Plow Bolts vs. Carriage Bolts

Plow Bolts vs Carriage Bolts: What Is the Difference?

Plow bolts and carriage bolts can look similar at a glance. Both have smooth, low profile heads and a feature under the head that helps prevent the bolt from turning. They are designed for different jobs though. Understanding plow bolts vs carriage bolts helps you choose the right fastener for heavy equipment, wear parts, and wood or structural connections.

At Springs Fastener, you can go directly to our dedicated categories for plow bolts and carriage bolts, and explore our in depth plow bolts guide and carriage bolts guide to dive deeper into each style.

What Is a Carriage Bolt?

A carriage bolt is a round head, square neck bolt often used where you want a smooth, domed head on one side and a nut on the other. The square section under the head bites into the material to keep the bolt from spinning while you tighten the nut.

Typical features of carriage bolts include:

• Round or dome head: A smooth, low snag head that is common in wood construction, fencing, and hardware assemblies.
• Square neck under the head: Designed to lock into wood or a square hole so the bolt holds still while the nut is tightened.
• Full body diameter: A straight shank with standard bolt threads at the end for a nut and washer.
• Common uses: Wood to wood and wood to metal joints in decks, fences, playgrounds, and other structures where a smooth head is preferred on the exposed side.

For more detail on head styles, neck dimensions, and typical applications, see our resource What Are Carriage Bolts?.

What Is a Plow Bolt?

Plow bolts are heavy duty bolts with a countersunk head that sits flush with the wear surface. They are most often used on equipment where the bolt head is exposed to abrasion, such as plow blades, grader blades, loader buckets, and other ground engaging tools.

Typical features of plow bolts include:

• Countersunk, flat or oval head: The head fits into a tapered hole so it sits flush or slightly below the working surface to reduce wear and snagging.
• Square neck or other anti rotation feature: Helps lock the bolt in the countersunk pocket so it does not turn while the nut is tightened.
• High strength design: Plow bolts are usually produced in higher grades suitable for the shock and vibration loads of heavy equipment.
• Common uses: Attaching cutting edges, wear plates, and other ground engaging parts where exposed bolt heads would be quickly worn away.

For a deeper look at head profiles, grading, and installation tips, review our Plow Bolts Guide.

Head Shape and Surface Profile

One of the easiest ways to see the difference between plow bolts vs carriage bolts is to look at the head and how it relates to the surface.

• Carriage bolts: The round head usually sits proud of the surface. That works well in wood and structural applications where some bolt head projection is acceptable or even desirable for appearance.
• Plow bolts: The countersunk head is meant to sit flush with the wear surface so material flows over it. This is critical on plow blades, grader edges, and bucket lips where raised bolt heads would be quickly damaged.

If you need a smooth working surface that sees abrasion, a plow style head is usually the right choice. If you need a smooth, low snag head on the outside of a joint in wood or steel, carriage bolts are often a better fit.

How They Lock Against Rotation

Both bolts use a feature under the head to resist spinning while the nut is tightened, but they do it in slightly different ways.

• Carriage bolts: The square neck is designed to bite into wood or fit into a square hole. Once seated, it keeps the bolt from turning so you can tighten the nut from the opposite side.
• Plow bolts: The tapered head fits in a countersunk pocket and is often combined with a square neck or specially shaped head. When installed in the matching countersink, the bolt locks in position and resists rotation even under heavy vibration.

In both cases, the locking feature works together with a nut and, in many cases, a flat or lock washer from our washers category to complete the assembly.

Strength, Grades, and Materials

Plow bolts and carriage bolts are available in different materials and grades. The right choice depends on the loads and environment.

• Carriage bolts: Commonly supplied in low carbon steel for general use, and in higher grades or stainless where more strength or corrosion resistance is needed. You can explore options in our carriage bolts category and match them with nuts and washers appropriate to your application.
• Plow bolts: Typically manufactured from higher strength steel to handle impact, bending, and vibration on heavy equipment. Many users pair these with high strength nuts and hardened washers where space allows.

For corrosive or outdoor environments, stainless versions from our stainless steel bolts and matching stainless nuts can provide longer service life.

Typical Applications: Plow Bolts vs Carriage Bolts

Best Uses for Carriage Bolts

• Decks, docks, and timber framing where a smooth, domed head is desired on the exposed side
• Fences, railings, and guardrails that pass through wood or composite materials
• Playground equipment and site furnishings where a low snag, vandal resistant head is helpful
• Wood to steel joints where the square neck fits a punched square hole in a bracket or plate

For these applications, start with our carriage bolts selection and pair them with the right nuts, washers, and, when needed, threaded rod for longer runs or custom fabrication.

Best Uses for Plow Bolts

• Snow plow cutting edges and shoes
• Motor grader blades and road maintenance equipment
• Loader buckets, dozer blades, and other ground engaging tools
• Wear plates and liners where a flush fastener head is required

In these high wear, high impact environments, plow bolts are designed to sit flush with the surface and stay in place. They are commonly installed with heavy hex or high strength nuts and, where needed, hardened washers on the non wear side of the assembly.

Plow Bolts vs Carriage Bolts: Quick Comparison

• Head shape: Carriage bolts have a round head that sits above the surface. Plow bolts have a countersunk head that sits flush in a tapered hole.
• Locking feature: Both use a square or shaped section under the head. Carriage bolts bite into wood or a square hole. Plow bolts lock into a countersunk pocket designed for heavy duty applications.
• Primary use: Carriage bolts are common in wood and structural connections where a smooth head is desired. Plow bolts are built for wear surfaces and heavy equipment where bolt heads must be protected.
• Strength focus: Carriage bolts are used from light duty through structural work depending on grade. Plow bolts are usually heavy duty and focused on high impact and abrasion environments.

Build Your Bolt Assemblies with Springs Fastener

Whether you are outfitting heavy equipment or building wood and steel structures, Springs Fastener can supply the right bolt style for your job. Compare plow bolts and carriage bolts, then complete your assembly with compatible nuts, washers, and other bolts and threaded products.

If you have a specific equipment model, drawing, or bill of materials and want help choosing between plow bolts vs carriage bolts, use our Request for Quote form or reach out through our Contact Us page. Our team can help you match head style, grade, and finish to your application so your fasteners perform reliably in the field.