#3 domed head plow bolt - earnest machine

Earnest Technical Bulletin

#3 Domed Head Plow BoltStandard Thread and Body Length

Cleveland • Atlanta • Indianapolis • England EarnestMachine.com 800.327.6378

Domed Head Designs Supplied by Earnest (per Cat 1E44)

Flat Head(per ASME B18.9)

Industry practice is to call a # 3 head plow bolt that is made to the dimensional requirements of ASME B18.9 as a “flat” head design and to call a plow bolt that is made to the heavy duty head design specified by the Caterpillar standard 1E44 as a “domed” head design.

The expression “domed” head is more than the presence of the bump or domed area that is on the top of the head. The height of the entire head is heavier and the length of the square is more substantial on a “domed” head as compared to a “flat” head design.

Different manufacturers have different heights that they make the “domed” bump on top of the head to but the overall head and square thickness must meet the Cat standard. Some manufacturers will make the height of the dome more substantial and the feed thickness (the side height on the OD of the head) a little smaller. Some manufacturers will make the “domed” portion relatively small and make the feed thickness heavier.

Domed Head with small dome height

large feed thickness

Domed Head with large dome height

small feed thickness

FeedThickness

Dome HeightDome Height

FeedThickness

HeadThickness

HeadThickness

Dome Head Plow Bolts are designed to provide added ease of assembly and greater resistance to failure in

service as compared to a standard flat head design. A domed head style is designed to be interchangeable in any application that is using a flat head style with the following added benefits:

• Thicker domed head provides greater wear resistance.

• Specialized head diameter provide for a tighter fit in countersunk holes.

• Deeper depth of square provides fuller engagement.

• Smaller transition angle on the corners of the square provides for a greater resistance againstspinning in the hole during installation.

• Tighter tolerance on the body diameter minimizes the potential of the bolt moving in the hole, which can result in the assembly coming loose and causing rounding out of the installation holes.

Size Head Diameter Body Dia.

Dome Hgt

Feed Thick

Width of Square

Depth of Head &Square

Fillet Rad Corner Rad Transition

Angle

A D E F G S FR CR N Max Min Max Min Max Min Max Min Max Min Max Min Max Min Nominal

5/8 – 11 1.044 1.013 .625 .611 .10 .050 .640 .625 .516 .466 .062 .015 .094 .030 30° 3/4 – 10 1.200 1.169 .750 .735 .11 .090 .765 .750 .581 .541 .125 .031 .109 .030 30° 7/8 – 9 1.409 1.369 .875 .859 .11 .100 .906 .875 .663 .613 .125 .031 .125 .050 30° 1 – 8 1.597 1.557 1.000 .983 .12 .100 1.031 1.000 .737 .677 .125 .031 .141 .050 30° 1 1/8 – 7 1.910 1.790 1.125 1.098 .18 .120 1.160 1.125 .810 .765 .125 .031 .156 .062 30° 1 1/4 - 7 2.087 1.969 1.250 1.223 .19 .140 1.290 1.250 .945 .892 .177 .062 .172 .062 30°


Flat Head vs Dome HeadPlow Bolts


The term “plow bolt” can mean something different to different people. Over the years several head designs have been used to attach a blade to a plow and have been called plow bolts. These different head styles have been given numbers (#1 head, #2 head, #3 head, etc) to differentiate the different head designs.

In today’s market, the most commonly used head style is the “# 3 Head”, so today when someone ask for a “plow bolt” we assume they are asking for the # 3 head.

Manufacturers of # 3 head plow bolts typically make the larger diameter sizes (5/8 and larger) with a heavy duty head that is commonly called a “domed” head. The smaller diameters (1/2” and less) are made with what is called a “regular” or “flat” head style.

The # 3 Domed Head style is the most popular style used for larger snow plows (as used by highway departments) and for earthmoving equipment. For small plow applications the “carriage” bolt head design is the most common one used

Note also that different industries can use different names for this same item. Earthmoving equipment manufactures call these bolts “cutting blade bolts”, “scraper blade bolts” or “ground engagement hardware bolts”.

Shown below are the different head styles that have been used in “plow” applications over the years.

(non−designated) Clipped Head

No. 11Chattanooga Head

No. 8 Contour Head(Elliptical Head)

No. 4Square Head

No. 6Large Key Head

No. 3Flat Round Head Square Neck

No. 2Round Head

No. 1Key Head

No. 3Domed Round Head Square Neck

(Scraper Blade Bolt)

No. 7 Reverse Key Head(Bucket Tooth Bolt)


Plow Bolt Head Designs


An “oversized head” plow bolt is a plow bolt that has a larger head size than is standard for the thread size.

Example: For the 3/8 – 16 size, the threads are 3/8 – 16 but the head is the size that would be found on a standard 7/16” plow bolt.

The “Oversized Head˜ design is used in applications where the blade is manufactured to accept a larger head size than the hole drilled in the mold board of the blade (example: blade has a 1/2” square punched into it but mold board has a 7/16 hole drilled in it). The increased engagement area of the head helps to distribute the forces, which are encountered in use, over a larger area to prevent damage to the blade and the engagement hole. The larger head diameter provides a greater wear area for increased life.

“Oversized Head˜ Plow Bolts come threaded to the head to fit a variety of grip ranges.

E5

L

Earnest #3 Oversized Head Plow Bolt Tolerances

Size (Thread

Dia)

Head Diameter Depth of Square

Width of Square

Corresponding Plow Bolt Head

Size

A S B Max Min

Sharp Min Max Min Max Min

3/8 – 16 7/16” Head Size .826 .781 .766 .364 .328 .450 .438 7/16 – 14 1/2” Head Size .945 .890 .875 .417 .375 .515 .500

Note that the Oversized Head style is not the same as the “Repair˜ style listed in ANSI B18.9.

Compared to a Standard #3 Head Plow Bolt

Dimension that a standard #3 head plow bolt is made to (per ANSI B18.9 – Regular Series)

Size Head Diameter Depth of Square Width of Square

A S B Max Min

Sharp Min Max Min Max Min

3/8 – 16 .708 .671 .656 .312 .281 .387 .375 7/16 – 14 .826 .781 .766 .364 .328 .450 .438 1/2 – 13 .945 .890 .875 .417 .375 .515 .500


#3 Oversized Flat Head Plow Bolts Grade 5


Earnest Machine Products line of #3 Head Plow Bolts in sizes 3/8 to 5/8 diameters are manufactured to the dimensions specified by ASME/ANSI B18.9 for Regular Head Series.

Max Thread Length

CR

Min Thread Length

Length

ASME/ANSI B18.9 Plow Bolts – # 3 Flat Head Tolerances (Regular Head Series)

Size

Head Diameter

Width of Square

Feed Thick

Head Thickness

Corner Rad

A B F S CR Max Min Max Min Max Min Max Min Max

3/8 – 16 .708 .656 .387 .375 .031 .000 .312 .281 .047 7/16 – 14 .826 .766 .450 .438 .036 .000 .364 .328 .047 1/2 – 13 .945 .875 .515 .500 .042 .000 .417 .375 .047 5/8 – 11 1.147 1.063 .640 .625 .050 .000 .506 .456 .078 Earnest also stocks the Dome Head style in sizes 5/8 and larger.

The thread lengths for Earnest line of plow bolts in these sizes will have a minimum thread length of 2 x Dia + 1/4 to a maximum thread length of threaded to the head.

Flat Head Plow Bolt Thread Lengths

Overall Length

Thread Length per Bolt Diameter 3/8 7/16 1/2 5/8

Min Max Min Max Min Max Min Max 1 T to H - T to H - T to H - T to H -

1 1/4 T to H - T to H - T to H - T to H - 1 1/2 1 T to H T to H - T to H - T to H - 1 3/4 1 T to H 1 1/8 T to H 1 1/4 T to H T to H -

2 1 T to H 1 1/8 T to H 1 1/4 T to H T to H - 2 1/4 1 T to H 1 1/8 T to H 1 1/4 T to H 1 1/2 T to H 2 1/2 1 T to H 1 1/8 T to H 1 1/4 T to H 1 1/2 T to H 2 3/4 1 T to H 1 1/8 T to H 1 1/4 T to H 1 1/2 T to H 3 to 6 1 T to H 1 1/8 T to H 1 1/4 T to H 1 1/2 T to H

T to H = Threaded to Head

Earnest Technical Bulletin 5/2/12

#3 Regular Flat Head Plow Bolt

EMP

SP 1

170M

The Earnest Machine Products line of #3 Dome Scraper Bolts are manufactured to a higher hardness and strength (170,000 psi) than our standard Grade 8 line to provide additional wear resistance for demanding scraper blade applications. The head design is the same as our grade 8 line to fit in all # 3 Head plow bolt applications. The domed head design provides added ease of assembly and greater resistance to failure in service as compared to a standard flat head design.

• Higher hardness and strength along the domed head provides added wear resistance.• Specialized head diameter provides for a tighter fit in countersunk holes.• Head design will fit in all applications designed for # 3 head bolts• Deeper depth of square provides fuller engagement.• Smaller transition angle on the corners of the square provides for a greater resistance

against spinning in the hole during installation.• Tighter tolerance on the body diameter for sizes 5/8 and larger, minimizes the potential of

the bolt moving in the hole, which can result in the assembly coming loose and causingrounding out of the installation holes.

170M head marking ensures the highest strength and best wear resistance.

• 170,000 psi minimum Tensile Strength• 140,000 psi min Proof Load Strength• Hardness Rc 37/42

Fr

CR

IP

1 M7D

A

Min Thread Length

F

E

S

EMP

Length

0

S

G

Size Head Diameter Body Dia. Dome

Hgt Feed Thick Width of

Square Depth of Square

Fillet Rad Corner Rad Transition Angle

A D E F G S FR CR N Sharp Max Min Max Min Max Max Min Max Min Max Min Max Min Max Min Nominal

5/8 – 11 1.197 1.044 1.013 .625 .611 .10 .120 .050 .640 .625 .516 .466 .062 .015 .094 .030 30° 3/4 – 10 1.488 1.200 1.169 .750 .735 .11 .160 .090 .765 .750 .581 .541 .125 .031 .109 .030 30° 7/8 – 9 1.745 1.409 1.369 .875 .859 .11 .170 .100 .906 .875 .663 .613 .125 .031 .125 .050 30° 1 – 8 1.933 1.597 1.557 1.000 .983 .12 .170 .100 1.031 1.000 .737 .677 .125 .031 .141 .050 30° 1 1/8 – 7 - 1.910 1.790 1.125 1.098 .18 .160 .120 1.160 1.125 .810 .765 .125 .031 .156 .062 30° 1 1/4 - 7 - 2.087 1.969 1.250 1.223 .19 .180 .140 1.290 1.250 .945 .892 .177 .062 .172 .062 30° 1 3/8 – 6 - 2.323 2.205 1.375 1.345 .22 .200 .160 1.421 1.370 1.063 1.010 .177 .062 .187 .062 30° 1 1/2 – 6 - 2.520 2.401 1.500 1.470 .25 .200 .160 1.559 1.496 1.181 1.122 .177 .062 .203 .078 30°

Earnest Technical Bulletin 5/1/12#3 Dome Scraper Bolt 170M Strength Level

E

M0

8

51PS1

The Earnest Machine Products line of #3 Dome Head Plow Bolts are specially design to provide added ease of assembly and greater resistance to failure in service as compared to a standard flat head design.

• Thicker domed head provides greater wear resistance.• Specialized head diameter provide for a tighter fit in countersunk holes.• Head design will fit into all applications designed for # 3 Heads.• Deeper depth of square provides fuller engagement.• Smaller transition angle on the corners of the square provides for a greater

resistance against spinning in the hole during installation.• Tighter tolerance on the body diameter for sizes 5/8 and larger, minimizes the

potential of the bolt moving in the hole, which can result in the assembly comingloose and causing rounding out of the installation holes.

Two strength levels are available (depending on size and availability):

• Grade 5 (per SAE J429) 120,000 psi minimum Tensile StrengthStandard Duty, Good Strength to Toughness Ratio

• Grade 8 (per SAE J429) 150,000 psi minimum Tensile StrengthHeavy Duty, Best Strength to Toughness Ratio

Size Head Diameter Body Dia. Dome

Hgt Feed Thick Width of

Square Depth of Square

Fillet Rad Corner Rad Transition Angle

A D E F G S FR CR N Sharp Max Min Max Min Max Max Min Max Min Max Min Max Min Max Min Nominal

1/2 – 13 .945 .890 .875 .500 .483 - .042 - .515 .500 .417 .375 .062 - .047 - 30° 5/8 – 11 1.197 1.044 1.013 .625 .611 .10 .120 .050 .640 .625 .516 .466 .062 .015 .094 .030 30° 3/4 – 10 1.488 1.200 1.169 .750 .735 .11 .160 .090 .765 .750 .581 .541 .125 .031 .109 .030 30° 7/8 – 9 1.745 1.409 1.369 .875 .859 .11 .170 .100 .906 .875 .663 .613 .125 .031 .125 .050 30° 1 – 8 1.933 1.597 1.557 1.000 .983 .12 .170 .100 1.031 1.000 .737 .677 .125 .031 .141 .050 30° 1 1/8 – 7 - 1.910 1.790 1.125 1.098 .18 .160 .120 1.160 1.125 .810 .765 .125 .031 .156 .062 30° 1 1/4 - 7 - 2.087 1.969 1.250 1.223 .19 .180 .140 1.290 1.250 .945 .892 .177 .062 .172 .062 30° 1 3/8 – 6 - 2.323 2.205 1.375 1.345 .22 .200 .160 1.421 1.370 1.063 1.010 .177 .062 .187 .062 30° 1 1/2 – 6 - 2.520 2.401 1.500 1.470 .25 .200 .160 1.559 1.496 1.181 1.122 .177 .062 .203 .078 30°

Earnest Technical Bulletin 5/1/12

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Grade 8Grade 5

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ISPMO51

E5

#3 domed head plow bolt - earnest machine

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