High Clearance Trench Box System
Griffo Arch Spreader
Description
Before you hire
Arch spreader hire earns its keep on trenches where headroom is the problem, pipe diameter, culvert size or twin runs that a standard strut can’t clear. If your trench doesn’t need that extra clearance, a standard Legend Pro strut set up will do the job for less.Confirm your target trench width against the Griffo Arch Spreader Configuration column before you order. The achievable lengths are fixed combinations, not a continuous range, so a non standard width may need a custom build.Always confirm total system weight with Legend Hire before lifting. The weights in the tables above are approximate, and your lifting chain or sling capacity needs to match the actual load.This page isn’t a substitute for a certified temporary works design. Where your site conditions raise a design question, talk to Legend Hire’s engineering team.Call 1300 890 890 or request a quote online to check availability for your dates.
Applications
Arch spreader hire earns its place on trenches where a standard strut won’t give you enough room to work:
- Large diameter pipe installation
- Boring pits
- Box culverts
- Twin pipe installations
If your application isn’t listed here, talk to Legend Hire’s engineers before you book. Clearance and load requirements are specific to your excavation.
Features
- Steel post and steel beams: built for load bearing duty on site.
- Modular design: combine 125mm, 250mm, 500mm, 1000mm and 2000mm beam sections to match your trench width.
- AS 4744.1:2025 certified: every panel carries a unique serial number for full traceability.
- High clearance: 2400mm under strut clearance.
- Raw galvanised finish: built for demanding site conditions.
- Simple install: designed for a single excavator using the lower in place technique.
Inclusions
Graphs
Videos
Specifications
| Model Name | Griffo Arch Spreader |
|---|
Components and Available Sizes
The End Post-to-Beam and Beam-to-Beam connections are each made with 10 × M20 bolts.
| Component | Length | Weight |
|---|---|---|
| End Post | 690 mm each | 380kg |
| Beam Section | 125 mm | 55kg |
| Beam Section | 250 mm | 70kg |
| Beam Section | 500 mm | 110kg |
| Beam Section | 1000 mm | 169kg |
| Beam Section | 2000 mm | 306kg |
* Specifications are approximate. Always confirm total system weight prior to lifting. Engineering advice available from Legend Hire. Certified to AS 4744.1:2025.
Available Panel Sizes
BASE BOX — LOWER PANELS
116mm profile covers 1.8m to 4.0m panels. 166mm profile covers 5.0m to 7.2m panels. Strut size is SHS125x10mm, weight approximately 36kg/m.
| Dimensions (L × H m) | Under Strut Clearance (mm) | Panel Thickness (mm) | Panel Weight kg | Box Weight with 1m Struts (kg)* | Triangular Loading (kPa) | Uniform Loading (kPa) |
|---|---|---|---|---|---|---|
| 1.8 × 2.4 | 1400 | 116 | 403 | 951 | 80 | 41 |
| 2.4 × 2.4 | 1400 | 116 | 480 | 1105 | 80 | 41 |
| 3.0 × 2.4 | 1400 | 116 | 558 | 1261 | 75 | 38.5 |
| 3.5 × 2.4 | 1400 | 116 | 622 | 1389 | 70 | 36 |
| 4.0 × 2.4 | 1400 | 116 | 678 | 1501 | 65 | 33.5 |
| 5.0 × 2.4 | 1400 | 166 | 1095 | 2335 | 80 | 41 |
| 6.0 × 2.4 | 1400 | 166 | 1296 | 2737 | 70 | 36 |
| 7.2 × 2.4 | 1400 | 166 | 1535 | 3215 | 55 | 28 |
EXTENSION BOX — UPPER PANELS
| Dimensions (L × H m) | Under Strut Clearance (mm) | Panel Thickness (mm) | Panel Weight kg | Box Weight with 1m Struts (kg)* | Triangular Loading (kPa) | Uniform Loading (kPa) |
|---|---|---|---|---|---|---|
| 1.8 × 1.7 | 900 | 116 | 329 | 803 | 80 | 41 |
| 2.4 × 1.7 | 900 | 116 | 387 | 919 | 80 | 41 |
| 3.0 × 1.7 | 900 | 116 | 448 | 1041 | 75 | 38.5 |
| 3.5 × 1.7 | 900 | 116 | 498 | 1141 | 70 | 36 |
| 4.0 × 1.7 | 900 | 116 | 545 | 1235 | 65 | 34 |
| 5.0 × 1.7 | 900 | 166 | 925 | 1995 | 80 | 41 |
| 6.0 × 1.7 | 900 | 166 | 1025 | 2195 | 75 | 38.5 |
| 7.2 × 1.7 | 900 | 166 | 1208 | 2561 | 60 | 31 |
116 mm profile: 1.8–4.0 m · 166 mm profile: 5.0–7.2 m
Available Strut & Arch Spreader Lengths
| Length (mm) | Internal Clearance (mm) | External Clearance (mm) 116 mm profile (1.8–4.0 m panels) | External Clearance (mm) 166 mm profile (5.0–7.2 m panels) | Griffo Arch Spreader Configuration |
|---|---|---|---|---|
| 455 | 755 | 987 | 1087 | N/A |
| 580 | 880 | 1112 | 1212 | N/A |
| 705 | 1005 | 1237 | 1337 | N/A |
| 830 | 1130 | 1362 | 1462 | N/A |
| 955 | 1255 | 1487 | 1587 | N/A |
| 1080 | 1380 | 1612 | 1712 | N/A |
| 1205 | 1505 | 1737 | 1837 | N/A |
| 1368 | 1668 | 1900 | 2000 | 2 × End Post |
| 1493 | 1793 | 2025 | 2125 | 2 × End Post + 1×125mm |
| 1618 | 1918 | 2150 | 2250 | 2 × End Post + 1×250mm |
| 1743 | 2043 | 2275 | 2375 | 2 × End Post + 1×250mm + 1×125mm |
| 1868 | 2168 | 2400 | 2500 | 2 × End Post + 1×500mm beam |
| 1993 | 2293 | 2525 | 2625 | 2 × End Post + 1×500mm + 1×125mm |
| 2243 | 2543 | 2775 | 2875 | 2 × End Post + 1×500mm + 1×250mm + 1×125mm |
| 2455 | 2755 | 2987 | 3087 | N/A |
| 2493 | 2793 | 3025 | 3125 | 2 × End Post + 1×1000mm + 1×125mm |
| 2743 | 3043 | 3275 | 3375 | 2 × End Post + 1×1000mm + 1×250mm + 1×125mm |
| 2993 | 3293 | 3525 | 3625 | 2 × End Post + 1×1000mm + 1×500mm + 1×125mm |
| 3243 | 3543 | 3775 | 3875 | 2 × End Post + 1×1000mm + 1×500mm + 1×250mm + 1×125mm |
| 3493 | 3793 | 4025 | 4125 | 2 × End Post + 1×2000mm + 1×125mm |
| 3743 | 4043 | 4275 | 4375 | 2 × End Post + 1×2000mm + 1×250mm + 1×125mm |
| 3993 | 4293 | 4525 | 4625 | 2 × End Post + 1×2000mm + 1×500mm + 1×125mm |
| 4243 | 4543 | 4775 | 4875 | 2 × End Post + 1×2000mm + 1×500mm + 1×250mm + 1×125mm |
| 4493 | 4793 | 5025 | 5125 | 2 × End Post + 1×2000mm + 1×1000mm + 1×125mm |
| 4743 | 5043 | 5275 | 5375 | 2 × End Post + 1×2000mm + 1×1000mm + 1×250mm + 1×125mm |
| 4993 | 5293 | 5525 | 5625 | 2 × End Post + 1×2000mm + 1×1000mm + 1×500mm + 1×125mm |
| 5368 | 5668 | 5900 | 6000 | 2 × End Post + 2×2000mm |
| 5493 | 5793 | 6025 | 6125 | 2 × End Post + 2×2000mm + 1×125mm |
| 5743 | 6043 | 6275 | 6375 | 2 × End Post + 2×2000mm + 1×250mm + 1×125mm |
* Strut size SHS125x10mm. Weight: 36kg/m approx.
Installation
Step 1. Prepare the Beam Connection Section
Lay the arch spreader beam connection sections flat on a level, firm surface. Space them to match the waler locations on the shoring box panels. Verify spacing with a tape measure, or use spacing chains equal to the waler-to-waler distance. Position the timber sleepers where the end posts will sit.
Step 2. Connect the Beam Sections & End Posts
Connect the appropriate beam sections (125mm, 250mm, 500mm, 1000mm or 2000mm, as required for your target trench width) to the beam connection sections on the ground. Refer to the Griffo Arch Spreader Configuration column above to find the correct combination for your required width. Ensure all bolts are tightened. Lay the arch spreader end posts on the ground using 1 x quarter sleeper under the end post and 3 x quarter sleepers beneath for support, with the posts correctly aligned to the beam connection sections. Once in position, install the M36 bolt and nut. Ensure all bolts are well tightened: this is a critical step.
Step 3. Lift and Lower the Shoring Panels
With the arch spreader assembly on the ground, lift the shoring panels using the excavator and lower them onto the arch spreader end posts. Ensure both panels are seated correctly on the post. While the shoring box panels are still on the ground, install all connection pins through the panel and the arch spreader end post. Ensure all pins are fully inserted and secured with keepers before lifting.
Step 4. Lift the Assembled System
Using appropriate certified lifting chains attached to the lifting points on the beam connection section, lift the complete shoring box and arch spreader assembly slowly off the ground. Lifting chains and slings must sit at 45° to horizontal. Verify total system weight before lifting, and confirm lifting chain and sling capacity is adequate.
Step 5. Install the Last Pin
Once the box is in the vertical position and still supported by the excavator on hanging chains, install the pins through the end posts to fully secure the box so it’s self supporting.
Step 6. Install the Upper Extension Box (if required)
Once the base box is positioned in the excavation, stack the upper extension box panels using the panel connectors. Install struts at the upper level according to the Griffo Arch Spreader configuration you selected.
Step 7. Check and Inspect
Once the system is in position, inspect all pins, connections and struts before work starts. Confirm the shoring system is plumb, with no movement or deformation. Report any signs of distress immediately, and halt work until a competent person has assessed it.
Downloads
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