What You Need to Know About Bucket Elevators
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Q. I have a requirement for a bucket elevator to move grain. Which type of bucket elevator should I implement and what are the critical specifications I need to provide and/or meet? — P.A.W.
A. An excellent question, but a complete answer requires more space than we have in this issue, so we will start with a review of bucket elevator types and their common applications, and then we will go over some of the important specifications for this technology in next month’s newsletter.
Bucket Elevator Design Fundamentals, Part 1
Bucket elevators are commonly used for moving flowable bulk materials vertically. Bucket elevators can move a variety of bulk materials efficiently, those with low to high densities and fine to large particle sizes.
Common Materials handled with Bucket Elevators:
- Fertilizer
- Sand
- Rock/Aggregates
- Grain
- Animal Food Products
- Pet Food Products
- Meals
- Minerals
- Food Grade Products
- Seeds
Styles of Bucket Elevators:
Centrifugal Discharge
Elevator buckets discharge product freely by centrifugal force. Centrifugal force “flings” material out of the bucket into the discharge spout located at the top of the elevator. Used for free-flowing products like grain and feed (Higher Belt Speeds).
Continuous Discharge
Elevator buckets discharge product on top of each other using the triangular shape/slope of the bottom of the preceding bucket to form a chute that discharges product into the discharge spout located at the top of the elevator. Used for sticky and non-free-flowing products that would not discharge readily in a centrifugal style elevator (Lower Belt Speeds).
Positive Discharge
This style of elevator operates off of a double-strand chain on which buckets are held in place by two pins that allow the bucket to swivel. Elevator buckets discharge when the bucket is mechanically tripped to flip into the discharge spout located at the top of the elevator. The buckets hang level unless they are in the discharge position. This style of elevator is used to elevate products such as popcorn, candy, potato chips, etc. where the concern is gentle handling to prevent damage (Low Chain Speeds).
Basic Components of a Bucket Elevator
- Belt or Chain and Buckets
- Head Section
- Tail Section/Boot
- Intermediate Casing
- Drive and Motor
- Accessories/Ancillary Devices
Proper design/selection of the basic components and style of elevator is determined by the desired conveying capacity and the product characteristics:
- Abrasive/Non-Abrasive
- Corrosive/Non-Corrosive
- Free Flowing/Sticky or Non-Free Flowing
- Density
Look for more on this topic in our next issue.
Answered by Curtis R. Cook, Vice President of WL Port-Land Systems, Inc. He has over 30 years of experience in design, operations, and maintenance of bulk solids storage and handling facilities.