Gravity conveyor can be installed on a horizontal or decline position. When installed horizontally the most likely application will be for an assembly operation or for order picking. When used on a decline, its more likely application is a gravity flow system. A gravity system is less expensive than a powered system, however a gravity conveyor doesn’t provide a positive flow of packages.
The degree of pitch needed for a gravity conveyor will depend on a number of factors:
1. The type of conveyor used, roller type or skatewheel type.
2. Are the bearings clean and dry or are they grease packed (grease packed bearings roll at a slower speed.)
3. Weight and Slide of package
4. The quality of firmness of the package bottom. This is very important!
ALWAYS TEST YOUR PRODUCTS TO BE MORE ACTUATE ON YOUR SLOPE DIMENSION.
Here are a few examples
ITEM —> WEIGHT —> SLOPE OF CONVEYOR (in inches per 10′ ft.)
Barrels –> 5″ inch
Boxes (wood) –> 15-20 lbs. –> 6″ to 6 1/2″ inch
Boxes (wood) –> 100-200 lbs. –> 3″
Cartons –> 3-5 lbs. –> 9″ inch
Cartons –> 25-30 lbs. –> 5″ inch
Pans, Tote –> 2 1/2″ – 5″ inch
The flow rate of the boxes on a gravity conveyor is also affected by the acceleration effect of a spinning roller or wheel which is still spinning after a box has moved over it. All of this causes boxes to go faster and faster. There are restraining devices and retarding plates available to slow boxes down. Another way to slow the movement of boxes is to change the angle of the incline. Example, you may go 10′ or 20′ feet at a certain decline and then level out the conveyor for 5′ or so.
There are two basic types of gravity, roller and skatewheel:
Wheel Conveyors: Any item which has a smooth, flat bottom. These items can be 6″ inches over each side. That is not too much. Extra wide items such as plywood can be moved fine, but make sure to center it before trying to push it. When using skatewheel conveyor, use as many wheels as possible to obtain the best results.
Roller Conveyors: Any items with an uneven or open bottom, or with a rim on the bottom. These items should never be bigger around than the roller are long.
Material Flow & Conveyor Systems, Inc. carries and sells an excellent selection of conveyors!