Most of the time, locating rings are commonly overlooked. They are also affordable and people usually assume that there isn’t any visible issue with the rings. Once the rings do fail though, it can take the whole bearing assembly out of service with little to no warning.
There are some things that can be done to avoid this.
Bearing assembly makes unusual noise
One of the first signs that something is wrong is with the noise. You may notice a low rumble and unusual vibrations. If the bearing is moving out of place, the locating rings will stop that movement. If the rings are worn out or seated the bearing will be able to move and that will produce noise.
There is a specific difference between continuous rumble and intermittent knocks. Usually the intermittent knock means that the ring has lost its grip.
Visual Signs of Wear or Damage
With the housing open — whether it’s a scheduled inspection or otherwise — examine the ring on the part. Signs like scratches on the surface, flattening on the ring’s face, or any other deformation around the ring bore will mean replacement is due. Locating rings should sit better. Signs of fretting or material transfer on the ring face means movement between the ring and housing is happening.
Shaft’s Axial Movement
For this part, it’s better to use a dial gauge instead of an estimation since it’s a better way to measure it. If there is an axial movement and there shouldn’t be any, that’s a sign that the bearing is not retained. In plummer block and flanged housing, the locating ring is what keeps the outer ring of the bearing fixed in the axial direction. If this is not the case — wear, wrong size, or the ring is damaged — movement will occur.
If this type of movement is present for a long period of time, it will increase the wear on the bearing, which means that what should have been a simple fix is now a larger problem.
Malfunction due to excess heat.
Heat that seems excessive to load and speed conditions may in some cases be caused by a poorly seated or worn locating ring. When the bearings are able to move axially, even by a fraction of a millimeter, they create a friction that they otherwise wouldn’t make. Not all overheating problems point to this – lubrication and bearing condition are usually the first things to consider – however, if all of these are fine and the temperatures are still high, the ring is worth being investigated.
The ring can be moved during inspection. This is obvious, but most people still miss this.
The making of the ring is the most obvious thing to miss when constructing these assemblies. If the locating ring is movable by hand when the assembly is not moving, it is not doing its purpose. A locating ring that is fitted correctly and undamaged should not have any play. If there is movement then it has to be replaced.
When to replace, not to just inspect.
If you are already replacing a bearing, it is best practice to replace the locating rings at the same time. It is a false economy to reuse old rings in new bearings – you are adding a potential failure point to what should be a clean assembly. This also goes when you cannot determine the history of the ring, or if the ring has been heavily loaded for a long time.
You can identify locating rings by their prefix FRB, diameter, and bore width. Size is important — a ring that is too small will not hold the bearing and a ring that is too large will not sit properly in the housing groove.
If you are not sure which specification to go with, it is best to cross-refer the housing dimensions before you place the order.