![ASME B18.5 Grade 2/5/8 Round Head Carriage Coach Bolts Fasteners Square Neck](//www.micstatic.com/athena/img/transparent.png)
Round Head Square Neck Bolt / Carriage Bolt
A carriage bolt (also called coach bolt and round-head square-neck bolt) is a type of bolt. It is also known as a cup head bolt in Australia and New Zealand.
It is distinguished from other bolts by its shallow mushroom head and the fact that the cross-section of the shank, though circular for most of its length (as in other kinds of bolt), is square immediately beneath the head.[2] This makes the bolt self-locking when it is placed through a square hole in a metal strap. This allows the fastener to be installed with only one wrench, working from the opposite end. The head of a carriage bolt is usually a shallow dome. The shank has no threads and its diameter equals the size of the square cross-section.
The carriage bolt was devised for use through an iron strengthening plate on either side of a wooden beam, the squared part of the bolt fitting into a square hole in the ironwork. It is common to use a carriage bolt on bare timber, the square section giving enough grip to prevent rotation.
Standard |
ANSI/ASME B18.5 |
Strength Grade |
Gr 2, 5, 8 or SS 304/316 |
Material |
Q195/35K/10B21/40CR/Stainless Steel 304/316 |
Size |
Dia 1/4''-5/8'' or customized |
Exterior Finish |
Plain/Zinc/Black/Decromet |
Package |
Bulk in carton, small box, or customized |
![ASME B18.5 Grade 2/5/8 Round Head Carriage Coach Bolts Fasteners Square Neck](//www.micstatic.com/athena/img/transparent.png)
ASME B18.5
Nominal Size or Basic Diameter |
E |
A |
H |
J |
T |
U |
Body Diameter |
Head Diameter |
Head Height |
Slot Width |
Slot Depth |
Fillet Radius |
Max |
Min |
Max |
Min |
Max |
Min |
Max |
Min |
Max |
Min |
Max |
Min |
1/4'' |
0.2500 |
0.2500 |
0.2450 |
0.4370 |
0.4180 |
0.1910 |
0.1750 |
0.0750 |
0.0640 |
0.1170 |
0.0970 |
0.0310 |
0.0160 |
5/16'' |
0.3125 |
0.3125 |
0.3070 |
0.5620 |
0.5400 |
0.2450 |
0.2260 |
0.0840 |
0.0720 |
0.1510 |
0.1260 |
0.0310 |
0.0160 |
3/8'' |
0.3750 |
0.3750 |
0.3690 |
0.6250 |
0.6030 |
0.2730 |
0.2520 |
0.0940 |
0.0810 |
0.1680 |
0.1380 |
0.0310 |
0.0160 |
7/16'' |
0.4375 |
0.4375 |
0.4310 |
0.7500 |
0.7250 |
0.3280 |
0.3020 |
0.0940 |
0.0810 |
0.2020 |
0.1670 |
0.0470 |
0.0160 |
1/2'' |
0.5000 |
0.5000 |
0.4930 |
0.8120 |
0.7860 |
0.3540 |
0.3270 |
0.1060 |
0.0910 |
0.2180 |
0.1780 |
0.0470 |
0.0160 |
9/16'' |
0.5625 |
0.5625 |
0.5550 |
0.9370 |
0.9090 |
0.4090 |
0.3780 |
0.1180 |
0.1020 |
0.2520 |
0.2070 |
0.0470 |
0.0160 |
5/8'' |
0.6250 |
0.6250 |
0.6170 |
1.0000 |
0.9700 |
0.4370 |
0.4050 |
0.1330 |
0.1160 |
0.2700 |
0.2200 |
0.0620 |
0.0310 |
3/4'' |
0.7500 |
0.7500 |
0.7420 |
1.2500 |
1.2150 |
0.5460 |
0.5070 |
0.1490 |
0.1310 |
0.3380 |
0.2780 |
0.0620 |
0.0310 |
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