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Overhead Cranes
Due to the vast variety of overhead cranes in service there is no 'standard'
rope construction which would fit all types. In most cases, cranes made
in North America require imperial size ropes either, Class 6x19 or 6x36
are the traditional choices.
To enhance the crane performance the use of Python® High Performance
rope is recommended. Python® wire rope can replace traditional 6-strand
constructions without any changes to the crane, other than making sure
the sheaves and drum are in good condition.
If you upgrade from a standard strength 6-strand or 6-strand die-drawn
type select Python® Super 8C, in either left- or
right hand lay. This type exceeds the breaking strength requirement and
will greatly outperform any traditional rope due to the strand compaction
process. When using left- and right hand lay rope in tandem we recommend
corresponding drum grooving to ensures the most stable rope block you
can imagine. A further increase in breaking strength (between 1% and 7%
depending on tensile class) can be achieved by selecting Python®
Super 8V which is a swage compacted type.
If you experienced some block twisting and can not use left- and right
hand lay rope in tandem you want to select Python® MULTI
or Python® Elite. Even slight block twisting is a
constant inconvenience when you have to position a C-clamp into stacked
coils, for example.
Another application is where both rope ends are attached to the drum.
The result is that 1/2 of the rope always spools into a incorrect drum
grooving direction. Particularly 8-strand ropes without a plastic coated
core (as provided by most OEM's) tend to torque resulting in loose strands
and waviness. Using Python® MULTI reduces and, in
most cases, eliminates such problems. Because of it's very unique construction
Python® MULTI does NOT require corresponding drum grooving and still
has shown the highest degree of service life increase of all Python types.
Some North American made overhead cranes have been converted, or can be
converted, to higher lifting capacities using high strength Python®
SUPER 8C, Python® Power 9V or Python®
Ultra compacted constructions. We suggest not to attempt to convert
your crane without professional advice, nor to select such without consultation
with your local Python Distributor.
Overhead Cranes and Rotation Resistant Ropes
As a rule, Non-Rotating or Rotation Resistant rope types shall only be
used if the lower sheave block tends to spin and Python® Multi did
not cure the problem. Generally, non-rotating ropes will have a LOWER
fatigue life than standard constructions, although they seem to have 'finer'
wires and appear to be more flexible. Specifically 9x17 spin resistant,
19x7, 19x19, and 24x7 rotation resistant ropes tend to break up from the
inside and require frequent and careful inspections. Most of these rope
types on overhead cranes are smaller sizes between 5/16" and 7/16"
(between 5 mm and 11 mm).
For larger diameter non-rotating ropes (> 1/2” or 13 mm) we recommend
Python® Lift or Python®-Hoist
with a plastic coated core to prevent premature internal wire breaks.
Under no circumstances do we recommend Python® Compac 18
for such applications.
Scrap and Grab Cranes, Piledrivers
These are, in essence, "wire rope destruction machines". Some
users had good results with 6x19 COMPAC® ropes, others prefer the
simplicity of standard 6x19 ropes. For shock loading applications some
users have had very god results with Python® Super 8C
yet there were reports also of good performance with plastic (impregnated-delete)
filled rope types (BXL), PFV or Cushion ropes are some trade names). In
essence, we believe that the human factor, crane design, crane location,
and scope of work creates such a mix of conflicting requirements that
we, as the rope supplier, can only suggest that whatever works best for
YOU in YOUR specific situation is also the best rope for you. This may
not be the case for the chap next door.
Hoisting Rope for Mobile Cranes
Most of the smaller capacity US made cranes like Grove, Terex, P&H,
Century, National, operate best with Python® Compac 18.
It's compacted outer rope surface is superior on multiple layer drums
where traditional ropes tend to fail due to friction damages at the winding
crossover points. However, Python® Compac 18, when
used to it's full fatigue life, tends to break up from the inside out
(as all 19x7/19x19 rope do). Therefore, in high cycle applications and
for some high load ratings (e.g. on Manitowoc's) Python®-LIFT
ropes are either already installed by the crane manufacturer, or are the
recommended upgrade choice. As an alternate rope selection we recommend
Python® Compac 35 as this rope combines high strength,
low rotation and die-drawn strands at a very attractive price.
Under NO circumstances do we recommend the so called '8x19 spin resistant'
rope construction. In service this type of rope WILL break from the inside
out and when used with one end free to rotate loses up to 40% of its breaking
strength. Catastrophic and unexpected rope failures are the result.
Hoist Rope on Tower Cranes
For tower cranes we do not recommend the use of 19x7 or 19x19 style rope
types; this includes our Python® Compac18. Rotation
Resistant ropes (having less than 14 outer strands) are very difficult
to inspect since they tend to fatigue from the inside of the rope. Also,
nearly all European tower cranes require high strength non-rotating ropes
and neither 19x7 nor 19x19 types fulfill the demand on strength and/or
on non-rotating properties.
For the older Pecco "double sheave lower suitcase block", which
is used strictly in a 2-line configuration, a regular 6x36 IWRC rope is
sufficient, provided the building height is no more than 10-12 floors.
Here, large line spacing prevents the block from spinning.
For all other cranes we recommend Python® Compac 35.
For extremely high strength requirements Python® Lift
ropes are the choice.
Linden, some Kroll- and Comedil tower cranes which have the 3- or 4 sheave
arrangement in the block are 'rope killers'. The reverse bend in such
systems is so severe that short rope life MUST be expected. Under NO circumstances
should you use 19x7/19x19 ropes. Even if you use our Python® non-rotating
ropes we will NOT guarantee against bird-cages and other
rope deformations as a result of such reeving systems. There have been
reported sudden and unexpected rope failures. Such set ups are quick and
easy to convert from a 2 part to a 4-part line but it's not ideal from
a wire rope standpoint ... and there is nothing we can do about it; you
simply have to learn to live with it and INSPECT ... INSPECT ... INSPECT
!
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