The forks are the only part of the truck that touches the load, and they take constant friction, bending stress, and impact. Worn, bent, or wrongly sized forks aren't just a maintenance issue. They're a load-handling safety risk. This guide covers how forks are classified, how to size a replacement, and when a fork must come out of service.
Forklift Forks
1. Fork Mounting Classes (ITA, Based on ISO 2328)
Forks aren't interchangeable. They're classified by the carriage they hang on, measured as the distance between the top and bottom of the carriage bars. These are the ITA (Industrial Truck Association) classes, whose dimensions follow ISO 2328, the standard for hook-type fork arms and carriages.
| ITA Class | Carriage Height | Typical Truck Capacity (approx., at a 24 in load center) |
|---|---|---|
| Class 1 | 13 in (330 mm) | Under about 2,000 lb |
| Class 2 | 16 in (406 mm) | About 2,000–5,500 lb |
| Class 3 | 20 in (508 mm) | About 5,500–10,000 lb |
| Class 4 | 25 in (635 mm) | About 10,000–17,500 lb |
| Class 5 | About 28.7 in (728 mm) | About 17,500–24,000 lb |
Each class also has 'A' and 'B' variants that differ in the clearance under the lower hook. Capacity ranges differ slightly between published tables, so match forks to your truck's data plate and the manufacturer's specification rather than to a table alone. If you're unsure which class you have, measure the carriage height.
2. Fork Sizing
A replacement fork is specified by thickness × width × length, plus the class.
- Width: commonly 4 in for Class 2, 5 in for Class 3, and 6 in for Class 4. Wider forks spread weight over a larger area.
- Thickness: depends on class and rated capacity. Typical examples are about 1.25–1.5 in for Class 2, about 1.75 in for Class 3, and about 2 in for Class 4.
- Length: 42 in is the most common, with 48 in also widely used. As a rule, forks should reach at least two-thirds of the way under the load. Longer forks can strike the pallet behind in racking, and shorter ones let the load overhang the tips and push its center forward. See our guide to load center for how that affects capacity.
Fork capacity must match the truck's rated capacity at its rated load center. Don't mix forks of different ratings on one truck.
3. Inspection and the 10% Rule
The relevant standards are ISO 5057 (inspection and repair of fork arms in service) and ANSI/ITSDF B56.1.
The wear limit: forks wear fastest at the heel, the bend between the blade and the shank. A fork whose blade thickness at the heel has worn to about 90% of its original thickness (10% wear) must be taken out of service, because at that point its load-carrying capacity has dropped by roughly 20%.
How to check:
- Measure the blade thickness near the heel with a fork caliper.
- Compare it to the original thickness, taken from the manufacturer's specification or the marking on the fork, or from a new fork of the same type.
- A common shortcut is to compare heel thickness to the shank on the same fork. That only works if the shank hasn't worn and has the same nominal thickness as the blade, and it doesn't work for tapered forks. When in doubt, use the original specification.
Also remove a fork from service if you find:
- Cracks, especially at the heel and around the hook welds. Even a hairline crack can lead to a sudden break under load.
- Uneven tip height: if the tips of a pair differ by more than about 3% of the blade length, the forks are bent.
- A bent blade or shank, usually from impact or from prying with the forks.
- A damaged or missing positioning lock, or badly worn hooks.
- Missing or unreadable marking, since you can no longer verify its rated capacity.
How often: do a visual check as part of the daily pre-shift inspection. Formal measurement at least once a year is the usual baseline, and more often for heavy-duty or multi-shift use. Follow ANSI/ITSDF B56.1 and your fork manufacturer's instructions for the exact interval.
4. Common Fork Types
- Standard hook-type (ITA) forks: the industry norm for most counterbalance trucks and many other trucks.
- Shaft/pin-mounted forks: common on larger construction trucks and telehandlers, where forks slide on a heavy-duty pin.
- Bolt-on forks: used with certain attachments and heavy-duty applications.
- Coil forks: a rounded inner profile for carrying cylindrical loads such as steel coils and concrete pipes without damaging them.
- Folding forks: for tight spaces or when forks must be folded for transport.
- Fork extensions and weighing forks: accessories for long loads or on-fork weighing. Extensions reduce capacity, so check the de-rated figure. See our guide to load center.
5. Repairing a Cracked Fork
Don't weld it. Industry standards and fork manufacturers don't allow field welding repair of cracked forks. A fork's strength comes from controlled heat treatment, and the heat of welding changes the steel around the repair, leaving it brittle and prone to sudden failure. A cracked fork needs to be replaced. Any repair should go through the fork manufacturer.
6. Why Forks Wear Out Early
- Dragging the forks on the floor. Travel with the forks about 100–150 mm (4–6 in) above the ground.
- Prying, pushing, or dragging loads with the forks, which bends them.
- Impact against racking and walls.
- Using the wrong fork for the load, such as undersized forks for heavy, long loads.
Operator training on these habits is the cheapest way to extend fork life. See our forklift safety rules and daily maintenance checklist.
Frequently Asked Questions
Can I weld a crack in a forklift fork? No. See Section 5.
How often should I inspect my forks? Daily visually, with formal measurement at least annually and more often in severe or multi-shift use, per ANSI/ITSDF B56.1 and the fork manufacturer.
Why do my forks wear out so fast? The most common cause is dragging them on the floor, followed by impact and prying. Check the wear at the heel, not just the tips.
What fork class do I need? Measure the carriage height and match the class in Section 1, then match capacity to your truck's data plate.
Standards Referenced
- ISO 2328: hook-type fork arms and fork arm carriages, mounting dimensions
- ISO 2330: fork arms, technical characteristics and testing
- ISO 5057: inspection and repair of fork arms in service
- ANSI/ITSDF B56.1: safety standard for low-lift and high-lift trucks
🏆 Maoxiang: Forged for Strength
At Maoxiang, we know that the fork is the 'business end' of your machine. We don't cut corners on metallurgy.
Full-Heel Forging: Our forks are forged with a reinforced heel to resist the extreme stress of high-cycle lifting.
Premium Heat Treatment: We use a controlled quenching and tempering process to ensure the perfect balance of hardness (for wear resistance) and ductility (to prevent snapping).
Certified Quality: Every fork we ship is stamped with its Load Capacity and Batch Number, ensuring 100% traceability and peace of mind for your safety audits.
Tell us your truck model, carriage class, pallet size, and typical load, and we'll specify the right forks, or help you check the forks you already have against the wear limits above.
