Handling of wire ropes

The correct ways to unreel, reel and install steel wire rope.

Handling wire ropes correctly

Wire rope should be installed by well trained and competent personnel. Wire ropes on a coil should be laid out to prevent twisting or kinking. Wire on a drum should be unwound with a suitable device (such a reel stands or rotating table) and correctly orientated.

Non-rotating ropes are balanced to reduce their tendency to twist or spin in either direction. However, they are very pliable and incorrect handling can put twists into the rope.

As twists are put into a rope, the outer strands become shorter and the inner core slips along the rope. The inner core then protrudes from the end and the outer strands bulge into bird caging. This may cause the inner core to break as it takes all the load. This is why brazing and seizing the ends is important to maintain balance in the rope.

Non-rotating ropes can be used successfully as single and multi-fall crane hoist ropes. However, bird caging at the anchorage is a common fault when they are reeved up as luffing ropes.

A photo of bird caged wire rope is seen below. This occurs when the end of the rope is released either from a braze or seized end. This allows the release of the left and right hand layers which were holding the rope in a torque neutral position.

Example of birdcaging wire rope

Unreeling rope

When taking rope off the reel, take care to ensure the rope cannot be twisted or untwisted as this may cause some kinking.

It is best practice to maintain some back tension during installation and pay it out straight.

The correct method of unreeling is to:

1. remove short rope lengths by rolling the reel along the floor
2. remove a rope off a reel by slackening the rope and wrapping it off in a figure eight. Pull the rope away once the reel has been lifted clear.
3. Rolling a coil along the floor will prevent kinking.

Unreeling rope

Reeling rope

When reeling rope, avoid reverse bends and maintain rope tension at all times to:

• minimise torque
• prevent the rope kinking
• run or install the rope correctly, like in the image below.

Braking with a plank against the reel flange

Braking with an adjustable friction drum on the shaft or side plate

Correct way to reel rope

To ensure good spooling of the first layer on a flat drum tap turns with a rubber mallet. Floor measure ropes if precise measurements are required.

If wire rope is spooled onto a hoist drum incorrectly, torque or twist can be introduced into the system.

For example, off the top of the master spool and onto the underside of the receiving spool like in the image below.

Incorrect way to reel rope

The wire rope might twist the hook block or lay incorrectly on the drum. This may affect the safe operation of equipment.

Cable pulling stockings

Cable pulling stockings come in a variety of configurations. They are used for:

• reeving wire ropes through purchases
• fitting cables in various places where the opening or access is restricted.

Cable pulling stockings

Cable pulling stockings diagram

Cable pulling stockings are very useful where the boom head, luff drum, and hoist winch of tower cranes are high above the ground.

A fibre rope is first reeved and attached to the drum. Then, it is attached to the rope which is fitted with a cable pulling stocking. The rope is then pulled through the system by the fibre rope.

Cable pulling stockings must not be used for load lifting purposes.

Method for replacing an old rope

Follow these steps to replace an old rope:

1. Cut the eye splice or metal clamp from the end of the old wire rope in the crane.
2. Remove grease from the cut end of the old wire rope for a distance of approximately one metre. Also remove grease from the new wire rope for a similar distance.
3. Slide one cable pulling stocking on to the end of the crane wire rope. Place a short seizing on the wire rope (using a mallet) so that it is under the cable pulling stocking about 50mm from the stocking end caps. Place a second secure seizing, using a stout cord or copper strand around the end of the stocking between the first seizing and the stocking end caps.
4. Repeat step 3 with the second cable pulling stocking on the end of the new wire rope.
5. Join the eyes of both cable pulling stockings with enough number of turns of nylon cord. Then securely tie the cord. The use of nylon lacing to connect the two stockings makes snagging at sheaves and other points where clearance is at a minimum less likely.
6. The winch of the crane then hauls the new wire rope into the crane. When the join of the new and old rope reaches the winding drum, the new rope is disconnected from the old rope. It is anchored temporarily to a suitable part of the adjacent structure. The old rope is then removed from the drum and then the new rope is anchored to the drum and wound on. Cable pulling stockings allow the rope joint to pass smoothly around the sheaves.

How to replace an old rope with cable pulling stockings

Installation

Always conduct rope installation as per the manufacturer’s operation manual.

Reeving diagram

There is a danger of kinking or putting turns into uncoiled rope when uncoiling it from the manufacturer's spool or reel.

If a loop forms in the slack rope, a kink will form as the rope is drawn tight, or wound on to a drum. If this happens, discard this section of the rope.

Mount reels or spools onto a shaft so that the reel will revolve when the rope is pulled off. Take care to brake the spool to keep tension on the rope as it is spooled on or off the drum.

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