Mounting instructions for Extreme Bearing housings
Mounting an Extreme Bearing step by step
- Put some grease on the seal lip.
- Position both bearing units onto the shaft and bolt the bearing housing to the machine frame but do not tighten the bolts all the way yet.
- Check if the shaft has the correct level on the machine frame.
- Tighten the attachment bolts of the housing to the frame.
- Start the clamping procedure on the drive (fixed) side, never on both sides at the same time!
- Method 1: As shown in the diagram (fig. 1), position the outer edge of the bearing race exactly level with the outer edge of the bearing housing to maintain inner bearing clearance after tightening the bearing adapter sleeve.
In case you want highly accurate axial positioning on the shaft, position only the bearing on the fixed side in the casing. As shown in figure 2, the position of the outer edge of the bearing race is not exactly level with the outer edge of the bearing housing after tightening the bearing adapter sleeve. This difference is indicated by A in figure 2 and the table shows the recommended values for A in mm depending on the diameter of the shaft.
7. The locking mechanism for the bearing is based on an adapter sleeve. First put some grease on the locking nut, both on the thread and the front surface.
9. Place the locating ring in position and then screw on the locking nut with its chamfer side facing the bearing. Before starting the final tightening procedure, the bearing should be pushed up onto the tapered seat until the bearing inner ring cannot be rotated relative to the shaft. Then turn the nut through the tightening angle as given in the table for spherical roller bearings. The bearing will be displaced axially (inwards) on the tapered seat during tightening. The residual clearance of the roller bearing should be checked if possible.
13. Check that the shaft is not too long in case you want to use a closed blue cover seal. If you have a bearing for a drive situation, use an open cover with a shaft seal. In that case, put some grease on the seal lip and carefully push the seal over the shaft.
14. If you have chosen Method 1 at step 6 in the instructions, the shaft with the bearing shall have about one millimetre clearance backwards by mounting on the fixed side. In case your construction demands Method 2 with highly accurate axial positioning, check the position. If there is too much displacement, undo steps 6-14, correct the position and repeat the steps again.
15. Tighten the cover with the attachment bolts.
16. The last step is to fill up the bearings with grease. Slowly pump the grease into the bearing unit while rotating it by hand and stop pumping as soon as you notice that no air is gradually passing the seals. If you pump too fast, the trapped air will push the excess grease out of the bearing before it is full.
Important information for initial greasing if it is a pressure-tight bearing unit
In some configurations, the bearing units from Extreme Bearing are pressure-tight. Therefore it is necessary to keep the cover a little bit open while you do the initial greasing. Otherwise problems like in the picture shown here can occur.
In addition, whenever it is necessary to add some more grease later, you should always take care not to create over pressure in the housing. The Extreme Bearing units are pressure-tight when used with the following configurations of seals: AS/AS, AS/VK, CL/CL and CL/VK.
Please inform your maintenance crew about this special service operating instruction. After filling with grease, it could be helpful to take away the grease nipples completely and exchange them with a standard stainless steel bolt, so it will be impossible to make mistakes.
Points to consider prior to mounting
1. Check the tolerance of the shaft
- The shaft should be clean, dry and free from grease.
- Make sure that the shaft is free of any surface damage such as burrs from set screws and scratches. If not, remove the burrs and scratches with a fine file. We prefer a fine file over emery cloth so that you only take away the high spots without affecting the main shaft tolerance.
- Check if the shaft bearing seat is within tolerance, preferably at three cross-sections 20 mm apart in the position where the bearing will be placed. These positions are shown as 1, 2 and 3 in the diagram and three measurements should be taken around the cross-section at A, B and C. Measure the cylindricity with a micrometer in these three locations on the circumference: A, B and C.
2. Check the hardness and surface roughness of the shaft
The hardness of the shaft should be a minimum of HRc 55. In general, shafts of carbon steel or stainless steel are most suitable. What’s even more important than a correct interference fit of the oil seal, is a perfectly smooth shaft in the region of the seal. The surface roughness of the shaft (Ra value) depends on the average profile depth of the tool marks caused by the machining process.
For normal circumstances, the shaft in the region of the seal must have a surface roughness of approximately:
- Ra = 0.4 to 0.8 mm
- CLa = 8 to 25 mm
- Rz = 1.0 to 4.0 mm
- Rmax ≤ 6.3 mm
3. Decide on the fixed side
- Each shaft will have a fixed bearing location (mounted first) and a floating location (mounted second). If an Extreme Bearing is to be used on a drive shaft, it is required that the fixed side be the motor drive side. To minimize the risk of any confusion, we strongly recommend the fixed side be the drive side, as depicted in the diagram.
4. Allow for thermal expansion and contraction
There is a total clearance available for thermal expansion that is equal to the thickness of the location ring. The expansion and contraction of material must be considered in order to maintain the clearance that is required to operate the bearing well. In the diagram, the clearance for contraction by cooling is indicated by C and the clearance for expansion by heating is indicated by B. The table shows the maximum values for C and B depending on the diameter of the shaft.
More information about therminal expansion you can find here
Calculate the maximum shaft length depending on the temperature in your application. In case you need to mount a long shaft, it is necessary to calculate the thermal expansion or contraction and adjust the bearing position to take this into account. As an example, a stainless steel shaft of 1 metre will become 0.023 mm longer when the temperature rises by 1°C and a carbon steel shaft of 1 metre will become 0.016 mm longer when the temperature rises by 1°C. The table shows the maximum shaft length depending on how the temperature changes during operation after the time of installation.
For more information
If anything is unclear, do not hesitate to contact us for more information. Our engineers are happy to help you.