GINDIN: продукция Union Rope в России

PRODUCT BULLETIN DRUM CRUSHING ON BOOM HOISTS February 2014 Causes of crushing When wire rope is properly spooled in multiple layers on a drum, crushing will occur first at the cross-over points on the drum. These are the points where the wire rope coming onto the drum moves from one valley to the next on the layer below and “crosses over” a wrap of wire rope on the layer below. Because there is a single rope-to-rope contact point here (versus two when it is in the valley), the contact pressure is higher, thus this is where crushing occurs first. Each layer of wire rope on a drum crosses over two wraps on the layer below during each revolution of the drum. When crushing occurs at these points, it creates a repeating pattern of two crushed areas that match the wire rope’s circumference around the drum. Effect of crushing Crushing can affect the strength and service life of a wire rope. This is recognized in OSHA regulations on crawler, locomotive and truck cranes when it states: 1910.180(g) “Rope inspection.” - 1910.180(g)(1) “Running ropes.” A thorough inspection of all ropes in use shall be made at least once a month …. Any deterioration, resulting in appreciable loss of original strength shall be carefully observed and determination made as to whether further use of the rope would constitute a safety hazard. Some of the conditions that could result in an appreciable loss of strength are the following:... 1910.180(g)(1)(vi) Severe kinking, crushing, cutting, or unstranding. The OSHA requirement recognizes that some deterioration doesn’t reach the “appreciable loss of original strength” level and that crushing can be less than “severe”. The person doing wire rope inspections, qualified by training and/or experience, must evaluate the severity of the crushing. ASME B30.5 (Mobile & Locomotive Crane) has this to say about crushing and removal criteria: 5-2.4.3 Rope Replacement (a) No precise rules can be given for determination of the exact time for rope replacement since many variable factors are involved. Once a rope reaches any one of the specified removal criteria…[it must be replaced before the next work shift]. (b) Removal criteria for rope replacement shall be as follows:... (4) kinking, crushing, birdcaging, or any damage resulting in distortion of the rope structure.