Apparatus for detensioning stranded cable

Claim 2

In an assembly for anchoring stranded cables or the like under tension and detensioning cables anchored therein wherein an anchor block is provided with a cable passageway for each cable extending from one end of said anchor block to the other so that a cable to be anchored therein may be advanced therethrough, said cable passageway being shaped at one end to form a seat facing in the direction of tensioning to receive a cable gripping wedge, the combination therewith of: cable gripping wedge means releasably positioned in the seat formed in each cable passageway, said wedge means normally being movable into the seat formed to grip a cable advanced under tension through said passageway and whereby to anchor the cable under tension therein; and wedge-releasing means movable through each passageway from the opposite end of each cable passageway to engage said wedge means and prevent its movement into the seat whereby the cable therein may be detensioned and each wedge-releasing means including a tubular member disposed in the end of said cable passageway remote from the seat formed therein for movement along said passageway and common actuating means for advancing said tubular members against the inner ends of said wedge means in each cable passageway.

Claim 3

The invention recited in claim 1, wherein the seat formed in each cable passageway extends from a point within said anchor block to the one end and has an outwardly expanding cross section, said wedge means has an inner end which is inserted in in the seat formed in the cable passageway, and said wedge-releasing means is movable against the inner end of said wedge means.

Claim 4

The invention recited in claim 1, wherein said actuating means comprises a common support member for said tubular member and a control member extending through said anchor block and connected to said support member for advancing said tubular members through said cable passageway.

Claim 5

The invention recited in claim 3, wherein said control member is defined by an elongated screw movable into threaded engagement with a threaded portion on said support member to control movement of said tubular members.

Claim 6

The invention recited in claim 4, wherein each of said tubular members is defined by semi-cylindrical portions in the end of said cable passageway remote from the seat formed therein for movement along said cable passageway.

Claim 7

The invention recited in claim 1, wherein a plurality of said cable passageways are defined in said anchor block, one of said wedge means is positioned in the seat formed in each of said cable passageways, and said wedge releasing means is operable to simultaneously engage all of said wedge means to prevent their being seated in said cable passageways so as to separate said wedge means from their associated cables and permit the cables in said cable passageways to be detensioned.

Claim 8

An assembly for anchoring a stranded cable or the like under tension in a concrete structure and selectively detensioning the cable anchored therein, comprising: a bearing plate for mounting in the concrete structure; an anchor block mounted on said bearing plate and having at least one exposed cable passageway defined therein, said cable passageway extending from the end of said anchor block adjacent said bearing plate to its opposite end so that a cable to be anchored therein may be advanced therethrough, said cable passageway having a cylindrical portion joined with a frusto-conical seat portion, said cylindrical passageway portion extending from the end of said cable passageway adjacent said bearing plate to said frusto-conical seat portion, said frusto-conical seat portion expanding outward from said cylindrical passageway portion to the end of said cable passageway remote from said bearing plate; a frusto-conically shaped cable gripping wedge positioned in said frusto-conical seat portion of said cable passageway, said wedge being operable to grip a cable advanced through said cable passageway and seat in said frusto-conical seat portion whereby to anchor a cable under tension therein; a cylindrical push tube positioned in said cylindrical passageway portion for movement along said cable passageway, said push tube having a predetermined longitudinal dimension which is greater than the length of said cylindrical passageway portion; a movable push plate positioned for pushing said push tube against said wedge whereby to unseat said wedge from said frusto-conical seat portion and separate said wedge from a cable therein; and detensioning screw means connected to said push plate for mechanically moving said push plate and thereby said push tube so as to unseat said wedge.

Claim 9

An assembly for anchoring a stranded cable or the like under tension in a concrete structure and selectively detensioning the cable anchored therein, comprising: a bearing plate for mounting in the concrete structure; an anchor block mounted on said bearing plate and having at least one exposed cable passageway defined therein, said cable passageway extending from the end of said anchor block adjacent said bearing plate to its opposite end so that a cable to be anchored therein may be advanced therethrough, said cable passageway having a cylindrical portion joined with a frusto-conical seat portion, said cylindrical passageway portion extending from the end of said cable passageway adjacent said bearing plate to said frusto-conical seat portion, said frusto-conical seat portion expanding outward from said cylindrical passageway portion to the end of said cable passageway remote from said bearing plate; a frusto-conically shaped cable gripping wedge positioned in said frusto-conical seat portion of said cable passageway, said wedge being operable to grip a cable advanced through said cable passageway and seat in said frusto-conical seat portion whereby to anchor a cable under tension therein; a cylindrical push tube positioned in said cylindrical passageway portion for movement along said cable passageway, said push tube having a predetermined longitudinal dimension which is greater than the length of said cylindrical passageway portion; a movable push plate positioned for pushing said push tube against said wedge whereby to unseat said wedge from said frusto-conical seat portion and separate said wedge from a cable therein; and detensioning screw means connected to said push plate for mechanically moving said push plate and thereby said push tube so as to unseat said wedge.

Claim 10

The invention recited in claim 7, wherein said push plate abuts against the end of said push tube extending from the end of said cable passageway adjacent said bearing plate.

Claim 11

The invention recited in claim 7 wherein said push tube is rigidly secured to said push plate for movement therewith.

Claim 12

The invention recited in claim 7 wherein a plurality of said cable passageways are defined in said anchor block, one of said wedges is positioned in said frusto-conical seat portion of each of said cable passageways, said push plate is positioned for simultaneously pushing each of said push tubes against its associated one of said wedges whereby to unseat each of said wedges from its associated one of said frusto-conical seat portions, and at least one of said detensioning screw means is connected to said push plate.

Claim 13

An assembly for anchoring a stranded cable or the like under tension in a concrete structure and selectively detensioning the cable anchored therein, comprising: a bearing plate adapted for mounting in the concrete structure; an anchor block mounted on said bearing plate and having at least one exposed cable passageway defined therein, said cable passageway extending from the end of said anchor block adjacent said bearing plate to its opposite end so that a cable to be anchored therein may be advanced therethrough, said cable passageway having a seat portion at one end facing in the direction of tensioning of said cable and expanding outward from said passageway portion to the end of said cable passageway remote from said bearing plate; a cable gripping wedge positioned in said seat portion of said cable passageway, said wedge being operable to grip a cable advanced through said cable passageway and seat in said seat portion whereby to anchor a cable under tension therein; a push tube positioned in said passageway portion behind said seat portion for movement along said cable passageway; a movable push plate engageable to advance said push tube against said wedge whereby to unseat said wedge from said frusto-conical seat portion and separate said wedge to permit detensioning of a cable therein; and detensioning screw means extending through said anchor block and bearing plate for connection to said push plate and operative to mechanically move said push plate against said wedge to hold said wedge away from said cable when said cable is detensioned.

Claim 14

An assembly for anchoring a stranded cable or the like under tension in a concrete structure and selectively detensioning the cable anchored therein, comprising: a bearing plate adapted for mounting in the concrete structure; an anchor block mounted on said bearing plate and having at least one exposed cable passageway defined therein, said cable passageway extending from the end of said anchor block adjacent said bearing plate to its opposite end so that a cable to be anchored therein may be advanced therethrough, said cable passageway having a seat portion at one end facing in the direction of tensioning of said cable and expanding outward from said passageway portion to the end of said cable passageway remote from said bearing plate; a cable gripping wedge positioned in said seat portion of said cable passageway, said wedge being operable to grip a cable advanced through said cable passageway and seat in said seat portion whereby to anchor a cable under tension therein; a push tube positioned in said passageway portion behind said seat portion for movement along said cable passageway; a movable push plate engageable to advance said push tube against said wedge whereby to unseat said wedge from said frusto-conical seat portion and separate said wedge to permit detensioning of a cable therein; and detensioning screw means extending through said anchor block and bearing plate for connection to said push plate and operative to mechanically move said push plate against said wedge to hold said wedge away from said cable when said cable is detensioned.