How to Protect the Loader Bucket

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When producing asphalt, few items around the plant are more versatile and flexible than the plant’s front end loader. Yes, it loads the plant’s bins with aggregate for production, but it also must maintain the stockpiles, grade the road (in most cases), as well as load customer trucks. The bucket on the plant’s front end loader is the business end of this machine and protecting the bucket is truly protecting an important investment.

Buckets come in many shapes and sizes. You can have a permanently mounted bucket or a quick-disconnect; you can have a straight-lipped bucket or a spade-nose; you can have straight cutting edges or teeth and segments. For the purpose of this discussion, we will concentrate on the most common arrangement of a pinned on straight-lip bucket with standard cutting edges.

The steps required to maintain and protect a front end loader bucket will begin with an evaluation of the individual plant’s situation. How abrasive is the material being used? What is the annual tonnage that this plant produces?

Does the loader run primarily during daytime hours or does this plant run around-the-clock operations? The answers to these questions will determine how often a bucket must be examined as well as how heavily it must be protected.

Let’s start with an overall visual inspection:

• Are there cracks in the structural components?
• Are the attachment points solid or are they worn with cracks visible?
• What is the condition of the moldboard? Is it solid and strong or scalloped and weak?
• How about the vertical corners? Are they still thick and strong or worn thin and weak?
• Is there a bucket liner and, if so, what is its condition?
• Are the side walls solid or worn with holes present?
• Is the bucket floor flat and serviceable or worn thin, wavy and cracked?

This is a good example of “don’t let this happen to you.” This bucket was not adequately protected from wear and ended up needing to be rebuilt or replaced. Yes, good wear parts are a sizeable investment, but they are still cheaper than a new bucket.

Now let’s evaluate the bucket’s normal wear parts:

• What condition is the cutting edge in? Is it still projecting in front of the moldboard enough to protect the moldboard from excessive wear? Is the cutting edge wearing flat from proper use of the loader’s flotation or is the edge wearing mainly on the front portion indicating the bucket is being run with a raised bucket? A new cutting edge is one of the quickest ways to enhance the effectiveness of any bucket.
• How do the heel plates look? Are they even present? I have seen many cases where a bucket required a rebuild because it was run without heel plates for so long the bolt holes were worn away. In many cases a loader manufacturer has calibrated the bucket leveling system to work best when a new set of heel plates is mounted to the bucket.
• Is the moldboard in good condition? Does it have “scalloped” wear between the bolts or is it warped from hardfacing? We often find buckets where the heat introduced by hardfacing or other welding has warped the moldboard so badly the end blades are resting on the ground, yet the center of the bucket sets proud by 1.5 inches or more. In this condition the cutting edges will wear very unevenly. The end blades will wear quickly while the center blades will be barely touched.

One of the primary issues to consider is the fact that the point where the moldboard welds to the vertical wall represents one of the highest stress points on the bucket. If this juncture is weak then the entire bucket is weak. Protecting this corner is essential to ensuring long bucket life.

How can we prevent some of these issues and extend the life of a front end loader bucket? Armoring that bucket with the proper combination of easily replaceable wear parts is one good way. When it comes to protecting loader buckets, size doesn’t matter, according to Micky Brewer, owner of MKB Welding.

“Buckets moving rock and sand all day take a beating,” he said. “Large or small, they need liners. All too often, we are replacing bucket floors when a liner kit should have been installed from the start. Side plates also need protection.”

Here are some of the replaceable wear parts that can help extend bucket life.

• A high quality cutting edge is paramount. A standard heat-treated steel will suffice in general conditions. If your wear factor is higher you should consider a Tungsten Carbide Impregnated version.
• Moldboard base edge cap systems are a great way to prevent the heavy “scalloping” type wear seen on moldboards. They are easily replaceable, mounting with only the cutting edge bolt yet completely preventing wear to the moldboard.
• Vertical wall side cutters are a critical element of the bucket protection arsenal. By extending in front of and across the face of a vertical wall, these side cutters will prevent the verticals from getting thin and weak.
• Side wall wear plates, cut to fit each individual bucket, can prevent the need to cut out and replace a bucket side wall.
• Bucket liners. While not necessary in all materials and environments, a bucket liner system will prevent holes that weaken a critical bucket area.

Now let’s look at some best practices to help extend the life of your bucket:

One of the quickest and most cost-effective ways to extend bucket life is to simply replace wear parts when they are worn. A wear part’s job is to serve as a sacrificial component—it wears away instead of the base steel. Let it. Replacing these parts on time will protect the underlying bucket component.

Armor your bucket when it is new and still in great condition thus allowing the wear parts to take the beating. Doing so will ensure a bucket remains strong throughout its life and that of the loader.

Avoid hardfacing when possible. The heat introduced into the bucket’s steel will inherently weaken the very metallurgical properties that you have spent a lot of money on. Plus, you risk warping the moldboard and reducing cutting edge life.

Invest in an ultrasonic thickness tester if your company does not own one. They are by far the quickest and easiest way to get an accurate measurement of a component’s remaining life. Just remember that you are only measuring the top layer of steel. For example, if you use one of these to measure a bucket liner, it cannot also measure the thickness of the base steel underneath.

If your loader has an automatic levelling system, use it. Running your bucket at the proper angle provides the proper alignment of components and will ensure maximum efficiency and wear life of components.

We have learned that, nationwide, an asphalt plant’s wear needs fall along a continuum. Some plants need a lot of protection while others need very little. Consequently, you can look at these bucket protection ideas with an “a la carte” mentality—use the items necessary for your location but forget about the rest.