All you need to know about drag chain conveyor!
Drag chain conveyor is a tough fighter in the world of conveyors. They play with all kinds of bulk material handling jobs. Let it be cement, wood chips or corn. Drag chain conveyor is an efficient transport equipment to handle it.
We will see all the details, features, design, advantages and disadvantages of these workhorses here.
What is drag chain conveyor?
A drag chain conveyor is a special bulk material handling equipment, which conveys a wide variety of product types like powder, fiber, pellets, granules, and flakes. It is highly durable and efficient.
They are used in almost all processing and manufacturing factories for transporting bulk solid particles. The special design of these conveyors makes it easy for continuous transfer of the product.
In a drag chain conveyor, a specially designed chain holds a series of pads. These pads are termed as flights. There will be a pin or a holding screw mechanism to hold these flights to the central chain links.
An example of drag chain conveyor is shown below. The white Teflon pads seen on both sides are the flights. The white chain in the image, which is gear motor driven using compatible sprocket and safety mechanism, holds and moves these flights.
How does a drag chain conveyor work?
The drag chain drags all these flights in a particular direction. The product enters through a hopper at one end of the conveyor. The flights form a compartment to carry the product to the delivery point. The flights drag the product to the other end of the conveyor. At the other end, the product ejection happens through an outlet window.
Each compartment will have an almost equal quantity of product. The dosage of the product at the output depends on the speed of the chain and the delivery to the conveyor system.
Main components of a drag chain conveyor:
- Gear Motor
- Specially designed and highly durable chain (stainless steel or high-quality Teflon)
- Links with option to attach flights
- Sprockets for the chain
- Safety mechanism for the chain (Overload protection is an important factor. If the chain is broken or damaged during operation, it is very difficult to repair it)
- Completely enclosed design with doors or inspection window. (This will protect the product from dust and dirt. It will also protect the environment while running powdered products)
- Safety switches for the doors and windows.
Design of drag chain conveyor:
The material is being moved altogether in the drag chain conveyor, with an equal amount of product in each flight compartment. This gives an advantage over the gear motor power.
The KWS Manufacturing Drag Conveyor Engineering Guide says that “as the material is moved En-Masse, horsepower requirements can be as much as half of that of alternative means of conveyance”.
En-Masse is a term that means altogether, or completely. The flights are capable of carrying the product with each compartment completely filled or occupied.
Following are the major factors considered during the design stage
The material to be conveyed
The design process starts from studying the properties of the material that are in the question.
Drag chain conveyor are capable of conveying a wide variety of products:
Food Products : Beans products, Peanut products, Corn products, Soybean products etc
Grain and Cereals : Rice, wheat, oats, all types of granules and flakes
Animal Feeds : All kinds of animal feed ingredients
Chemicals and Minerals : Cement, Sand, fly ash, limestone, ores, coal, powders, fertilizers.
Biomass and waste : Wood pellets, wood chips, straw pellets, dried sewage sludge
The physical properties data of the conveying material is important. It will help the conveyor manufacturers to select the most appropriate type of conveyor and installation.
Inclination and height of the delivery point
The inclination of the conveyor and the delivery is another important factor. These data will help to calculate the Lift HP or Lift Horsepower. This is the power required to lift the material to the planned height.
Assessment of the area of installation is necessary to decide the inclination needs. It is important that the machine and the working plane are perfectly leveled. The conveyor will have height adjustments to achieve the level too.
Vibration damper elements between the feet of the machine and the resting surface is a good choice too. This will improve the mechanical efficiency in the long term.
Consideration of following numbers is essential for the horsepower (HP) calculation.
Empty HP : Power to overcome the friction in the power transmission system, chain/sprockets, and the flights dragging on the bottom of the trough
Live HP : Power to overcome the friction of the material sliding along the bottom of the housing over the length of the conveyor.
Lift HP : Power required lifting the material the required height of inclination.
Calculation of the chain pull is from the total Horsepower, speed of the chain, speed factor etc. It is required to determine the type of chain to be used. The details calculations and formulas are available in the “Drag Conveyor Engineering Guide” from KWS Manufacturing Company.
Advantages and Disadvantages of Drag chain conveyor
|En Masse transportation of bulk materials compared to other conveyors||Shorter transportation distance compared to Belt Conveyors|
|Multiple inlet and outlet possible||Larger Power requirements than conveyor belts or vertical bucket elevators|
|Excellent for elevation purpose. 90 Degree inclination is also possible.||High Initial investment compared to conveyor belt systems.|
|Highly durable with very low maintenance|
Maintenance of drag chain conveyor
Drag chain conveyor needs very less maintenance. However, a routine checkup is essential for these machines.
The most critical element, the chain itself, needs to be monitored. The chain will get stretched after initial installation. Later during operation, the following things need to be checked/maintained regularly.
- Chain tension
- Pins or the holding mechanism of links
- Sprocket teeth
- The play in the flights
- Safety sensor function
- Tension adjustment mechanism and/or spring condition
- Oil level of the gear boxes
- Lubrication of bearings
The drag chain conveyors are available in different size and capacities. The installation could be vertical, horizontal, or inclined. Depending on the capacity requirements and the product type, drag chain conveyor manufacturers could design a most suitable solution for your plant.
These versatile conveyors would be a highly durable and low maintenance solution for achieving your efficiency targets.