| abstract |
A web sling, such as one of the endless, standard eye-and-eye or twisted eye type, is made from a web of woven synthetic organic polymeric plastic strands, such as those made from nylon, aramid or polyethylene terephthalate filaments, with a lamina of elastomeric material, such as polyurethane, vulcanized or cured onto a load contacting area thereof. The elastomeric material penetrates surface openings between the polymeric plastic strands but may be prevented from penetrating through the web, when so desired. To assist the elastomer in holding tightly to the strands there is applied to the web before vulcanizing a thin coating of a curable adhesive material, such as resorcinol-formaldehyde. In preferred embodiments of the invention particular thicknesses of filaments, strands, webs, adhesive coatings and elastomeric coverings are employed, the sides of the web are also integrally covered with the elastomer in the areas thereof designed to contact a load to be lifted or carried and the areas thereof designed to contact the lifting member are also so covered. Also within the invention are methods of manufacturing the described webs and slings. The slings of this invention are longer lasting than conventional nylon, aramid or polyester fiber slings because the elastomeric covering physically separates the fibers of the web from contact with loads carried by the slings and protects the web against abrasion and cutting by the load, helps to reduce any shocking forces applied to the web by shifting of loads or jerking of the sling by lifting mechanisms and better secures the load in position in the sling. Similarly, when the lift contacting portions of the sling are covered with vulcanized elastomer they also last longer, primarily due to the elastomeric covering protecting against abrasion and cutting of the polymer filaments and strands by the lifting hook or other lifting member. |