Document N2vav38pjk23o8jkzwOnE5YRD

26--Ropes, Chains, and Slings TABLE 26-G GROOVE DIAMETER TOLERANCE IN RELATION TO WIRE ROPE DIAMETER Rope Size(tn) and Vi6 Vs to V* met 'Via to 1 '/a incl iVia to I'/, incl 1*/ia to 2'/4 incl 2s/i and larger Amount that groove diameter should be larger than nominal rope diameter fin ) Used New 'It* '/m Vm V|6 Va Vm Via '/a Vm Via '/a V Source API Spec RP-9B. March 1966, Use and Care of Wire Rope shown in Table 26-G, for new and remachined grooves 3. The depth of the groove should be approx imately 20 percent of the nominal diameter of the wire rope The crests between the grooves should be rounded off to the circu lar contour, which will provide the recom mended groove depth So far as the life of wire rope is concerned, the condition and contour of sheave grooves are important Sheave grooves should be checked periodically and should not be allowed to wear to a smaller diameter than those shown for used grooves in Table 26-G If they become worn more than this, a re duction m rope life can be expected Recon ditioned sheave grooves should conform to the tolerance, shown in Table 26-G, for new (or remachined) grooves On all new sheaves, the grooves should be made for the size of rope specified The bottom of the groove should have a 150degree arc of support, and the sides of the groove should be tangent to the ends of the bottom arc The total depth of the groove should be IX times the nominal diameter of the rope, and the radius of the arc should be one-half the nominal rope diameter plus the tolerance, shown in Table 26-G, for new (or remachined) grooves Multiple layer winding on drums should be avoided, if possible, because the rope will mash and jam and its hfe will be shortened 722 materially, particularly at the point where the rope rises to the next layer Where practic able, the drum should be of such diameter and length as to take all the rope in a single layer. Crushing and excessive wear of wue rope are minimized by use of helically grooved drums with capacity for one layer of rope In any case, the number of layers should be limited to three Rope lifters are recom mended when two or more layers are wound on drums To distribute wear at crossover points uniformly, 1J* wraps can be cut off every six months or three or four tunes during the life of the rope In no case should there be fewer than three full wraps on a drum In general, wire rope bending--first in one direction and then m the opposite--over sheaves or drums wears out rope faster than any other known cause and should be avoided It is desirable that the fleet angle" not ex ceed 1 degree, 30 minutes, to reduce any tendency for the rope to open-wind Also, a minimum limit of 0 degree, 30 minutes, to assure the rope's starting back on the next layer, has been found desirable Adherence to these specifications will help ensuie uni form winding on smooth-faced drums and will The fleet angle is the included angle between the rope winding on the drum and a line perpen dicular to the drum shaft and running through the head or lead sheave