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Plow bolt plough bolt screw
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Product introduction
Plow Bolts / Plough Bolts – Technical Overview
1. Definition and Design Overview
A plow bolt (also spelled plough bolt) is a specialized heavy-duty fastener designed for flush-mounting applications in agricultural, construction, and earth-moving equipment. Unlike standard carriage bolts, plow bolts feature a countersunk head that sits flush with or below the surface of the material, eliminating protrusions that could snag or cause damage during operation.
The plow bolt was originally devised to hold replaceable plowshares to the moldboards of iron plows. Today, these fasteners continue to be used wherever a protruding head is undesirable—including cultivators, earthmoving implements, bulldozers, graders, snowplows, and mining equipment.
Key Design Features:
| Feature | Description |
|---|---|
| Head Style | Flat countersunk or slightly domed, low-profile head |
| Neck Type | Square neck under the head prevents rotation during tightening |
| Mounting | Sits flush within pre-drilled countersunk holes with chamfered edges |
| Installation | Square neck locks into the hole, allowing one-wrench installation from the nut side |
2. Head Types
Plow bolts are available in two primary head configurations:
| Head Type | Description | Application |
|---|---|---|
| #3 Flat Head | Standard flat countersunk head for flush mounting; most common configuration | Confined operational systems, general-purpose plow applications |
| #3 Dome Head | Slightly domed, low-profile head offering increased bearing surface and wear resistance | High-wear environments, applications requiring enhanced durability |
Dome head bolts generally provide better resistance to damage than flat head bolts. Head angle typically ranges from 80° to 82°.
3. Dimensional Standards
Plow bolts are manufactured according to recognized international standards that ensure interchangeability and consistent quality.
3.1 ASME B18.9 (Inch Series)
The primary standard for inch-series plow bolts in North America. ASME B18.9 covers general and dimensional data for plow bolts recognized as American National Standard. Key dimensional parameters include:
| Dimension | Typical Value (5/8"-11 example) |
|---|---|
| Head Diameter (max) | 1.094" – 1.147" |
| Head Height (max) | 0.426" – 0.506" |
| Square Width | 0.625" – 0.640" |
| Head Angle | 80° – 82° |
| Thread Fit | 2A |
3.2 DIN 608 (Metric Series)
The European standard for plough bolts with flat countersunk head and square neck. Available in metric thread sizes from M8 upward.
| Specification | Typical Value |
|---|---|
| Thread | M8, M10, M11, M12, M14 |
| Strength Classes | 8.8, 10.9 |
| Tensile Strength (10.9) | 1000 N/mm² |
3.3 ISO 7852:1983
Specifies the shapes and dimensions of plough bolt heads (excluding thread dimensions) used for mounting cutting edges, end bits, and bucket teeth on earth-moving machinery as defined in ISO 6165. This standard ensures interchangeability across manufacturers.
3.4 BS 6490:1984
British Standard covering shapes and dimensions (excluding thread dimensions) of plough bolt heads for earth-moving machinery.
4. Material Grades and Strength Properties
Plow bolts are manufactured in various strength grades to suit different application requirements.
4.1 Grade 5 Plow Bolts
Grade 5 plow bolts are made from tempered medium carbon steel and are heat-treated, oil or water quenched, and tempered at a minimum temperature of 800°F.
| Property | Value |
|---|---|
| Tensile Strength | 120,000 psi |
| Material | Medium carbon steel (AISI standards) |
| Heat Treatment | Quenched and tempered |
| Typical Finish | Zinc-plated, black oxide, or plain |
4.2 Grade 8 Plow Bolts
Grade 8 plow bolts are manufactured from high-grade heat-treated alloy steel, providing superior strength for heavy-duty applications.
| Property | Value |
|---|---|
| Tensile Strength | 150,000 psi |
| Rockwell Hardness | HRC33 – HRC39 |
| Material | Alloy steel |
| Meets Standards | SAE J429, ASTM A325, ASTM A574 |
4.3 Grade 9 / A9 Plow Bolts
For extreme-duty applications, Grade 9 (A9) plow bolts offer even higher strength.
| Property | Value |
|---|---|
| Tensile Strength | 170,000 psi minimum |
| Material | Alloy steel |
4.4 Metric Strength Classes (DIN 608)
| Class | Tensile Strength | Typical Application |
|---|---|---|
| 8.8 | 800 N/mm² | General-purpose agricultural |
| 10.9 | 1000 N/mm² | Heavy-duty applications |
4.5 Grade Comparison
| Grade | Tensile Strength | Hardness | Characteristics |
|---|---|---|---|
| Grade 5 | 120,000 psi | Medium | Good balance of strength and ductility |
| Grade 8 | 150,000 psi | HRC33-39 | Higher strength, more brittle |
| Grade 9 | 170,000 psi | Higher | Maximum strength for extreme duty |
5. Material Options
Beyond carbon and alloy steel, plow bolts are available in various material specifications:
| Material | Typical Grades | Application |
|---|---|---|
| Carbon Steel | SAE J429 Gr.2, 5 | General-purpose fastening |
| Alloy Steel | SAE J429 Gr.8, A9 | High-strength, heavy-duty |
| Stainless Steel | 304, 316, 302 | Corrosion-resistant environments |
| Heat-Treated Alloy | ASTM A325 | Structural and heavy equipment |
6. Finishes and Coatings
| Finish | Characteristics | Environment |
|---|---|---|
| Plain | Uncoated; basic protection | Dry, indoor applications |
| Black Oxide | Corrosion resistant in dry environments | Dry, moderate conditions |
| Zinc-Plated | Moderate corrosion resistance | Wet or humid environments |
7. Applications
Plow bolts are essential fasteners in industries where equipment endures high impact, vibration, and abrasive wear.
Primary Applications:
| Industry | Equipment / Components |
|---|---|
| Agriculture | Plows, cultivators, harrows, forage harvesters, subsoilers |
| Construction | Bulldozers, graders, scrapers, excavators |
| Mining | Rock quarry equipment, cutting edges, bucket teeth |
| Snow Removal | Snowplows, blade attachments |
| Earth-Moving | Cutting edges, end bits, scraper blades |
Specific Components Fastened:
Plow cutting edges to plow beams
Shovels to cultivators
Cutting edges and end bits on earth-moving machinery
Blade attachments and ground engagement hardware
8. Plow Bolt vs. Carriage Bolt – Key Technical Differences
Though often confused, plow bolts and carriage bolts have distinct design differences:
| Feature | Plow Bolt | Carriage Bolt |
|---|---|---|
| Head Profile | Countersunk (flat or domed), sits flush | Smooth, domed, sits above surface |
| Head Angle | Angled underside (80°-82°) | Flat underside |
| Application | Heavy equipment, metal-to-metal | Smaller equipment, wood-to-metal |
| Neck Design | Square neck under head | Square neck under head |
| Typical Equipment | Excavators, bulldozers, graders | Snowplows on pick-up trucks |
9. Summary of Key Specifications
| Parameter | Grade 5 | Grade 8 | DIN 608 (10.9) |
|---|---|---|---|
| Standard | ASME B18.9 / SAE J429 | ASME B18.9 / SAE J429 | DIN 608 |
| Tensile Strength | 120,000 psi | 150,000 psi | 1000 N/mm² |
| Material | Medium carbon steel | Alloy steel | Steel |
| Hardness | — | HRC33-39 | — |
| Head Angle | 80°-82° | 80° | — |
| Neck Type | Square | Square | Square |
| Typical Thread | UNC coarse | UNC coarse | Metric coarse |
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