1. The basic load math (every lift planner needs this)
The load on each outrigger is calculated from crane weight, counterweight, boom angle, and the lifted load. For a 250-tonne all-terrain crane lifting 50 t at 24 m radius:
- Maximum corner load (front-side outrigger): ~165 t
- Outrigger float footprint: 0.65 m × 0.65 m = 0.42 m²
- Pressure on float without pad: 165 t / 0.42 m² ≈ 392 t/m² (3.84 MPa)
- Soft clay safe bearing capacity: 10-15 t/m²
Without a pad, the outrigger pressure is 26-40× higher than the soil can take. The pad's job is to spread that load over enough area to drop pressure below the safe bearing capacity.
Required pad area = corner load / safe bearing capacity. For our example: 165 t / 10 t/m² = 16.5 m². That's a pad of approximately 4.0 × 4.0 m — too big to carry. Most cranes use 2-3 stacked pads in a pyramid pattern instead, with each layer redistributing load over a wider area.
2. Why UHMWPE is the right material
An outrigger pad has three jobs: spread load, take impact, and survive ground contact. Materials commonly used:
| Material | Pros | Cons |
|---|---|---|
| Hardwood timber | Cheap | Splits, rots, splinters under load |
| Steel plate | Strong | Heavy (~80 kg/m² @ 10mm), conducts cold/heat, can deform |
| Aluminum | Lighter than steel | Fatigues, dents, expensive |
| UHMWPE | Light (~93 kg/m² @ 100mm), no rot, no splitting, sub-zero impact, 25-year life | Higher upfront cost |
UHMWPE pads are now standard issue from Liebherr, Tadano, Manitowoc, Grove, Terex and Sany factory lift kits.
3. Thickness chart for common crane sizes
Always use a stack of 2-3 pads in a pyramid (largest at bottom) when ground bearing is < 15 t/m². For piped/sandy backfill, use 3 layers minimum.
| Crane Class | Max Outrigger Load | Pad Size (mm) | UHMWPE Thickness |
|---|---|---|---|
| Mini-crawler / Mobile 30 t | 30 t | 600 × 600 | 40 mm |
| Mobile 50-90 t | 60 t | 750 × 750 | 50 mm |
| Mobile 100-200 t | 120 t | 1000 × 1000 | 60 mm |
| All-terrain 250-400 t | 200 t | 1200 × 1200 | 80 mm |
| All-terrain 500-700 t | 350 t | 1500 × 1500 | 100 mm |
| Crawler 800-1200 t (Liebherr LR1750) | 500 t+ | Stacked 2 × 100mm pyramid | 2 × 100 mm |
4. The 4 most common spec mistakes
Mistake 1: Using one pad size for the whole lift kit. The crane's front outriggers see 60-80% of total load. Use bigger pads on the load-side; smaller pads on the back are fine.
Mistake 2: Forgetting the rope handle. A 100mm × 1500mm × 1500mm UHMWPE pad weighs 210 kg. Without a rope handle (or 4 stainless lifting eyes), riggers will damage the pad or themselves moving it.
Mistake 3: Trusting the manufacturer's max-load sticker without checking soil. A '200 t pad' assumes stiff clay (40 t/m²). On soft fill, the same pad rates only ~80 t. Always do a site soil-bearing test or have a geotech sign off.
Mistake 4: Skipping the chamfered edge. Square-cut pads dig into asphalt at the corners and crack the pad in 6-12 months. JSLT pads are supplied with 25 mm × 45° chamfer all around as standard.
5. JSLT outrigger pad SKUs
Standard sizes available from stock; custom dimensions / colors / handle types built to order in 12-18 days. Send your crane model + max corner load to claire@jsltupe.com for a sized quote.
📊 Live Pricing & MOQ (FOB Qingdao)
Real factory prices from verified export records. Verified inventory. Lead time 15-30 days.
| Product | Price (FOB) | MOQ | Material | Image |
|---|---|---|---|---|
| UHMWPE PE Sheet Ultra High Molecular Weight Polyethylene Board | Quote on request | 1 kilogram | UHMWPE |  |
| Antistatic UHMW-PE PE1000 Plastic Board ESD Black Sheet | Quote on request | 1 kilogram | UHMWPE PE1000 |  |
| Food Grade UHMWPE Sheet Ultra High Molecular Weight Polyethylene | Quote on request | 1 kilogram | UHMWPE | |
| Factory PE Material Outdoor Temporary Road Mats Heavy Duty | Quote on request | 1 kilogram | HDPE/UHMWPE |  |
❓ Frequently Asked Questions
❓ How heavy is a UHMWPE outrigger pad?
UHMWPE has a density of 0.94 g/cm³, so a 100mm × 1.0m × 1.0m pad weighs ~94 kg. A steel pad of equivalent strength would weigh 250-300 kg.
❓ Can I stack pads in a pyramid?
Yes — stacking 2-3 pads in a pyramid (largest at bottom, smallest under the float) is standard practice when ground bearing is below 15 t/m². It can multiply effective bearing area by 4-9×.
❓ Do UHMWPE pads work on hot asphalt?
Yes — UHMWPE doesn't soften until +80 °C. On hot summer asphalt at +60 °C, the pad will float on the surface and not sink. Steel pads can sink into hot asphalt.
❓ How long do UHMWPE outrigger pads last?
Typically 15-25 years with normal industrial use. Failure modes are usually mechanical (forklift damage, dropped from truck) rather than wear.
❓ What thickness do I need for a Liebherr LR1300?
For an LR1300 lifting near max capacity (300 t), use 100 mm UHMWPE 1500×1500 mm as primary pad, plus a 100 mm 2000×2000 mm distribution pad below. We supply this kit standard for European crawler crane fleets.
Need a quote on these materials?
Email Claire — full pricing, samples, CIF delivery to your nearest port within 12 hours.
📩 claire@jsltupe.com 💬 WhatsApp Direct