Bridon Ropes Limited
Carr Hill
Doincaster
South Yorkshire
England
Telephone (0302) 344010
FAX (0302) 382263
Telex 547981
RAB/SB
8th January, 1992
Masto Wire
Service A/S
Industrigt
14,
P.O. Box
1615 Valhalla,
4602
Kristiansand,
S. Norway
For the
attention of T. Krageboen M.D.
Dear Sir,
I would
like to take this opportunity to advise you of Bridon Ropes’ experience with
the use of your Masto high pressure wire rope lubrication system.
Bridon
Ropes has used Masto machines in its factories for over 10 years, in cases
where a special lubricant coating is required on particular wire ropes. The
equipment is sometimes used in preference to re-setting the rope closing
machine lubricant feed for short length production. Over the years the machines
have given dependable service over a wide range of rope sizes and
constructions, and have given satisfactory seal lives. The machines are also
used for pre-delivery lubrication in Bridon Service Centres.
For the last
three years Bridon Ropes has used the machines on site for maintenance of
customer ropes, and has distributed them worldwide along with the Bridon Ropes
range of rope lubricants.
The Masto
machine was selected for distribution by Bridon Ropes, after investigation of
several alternative machines, for the following reasons:-
Bridon
Ropes has developed an internal standard for use of the Masto Machine, which
defines the necessary steps to take to ensure correct performance, and the
conditions necessary for effective use.
A copy of
this standard is enclosed.
Whilst the
Masto unit itself, and the seals are effective in achieving good high pressure
lubrication, with penetration and cleaning of detritus from even large diameter
6 stranded ropes there are 3 major factors which effect performance of the
machine.
These are
as follows:-
1.
A pump
must be used which is capable of supplying lubricant to the Masto unit in
volumes necessary for thorough application at a particular rope speed.
e.g. A large 6 strand rope will take 1.5% of its
weight in grease and at 40 metres per minute on a 48mm rope, for example, the
grease demanded by the Masto unit is 5.5kg per minute at 20-25 Bar. Many pumps
are not capable of such output.
2.
The
lubricant used must be a free flowing type, and thixotropic gel type products
such as Brilubes 60 & 70 have been found to be the most effective. These
lubricants are equivalent to an N.L.G.I. No 2 grease in consistency but their
thixotropic nature ensures good flow under pressure.
3.
Seal
size is also important. This should always be 1-2mm less than the rope
diameter, so that when the machine is fitted to the rope it is not free to move
except with some effort.
This is most important for pressure generation, which is the fundamental key to
the Masto’s performance.
Under these conditions the Masto unit will pump grease into the rope at up to
25 Bar, with very little leakage of lubricant, even on 6 stranded ropes.
It should be noted that the seals depend on internal pressure in order to
perform correctly. If the seals are slack, pressurisation will not occur. If
pressurisation does not occur the bell shaped internal profile of the seals
will not bed down into the gussets of the rope strands and ineffective
lubrication and leakage will occur.
The outside of the rope will not be heavily loaded with grease under correct
conditions, but this is not important in a working rope.
After lubrication excess grease will exude from the rope as the internal
pressure declines and this will provide good surface lubrication.
Please note it is not possible to achieve good high pressure internal
lubrication and thick external coating, on one pass. This can be achieved
however by running the rope a second time with loose seals.
Other problems which effect the performance of the Masto Unit are as follows:-
i.
Inadequate
air volume and pressure.
ii.
Excessive
rope speed – this should always be balanced against demand for grease and pump
capability.
iii.
The
omission of a follower plate in the grease pail can lead to grease cavitation
and intermittent lubricant application.
It should also be noted that, whilst the machine will clean off existing
lubricant, mud etc., ait will not remove hard dry rust and solid bitumastic
lubricant completely. This problem can be largely overcome by pre-soaking the
rope in a solvent such as white spirit, or sometimes by lubricating the rope
twice.
However Bridon Ropes’ view is that ropes allowed to deteriorate to such a
condition are often beyond the pint where service lubrication will benefit performance.
It should be noted that lubricant penetration depends upon strand gap in the
rope. If the rope is so worn that there are no strand gaps left, penetration
will be limited. Again, the rope is likely to be beyond recovery.
Pressure lubrication is most effective when used on ropes in good condition as
a preventative maintenance operation and tests at Bridon Ropes have
demonstrated that well lubricated ropes will have a fatigue life up to 300%
longer than dry ropes.
Yours
faithfully,
Product
Manager