Calculating the normal force due to moment load on a thrust bearing

In summary, the design will have two rings with sliding pads fixed on the bottom ring. The top ring slides over the blue pads. The blue pads are made of an plastic with a low coefficient of friction. The axial and moment loads will need to be large enough to keep the bearing in place, but once that is the case the pressure on the pads will be acceptable.
  • #1
vatuhiva
3
0
TL;DR Summary
Calculating the normal force in the bearing pads of a thrust-bearing due to axial and moment loads.
Hello all!

I have a mathematical question for you. I'm trying to design a thrust bearing that can withstand axial and moment loads. I've added a picture of a similar design. The design consists of two rings (grey) and sliding pads (blue) fixed on the bottom ring. The top ring slides over the blue pads. The blue pads are made of an plastic with a low coefficient of friction. I would like to calculate the required force needed for the bearing to turn. therefore I need to know the force acting on the individual pads. I would also like to check whether the pressure on the individual pads will be acceptable.

The axial load will need to be large enough to keep the bearing in place. But once that is the case the moment load will put an extra force on the pads on the right side of the bearing and relieve the pads on the left. I trying to find any formula's that could help me solve this issue but sofar I haven't been able to find suitable information regarding this issue.

I hope there are people out there that can help me a bit further! I there are any question I will be happy to answer those!

Knipsel.PNG
 
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  • #2
vatuhiva said:
Summary: Calculating the normal force in the bearing pads of a thrust-bearing due to axial and moment loads.

the moment load will put an extra force on the pads on the right side of the bearing and relieve the pads on the left
Silly question , but why is there a moment? Is the shaft not constrained along its axis.
 
  • #3
256bits said:
Silly question , but why is there a moment? Is the shaft not constrained along its axis.
not a silly question, the shaft is not constrained along its axis. Also, the shaft is extremely short, the length of the shaft is the same as the diameter of the bearing
 
  • #4
If the shaft is not restrained radially, will there be a problem of keeping the two rings in alignment with each other?
Also, can you show us a detail drawing of the most heavily loaded segment (plastic pad on the right) with load vectors as you see them on this one pad.
 
  • #5
AZFIREBALL said:
If the shaft is not restrained radially, will there be a problem of keeping the two rings in alignment with each other?
Also, can you show us a detail drawing of the most heavily loaded segment (plastic pad on the right) with load vectors as you see them on this one pad.
Hi Azfireball,

this is a simplified version of the final design, in the final design the rings will be radially constrained, but it will be done in such a way to have no effect on the loads previously presented.

below I edited the drawing to have a crosssection of the heaviest loaded pad. The forces will be perpendicular to the pad. Does this answer you questions?
1572962376016.png
 
  • #6
Is the bottom plate stationary (Fixed in position?)
Are the rub segments fixed to the lower plate?
Are the aspect dimensions (height to width) of the rub segment accurately depicted in the new rub segment detail drawing?
 

What is a thrust bearing?

A thrust bearing is a type of bearing designed to handle axial loads, or loads that act parallel to the axis of rotation. It is commonly used in machinery to support rotating shafts and prevent them from moving in the axial direction.

How is the normal force on a thrust bearing calculated?

The normal force on a thrust bearing can be calculated by multiplying the moment load applied to the bearing by the distance from the center of the bearing to the point where the load is applied. This results in a force acting perpendicular to the bearing's surface, which is known as the normal force.

What factors affect the normal force on a thrust bearing?

The normal force on a thrust bearing is affected by several factors, including the magnitude and direction of the moment load, the distance from the center of the bearing to the point of load application, and the geometry and material properties of the bearing itself.

Why is it important to calculate the normal force on a thrust bearing?

Calculating the normal force on a thrust bearing is important because it helps engineers and designers determine the appropriate bearing size and type for a given application. It also ensures that the bearing is able to withstand the applied load without failing or causing excessive wear.

Can the normal force on a thrust bearing be greater than the applied load?

Yes, the normal force on a thrust bearing can be greater than the applied load. This is because the moment load applied to the bearing can be amplified by the distance from the center of the bearing, resulting in a larger normal force. It is important to consider this when selecting a thrust bearing to ensure it can handle the expected normal force without failure.

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