The Features of an Eye Bolt

• Eye — a loop that may be formed by bending the shank or by forging
• Shank — a threaded shaft beneath the eye
• Shoulder (not present on all eye bolts) — a larger diameter section between the eye and the shank that adds strength

What Are Eye Bolts Used For?

• Lifting — eye bolts attach to machines and then a load so it can be picked up by a rigging assembly.
• Lashing and tying down — eye bolts are fixed to a structure or vehicle and used as an attachment points for cables, chains, or wires used to secure a load.
• Suspending — eye bolts are often used to suspend cables and other components.
• Fencing — eye bolts connect wires and cables to fence posts, and they are often used as an attachment point for cables that provide additional support for fences and other structures. 

Installing Different Types of Eye Bolts

• Ensure the eye and the shank are free from bends or distortions.
• Verify that the eye bolt's working load limit (WLL) or rated capacity (RC) is sufficient to support the expected load and any accompanying rigging components. To learn more about working load limits and rated capacities, read our Rigging Hardware Introduction.
• Ensure the eye bolt has not been modified or machined. Removing material from an eye bolt can reduce its WLL.
• Verify that the shank's threaded section has the same thread diameter and pitch as the mating hole or nut. Do not attempt to force an eye bolt into an incompatible thread.
• Ensure that the threads on the shank and receiving hole are clean and free of debris.
• Ensure the load is applied in line with the plane of the eye. You may have to use washers as shims to align the eye correctly.
• Visit our Best Practices When Using Lifting Eye Bolts blog for a detailed look on how to best use lifting eye bolts. 

Installing Bent Wire Eye Bolts

Bent wire eye bolts, also known as closed or turned eye bolts, begin as a wire or rod which is bent at one end to form the eye. Bent wire eye bolts are an excellent choice for light‑duty applications such as tie‑downs, suspending or hanging objects, in fencing, or for routing cables. However, they are not suitable for lifting, scenarios that involve shock loading, or other heavy‑duty applications. When placed under excessive load, the eye may open or break off. They are also not suited for off‑axis angled loading, which may cause the shank or eye to bend. 

In addition to the general eye bolt installation best practices above, the tapped hole for a bent wire eye bolt should have a minimum depth of 1.5 times the bolt's diameter. 

DIN 582 Lifting Eye Nuts Ring Nuts

Installing Lifting Eye Bolts

Lifting eye bolts can support significantly higher loads than wire eye bolts. Lifting eye bolts are either forged or cast and, in contrast to bent wire eye bolts, feature an eye that is a complete circle integrated into the shank; it cannot "unbend" and is less likely to break. Forging can create heavier and more robust eye bolts than bending. Plus, the forging process changes the metal's grain structure, resulting in a stronger, harder eye bolt. 

When drilling and tapping a hole for a machine eye bolt, make sure the hole is as deep as the length of the shank plus one‑half the diameter of the shank while also following general installation guidelines. 

Shoulder Pattern Eye Bolts

Lifting eye bolts are available with or without a shoulder. Shoulder pattern eye bolts feature a metal platform between the shank and the eye that strengthens the interface between the two components. The shoulder also provides added strength for angular lifting, reducing the likelihood of the eye bolt bending or distorting. However, like all eye bolts, a shoulder eye bolt is strongest along the axis of its shank. Rated capacities are substantially reduced for off‑axis loads. 

You should use shoulder eye bolts in applications where force is applied at an angle to the bolt's axis. If you intend to apply a non‑axial load to the eye bolt, verify that it is rated for the expected load at the planned angle. Weight‑bearing capacity is significantly reduced by angled loading, even for shoulder eye bolts, which are designed to support non‑axial loads. ASME‑B30.26 states that "when used for angular loading... the WLL must be reduced." The WLL reduction depends on the angle: for example, loads at 6° to 15° from vertical reduce the WLL to 55% of the eye bolt's rated capacity. 

Plain Pattern Eye Bolts

Eye bolts without a shoulder are referred to as plain pattern eye bolts. Plain pattern eye bolts are suitable for vertical lifting, but only if the load is in line with the shank. They should not be used for angled lifting. 

Eye bolts without a shoulder are referred to as plain pattern eye bolts. Plain pattern eye bolts are suitable for vertical lifting, but only if the load is in line with the shank. They should not be used for angled lifting. 

Installing Nut Eye Bolts

Nut eye bolts have a partially threaded shank with the threaded portion on the shank's end. As the name suggests, nut eye bolts are inserted through the load and secured with a nut. In contrast, lifting eye bolts have a fully threaded shank that is screwed into a hole tapped for that purpose.  

When installing a nut eye bolt into an untapped hole, make sure the shank is long enough for the threaded portion to protrude from the lower surface. You should be able to tighten the nut firmly against the bottom surface while the shoulder, if present, is snug against the upper surface. The nut's threads should be fully engaged with the shank — don't use a nut eye bolt if you can only partially engage the nut. 

If the unthreaded portion of the shank protrudes below the lower surface, use flat washers between the upper surface and the shoulder to raise the bolt so you can properly install the nut. 

Installing Swivel Hoist Rings

While swivel hoist rings are in a different category than eye bolts, they serve the same purpose and are worth mentioning here. Often referred to as swivel eye bolts, swivel hoist rings feature a fully threaded shank, a bail (a u-shaped, rotating eye), and multiple body components that allow the ring to pivot at 180® and swivel at 360® without compromising the WLL.  

Swivel hoist rings offer the convenience of lifting from any direction. This differs from the lifting eye bolt design, which is suitable for straight-line loads and some angled loads (if you factor in a reduced WLL). The hoist ring’s versatility allows for easy attachment to various rigging points and enables the load to sway and turn. This capability facilitates safer lifting environments when the load is susceptible to movement.