• Automotive
• voyager14
In summary, the conversation discusses the analysis of a tapered roller bearing used in a differential. The input torque and bore size of the bearing are known and the goal is to find the radial and axial forces, as well as other parameters like C10, L10, rated load, and lifetime. The conversation also mentions the importance of the pitch radius and position of the bearing in the differential assembly. The speaker suggests finding resources to help with the analysis, mentioning that pinion bearing selection is usually based on experience rather than computation. They also mention the need to consider the preloading of the bearings and solving a vector problem to find the forces on the bearings.
voyager14
Hi

I'm analyzing a tapered roller bearing as part of a differential. I know the shaft is providing input torque of 333.5 N-m @ 4000RPM, and I know the bore size of the bearing, 30mm. I need to find the radial and axial forces given that torque, so I can move on to finding C10, L10, rated load, and lifetime.

I've tried:
1. Diving torque by bore radius (which I realized is tangential force, which is different)
2. Using
Fr = m(ω)2r
where
ω = (RPM/60)2π
this got me
Fr = 1052N or 1.052kN

I don't know if that's correct, and I could also use help with the axial force.
Thank you.

If the tapered roller bearing is one of two on the input shaft to the pinion, then the pitch radius of the pinion, and the position of the two bearings will be important.

If the tapered roller bearing is one of the two that supports the differential assembly in the carrier, (axial with the axle shafts), then the pitch radius of the crown wheel will be important.

You will need to know the profile and the offset of the hypoid pinion and crown to resolve the axial forces.

Baluncore said:
If the tapered roller bearing is one of two on the input shaft to the pinion, then the pitch radius of the pinion, and the position of the two bearings will be important.

If the tapered roller bearing is one of the two that supports the differential assembly in the carrier, (axial with the axle shafts), then the pitch radius of the crown wheel will be important.

You will need to know the profile and the offset of the hypoid pinion and crown to resolve the axial forces.

Thank you. It is one of the bearings on the input shaft to the pinion. Are there any resources you know of to help walk me through this?

voyager14 said:
Are there any resources you know of to help walk me through this?
I don't know of a reference, but will take a look.

Pinion bearing selection is not normally a computed parameter, it has evolved through experience. If it fails, differential manufacturers will use the next bearing up, if it never fails, try the next smaller bearing.

Radial and axial thrust may not be the critical selection parameters. The pinion bearings are always pre-loaded against each other, in order to hold the pinion in a well defined position relative to the crown wheel.

If you know the 3D position and direction vector, normal to the pinion contact area on the crown, you should be able to solve the vector problem to find the forces on the two bearings due to the input shaft torque.

## 1. How do you calculate the radial load for a tapered roller bearing?

To calculate the radial load for a tapered roller bearing, you will need to know the applied loads, the bearing geometry, and the bearing material properties. The formula for calculating the radial load is: Fr = (Fa + Fr)/(cosα + sinα), where Fr is the radial load, Fa is the applied axial load, and α is the bearing cone angle.

## 2. What is the axial load capacity of a tapered roller bearing?

The axial load capacity of a tapered roller bearing depends on the bearing geometry, material properties, and the applied loads. The maximum axial load capacity is typically listed in the bearing manufacturer's specifications. It is important to not exceed this maximum capacity to avoid premature bearing failure.

## 3. How do you determine the bearing life for a tapered roller bearing?

The bearing life for a tapered roller bearing can be determined using the basic bearing life equation: L10 = (C/P)^p, where L10 is the calculated bearing life in millions of revolutions, C is the basic dynamic load rating of the bearing, P is the equivalent dynamic bearing load, and p is a constant based on the bearing type. The bearing life can also be calculated using various online bearing life calculators.

## 4. What is the difference between radial and axial loads for a tapered roller bearing?

Radial loads act perpendicular to the axis of rotation, while axial loads act parallel to the axis of rotation. In a tapered roller bearing, the radial load is supported by the rollers and the axial load is supported by the bearing's inner and outer rings. It is important to calculate both the radial and axial loads to ensure proper bearing selection and performance.

## 5. What factors can affect the radial and axial loads for a tapered roller bearing?

The radial and axial loads for a tapered roller bearing can be affected by various factors such as the applied loads, bearing geometry, bearing material properties, operating conditions, and mounting methods. It is important to consider all of these factors when calculating the loads for a tapered roller bearing to ensure optimal bearing performance and longevity.

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