Actual Breaking Loads (or effective breaking loads)
the load of the rope breaks, is always higer than the minimum breaking load
Abrasion occurs primarily in the outer wires. Ropes with fewer large outer wires, e.g. 6×19 seal, exhibit longer rope life under abrasive conditions than those with many smaller outer wires, e.g. 6×36 Warrington-Seale.
Fatigue is running ropes is normally caused by repeated bending of ropes under tensile loading, such as when they run through sheaves or spool on and off a drum.
(calculated breaking load) is the theoretical value which a wire refers to the sum of the breaking loads of the single wire. it’s not useful in order to define the steel wire rope breaking load.
An assembly of several (usually six) single layer stranded ropes (referred to as unit ropes) laid helically over a core (usually a seventh single layer stranded rope)
Rope in which the outer strands, prior to closing of the rope, are subjected to a compacting process such as drawing, rolling or swaging.
Rope which is subjected to a compacting process after closing, thus reducing its diameter.
Corrosion, in a combination with fatigue, is often a main cause of wire rope deterioration in service. Except under very dry conditions, there is always some corrosion of unprotected (bright or uncoated) steel wires.
If crushing is anticipated to be a primary cause of deterioration when multi-layer spooling, consideration should be given to selecting a rope with compacted outer strands or a compacted rope.
The resulting classification of mechanism (M4, M5, etc..) shall be taken into account when establishing the minimun design factor and the minimun drum and sheaves sizes. Permanent distorsions within the ropes will occur when using ratios of 10:1 and less and that a minimun ratio of 16:1 be used for a rope operating around sheaves.
The Fleet Angle should be no greater than 2° for rotation-resistent rope and no greater than 4° for single layer ropes. Fleet angle can be reduced by , for example:
a) decreasing the drum width and/or increasing the drum diameter.
b) increasing the distance between the sheaves and the drum
The ratio between the sum of the nominal cross-sectional areas of all the load bearing wires in the rope and the circumscribed area of the rope based on its nominal diameter.
Visual check on the condition of the rope to identify obvius damages or deterioration which might affect its fitness for use.
left hand lang lay (designated Ss)
stranded rope in which the direction of lay of the wires in the outer strands is the same as that of the outer strands in the rope. in this case Left.
Left Hand Regular Lay ( designated Sz )
stranded rope in which the direction of lay of the wires in the outer strands is in the opposite direction to the lay of the outer strands in the rope. in this case left.
See M.B.L. (Minimum Breaking Loads)
Minimum Breaking Loads
it’s the minimum breaking load requied, usually indicated in tables, and declared in the test certifcate, useful for the calculation of the safe working load SWL
stranded rope in which the wires in the strands and the strands in the rope have their internal stresses reduced resulting in a rope in which, after removal of any serving, the wires and the strands will not spring out of the rope formation.
Right Hand Lang Lay (designated Zz)
stranded rope in which the direction of lay of the wires in the outer strands is the same as that of the outer strands in the rope. In this case right.
Right Hand RegularLay ( designated Zs )
stranded rope in which the direction of lay of the wires in the outer strands is in opposite direction to the lay of the outer strands of the rope. In this case right.
A grouping of rope constructions where the number of outer strands and the number of wires and how they are laid up are within defined limits, resulting in ropes within the class having similar strength and rotational properties.
a number corresponding to a wire tensile strength grade on which the minimum breacking force of a rope is calculated (N / mm2 )
Stranded rope designed to generate reduced levels of torque and rotation when loaded and comprising an assembly of two or more layers of strands laid helically around the center, the direction of lay of the outers strands being opposite to that of the underlying layer
the groove radius “r” should lie within the range from 0,525d to 0,55d, with 0,537 5d as the optimum, where “d” is the nominal rope diameter.
Visual examination carried out by a competent (trained and experienced) person, and where necessary, supplemented by other means, such as measurement or electro-magnetic non-destructive testing, in order to detect damage or deterioration which might affect the fitness for use of the rope.
is the length measured parallel to the longitudinal axis of the strand of the rope, which is necessary to a wire strand to make one complete revolution around the strand of the rope.