Quantcast Overhead, Secondary And Deflecting Sheaves - mo1180129

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If the tensions do not appear to be substantially the same, equalization of the rope lengths should
be recommended. If ropes are dirty or over lubricated, a proper inspection may not be possible
unless the dirt or excess lubricant is removed. Lubrication. The lubrication of a wire rope applied during its manufacture may not last
the full life of the rope and the rope may have to be relubricated periodically. Proper lubrication
of suspension ropes will prolong rope life by reducing abrasive action of wire on wire or strand
on strand and will retard deterioration of the fiber cores, eliminate distortion of the rope and
retard corrosion by providing a moisture repellant coating. As a practical guide to the need for
lubrication, a finger wiped in a sheave groove should show a faint smudge and have a slightly
oily feel. If this test leaves the finger dry and clean, lubrication is advisable. Excessive or
improper lubricants may, in the case of traction elevators, seriously reduce the available traction
and cause rope slippage. The lubricants and the amount used should be limited to those supplied
or approved by established elevator or wire rope manufacturers. Slide of the ropes during
acceleration or retardation may be an indication that the lubrication is excessive. To determine
this, it will usually be necessary to observe the ropes where they pass around the driving machine
sheave during acceleration and retardation. Some rope creepage is normal. In the case of
winding drum machines, excessive lubrication does not create a hazardous condition, and should
not interfere with the proper inspection of ropes.
4.3.2 Overhead, Secondary And Deflecting Sheaves
The overhead secondary and deflecting sheaves should be examined and tested with light
blows from a hammer. If the resulting from the blows is dull and flat, unlike the ring given by
sound metal, the sheave parts should be examined carefully for cracks. If no cracks are visible, it
is possible to detect very minute or hair cracks by covering the suspected section with machine
oil, allowing it to stand a few minutes, wiping off all surplus oil with a rag or waste, and then
coating the part with chalk. The machine oil taken up by the crack will cause a brown stain on
the chalk. This indication may be hastened by again tapping the suspected part lightly with a
hammer or by having the car make a round trip. Examine the sheaves for worn grooves and
determine whether all ropes seat to the same depth in the grooves. Look for evidence of any
misalignment of sheaves. Determine whether bearing bolts are secure. Sheave shafts and
bearing should be inspected for wear and other defects. Determine that the shafts and bearings
are adequately lubricated.


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