Gravity conveyors are used in distribution warehouses, assembly lines, and shipping departments throughout the world. With routine maintenance and care to the frames, conveyor rollers
, and other parts, a gravity conveyor can last for many years. The rollers in these conveyors can get dirty or damaged, and eventually they need replacement. Thankfully, conveyor rollers are easily replaceable, and doing so will extend the life of the conveying system. Another common situation is there simply needs to be more rollers added to an existing system to help parts move more smoothly along the conveyor when replacing conveyor rollers.
Between Frame (BF) Distance: Measure the frames that the rollers will fit into from one side to the other in inches or mm. Replacement conveyor rollers are often referred to according to the BF (Between Frames) size they are made to e.g. 18″BF Gravity Roller. Common between frame widths are 10″, 15″, 16″, 21″, and 22″
Diameter of the roller: Common sizes are 1-3/8″ (1.4″) , 1.9″, 2.5″ and 2-9/16″. It’s tough to measure this with a tape measure, so use a pair of calipers or more precise measuring instrument to ensure you have the right diameter
Retention system: In order to fit into the frames, rollers are generally spring loaded on one side. But sometimes rollers have springs on both sides, or use pins through the shaft instead of springs
Surface finish: Galvanized (zinc plated) is a common finish, while heavier duty rollers are sometimes mild steel
Axle configuration: North American gravity roller conveyors usually have hexagonal axles of 7/16″ or 11/16″ for medium and larger diameter rollers. Smaller rollers typically use a 1/4″ round steel axle. Measure the size of your existing roller axles
Grooves or drive system: Rollers may have dual grooves (for O-Ring drive systems), pulleys for ribbed drives or sprockets attached
Centers: Measure the center distance from one gravity roller to the next. This will help you calculate how many you need!
Once you have that information, you can buy online or call us for help. If you’re wanting to learn more, read on….
How conveyor rollers are assembled
A crimped gravity conveyor roller has a tube which is crimped down over the bearing to hold it in place. Bearings installed in this
manner are non-replaceable.
Edges of tube are bent towards the center.
A press fit roller has a tube which is counter bored to the correct inside diameter for the bearing to be press fit into
place or slip fit for large diameter rollers.
When replacing conveyor rollers, an important defining factor is the material the conveyor rollers are constructed of. The most common type being galvanized steel as it is cost effective, and resists rust. Other materials include; stainless steel for wet applications and for food preparation, and PVC or polyurethane coated rollers for non-marring applications.
Roller Diameter and Gauge
Roller diameter is determined by measuring the width or outside diameter of your roller. 1-3/8″, 1.9″, and 2-1/2″ diameters are common sizes, but other special sizes exist. Normally standard gauges (wall thickness) are based upon roller diameter. Think about the way the conveyors are used when replacing conveyor rollers. Locations that are loaded by fork lifts or where items are impact loading (dropped), these rollers should have a thicker wall than the rest of the conveyor system, giving it a greater load capacity and strength. Remember, don’t round your measurements, use a precision tool, such as calipers, to measure roller diameter.
Axles and Retention
The axle size is determined by measuring the diameter of a round axle or measuring from flat side to flat side on a hex axle. Common axle sizes are 1/4″ round, 7/16″ and 11/16″ hex axles. Most axles are made from plain steel. The vast majority of axle types are spring retained on one end, but may also be pin retained so that the roller may be locked into place with the use of retaining pins.
Identifying Axle Retention
Determine the axle retention by pressing one end of the axle in; if the axle pushes in, it is spring retained on the
Repeat this process on the other end of the axle, if the axle reacts the same it is dual spring retained.
If the roller has sprockets or grooves it is important to identify which end the spring is on.
Pin retained axles will have holes in the ends of the axles to insert the pins. When the pins are removed the axle
can be removed.
Identify the type of pin. Our standard options include the cotter pin and hog pin.
A plain axle will not have any type of retention. No pins or springs will be holding the axle in place.
For a proper fit, you will also need to know your axle’s overall length and extensions. Use a tape measure to measure from the end of one axle to the other to get overall length, and for axle extension (how far the axle sticks out from the bearing on each end) measure from end of the bearing to the end of the axle. This must be done on both sides as the axle extension might be different on each end. Measure to the nearest 1/32″.
Non-precision bearings are standard for most rollers in conveyor roller replacement projects. These are free rolling bearings and are cost effective. Greased packed bearings are normally used for power conveyor applications or harsh environments. Precision ABEC 1 bearings are used when noise levels are a concern or when the rollers will be required to travel at a high speed.
Replacement conveyor rollers are a viable method of prolonging the life of your conveying system. Ordering replacement rollers is an easy process when you can provide the above information. However, there are many instances where you may not have access to all of the information needed. In any situation, please do not hesitate to call Ultimation Industries at 586-771-1881. We can walk you through the process, and help ensure you get the right rollers as quickly as possible.
Original link: https://www.ultimationinc.com/blog/conveyor-rollers-info/