Description
William Hackett Hack10 Grade 10 Oversize Master Link Sub Assembly
The William Hackett Hack10 Grade 10 Oversize Master Link Sub Assembly is a heavy-duty top fitting for high-capacity multi-leg chain slings. It acts as the connection point between the sling legs below and the lifting machine above. Each sub assembly has an oversize master link with two sub links welded in place, for use in both three leg and four leg chain slings.
The oversize master link gives a larger inside aperture than the standard Hack10 sub assembly. That makes it the right choice when the sling must fit a larger crane hook or lifting attachment, or when heavier lifts call for higher Working Load Limits.
Grade 10 Strength for Heavy Lifting
Manufactured from alloy steel, the Hack10 oversize sub assembly offers Working Load Limits from 40 tonnes to 100 tonnes. Grade 10 is 25% stronger than the Grade 8 equivalent, so you get greater lifting capacity without a disproportionate increase in component size and weight.
Welded Sub Link Construction
The two sub links are welded to the oversize master link, which forms a single, fixed unit. This gives the sling legs a dedicated, correctly sized connection point and keeps the assembly simple to inspect and rig.
Tested for Quality and Traceability
Each sub assembly is crack detected after heat treatment and proof load tested to 2.5 times its Working Load Limit. These checks help confirm the integrity of each component before it enters service.
Wide Operating Temperature Range
The Hack10 oversize sub assembly can be used from -40°C to +200°C with no reduction in Working Load Limit. This makes it suitable for cold outdoor sites, renewables work and warmer industrial settings.
Size & Compatibility
The oversize sub assembly is available for chain sizes from 20mm to 32mm, with Working Load Limits from 40 tonnes to 100 tonnes. It is designed to be used with:
- Hack10 Grade 10 lifting chain
- Hack10 three leg and four leg chain sling assemblies
- Larger crane hooks and lifting attachments that need a bigger master link aperture
- Compatible Hack10 connectors, hooks and coupling components
Ideal Applications
The William Hackett Hack10 Grade 10 Oversize Master Link Sub Assembly is suitable for:
- Building high-capacity three leg and four leg Grade 10 chain slings
- Slings that must fit large crane hooks or lifting attachments
- Heavy engineering, fabrication and steelwork lifting
- Construction and civil engineering projects
- Renewables, including wind energy installation and maintenance
- Repairing or replacing the top fitting on existing heavy-duty Hack10 slings
Technical Specifications
| Specification | Details |
|---|---|
| Brand | William Hackett |
| Range | Hack10 |
| Product | Grade 10 Oversize Master Link Sub Assembly |
| Grade | Grade 10 |
| Configuration | Oversize master link with two welded sub links |
| Suitable For | 3 leg and 4 leg chain slings |
| Material | Alloy steel |
| Working Load Limit | 40t – 100t, depending on size |
| Chain Size Range | 20mm – 32mm |
| Proof Load Test | 2.5 x WLL |
| Safety Factor | 4:1 |
| Operating Temperature | -40°C to +200°C without reduction in WLL |
| Testing | Crack detected after heat treatment; proof load tested |
| Standards | EN 1677-1, ASTM A952/A952M and DIN PAS 1061; suitable for chain slings certified to EN 818-4 |
| Sectors | Construction, Industrial, Renewables |
Size & Dimension Chart
| Part Code | Description | WLL (t) | Chain Size (mm) | A (mm) | B (mm) | C (mm) | D (mm) | E (mm) | F (mm) | Mass (kg) |
|---|---|---|---|---|---|---|---|---|---|---|
| 350.450+ | HA45QA OS+ | 40.0 | 20 | 45 | 320 | 175 | 36.0 | 270 | 140 | 25.09 |
| 350.500+ | HA50QA OS+ | 51.0 | 22 | 50 | 350 | 195 | 45.0 | 320 | 175 | 40.89 |
| 350.650+ | HA65QA OS+ | 75.0 | 26 | 65 | 410 | 220 | 50.0 | 350 | 195 | 66.10 |
| 350.750+ | HA75QA OS+ | 100.0 | 32 | 75 | 450 | 250 | 65.0 | 410 | 220 | 115.02 |
Dimensions refer to the William Hackett product drawing.

Capacity & Load Information
The Working Load Limit of the Hack10 oversize sub assembly depends on the size you select. The 40t–100t range covers the whole product range and does not apply to every size. Always choose the sub assembly to match the chain size and the required WLL of the complete sling.
The WLL of a finished three or four leg sling depends on its configuration, the leg angle and its lowest-rated component, which may be the chain rather than the master link. Take into account any applicable reduction factors, such as shock loading, edge loading or asymmetric loading, as set out in the manufacturer’s instructions.
Technical information
| Weight | N/A |
|---|---|
| Product Type | Master Link |
| Component Type | Master Link |
| WLL | 40t, 51t, 75t, 100t |
| Gauge | 20, 22, 26, 32 |
| Grade | 10 |
Key Features
- William Hackett Hack10 Grade 10 oversize master link sub assembly
- Oversize master link with two welded sub links
- Larger aperture to suit bigger crane hooks and lifting attachments
- Suitable for three leg and four leg chain slings
- Working Load Limits from 40 tonnes to 100 tonnes
- Available for chain sizes from 20mm to 32mm
- Grade 10 strength: 25% stronger than the Grade 8 equivalent
- Manufactured from alloy steel
- Manufactured in accordance with EN 1677-1, ASTM A952/A952M and DIN PAS 1061
- Suitable for use in chain slings certified to EN 818-4
- Crack detected following heat treatment
- Proof load tested to 2.5 x WLL
- 4:1 safety factor
- Operating temperature from -40°C to +200°C without WLL reduction
- Suitable for construction, industrial and renewables sectors
Safety & User Instructions
- Select the sub assembly to suit the chain size, the crane hook and the required WLL of the complete sling.
- Do not exceed the Working Load Limit of the sub assembly or the finished sling.
- Use only with compatible Grade 10 chain and components; do not mix grades within an assembly.
- Make sure the master link sits freely and centrally in the crane hook before lifting.
- Check that each sling leg is correctly connected to its sub link.
- Inspect the master link, sub links and welds before every use for wear, cracks, deformation, nicks or corrosion.
- Take out of service any sub assembly showing damage, distortion or excessive wear.
- Avoid shock loading and sudden application of load.
- Do not use outside the -40°C to +200°C operating temperature range.
- Do not modify, weld or heat-treat the sub assembly.
- Follow all manufacturer instructions and make sure the equipment is thoroughly examined in line with LOLER.
