Examples of Broken Wires

Engineering Data

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On occasion, a single wire will break shortly after installation. However, if no other wires break at that time, there is no need for concern. On the other hand, should more wires break, the cause should be immediately investigated.

On any application, valley breaks (where the wire fractures between strands) should be given serious attention. When two or more such fractures are found, the rope should be replaced immediately.

NOTE: No valley breaks are permitted in elevator ropes.

Once broken wires appear within a rope operating under normal conditions many more will show up within a relatively short period. Attempting to squeeze the last measure of service from a rope that is beyond the allowable number of broken wires will create an intolerably hazardous situation.

Examples of Broken Wires

A wire broken under a tensile load that has exceeded its strength is recognized by the “cup and cone” configuration at the fracture point (Rope A). The necking down of the wire at this point shows that failure occurred while the wire retained its ductility. Shear-tensile fracture (Rope B) occurs in wire subjected to a combination of transverse and axial loads. Fatigue breaks are usually characterized by squared-off ends perpendicular to the wire either straight across or Z-shaped (Ropes C and D).

Electric Arc

Rope that has either been in contact with a live power line or been used as “ground” in an electric welding circuit, will have wires that are fused, discolored and/or annealed, and must be removed.

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Seals Engineering Data

Oil and grease seals are critical to machine availability. Careless storage, handling, removal and installation can contribute to reduced service life of machine components and higher cost of operation.

Seals come in all sizes, shapes and materials. Wherever possible, the manufacturer has specified the use of the most common solid molded element type seals for use on electric rope shovels.

All types of oil and grease seals have a limited shelf life. Store seals in a cool, dry location protected from direct sunlight. Keep in sealed containers or packaging until ready to use. Seals keep lubricant clean and contained in their respective housings, bearings or passageways. Always handle seals carefully to prevent exposure to nicks, bends or pinching. Do not wash them in solvents as some solvents may destroy properties of the seal.

Seal Installation

Solid molded seals are installed at time of manufacture with interference fit between seal and bore. This method of installation creates an oil tight fit. When partial disassembly of a machine component involves removal of solid molded seal before reassembly inspect it carefully for cuts, nicks or cracking. Replace with a split seal if complete disassembly is inconvenient or with a new solid molded seal. Split seals, especially those made with interference fit at butt, also install with compression at the joint. Split seals used as substitutes for solid molded seals should be replaced at next major component overhaul.

Do not cut a solid seal and reuse for a split seal.

Check shaft for scratches, burrs or surface roughness that may cut or score the lip of seal. Be aware of sharp threads keyways or splines over which the seal must travel. Protect seal lip by covering these interferences with tape.

Inspect the bore area for surface roughness, dirt or burrs. Remove and clean as required. The bore and shaft need .0625 in. (1.588 mm) chamfer to accommodate a leak free installation. If shaft or bore do not have chamfer, carefully provide one by trimming inside flange of seal.

Determine the correct direction for lip installation and start the seal into the cavity by finger pressure, then tap evenly all around until seated or flush with the housing face. (Tap only on outer edge of seal with hammer on wood block.)

A double seal, installed back to back can be used to retain grease or oil plus be more effective in preventing egress of contaminants.