 24/3909 Plural-strand cord or rope

Abstract

An apparatus and a method are disclosed for inducing torsion-free axial tensile stress in a tendon. The apparatus includes tapered wedge-grippers mounted on the tendon, an externally threaded hollow sleeve member with tapered inner surfaces concentrically mounted on the wedge grippers, and an internally threaded nut placed around the sleeve and in contact with a cooperating bearing surface through which the tendon projects. The sleeve is provided with a head having at least a pair of parallel surfaces which are engagable by a torque wrench for restraining it against rotation as the nut is rotated with a second torque wrench. The resultant movement of the sleeve together with interaction of the members of the apparatus results in torsion-free axial tensile stress in the tendon.

Claims

1. A tensioning apparatus adapted for employment with two torque wrenches coacting with only a plane surface of a body to induce torsion-free axial tensile stress in a linear member which extends from the body generally perpendicularly to the plane surface, the apparatus comprising:

wedge gripper means having an opening formed axially therethrough for generally concentric mounting on the linear member, an inner surface for gripping engagement of the linear member, and a tapered outer surface;

a sleeve member having an opening formed axially therethrough for generally concentric mounting on said wedge gripper means, a tapered inner surface for mateable contact and interaction with wedge gripper means tapered outer surfaces, and an outer surface with screw threads formed on a reduced diameter portion thereof and a separate and distinct integrally formed enlarged wrench engageable surface formed on another portion thereof for positive mateable mechanical engagement by one of the two wrenches, the enlarged wrench engagable surface having an outer dimension greater than the maximum thread diameter; and

a nut having an opening formed axially therethrough from end to end thus providing an inner surface with the inner surface having screw threads formed thereon for threadable contact with said sleeve member'"'"'s threaded surface, an integral, enlarged wrench engageable surface formed on the outer surface thereof for positive mateable mechanical engagement by the other of the two wrenches, and a plane surface formed on one end thereof for mateable contact with the plane surface of the body, wherein said enlarged wrench engageable surfaces on said sleeve member and said nut cooperate to limit the travel of the threaded portion of the nut on the threaded portion of the sleeve in one direction only.

2. The apparatus of claim 1 and said wedge gripper means includes at least a pair of spaced wedge grippers disposed in side by side relation about the linear member with each having an inner surface for engagement with the linear member and an outer tapered surface.

3. The apparatus of claim 2 and said wrench engagable surface of said sleeve member includes parallel surfaces engagable by the one torque wrench.

4. A method of applying tension to a linear member projecting from a bearing surface, the method comprising the steps of:

(a) providing at least a pair of spaced wedge grippers disposed in side by side relation about the linear member each gripper having an inner surface for engagement with the linear member and a tapered outer surface;

(b) providing a sleeve member having an opening formed axially therethrough for generally concentric mounting on the linear member over the wedge grippers, the sleeve having a tapered inner surface for mateable contact and interaction with the wedge grippers outer tapered surface and a outer surface with screw threads formed on a reduced diameter portion thereof and an integrally formed enlarged wrench engagable surface formed on another portion thereof for positive mechanical engagement by a first torque wrench the enlarged wrench engagable surface having an outer dimension greater than the maximum thread diameter;

(c) providing a nut having an opening formed therethrough from end to end thus providing an inner surface with the inner surface having screw theads formed thereon for threadable contact with the sleeve member'"'"'s threaded surface, an enlarged integral wrench engagable surface formed on the outer surface for positive mateable mechanical engagement by a second torque wrench, and a plane surface formed on one end thereof for mateable contact with the bearing surface;

(d) mounting the nut concentrically on the linear surface with the plane surface thereof in mateable contact with the bearing surface;

(e) mounting the sleeve member concentrically on the linear member, and threadably mounting the sleeve member in the nut;

(f) mounting the wedge grippers about the linear member and sliding them into the sleeve with the wedge grippers inner surface gripping the linear member and the tapered outer surface in mateable contact with the tapered inner surface of the sleeve member;

(g) engaging the sleeve member'"'"'s wrench engaging surfaces by the first torque wrench;

(h) engaging the nut'"'"'s wrench engaging surface by the second torque wrench;

(i) externally restraining the first torque wrench against rotation; and

(j) applying torque to the second torque wrench in a plane generally perpendicular to the axis of the linear member to cause rotation of the nut about the linear member in one direction and thus provide axial movement of the sleeve member and the wedge grippers away from the bearing surface which provides torsion-free axial tensile stress in the linear member, while axial rotation of the nut in the other direction, will result in a limited travel of the nut on the sleeve to the point where the integral enlarged wrench engagable surfaces on the nut and sleeve contact with one another.