Continuing the “Tools You May Not Know We Rent” series, today we cover swivels. Swivels play an important role in controlling a load under weight while also cutting the strain on other rigging hardware. To understand the benefits of utilizing swivels in your lifts, lets break down what a swivel is and when to use one.1.
What is a swivel?
At their core, swivels are two end connectors (jaw, eye or hook) that are joined at the middle. Swivels are used for rigging positioning on a payload, while some can also be used to swivel under load. This alleviates strain on the load and/or rigging in case of load movement or twisting while the load is lifted.
Types of Swivels
Positioning swivels are used to align rigging prior to the lift, reducing the stress seen on all rigging hardware. They are composed of two end fittings joined at the center by a threaded shaft and a nut. Once under load, they are held in place and no longer capable of swiveling during the lift. As their name implies, these are used solely to position hooks or hardware onto a pick point without damage. Common configurations are seen below:
- Eye-and-eye (double eye):
Similarly, ball bearing swivels are used to align rigging prior to a lift but can also swivel while under load. Ball bearing or roller thrust swivels are available in the same configurations as positioning swivels above. The main difference here is the capability to swivel under load, but frequency or speed of rotation also determines which style of ball bearing swivel to use. The two main types are as follows:
- Thrust ball bearing
- Tapered thrust roller (LGH stock)
Primary uses for swivels
When to use swivels depends on several factors, ranging from the intent of travel to the type of rigging used. Some uses have already been outlined above, however, there are additional considerations for when a swivel would be best for your lift.
- What type of wire rope are you using (if applicable)? Are you using rotation resistant wire rope or standard lay?
- Cranes utilize rotation resistant wire rope, but not all wire rope will carry those same characteristics. Rotation resistant wire rope is manufactured with the inner and outer strands laid in opposite directions to counteract one another. In other words, the inner may be right hand lay while the outer is left hand lay to minimize rotation.
- What are the ambient conditions of the lift site?
- In tight spaces where the load needs to rotate around obstacles or if there are heavy winds, positional swivels will not cut it. Having a load rotate during the lift without properly taking precautions can cause immense damage to the rigging and/or load.
- When using chain, is there any twist to the chain body that could cause poor alignment with the lifting lug?
- Yes, even chain is susceptible to twisting that may not be readily apparent until connecting to the payload. In this case, alignment swivels reduce strain on the lifting lug and the hook, preventing angular forces or premature wear.
For more on load control, read Guidelines For Using Tag Lines.
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