Back to Basics with Plow Bolts

Is it Plow or Plough Bolts? Whatever you call them, the Plow Bolt definition is a threaded fastener with a low-profile head that includes a feature like a square, keyway, etc, which permits the bolt to be held in position while the nut is tightened. 

Over the years, different manufacturers used varying bolts that had different heads to attach the blades to their machinery. This resulted in a general overuse of the term ‘Plow Bolt’. To differentiate the many Plow Bolt head types, fastener standards organisations assigned numbers to help identify them, ranging from #1 head to #11 head.

How does a Plow Bolt work?

Essentially, the bolts will attach the blade to the plow of the equipment. The Plow Bolts are used for a variety of applications, but mainly the following:

  • For bulldozers, the #3 Head Plow Bolt is used to attach the blade to the bottom of the plow, or as it’s often called, ground engagement hardware.
  • For excavators, the #7 Head Bolt can be used to attach the bucket teeth to the bucket, earning itself the name Bucket Tooth Bolt.
  • For agricultural plows, the Clipped Head Plow Bolt is used to attach the side cutters, or the tynes, to the plow.

Click here for a chart of all of the Plow Bolts style in the market.

tractor plow bolts

Bespoke Plow Bolts are usually needed when special attachments are designed for use on construction equipment. If the original equipment bolt does not fit the application, then specially designed bolts can be provided by Plow Bolt manufacturers like Earnest. 

How are Plow Bolts measured?

When measuring the length of a plow bolt, you include the height of the head in the length measurement (unlike a hex bolt or carriage bolt where you only measure from the bearing surface under the head to the end of the bolt).

What are the most common Plow Bolts used today?

As mentioned above, there are different Plow Bolt head types, ranging from #1 – #11. However, bolt types #1 and #2 were used by companies that are no longer functioning, and so are practically obsolete. The most commonly used bolt heads are #3 and #7. 

The #3 Domed Head Plow Bolt has a heavy-duty head design that provides greater wear resistance and better engagement in square holes. Earnest offers #3 Head Plow Bolts in either a flat head, domed head, or oversized head style.

Earnest Machine stock #3 Head Plow Bolts in Grade 5, Grade 8 and 170M, which is commonly referred to as Grade 9. The 170M product is designed to be stronger and more durable than the Grade 8. It provides excellent resistance to the more abrasive plow applications.

Earnest’s range of Plow Bolts are available in imperial and metric sizing. They are usually measured against the imperial US spec, ASME B18.9, and the metric German spec of DIN 605. Earnest’s range is mainly imperial, but metric is also available, along with bespoke designs.

For more information on Earnest’s Plow Bolt range, or to discuss any bespoke needs, please contact the team to see how we can help.

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