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A concrete anchor for securing the lanyard of a workman's harness to a fixed position on a concrete surface includes a cylindrical housing having an outer wall with openings therein and a rod that extends above the housing to which a harness can be attached. Hard metal balls within the housing are a

A concrete anchor for securing the lanyard of a workman's harness to a fixed position on a concrete surface includes a cylindrical housing having an outer wall with openings therein and a rod that extends above the housing to which a harness can be attached. Hard metal balls within the housing are associated with each opening and are dimensioned so that a portion of each ball can pass through each opening but the entire ball can not pass therethrough. A pair of cones within the housing move the balls radially outwardly as the cones are moved upwardly by the rod which is spring biased upwardly. A visual marker carried by the rod normally lies within the housing but is visible from outside of the housing if said rod has moved up by a predetermined amount. This gives an indication that the anchor has been used.

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1. A concrete anchor for securing the lanyard of a workman's harness to a fixed position on a concrete surface wherein said concrete surface has a cylindrically shaped bore formed therein, said anchor comprising: a substantially cylindrically shaped housing having a substantially cylindrically shape

1. A concrete anchor for securing the lanyard of a workman's harness to a fixed position on a concrete surface wherein said concrete surface has a cylindrically shaped bore formed therein, said anchor comprising: a substantially cylindrically shaped housing having a substantially cylindrically shaped outer wall and a substantially hollow interior, said housing having a length defined by a lower end and an upper end, the outer dimensions of said housing being such as to fit within said bore in said concrete surface;a first set of openings in said outer wall, said first set of openings being angularly spaced from each other but being located the same axial distance from said lower end of said housing;a first set of hard metal balls within said hollow interior of said housing, the number of balls being equal to the number of said first set of openings with one ball associated with each opening, the diameter of each ball being slightly greater than the size of said openings whereby a portion of each ball can pass through each opening but the entire ball can not pass therethrough;a second set of openings formed in said outer wall of said housing, said second set of openings being in axial alignment with each other but being angularly spaced from each other, said second set of openings being axially spaced from said first set of openings and a second set of hard metal balls associated with said second set of openings with one ball being positioned within each of said second openings;a first cone within said housing, said first cone being in contact with said first set of balls so as to be capable of moving them radially outwardly, said first cone being vertically moveable between a lower position whereby said first balls lie substantially within said housing and a plurality of vertical positions wherein said balls are forced radially outwardly so as to extend into said first set of openings;a second cone within said housing, said second cone being connected to said rod and being arranged to move said second set of balls outwardly as said rod is moved upwardly, said second cone being axially spaced from said first cone and being connected thereto by a screw thread;biasing means within said housing biasing said cone upwardly to bias said balls outwardly;a rod connected to the top of said first cone and extending upwardly through and out of said upper end of said cylinder, anda loop at the upper end of said rod to which said lanyard can be attached, whereby if a sufficient upward force is applied to said loop, said first cone is moved upwardly to force said first set of balls into said first openings. 2. The concrete anchor as claimed in claim 1 including a visual marker carried by said rod, said visual marker normally lying within said housing but being visible from outside of said housing if said rod has moved up by a predetermined amount. 3. The concrete anchor as claimed in claim 1 wherein said rod is connected to one of said first and second cones by a screw thread. 4. The concrete anchor as claimed in claim 1 wherein said openings in said second set of openings are radially offset from said openings in said first set of openings. 5. A concrete anchor for securing the lanyard of a workman's harness to a fixed position on a concrete surface wherein said concrete surface has a cylindrically shaped bore formed therein, said anchor comprising: a substantially cylindrically shaped housing having a substantially cylindrically shaped outer wall and a substantially hollow interior, said housing having a length defined by a lower end and an upper end, the outer dimensions of said housing being such as to fit within said bore in said concrete surface;a first set of openings in said outer wall, said first set of openings being angularly spaced from each other but being located the same axial distance from said lower end of said housing;a first set of hard metal balls within said hollow interior of said housing, the number of balls being equal to the number of said first set of openings with one ball associated with each opening, the diameter of each ball being slightly greater than the size of said openings whereby a portion of each ball can pass through each opening but the entire ball cannot pass therethrough;a second set of openings formed in said outer wall of said housing, said second set of openings being in axial alignment with each other but being angularly spaced from each other, said second set of openings being axially spaced from said first set of openings and a second set of hard metal balls associated with said second set of openings with one ball being positioned within each of said second set of openings;a first cone within said housing, said first cone having a conical surface, the conical surface of said first cone being in constant contact with said first set of balls so as to be capable of moving them radially outwardly, said first cone being vertically moveable between a lower position whereby said first balls lie substantially within said housing and a plurality of vertical positions wherein said balls are forced radially outwardly so as to extend into said first set of openings, said conical surface of said first cone being in constant contact with said first set of balls throughout the movement thereof;a second cone within said housing, said second cone being connected to said rod and being arranged to move said second set of balls outwardly as said rod is moved upwardly, said second cone being axially spaced from said first cone and being connected thereto by a screw thread;biasing means within said housing continuously biasing said cone upwardly to continuously bias said balls outwardly;a rod connected to the top of said first cone and extending upwardly through and out of said upper end of said cylinder, anda loop at the upper end of said rod to which said lanyard can be attached, whereby if a sufficient upward force is applied to said loop, said first cone is moved upwardly to force said first set of balls into said first openings and against the walls of said bore in said concrete while said first set of balls remain in contact with said conical surfaces of said first cone. 6. The concrete anchor as claimed in claim 5 including a visual marker carried by said rod, said visual marker normally lying within said housing adjacent said upper end of said housing but being visible from outside of said housing if said rod has moved up by a predetermined amount. 7. The concrete anchor as claimed in claim 5 wherein said rod is connected to one of said first and second cones by a screw thread. 8. The concrete anchor as claimed in claim 5 wherein said openings in said second set of openings are radially offset from said openings in said first set of openings.