Interactive Leaf Spring Rate, Deflection & Axle Load Capacity Calculator
Use this engineering calculator developed by XIANGZEWO Leaf Spring Engineering to calculate spring rate, working load at target deflection, maximum safe load at yield limit, and gross axle capacity for commercial truck leaf springs, trailer leaf springs, and custom leaf spring packs:
Interactive Leaf Spring Rate & Load Capacity Calculator (SAE J510 / JIS B 2710)
Calculate stiffness rate (N/mm & lb/in), safe working load (kg & lbs), gross axle rating, and bending stress limit for semi-elliptical, cantilever, and parabolic leaf springs.
412.6 N/mm
2,356 lb/in
2,734 kg
6,028 lbs per spring
4,518 kg
9,960 lbs @ Yield Limit
9.04 Metric Tons
Working Stress: 562 MPa (Safe)
Step-by-Step SAE J510 Leaf Spring Stiffness & Bending Stress Equations
When designing a replacement or custom pack, engineers balance two competing mechanical limits: stiffness rate (k) (which determines ride frequency and loaded chassis height) and maximum bending stress (σmax) at the center U-bolt clamping dead-zone.
- Graduated Leaf Shape Correction Factor (δ): Because a multi-leaf pack combines ng full-length master/military-wrap leaves with graduated stepped leaves (total n leaves), the theoretical laminated beam factor is δ = 3 / (2 + ng / n). For a typical 10-leaf truck pack with 2 full-length leaves, δ = 3 / 2.2 = 1.364.
- Bending Stress at Load P (σ): For a semi-elliptical spring of active span L (mm), width b (mm), and thickness t (mm), bending stress is σ = (3 · P · L) / (2 · n · b · t2). Under static curb load, working stress should remain between 450 MPa and 600 MPa; under maximum dynamic bump stop load, stress must not exceed the allowable yield limit of the selected steel grade (835 MPa for SUP9; 930 MPa for SUP9A; 980 MPa for SUP11A / 50CrVA).
- U-Bolt Clamping Dead-Zone (Effective Span Le): Rigid axle U-bolts clamp the center distance s (typically 100–160 mm on heavy trucks), preventing bending inside the clamp pad. For high-precision OEM calculations, subtract 0.5·s from the total eye-to-eye span L when entering Effective Span above.
750 lb to 5,000 lb Trailer & Light Truck Leaf Spring Load Capacity, Eye-to-Eye & Free Arch Chart
When selecting replacement trailer leaf springs or utility suspension assemblies, matching the per-spring load rating (750 lb to 5,000 lb), unloaded eye-to-eye length, free arch height, and leaf width (1-3/4", 2", or 2-1/2") prevents premature axle bottoming and shackle inversion. Note that leaf springs lose 1/2" to 3/4" of arch under static curb weight, stretching eye-to-eye length by 0.5" to 1.25".
| Capacity Per Spring (lbs / kg) | Gross Axle Rating (Pair) | Mounting Style | Width × Thickness | Leaves (n) | Unloaded Eye-to-Eye Length | Free Open Arch | Reference Part / Hub |
|---|---|---|---|---|---|---|---|
| 750 lbs (340 kg) | 1,500 lb Axle | Double Eye / Slipper | 1-3/4" (44.5 mm) × 6 mm | 3 Leaves | 20-3/8" to 25-1/4" (518–641 mm) | 3-1/4" (82 mm) | Light Utility Trailer Spring |
| 1,000 lbs (454 kg) | 2,000 lb Axle | Double Eye / Hook End | 1-3/4" (44.5 mm) × 6.5 mm | 3 Leaves | 20-3/8" to 25-1/4" (518–641 mm) | 3-1/4" (82 mm) | TRA-2740 Series |
| 1,250 lbs (567 kg) | 2,500 lb Axle | Double Eye | 1-3/4" (44.5 mm) × 7 mm | 3–4 Leaves | 23-1/8" to 25-1/4" (587–641 mm) | 3-1/2" (89 mm) | TRA-021 Series |
| 1,750 lbs (794 kg) | 3,500 lb Standard Axle | Double Eye (9/16" Bush) | 1-3/4" (44.5 mm) × 8 mm | 4 Leaves | 25-1/4" (641 mm) | 3.00" (76 mm) | TRA-2726 / UNA-212 |
| 2,000 lbs (907 kg) | 4,000 lb Tandem Axle | Radius End Slipper | 1-3/4" (44.5 mm) × 8 mm | 4 Leaves | 24-5/8" to 26-5/8" (625–676 mm) | 3-1/2" (89 mm) | 11436 Flat Trim Slipper |
| 2,500 lbs (1,134 kg) | 5,000–5,200 lb Axle | Double Eye / C-Hook | 1-3/4" or 2.00" × 8.5 mm | 4–5 Leaves | 25-1/4" to 26.00" (641–660 mm) | 3.00"–3-1/4" (76–82 mm) | TRA-699 Heavy Duty |
| 3,000 lbs (1,360 kg) | 6,000 lb Axle | Double Eye / Slipper | 2.00" (50.8 mm) × 9 mm | 5 Leaves | 25-1/4" to 27.00" (641–686 mm) | 3.00"–3-1/2" (76–89 mm) | TRA-2732 Series |
| 3,500 lbs (1,588 kg) | 7,000 lb Axle | Double Eye / Hook Slipper | 2.00" (50.8 mm) × 9.5 mm | 5–6 Leaves | 25-1/4" to 29-1/2" (641–749 mm) | 3-1/4"–3-1/2" (82–89 mm) | TRA-2260 Series |
| 4,000 lbs (1,814 kg) | 8,000 lb Heavy Axle | Open Eye / Flat Slipper | 2.00" (50.8 mm) × 10 mm | 6 Leaves | 29-1/2" to 30.00" (749–762 mm) | 3-1/2" (89 mm) | 8K Commercial Slipper |
| 5,000 lbs (2,268 kg) | 10,000 lb Utility / Hutchens | Radius Slipper / Hutch | 2-1/2" or 3.00" (63.5–76 mm) | 3–7 Leaves | 30-1/2" to 42.00" (775–1,067 mm) | 3-1/2"–4-3/4" (89–121 mm) | TRA-2726 / TRA-2727 / TRA-2728 |
Spring Steel Material Grade Cross-Reference Table (SUP9 / SUP9A / SUP11A / 50CrVA / 60Si2Mn)
All XIANGZEWO automotive and truck leaf springs are manufactured from virgin hot-rolled spring steel bars certified to JIS G 4801, SAE J404, DIN EN 10089, and GB/T 1222 standards. Selecting the proper alloy determines decarburization resistance, core hardenability across thick leaves (up to 56 mm), and bench fatigue life.
| JIS Grade (Japan) | SAE / ASTM (USA) | DIN / EN (Europe) | GB/T 1222 (China) | Key Alloying Chemistry | Tensile / Yield Strength | Core Hardness & Max Thickness | Primary Suspension Application |
|---|---|---|---|---|---|---|---|
| SUP9 | SAE 5155 | 55Cr3 (1.7176) | 55CrMnA | 0.52–0.60% C, 0.65–0.95% Mn, 0.65–0.95% Cr | ≥1,225 MPa / ≥1,080 MPa | 38–44 HRC (t ≤ 16 mm) | Standard multi-leaf trailer springs (TRA-2726, light pickup springs) |
| SUP9A | SAE 5160 / 5160H | 60Cr3 | 60CrMnA | 0.56–0.64% C, 0.70–1.00% Mn, 0.70–1.00% Cr | ≥1,275 MPa / ≥1,125 MPa | 40–46 HRC (t ≤ 28 mm) | Heavy-duty commercial truck leaf springs (Isuzu, Hino, Mitsubishi Fuso, Ford) |
| SUP11A | SAE 51B60H | 60CrB3 | 60CrMnBA | 0.56–0.64% C + 0.0005–0.0035% Boron (B) | ≥1,325 MPa / ≥1,175 MPa | 41–47 HRC (t ≤ 45 mm) | Thick Z-type air suspension link springs (Scania 1421060, BPW 880368) |
| SUP10 | SAE 6150 | 51CrV4 (1.8159) | 50CrVA | 0.47–0.55% C, 0.80–1.10% Cr, 0.10–0.25% V | ≥1,375 MPa / ≥1,225 MPa | 42–48 HRC (t ≤ 56 mm) | Long-span parabolic tapered springs (Isuzu 1-51130-961-0) & mining dump trucks |
| SUP6 / SUP7 | SAE 9260 | 60SiCr7 (1.7108) | 60Si2Mn | 0.56–0.64% C, 1.50–2.00% Si, 0.60–0.90% Mn | ≥1,274 MPa / ≥1,176 MPa | 39–45 HRC (t ≤ 14 mm) | Agricultural trailers, light utility packs, and standard multi-leaf helpers |
OEM Truck & Trailer Leaf Spring Part Number Cross-Reference Matrix
XIANGZEWO maintains over 300 production tooling dies for Japanese, European, and North American commercial vehicles. Below is the verified cross-reference index linking OEM part numbers to our direct factory specification pages:
| Vehicle / Axle Brand | Primary OEM Part Number | Additional Interchangeable OEM Numbers | Suspension Architecture & Specs | Direct Factory Spec Page |
|---|---|---|---|---|
| Isuzu (N-Series / F-Series / Giga) | 1-51130-961-0 | 8-97074-826-1, 8-98061-265-0, 8-97187-215-1, 8-97362-298-1, 1-51130-693-1, 8-94118-588-1 | Parabolic Tapered & Multi-Leaf (SUP11A / 50CrVA / SUP9A) | Isuzu 1-51130-961-0 Spec | Isuzu Hub |
| Scania (4-Series / P, G, R, T) | 1421060 | 1386555, 1440295, 1505832 | Heavy-Duty Air Suspension Trailing Arm & Parabolic Spring | Scania 1421060 Spec | Scania Hub |
| Hutchens / American Trailer | TRA-2726 | TRA-2727 (1-Leaf), TRA-2728 (3-Leaf), TRA-2732, TRA-2740, TRA-2260, TRA-699, TRA-021, 11436, 354-00, 365-00 | H9700 / H9600 High-Arch & Low-Arch Radius Slipper / Double Eye (SUP9) | TRA-2726 | TRA-2727 | TRA-2728 |
| Mitsubishi Fuso & Canter | MC413899/F | MB294519 (Canter Front), MK310031 (Canter Rear), MC113600, MC113601, MB111210/1, MB111211/2 | 70×10×8 Multi-Leaf (1200 mm Span) & Fuso Heavy Packs | MC413899/F | MB294519 | MK310031 |
| BPW & Fuwa Semi-Trailer | BPW 880368 / 24T | 05.082.13.48.0, 05.082.13.35.0, 05.082.12.66.0, 05.082.13.99.0, Fuwa T410012 (13T/16T/20T) | 100×46 mm Z-Type Air Link & 90/100/120 mm Bogie Multi-Leaf | BPW 880368 | BPW 24T | T410012 |
| Ford Truck (F-Series / Medium Duty) | SRI 43-698 / 43-1199 | E0HT5560EA, E4HT5560AA | 2.5" & 3.0" Multi-Leaf Rear Packs with Helper Leaves | Ford 43-698 | Ford 43-1199 |
| Freightliner & International | 46-1189 / 55-031 | A16-14021-000, 16-15678-000, Navistar 1661472C91 | 4.00" × 0.866" Tapered Eye & Slipper Commercial Truck Springs | Freightliner 46-1189 | International 55-031 |
| Nissan UD & Hino Trucks | 54010-Z3007-FA | 54010-Z5005, Hino 48110-E0120, 48210-37070 (300/500/700 Series) | 90×15 mm & 70×11 mm Heavy-Duty Berlin Eye / Double Eye Packs | Nissan 54010-Z3007-FA | Truck Spring Hub |
5. Verified Factory Specification Index: Commercial Pages, Suspension Architectures & 30 OEM Models
For procurement engineers comparing suspension architectures across our China Leaf Spring Manufacturer facility, XIANGZEWO (Zhengzhou Jingrui) provides full technical documentation across our Parabolic Leaf Spring Services hub, Custom Leaf Springs engineering portal, OEM Leaf Spring Catalog Shop, Leaf Spring Manufacturing FAQ, Technical Blog, and 24-Hour OEM Quotation Desk. Our specialized production lines cover Parabolic Tapered Leaf Springs, Conventional Multi-Leaf Springs, Long Taper Leaf Springs, Z-Leaf Air Suspension Springs, and Agricultural Equipment Leaf Springs.
Complete XIANGZEWO Leaf Spring Engineering Guides, Category Hubs & OEM Part Number Directory
Explore our direct IATF 16949:2016 factory technical guides, suspension architecture comparisons, and OEM replacement specification pages (2-hop direct engineering index):
1. Core Suspension Hubs & Custom Engineering Services
China Leaf Spring Manufacturer Home |
All Heavy-Duty Leaf Springs |
Commercial Truck Leaf Springs |
Utility & Semi-Trailer Leaf Springs |
Custom Leaf Springs by Drawing |
Parabolic Leaf Spring Services & Testing |
Parabolic Tapered Springs |
Multi-Leaf Springs |
Long Taper Springs |
Z-Leaf Air Suspension Springs |
Agricultural Leaf Springs |
OEM Catalog Shop |
About XIANGZEWO Factory |
Manufacturing FAQ |
Technical Blog |
Request a 24h OEM Quote
2. Truck & Trailer Brand Category Hubs
Isuzu Leaf Springs |
Scania Leaf Springs |
Mitsubishi Fuso & Canter Leaf Springs |
BPW Trailer & Bogie Leaf Springs |
Hutchens / American TRA Trailer Springs |
Semi-Trailer Bogie & Germany-Type Springs |
Air Link Trailing Arm Springs |
Air Beam Suspension Springs |
Ford Truck Leaf Springs |
Freightliner Leaf Springs |
International Navistar Leaf Springs |
Nissan UD Leaf Springs |
Toyota & Hino Leaf Springs |
Light-Duty & Export Truck Leaf Springs |
Volvo Truck Springs |
MAN Truck Springs |
Mercedes-Benz Truck Springs |
Hendrickson Suspension Springs |
Mack Truck Springs |
Iveco Truck Springs |
Kamaz Truck Springs |
GAZ Light Truck Springs |
Hyundai Truck Springs |
Volkswagen Commercial Springs |
Specialty OEM Leaf Springs
3. Direct OEM Part Number Specification Pages (30 Verified Models)
Trailer & Bogie Series:
Hutchens TRA-2726 (3L 76×20mm) |
Hutchens TRA-2727 Parabolic |
Hutchens TRA-2728 Low-Arch |
Hutchens TRA-2732 (8-Leaf) |
Hutchens TRA-2740 (3L 76×24mm) |
Reyco TRA-2260 (8-Leaf) |
Fruehauf TRA-699 (4-Leaf) |
Fruehauf TRA-021 Mono-Leaf (50CrVA) |
11436 Semi-Trailer Spring (9L 76×14mm) |
T410012 Germany-Type Trailer Spring (11L 100×12mm) |
BPW 24T Bogie Spring (18L 90×13/17mm) |
1.75" 4-Leaf Mobile Home & Utility Trailer Spring (750lb–1750lb) |
1.75" Tapered Mono-Leaf RV & Boat Trailer Spring |
80×20×1600mm 12-Leaf Heavy Trailer Pack
Commercial Truck & Air Suspension Series:
Isuzu 1-51130-961-0 Parabolic/Multi-Leaf |
Scania 1421060 Air Suspension Spring (100×47/45mm) |
BPW 880368 Air Link Spring (100×38mm 51CrV4) |
Forged Z-Type Air Beam Trailing Arm |
Mitsubishi MC413899/F, L200 MR448146 & Canter MB294519 |
Nissan UD 54010-Z3007-FA Parabolic (90×12mm 9L) |
Ford 43-698 Front Truck Pack (9L 100mm) |
Ford 43-1199 (431199) Truck Pack (4L 63mm) |
Freightliner 46-1189 Class 8 Pack (13L 76mm) |
International 55-031 Navistar Pack (13L 76mm) |
HPF5 Light Truck Spring (6L 70×11/13mm) |
IE2F P60/10/6V Light Commercial Spring |
TC P60/8/2 Light-Duty 3+2 Leaf Spring |
NDT P60/8/2 Front Parabolic Light Truck Spring |
3" Variable-Section Heavy Truck Parabolic Spring |
6–56mm Custom OEM Truck & Bus Leaf Springs (MAN/Volvo/Hino/YUTONG)
4. Technical Calculators, Load Charts & Industry Guides
Types of Leaf Springs: Cantilever, Semi-Elliptical & Full Elliptical Guide |
Interactive Leaf Spring Rate & Load Capacity Calculator |
110+ OEM Truck & Trailer Leaf Spring Cross-Reference Chart |
Parabolic Leaf Spring Services vs. Semi-Elliptic Multi-Leaf Guide |
3-Leaf to 6-Leaf Trailer Leaf Spring Load Chart (705lb–5000lb) |
Custom Truck Leaf Springs |
Agricultural Trailer Leaf Springs |
Automotive Aftermarket Leaf Springs |
Oilfield & Frac Trailer Leaf Springs |
Mining Dump Truck Leaf Springs |
Military-Wrap Tactical Leaf Springs |
Construction Mixer & Lowboy Leaf Springs |
Engineering Guides Archive |
Custom Industry Archive
Additional OEM Suspension Configurations: For specialized heavy-duty axle and air-suspension applications, compare our BPW 880368 Trailer Air Suspension Leaf Spring Arm, Heavy-Duty Trailer Air Beam & Trailing Arm Leaf Spring engineered with shot-peened SUP9A and 50CrVA alloy steel.
Frequently Asked Engineering & OEM Procurement Questions (FAQ)
How does leaf thickness affect leaf spring rate and load capacity?
Leaf spring stiffness (rate k) is proportional to the cube of single-leaf thickness (t^3), while maximum safe load capacity is proportional to the square of thickness (t^2). Increasing leaf thickness from 10 mm to 12 mm (+20%) increases spring stiffness by 72.8% and load capacity by 44%.
How do you measure eye-to-eye length and free arch on a worn trailer leaf spring?
Measure eye-to-eye length in a straight line from the center of one eye bolt hole to the center of the opposite eye bolt hole with the spring removed from the trailer (unloaded). Note that a worn or settled spring will measure 1/2 inch to 1 inch longer eye-to-eye and 1/2 inch to 3/4 inch lower in free arch than a brand-new spring of the same part number.
