This article is based on a webinar presented by Dean Wedekind, bucket specialist, Maxi-Lift Inc., Addison, TX (800-527-0657), held in late February as part of the Grain Elevator and Processing Society’s Online Exchange Conference.
When I first got started in the grain industry, I got a lot of my training from Clayton Ellsworth, who started EBM Corporation in Norfolk, NE. Clayton always said to pretend that you’re the product going through the bucket elevator, spouting, or transfer conveyor, etc. If you think about yourself as the product going through a bucket elevator, you will gain a better understanding about what might need to be done to handle that product to preserve grain quality better.
This concept also can be applied to equipment in a grain elevator. Imagine that you are the components of a bucket elevator. Thinking about how each component works can help you understand how to maintain them better.
Belting is one of the most important parts of a bucket elevator, and you need to make sure you have the correct belt for your application. In the grain industry, belts should be static-conductive, oil-resistant, and flame-retardant.
Two types of belts that are static-conductive, oil-resistant, and flame-retardant include:
Another important quality for belting is good traction, which helps the belt spin the correct way. Traction can be affected by adjusting the tension of the takeups in the boot. But you also need to have good slide lagging in the head pulley that bends to fit the pulley. Proper slide lagging has good traction that pulls the belt around, so that it doesn’t slip.
In addition to good lagging and belt tension, you need a crown on the head pulley and boot pulley, which allows the belt to track in the center of the pulley. Standard crowns typically are 1/8 inch per 12 inches of belt width.
Belting. With new belts, it’s common for them to stretch 1.5-2% in the first several days or weeks of their life. This can require you to take up the slack. Hopefully, the belt will operate fine going forward. But after a number of years of operation, you might notice the belt is stretching again.
This means the cords inside the belt are deteriorating and breaking down, which leads eventually to belt failure. This is why it’s important to inspect belting periodically for wear or loss of cover, such as in the image above right. Belt cover loss reduces traction and efficiency, as well as static conductivity. If the belt is unable to discharge static, a fire or explosion is more likely.
Buckets. The most common areas for elevator bucket wear are on the front lip, corners, and sidewalls. For buckets that perform digging in the boot, the wear will be even more severe. A digger bucket can help in these scenarios.
A digger bucket is slightly larger than a standard bucket and is designed to handle the abuse of the digging action in the boot better. Using a digger bucket protects the space before and after the adjacent buckets from being subject to as much wear.
Irregular wear patterns – those occurring in areas other than the front lip, corners, or sidewalls – are a sign of problems other than normal wear. We helped an elevator that was seeing c heavy wear only in one back corner of its buckets (See picture at left). We were able to determine the cause of the issue was an angled inlet feeding the bucket elevator that was forcing most of the material into the back corner of the buckets.
Wear certainly impacts performance of your bucket elevator, but there are a number of other areas to look for, as well.
Venting. One way to improve bucket performance is to add venting. Venting aids in proper bucket filling by making it easier for the product to displace the air in the bucket. And when it comes time to discharge, venting allows air to come into the bucket, helping the material to flow out of the bucket freely. There are different venting patterns for different applications.
Splices. Another key area that affects belt performance is the splice, and it’s also an area that can cause belt failure if installed improperly. Make sure you have the right splices for the right belt width. When it comes time to install the splices, a template is available that shows where holes should be drilled. It is recommended to use a power punch to create the holes, rather than a traditional drill.
Bolts. There are many different types of bolts available with varying properties. The standard elevator bolt is the No. 1 Norway (pictured on p. 75), which features a flat back and square shoulder. It is the most common and least expensive elevator bolt.
Norway bolts should be retightened over time, because they can loosen due to vibration.
Another common type is the fanged elevator bolt, which features teeth that stick into the belt to hold it in place. Because fanged bolts do not spin, it is possible to use a resistance nylon lock nut.
Although more expensive, some prefer fanged bolts to Norway bolts in certain applications, because they are much less likely to loosen due to vibration.
Throat plate. This is an often-overlooked area of the bucket elevator, but it plays a key role in the efficiency of your system. When installed properly and in good, working order, the throat plate ensures material is discharged from the bucket elevator, instead of returning down into the boot pit.
The throat plate should be positioned as close as possible to the buckets. Mechanical splices allow for a closer fit.
Hazard monitoring systems. Monitoring systems allow operators to know ahead of time when maintenance will be needed.
Some common types of monitoring technology:
Preventive Maintenance Tips
When inspecting your bucket elevator periodically, take regular, detailed photos of areas such as the buckets, belt, bearings, pulleys, throat plate, lining material, motor, and reducers. Keep the photos with the maintenance reports to help identify wear trends.
Tucker Scharfenberg, managing editor