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to Technical Information Main Page |
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Inspection
of Sheaves and Drums
Proper maintenance of the equipment on which the ropes operate has an important
bearing on rope life. Worn grooves, poor alignment of sheaves and worn parts
resulting in shock loads and excessive vibration will have a deteriorating
effect.
Sheaves should be checked periodically for wear in the grooves which may
cause pinching, abrasion, and bird-caging of the rope. If the groove shows
signs of rope imprints the sheave must be replaced or re-machined and re-hardened.
The same should be done on drums showing similar effect.
Poor alignment of sheaves will result in rope wear and wear on the sheave
flange. This should be corrected immediately.
Excessive wear in the sheave bearings can cause rope fatigue from vibration.
Large fleet angles will cause severe abrasion of the rope as it winds onto
the drum.
Furthermore, the rope will roll into the sheave groove introducing torque
and twist which may cause high stranding and bird-cages. |
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Dimension
of the Groove Radius
The very first item to be checked when examining sheaves and drums, is the
condition of the grooves. To check size, contour and amount of wear, a groove
gauge is used.
Two types of groove gauges are in general use and it is important to note
which of these is being used. The two differ in their percentage over the
Nominal Rope Diameter.
For new or remachined grooves, and for inspection of fitness for new ropes,
the groove gauge should be 1% over the maximum allowable Plus Tolerance
of the new rope; alternately, the sheave groove must measure 1% over the
Actual Rope Diameter intended to be installed.
Many groove gauges on the market are so called 'No-Go' gauges and are made
with Nominal plus 1/2 of permissible rope Plus Tolerance. If you use these
gauges be sure that the existing rope is SMALLER than this gauge. A rope
operating in an even slightly undersized groove, deteriorates faster and
may develop bird-cages. |
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Sheave gauges for rope sizes ranging from 8mm to 32mm and 1/4" to 1-1/2" are available from Unirope. |
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| Check bearings
for wobble, lubrication & ease of rotation |
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| Properly matched
rope & sheave groove |
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| Sheave groove
is undercut |
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New rope will
get
damaged beyond repair |
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| A sheave corrugated
by the rope's 'print'. This sheave will damage the rope |
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