Can you give more information on rope configuration, application arrangement with service and operating histories:

1. "Define non-sheave part of rope"

2. Note changes on when the rate of failures increased

3. Have you tried to apply a failure analysis tree of contributions to likely conditions such as:

a) altered operation parameters - tension, shock, ...... ?

b) manufacturer or manufacturing of rope changes investigated?

c) investigation of rope inspection for strand breakage initiation points using magnetic, xray or other inspection means

d) type of failure - ductile (fatigue), tension, torsion, shear, fretting, corrosion, electrolysis, metallurical properties change, etc.

e) these above excludes contact failures per your comments

f) instrumented system for load histogram?

4. General arrangement of installation would be extremely helpful in understanding the stress/strain

5. Have you looked into destructive failure analysis testing to see if the type of failure can be repeated in a laboratory?

There are good inspection methods that should give details on the location of the failure. Have you sent a specimen to a laboratory for a forensic report?

A more comprehensive response is possible with more definitive details on your history and design.

Regards,

Lawrence Nordell ■

Jason,

The answer to your question probably lies in your maintenance records, ie what has changed ?

We have addressed a similar question regarding the luffing ropes on a shiploader and found the the rope construction had been changed (for what would have appeared to be good reasons at the time). Some time later the reduced life was recognised, and not immediately tied to the change of rope construction. A second change of rope construction improved the rope life. Subsequent more fundamental changes to the reeving arrangement delivered further rope life improvements.

I am sure that you will find the answer to your question in your maintenance records. The changes may be subtle and may have been introduced over a significant period. You may need to go back to the fundamentals to understand the significance of the changes that you will find.

Good luck in your detective work.

John Spreadborough

Aspec Engineering

61 7 3842 3114 ■

Dear Jason,

one question before. Is the rope in the middle of loader or is the rope outside of the material. If the rope is in the material you never will be lucky with this loader i will be sure. Than you don´t must test other ropes they also will broken down.

Than the only thing that you can do is to make a guarantee to the company which build the loader and look to get back the money.

How many ropes are at the loader ?

A loader in this diameter must be have 3 ropes or more outside the material.

A rope with diameter 46 mm is very difficult to wrap at a drum. So it could be that the problem arrive at this place. Also let me know the diameter from the drum. We are not a rope manufacturer but we have while we build loaders many experience with loaders

Could you please send me a photo from loader and also one how and there the rope is brocken?

If you interest that we help you please send me this fotos.

Best regards

BS Vertriebsbuero

Bernd ■

This is a long shot. Sometimes in standing ropes there are wire breakages near the anchorages/sockets/rope eyes. If the anchorage does not provide all the necessary degrees of freedom then there is provision for strand wires to wear against each other. e.g. variations in fleet angles carry back down to the anchorages where the movements are finally blocked by the solder filling and this cracks the individual wires. Your rope anchors must provide rotation about a vertical axis to compensate for hoist trolley lateral movement on the rails. etc ... ■

Hi Gibbsy

For your ropes, U could ask

Has the rope spec/supplier changed

Has the maintenance practise changed

Has the mode of operation changed

Has any other changes been made to the system - by well intentioned personnell.ie mods

With our shiploadr, we use Casar (Germany)....they have programs to estimate rope life based on flexures....they have lots of options for ropes...plastic filled to prevent internal corossion and also formed wires to increase life...rubbing etc

U can get ropes and U can get ropes...all with the same MBF but with different service lives...

We use CASAR for this reason...plus they make stronger ropes.

U should be able to get more life out of yr ropes

Cheers

James ■

Hi Gibbsy

From yr photo - U say that the ropes break!!!

This is amazing.

Assuming a 20T grab, 30,000DWT ship and 2 cycles per grab and 12 ships , this equates to 36,000 cycles till breakage.

A 46mm dia ropes is also not small..seems large for the trolley motive provider.

Is the rope reeving system dual ropes or single rope reeved to both sides of the trolley.?

Looking at the photo and the indicated trolley movement, I can not see how the rope in the middle of the trolley travel can be "non sheaving"...

Assuming that the rope laod is at least 1/4 of the rope MBF ie FOS >=4.0...a rope failure by breaking would mean...

1/. the ropes loads are very high wrt MBF > if this were true, then overloading of other mech parts/components would certianly be present and their FOS would not be as high as 4

2/. the ropes are loosing a lot of their metallic area (LMA) to the point where the rope fails under load ie 75% of the rope has either worn away or the strand wires broken.

3/.or a combination of the above 2..

I am suspecting 2

Do the ropes always break in the same area?

Has the condition of the sheaves changed due to wear or are there any foreign object rubbing on the ropes casuing external mech damage?

Has any LMA testing of the ropes been done in the "expected" failure region by the at about mid service life > to see what is happening...ask Nobles or Bullivant to get their rope tester up on site. This should give U a good piccy of what is happening.

With the rope loads, the actual rope loads could be higher than design due to the acceleration forces required to change direction of the trolley and bucket plus the "spring" effect of the trolley ropes - long lenght between trolley and winch. Further, the tensioning device of the slck side may not be correctly adjusted...too tight or possible too slack (causing jerking of the trolley at direction changes)

Hope this helps in some way

Cheers

James ■