The dynamo eyebolt is the simplest lifting point there is: a forged eye on a threaded shank, screwed into a tapped hole. It is cheap, compact and does one job perfectly.
**That job is vertical lifting and nothing else.** A dynamo eyebolt has no collar, so there is nothing to resist a sideways pull. Load it at an angle and the bending force acts on the thread root, which is the weakest part of the component and the part you cannot see. This is not a derating question with a percentage attached — angular loading of a dynamo eyebolt is outside its design entirely. If your lift is not straight up, you need a collared eyebolt or a swivel hoist ring.
Key Features
- Drop forged and heat treated: High tensile steel, forged rather than machined, so the grain follows the shape of the eye.
- 5:1 minimum breaking load: A higher safety factor than the 4:1 used across the chain fittings ranges.
- BS 4278 performance: Meets the Working Load Limit requirements of the eyebolt standard.
- Eight metric sizes: M6 through M30, with W.L.L. from 0.1 tonne.
- Two finishes: Self colour or electro galvanised for corrosion resistance.
- Fully marked: CE, W.L.L., size and product ID mark.
- Inexpensive: From £2.36 list, so specifying the right one for each application is affordable.
Technical Specifications
| Product Code |
W.L.L. (t) |
A (mm) |
B (mm) |
C (mm) |
D (mm) |
E (mm) |
G (mm) |
H (mm) |
Weight (kgs) |
| EBDM6 |
0.1 |
6 |
22 |
9 |
27 |
18 |
17 |
5 |
0.07 |
| EBDM8 |
0.15 |
8 |
22 |
9 |
27 |
18.5 |
17 |
5 |
0.07 |
| EBDM10 |
0.25 |
10 |
22 |
9 |
27 |
18.5 |
17 |
5 |
0.07 |
| EBDM12 |
0.32 |
12 |
22 |
9 |
27 |
18.5 |
17 |
5 |
0.07 |
| EBDM16 |
0.63 |
16 |
29 |
11 |
34 |
23.5 |
23 |
6 |
0.14 |
| EBDM20 |
1.25 |
20 |
40 |
15 |
47 |
33 |
32 |
9 |
0.4 |
| EBDM24 |
2 |
24 |
51 |
19 |
60 |
41 |
40 |
12 |
0.8 |
| EBDM30 |
3.2 |
30 |
64 |
24 |
76 |
51 |
51 |
14 |
1.72 |
Full dimensional data and Working Load Limits for every size are on the specification sheet. The M30 is available to order.
BS 4278 | MBL 5 x W.L.L. | VERTICAL LIFTING ONLY | LOLER Ready
Drop forged high tensile steel, heat treated, meeting the Working Load Limit performance requirements of BS 4278. Minimum breaking load is five times the W.L.L. Marked with CE, W.L.L., size and product ID mark. This eyebolt is for vertical lifting only. It has no collar and must not be loaded at any angle. Under LOLER 1998, lifting accessories require thorough examination by a competent person at intervals not exceeding 12 months.
Suitable Applications
Dynamo eyebolts suit machinery and equipment with a tapped lifting hole where the lift is genuinely vertical: motors, gearboxes, pumps, transformers and machine tools lifted straight up by a single point. They are commonly fitted as permanent lifting points on equipment by manufacturers. Where a load has multiple lifting points and is lifted by a multi-leg sling, the legs are at an angle by definition and dynamo eyebolts are not suitable — that application needs collared eyebolts or swivel hoist rings.
More About This Product
Lifting points are the only part of a lifting assembly that stays with the load, and that changes how they should be thought about. A sling belongs to the lifting company and gets inspected on a schedule. An eyebolt tapped into a gearbox belongs to the gearbox, gets painted over, corrodes quietly and is still expected to work five years later when someone needs to move the machine.
Which is why the thread and the tapped hole matter more than the eyebolt itself. The fitting is certified; the hole in the casting is not, and a worn, corroded or under-depth thread will fail long before the eyebolt does.
Angular Loading and Why the Collar Exists
The single most consequential distinction in this category is between a plain eyebolt and a collared one, and it comes down to what happens when the pull is not vertical.
A plain eyebolt has no machined face bearing on the load. Pull it sideways and the entire bending moment acts on the thread root — the point where the shank meets the thread, inside the hole, where nobody can see it. Alloy steel is strong in tension and much less tolerant of bending at a stress concentration, which is why plain eyebolts have no published derating table for angular load. There is no permitted angle because the design does not accommodate one.
A collared eyebolt has a machined face that seats hard against the load. Side load is resisted by that face rather than by the thread, which is why collared eyebolts carry a derating table and plain ones do not. The collar only works if it is fully seated — wound down onto a clean flat face with no gap. A collared eyebolt not tightened home is a plain eyebolt.
A swivel hoist ring removes the decision entirely: it pivots and rotates to align with the pull whatever direction that is, which is why it costs more and why it is the right answer where different people rig the same load.
How to Use the Dynamo Eyebolt
- Confirm the lift is vertical: Single point, straight up. Any angle at all means the wrong component.
- Screw fully home: The eyebolt must seat completely against the face of the hole. A partially engaged thread carries a fraction of the load.
- Check thread engagement depth: The tapped hole must be deep enough for full engagement. Insufficient depth is a common and serious error.
- Check the material it is threaded into: The W.L.L. assumes sound steel. In aluminium, cast iron or a worn thread, the eyebolt is stronger than the hole.
- Inspect the thread before every use: Both the eyebolt and the tapped hole.
- Do not modify: Never weld, heat, machine or drill.
Warning: Dynamo eyebolts are for vertical lifting only. There is no permitted angular loading and no derating table, because the design does not accommodate it. Angular load acts on the thread root and can cause sudden failure. For any angled lift, use a collared eyebolt or swivel hoist ring.
Safety Information
- Vertical lifting only. No angular loading is permitted.
- Never exceed the marked Working Load Limit.
- The eyebolt must be screwed fully home and seated.
- Confirm the tapped hole depth allows full thread engagement.
- The parent material must be capable of carrying the load.
- Inspect the eyebolt thread and the tapped hole before every use.
- Withdraw any eyebolt showing thread damage, eye distortion, cracks or wear beyond the manufacturer’s stated limit.
- Never weld, heat treat, machine or repaint.
- Thorough examination by a competent person required at intervals not exceeding 12 months under LOLER 1998.
Inspection and Maintenance
The thread is where a dynamo eyebolt fails and where inspection should concentrate. Examine the full thread length for damage, stretching, corrosion and any sign of bending at the root, which indicates it has been loaded at an angle and is grounds for immediate withdrawal. Check the eye for distortion and elongation, measure against original dimensions and withdraw at the manufacturer’s stated wear limit. Inspect the seating face for damage, since an eyebolt that cannot seat cleanly cannot develop its rating. Also inspect the tapped hole in the parent material, which is outside the eyebolt's certification but is just as capable of failing.
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Frequently Asked Questions
Q: Can I use a dynamo eyebolt at a slight angle?
No. There is no permitted angle and no derating figure, because the component is not designed for it. Without a collar there is nothing to take a side load, and the bending acts on the thread root where you cannot see it. Even a small angle is outside the design.
Q: What is the difference between a dynamo and a collared eyebolt?
The collar. A collared eyebolt has a machined face that seats against the load and resists side loading, so it may be used at an angle with an appropriate reduction in W.L.L. A dynamo eyebolt has no collar and is vertical only. That single feature is the whole distinction.
Q: What if I have a four leg sling?
Then every leg is at an angle and dynamo eyebolts are the wrong component. Use collared eyebolts, or swivel hoist rings which align themselves with the load direction.
Q: Why is the safety factor 5:1 rather than 4:1?
BS 4278 requires it for eyebolts, where the chain fitting standards use 4:1. The higher factor reflects that an eyebolt depends on a threaded connection into material outside the manufacturer's control.
