US3703748A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Anchor for post-tensioning prestressed concrete
Assignee: KELLY SYSTEMS Inc
•
Filing: 1970-08-14
•
Granted: 1972-11-28
•
Expires: 1990-08-14
Abstract
Abstract This invention is an anchor for post-tensioning prestressed concrete including a case having a central bore through which a tendon passes, the internal wall of the case defining the central bore being tapered in a manner to form a compound angle with respect to the longitudinal axis of the case. A chuck comprising chuck segments is positioned within, and movable longitudinally with respect to, the case, the inner faces of the chuck segments being provided with a series of teeth engageable with the outer surface of the tendon which passes through the case and chuck. The compound angles of the case offers relief to the forward portion of the chuck segments in order to better distribute the forces exerted by the chuck segments on the tendon over the length thereof. Variations in the compound angles and/or the chuck segments permit use of the anchor for either locking engagement with a tendon or non-locking engagement therewith when anchor releasing is desired.
Inventors
- 👤 William F Kelly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 10:20
CPC Classifications
E; E04; E04C; E04C5/00; E04C5/08; E04C5/12; E04C5/122; F; F16; F16G; F16G11/00; F16G11/04; F16G11/044; F16G11/048; Y; Y10; Y10T; Y10T403/00; Y10T403/70; Y10T403/7047; Y10T403/7051; Y10T403/7052
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
311 words
An anchor for post-tensioning prestressed concrete comprising: a. an elongated case having an axial bore through which a tendon passes, b. the inner wall of said case defining the axial bore being tapered between the ends thereof, c. the angularity of the inner wall taper being altered at a point intermediate the length of said case, thereby providing first and second tapered working bore sections, d. the angularity of the taper of said first and second tapered working bore sections being in the range of 4* to 10* with respect to lines drawn parallel to the longitudinal axis of the case, e. a chuck of ductile material movably positioned within the axial bore of said case, f. said chuck including a plurality of chuck segments, and g. means for retaining said chuck segments together, h. the outer walls of said chuck segments being transversely arcuate and tapered longitudinally in the range of 4* to 7* with respect to a line drawn parallel to the longitudinal axis of the case, for wedging engagement with the tapered inner wall of said case, i. the inner face of each chuck segment being provided with rows of tendon-engaging teeth for engagement witH the tendon extending through the bore of the case, j. said chuck being drawn through said first tapered working bore section and partially through said second tapered working bore section upon pulling the tendon through the case, k. the angularity of the taper of said second tapered working bore section being less than the taper of said first working bore section, l. whereby the reduced taper of said second tapered working bore section affords relief to the leading portion of said chuck and permits deformation of the chuck to conform to the inner wall of said case, thereby distributing the forces exerted by the chuck teeth over the length of the chuck segments.
Claim 2
Dependent Claim
311 words
An anchor for post-tensioning prestressed concrete comprising: a. an elongated case having an axial bore through which a tendon passes, b. the inner wall of said case defining the axial bore being tapered between the ends thereof, c. the angularity of the inner wall taper being altered at a point intermediate the length of said case, thereby providing first and second tapered working bore sections, d. the angularity of the taper of said first and second tapered working bore sections being in the range of 4* to 10* with respect to lines drawn parallel to the longitudinal axis of the case, e. a chuck of ductile material movably positioned within the axial bore of said case, f. said chuck including a plurality of chuck segments, and g. means for retaining said chuck segments together, h. the outer walls of said chuck segments being transversely arcuate and tapered longitudinally in the range of 4* to 7* with respect to a line drawn parallel to the longitudinal axis of the case, for wedging engagement with the tapered inner wall of said case, i. the inner face of each chuck segment being provided with rows of tendon-engaging teeth for engagement witH the tendon extending through the bore of the case, j. said chuck being drawn through said first tapered working bore section and partially through said second tapered working bore section upon pulling the tendon through the case, k. the angularity of the taper of said second tapered working bore section being less than the taper of said first working bore section, l. whereby the reduced taper of said second tapered working bore section affords relief to the leading portion of said chuck and permits deformation of the chuck to conform to the inner wall of said case, thereby distributing the forces exerted by the chuck teeth over the length of the chuck segments.
Claim 3
Dependent Claim
40 words
The anchor of claim 1, wherein a. the working angle forming the first tapered bore section does not exceed 5* and the taper of said wedge segments is approximately 4*, for effecting locking engagement of said chuck with the tendon.
Claim 4
Dependent Claim
35 words
The anchor of claim 1, wherein a. the angularity of the taper forming the first tapered bore section is in the range of 5* to 10* with respect to the longitudinal axis of the case.
Claim 5
Dependent Claim
25 words
The anchor of claim 3, wherein a. the taper of said chuck segments is approximately 7* with respect to the longitudinal axis of the case.
Claim 6
Dependent Claim
38 words
The anchor of claim 1, with the addition of a. a removable adapter fitted in the bore at the small end of the case in order to permit use of said anchor for tendons of different size diameters.
Claim 7
Dependent Claim
26 words
The anchor of claim 1, with the addition of a. reaction plates extending outwardly from the periphery of said case in spaced relationship to each other.
Claim 8
Dependent Claim
31 words
The anchor of claim 1, with the addition of a. a support member at the small end of the case for aligning the tendon along the longitudinal axis of the anchor.
Claim 9
Dependent Claim
47 words
The anchor of claim 1, with the addition of a. a helical spring in the axial bore of said case between said chuck and the large end of said case, and b. a closure cap fitted over the terminal of the large opening of the case bore.
Claim 10
Dependent Claim
99 words
The anchor of claim 8, wherein a. said closure cap includes a body portion of semi-flexible, translucent material, and b. an annular flange extending from the periphery of the body portion for engagement with the terminal of said case, c. the central part of said body portion being internally thickened to provide a circular boss, the periphery of which is engaged by the last turn of said helical spring, d. said circular boss serving additionally as an abutment for a tendon placed in the anchor, the proper positioning of the tendon being visually determined through said translucent closure cap.
References Cited (Backward Citations)
US3399434A
Cited
US3524228A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-11-28 | 1976-05-29 | 1976-11-28 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-11-28 | 1980-05-29 | 1980-11-28 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-11-28 | 1984-05-29 | 1984-11-28 | $7700.00 | Window Closed / Lapsed |