Bolts
Carriage Bolts
Round Head Square Neck Bolts / Coach Bolts
Our carriage bolts feature a smooth, dome-shaped head with a square section beneath it that pulls into the wood or soft material during tightening, preventing the bolt from spinning. This self-locking design makes them ideal for wood-to-metal connections where only one side is accessible for tightening. Manufactured through precision cold heading, they deliver superior strength and a clean, tamper-resistant appearance.
Key Features
Smooth dome head for tamper-resistant, snag-free finish
Square neck locks into wood to prevent rotation
Precision cold-headed for superior grain flow strength
Available in carbon steel, stainless steel, and alloy steel
Multiple surface treatments for corrosion resistance
Custom lengths and sizes available on request
Technical Specifications
| Product Name | Carriage Bolts (Round Head Square Neck Bolts) |
| Chinese Name | 马车螺栓 |
| Brand | ZCM / Zhongchun |
| Standards | DIN 603, ISO 8677, GB/T 12, ANSI/ASME B18.5 |
| Grade | 4.8 / 8.8 / A2-70 / A4-80 |
| Material | Carbon Steel, Stainless Steel (304/316), Alloy Steel |
| Size Range | M5 - M20 |
| Length Range | 12mm - 200mm |
| Thread | Full Thread / Partial Thread |
| Head Type | Round (Dome) Head with Square Neck |
| Surface Treatment | Zinc Plated (White/Yellow/Blue), Black Oxide, HDG, Dacromet, Plain |
| Packaging | Carton + Pallet, or per customer request |
| MOQ | Contact us for details |
| Lead Time | 15 days for standard orders |
Applications
Carriage bolts are widely used in construction, agriculture, and woodworking applications where a smooth, tamper-proof finish and anti-rotation locking are required.
Wood-to-metal structural connections
Timber frame construction and deck building
Playground equipment and outdoor furniture
Agricultural machinery and fence assemblies
Dock and marine construction
Guard rail and barrier installations
Bridge and highway infrastructure
General carpentry and woodworking projects
Interested in Carriage Bolts?
Send us your specifications for a competitive quote. Standard orders delivered in 15 days.