MINING DIVISION
How to Achieve Maximum Wire Rope & Sheave Life on Draglines

Goal – To maintain a thick lubricant film on the sheaves and to have that lubricant film almost dry to touch or tacky dry. The rope lubricant must be able to maintain a boundary layer or sacrificial lubricant film on both the sheaves and drag ropes. The action of the ropes running over the sheaves will wear away this sacrificial boundary layer. Therefore, the rope lubricant must be able to establish and maintain a high retention lubricant film for periods of 30 minutes or more without replenishment.

Thick lubricant film maintained on drag sheaves; film thickness will build up as much as 10mm.

Over-Lubrication - If there is too much lubricant going onto the sheave, the lubricant film will be too wet, resulting in poor

Over-Lubrication will attract dirt and dust onto ropes. The lubricant will struggle to maintain a consistent lubricant film between ropes and sheaves.

retention on the sheave, which means too much lubricant will be transferred to the rope. This wet film will attract dirt and dust. Then as the rope runs over the sheave with the dirt and dust adhered to it, this will cause wear to both the rope and the sheave at the slide load contact points. Over-lubricating the sheave will result in a very thin boundary layer between the rope and sheave. This lubricant film will be thinner than the dust particles adhered to the rope, causing wear.

Under-Lubrication - Not enough lubricant going onto the sheave results in a dry rope and dry sheave, which means full metal-to-metal contact in the high load areas, causing plastic deformation and fatigue breaks.

Bel-Ray has been producing high performance mining products for years. We provide professional on site lubricant application advice as part of our ongoing customer service support. We know what is expected of our mining lubricants, and we know how they work and how to get the best possible performance from them.

Under-Lubrication will cause premature rope failure and fatigue breaks, which will normally happen on drag ropes 20 to 30 meters back from the bucket.

Through extensive research and development, Bel-Ray has produced a unique dragline rope lubricant called Drag Cable Lubricant Summer. Drag Cable Lubricant Summer has been formulated to achieve and maintain the correct sheave and rope coverage. Most dragline rope lubricants available today do not change in consistency when applied to the ropes and sheaves, resulting in poor lubricant retention properties, hard to maintain lubricant films on both sheaves and ropes, and high consumption rates. Rope lubes with poor retention properties, when used on draglines, will cause excessive lube fling-off inside the dragline house, resulting in increased house-keeping and operators turning the lube system off to decrease lubricant discharge from both the hoist and drag ropes. Does this sound familiar?

Many rope lubricants manufactured today are oil- or greasebased, designed to penetrate into the rope core. This type of rope lubricant works well in many applications. However, when you are talking about lubricating dragline hoist and drag ropes, from Bel-Ray’s experience, this type of rope lube does not perform well.

Why?

The loads placed on both the hoist and drag ropes on draglines, especially large diameter rope, 85mm to 150mm, are

Rope lube is normally sprayed on to the drag sheaves, which then transfers onto the drag ropes

huge. Most, if not all, rope manufacturers pre-lube these ropes internally during the manufacturing process. When new drag or hoist ropes are installed on a dragline, a large amount of the pre-lube oil will be extruded from the internals of the rope because of the huge forces placed on the rope, causing it to stretch and twist as it runs over the sheaves. The re-lubrication of these ropes is normally by spray or dripper, with the lubricant being applied to the sheaves, or in some cases, drippers will apply the rope lube to the top of the drag ropes with the excess transferred to the sheaves

The hoist ropes will normally have drippers at the boom point sheaves directed onto the hoist ropes at 11 o’clock in front of the sheaves. This is where the rope will flatten slightly and open the outer strands to allow some penetration to the external strands. Some draglines such as Marions are fitted with sprays or drippers at the gantry sheaves, which are also lubricated using drippers or sprays. Normally, the boom point drippers will apply rope lube to the front two-thirds of the hoist ropes. If hoist gantry drippers are operating, they will re-lubricate the back third of the hoist ropes and the hoist drum.

Hoist boom point drippers are usually located at 11 o’clock in front of the boom point sheaves.	Drag Cable Lubricant Summer will form a thick pliable layer on the externals of the hoist ropes, sealing the ropes and stopping moisture from entering the rope core, while reducing wear between the rope and sheave.	In most cases Drag Cable Lubricant Summer will provide good lubricant protection to the hoist rope drum and the back third of the hoist ropes once the hoist ropes have been end-for-ended.

However, many draglines only lubricate the hoist ropes at the boom point. Based on inspections of both hoist and drag ropes which have been sectioned, there is no evidence that the lube being applied to the externals of the hoist and drag ropes penetrates any deeper than the outer strands. This is understandable when you consider the huge forces applied to the ropes, and is why using a penetrating type rope lube on dragline ropes is a waste of time.

The lubricant applied to the ropes during manufacture will give the best and only protection to the inner cores of the ropes. We need to protect the outer strands of the ropes, sheaves, and the rope drum.

Wet oil-type rope lubes, especially on drag ropes, will not form a tough lubricant film; they will attract dirt and dust and will flick off the ropes inside the house. Drag Cable Lubricant Summer, however, will form a tough lubricant layer on both the sheaves and the drag ropes, almost dry to the touch.

When using Drag Cable Lubricant Summer on hoist ropes, it is necessary to apply enough rope lube each time to build up a thick outer layer on the external rope strands. This layer will remain pliable, effectively sealing the rope and preventing moisture, etc. from penetrating the internal strands.

Once the hoist ropes are end-for-ended, this thick layer of Drag Cable Lubricant Summer which has built up on the front two-thirds of the hoist ropes will afford some protection to the hoist drum and the back third of the hoist ropes through to the end of the hoist rope life.

In most cases, once the hoist ropes have been end-for-ended, the pre-lube oils excreting from the internals of the rope have stopped coming to the surface of the outer strand. The back third of the hoist ropes and the hoist drum can dry out completely. This situation is most common on draglines which only have lubricant applied at the boom point. Wear, commonly called rifling, may start to appear on the hoist rope drum. This condition is called rifling because it looks like the rifling you can see when you look down the barrel of a rifle. You need to get some lube back onto the hoist drum and the back third of the hoist ropes; this can be applied manually with a bucket or spray canister. In some cases, a drop down spray bar has been installed at the back of the hoist rope drum connected to the main open gear lube line running to the hoist open gears. This system will fire when the open gear lube system operates and can be left in place until a sufficient lubricant coating is applied to the hoist ropes and hoist drum.

Hoist ropes and the hoist rope drum can dry out completely when the ropes are end-for-ended. In this photo you can see rifling starting to appear on the hoist rope drum.	Sometimes a drop down spray bar is installed at the rear of the hoist rope drum. This can be lowered into place behind the hoist rope drum and runs off of the open gear lube system supplying lube to the hoist open gears.

Proven Results

To show the performance benefit using Drag Cable Lubricant Summer on your dragline ropes, we have BCM (Bench Cubic Meters) results from three of the P&H 9020 draglines operating in Australia. This data is based on the average BCMs achieved from the last 5 sets of hoist and drag ropes for each 9020 dragline.

Two of the P&H 9020 draglines are running 114mm ropes on both hoist and drag. One of the two, Ensham Coal Mine, has been using Drag Cable Lubricant Summer for the past 3 ½ years. The third P&H 9020 is running 102mm ropes. The best performing P&H 9020 on BCMs achieved for both hoist and drag is Ensham Coal Mine’s P&H 9020 running on Bel-Ray’s Drag Cable Lubricant Summer.