Round Head Square Neck Bolt

Product Code: MD-CVT-0004

A DIN 603 square-neck carriage bolt is also known as a square-under-head bolt. The square neck limits rotation during assembly. It is commonly used on agricultural implements and structural joints requiring high torque; the square section supports secure tightening with a spanner or socket. | Parameter | M6 | M8 | M10 | M12 | M16 | |---|---:|---:|---:|---:|---:| | p | 1.25 | 1.50 | 1.75 | 2.00 | 2.50 | | k max. | 3.88 | 4.88 | 5.38 | 6.95 | 8.95 | | k min. | 3.12 | 4.12 | 4.62 | 6.05 | 8.05 | | d2/dk max. | 16.55 | 20.65 | 24.65 | 30.65 | 38.80 | | d2/dk min. | 15.45 | 19.35 | 23.35 | 29.35 | 37.20 | | c/f max. | 4.60 | 5.60 | 6.60 | 8.75 | 12.90 | | c/f min. | 3.40 | 4.40 | 5.40 | 7.25 | 11.10 | | v max. | 6.48 | 8.58 | 10.58 | 12.70 | 16.70 | | v min. | 5.52 | 7.42 | 9.42 | 11.30 | 15.30 | | b, l ≤ 125 | 18.00 | 22.00 | 26.00 | 30.00 | 38.00 | | b, 125 ≤ l ≤ 200 | 24.00 | 28.00 | 32.00 | 36.00 | 44.00 | | b, l > 200 | — | 41.00 | 45.00 | 49.00 | 57.00 | ## What Is a Square-Neck Carriage Bolt? It is a special bolt with a square base or neck beneath the head. This square geometry is designed to increase stability and prevent rotation during assembly. ## Features - **High Torque Capacity:** The extra grip of the square section supports higher tightening torque. - **Material Options:** Stainless steel, zinc-plated steel and other metal versions may be available. - **Range of Sizes:** Various dimensions allow selection for the particular application. ### Advantages - **Easy Assembly:** It seats in a square hole or recess, preventing rotation while the nut is tightened and reducing the need to hold the bolt separately. - **Stability and Strength:** The square base improves the security of load-bearing and fixing joints. - **Multiple Applications:** Used in timber and steel structures, construction and automotive assemblies where the contact surface must resist bolt rotation. ## Differences from Standard Bolts - **Base Shape:** It has a square neck or base rather than the usual round under-head geometry. - **Rotation Resistance:** The square section provides additional resistance to turning during assembly. - **Application:** Intended for special joints with a square hole or recess, so its use is more specific than that of standard bolts.