US2262090A - Flexible load transfer device - Google Patents

Description

Nov. 11, 1941. A. E. BRlcKMAN ErAL 2,262,090

FLEXIBLE LOAD TRANSFER DEVICE Filed oct. i4, 1959 ,Q4/V E EEK/(MQW ma 650/965 4. ,64 W50/V,

Patented Nov. 11, 1941 FLEXIBLE OAD TRANSFER DEVICE Alan. E. Brickman, Rostravor Township, Westmoreland County, and George A. Gleason, Worcester, Pa., assignors to The American Steel and Wire Company of New Jersey, a corporation of New Jersey Application October 14, 1939, ASerial No. 299,564

2 Claims.

The present invention relates to a load transfer device for transverse joints in concrete roadways, walks and the like.

An object of the invention is to provide a load transfer device across a joint in a concrete roadl way and pavement having complementary units movable relative to each other upon the eXpansion and contraction of the roadway or pavement.

A further object is to provide a load transfer device which, in addition to having great resistance against shear, provides flexibility in the` invention in position in the concrete roadway or pavement;

Figure 2 is a section on line II-II off Figure 1-;

Figure 3 is a section on line IlI--III of Figure l; and,

Figure 4 is a detailed perspective of one of the laminated dowel members.

Referring more particularly to the drawing, the load transfer device, of the present invention,

includes two complementary members or units of identical construction designated generally at A and B.

Each unit forming one-half of the load transfer device comprises plates 2 and 3 of identical construction, maintained in spaced `relation to each other by a laminated structure 4. Each of the plates 2 and 3 has one of its ends bent laterally, as indicated at 5, from its normal horizontal plane so as to provide a good anchorage within the concrete slab sections.

The laminated structure 4, of each complementary unit, includes strip-like members indicated at 4a, 4b and 4c in frictional contact only with each other throughout the entire length of said laminated structure. The ends of said striplike members 4a., 4b and 4c are welded, in any conventional manner, as indicated at IB to plates I5 so that the ends of said laminated structure projecting beyond the flange I8 of plates I5 form a laminated dowel 4d.

The outside members 4a and 4c of each laminated structure may be Welded, if desired, in any conventional manner to said plates 2 and 3. The intermediate members 4b of each 'laminated structure is provided, upon one face, with a serrated surface or rack 'I overwhich is adapted to ride an inwardly pressed lip or pawl member 8 formed on each of plates 9 constituting a partof the housing within which said dowel 4d slides. The inwardly pressed lip or pawl 8 provides a shallow stiff sharp edge of suicient height to assure racked engagement even though some warpyage may be present due to forming of the plate 9. Finger grip catches I2 are provided on the plates 9 whereby the inwardly pressed lip or pawl 8 is capable of being lifted so as to disassemble the unit, i'f necessary.

The'plates 9 are of identical construction and include laterally extending flanges Il) and flanges I4, the latter flanges forming, in combination with the laminated structure and plates 2 and 3, dowel receiving pockets of a depth not less than the length of said dowel 4d within which the outside horizontal edges of the laminated dowel structure 4d is in slidable engagement with the horizontal edges 20 of said dowel receiving Dockets.

The plates 9 have a free movement with respect to the plates 2 and 3 as theyare not welded thereto but are secured at flange I4, by welding, to the ends of the laminateddowel members4a, 4b `and 4c, thus providing, due to the resiliency of the metal, spring pawl contact on the rack on said dowel members.

The plates I5 are provided with laterally extending flanges I8 which cooperate with the flanges I0, of plate 9, to vertically and horizontally align the units in relation to the joint.

The joint assembly is usually supported, during installation, by a `bulkhead (not shown) and pinned to the subgrade to withstand the flow of concrete used in forming the roadway or pavement slabs or sections after which the bulkhead plate or pins are removed and the joint assembly appears as shown in Figure 1.

In assembling the trans-load device, the units A and B are positioned `and arranged as shown in Figure 2 of the drawing so that the laminated dowel 4d, of unit A, extends through an aperture formed in a conventional type joint filler I9 into the dowel receiving pocket in unit B, while the laminated dowel 4d, of unit B, extends through the same aperture in said filler I6 and into the dowel receiving pocket of unit A, thereby providing a load transfer device having a laminated dowel construction which will offer great resistance to shear and will provide suicient flexibility to compensate for warpage of the pavement slabs or sections. Warpage cf a pavement or roadway slab may be a permanent condition which takes place When the concrete sets or hardens and is due to a difference in the rate of setting between the top and bottom portion of the slab, caused primarily by the difference' in the temperature between the top and bottom portion thereof. This slab warpage may also take place at any time after the concrete has permanently set, due to sudden changes in temperature. For example, during extremely low temperatures a pavement slab or section is contracted and should there be a sudden rise in temperature, due to exposure of the top surface of the concrete to heat or the sun, said surface of the slab will expand. in `advance of the bottom surface, thus'causing warpage of the slab section. By providing Ya construction including a laminated `dowel construction, suitably welded to the plates 9 and I5 and the spaced plates 2 and 3, it is obvious that such a construction will permit flexing of the joint to compensate for slab warpage.

The cooperation between the pawl 8 and the rack 1, of the respective units, provides a means for initially holding the component parts forming the load transfer device in proper position, upon the roadbed, until the concrete which is poured to form the slabs has set. After the load transfer device has become embedded in the concrete, the cooperative action of the pawl and rack, of the respective units, may be inoperative by shear Ythrough subsequent relative movement of the concrete.

In our Patent No. 2,212,680, dated August 27, 1940, and entitled Load transfer device, there is disclosed a construction which is generally similar to that of the present invention. The present invention, however, differs therefrom in the employment of the .laminated dowel elements 4d, and in details of construction used in combination therewith.

While Vwe haveshown and described a specific embodiment of the present invention, it will be seen that We do not wish to be limited exactly thereto, since various modifications may be made without departing from the scope of the invention, as defined by the following claims.

We claim:

1. A load transfer device for adjacent concrete road slabs, comprising a filler positioned between the road slabs and having an opening therethrough, a pair of like load transfer units disposed on opposite sides of said filler, each of said load transfer vunits having a dowel-receiving pocket in alignment with the opening in said filler, a dowel secured-to each of said load trans- -fer units and extending through the opening in the filler and into the dowel-receiving pocket in the other of said units, said dowels being reversed with respect to each other and each comprising aplurality of superposed frictionally contacting yelements slidably engaging the dowel-receiving pocketof the opposite load transfer unit and also the dowel secured to the latter, said dowel-receiving pockets being of a depth to closely embrace the upper and lower faces of the outer of the superposed frictionally contacting elements of said dowels, and means for anchoring each of said load transfer units in its respective concrete road slab.

2. A load transfer device for adjacent concrete road slabs, comprising a filler positioned between the road slabs and having an opening therethrough, a pair of like load transfer units disposed on opposite sides of saidv filler, each of said load transfer units having a dowel-receiving pocket in alignment with the opening in said filler, a dowel secured to each of said load, transfer units and extending through the opening in the filler vand .into the dowel-receiving pocket; in the other of said units, said dowels being reversed to each other and each comprising a plurality of superposed frictionally contacting elements slidably engaging the doWel-receiving pocket of the opposite load transfer unit and also the dowel secured to `the latter, means for anchoring each of said load transfer units in its respective concrete road slab, and means for initially restraining the displacement of the doWel of one load transfer unit from the doWel-receiving pocket of the-other of'said units.

ALAN E. BRICKMAN. GEORGE A. GLEASON.

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