Carriage Bolt

Product Introduction

• Standard Name: Carriage Bolt.

• Common Names: Carriage Screw, Square Neck Bolt, Round Head Square Neck Bolt.

• Product Definition: A bolt featuring a smooth dome or semi-circular head and a square-section neck (below the head). Its core design ensures that when inserted into a pre-drilled hole, the square neck wedges into the connected material (especially wood), preventing rotation when tightening the nut. This enables single-person, single-side operation.

Carriage Bolt Key Features

• Round Head and Square Neck Design: The head is smooth and domed, without a drive groove; a square

  neck below the head prevents rotation when inserted into material and facilitates unilateral tightening.

• Material and Coating: Commonly made of carbon steel, stainless steel, or zinc-plated, corrosion-resistant;

  medium strength grade (e.g., 4.6 or 8.8), suitable for non-high-load applications.

• Thread Structure: Partial thread (smooth shank below the head) for easy insertion; conforms to standards

  such as DIN 603 and ISO 8677.

• Various Sizes: Diameter M5-M20, length 20mm-300mm, larger head diameter provides uniform pressure

  distribution.

• Advantages: Simple installation, reliable anti-loosening, economical and practical, but not suitable for

  applications requiring frequent disassembly.

Working Principle

• Insertion and Embedding: The bolt is inserted into a pre-drilled hole, and the square neck embeds into

  the material (such as wood), preventing the bolt from rotating with the wrench.

• Fastening Process: Torque is applied from the other side using a nut; the threads generate an axial

  clamping force, securing the component.

• Anti-Loosening Design: The square neck provides mechanical locking, resisting vibration and loosening;

  the smooth shaft distributes stress, preventing material damage.

• Mechanical Balance: Under load, the square neck evenly transmits torque, a principle involving friction

  and embedding deformation.

Product Applications

• Woodworking and Furniture: Assemble bed frames, tables, chairs, or cabinets; the square neck

  embedding provides a stable connection.

• Construction Engineering: Secure wooden beams, fences, or decks; suitable for outdoor, non-corrosive

  environments.

• Carriages and Vehicles: Traditionally used for securing carriage bodies; now used on agricultural vehicles

  or trailers.

• Gardening and DIY: Install swings, fences, or pergolas; economical and easy to use.

• Industrial Equipment: Connect wooden bases or lightweight structures; stainless steel versions are

  moisture-resistant.