# Journal bearing reaction loads calculation

1. May 28, 2014

### gaber2611

Dear everybody here,

Here is a problem to solve, from shigley handbook for Machine design, it's about Journal bearing design for the shown shaft in the attachment, i know how to design the journal bearing, but i am a little bit confused about how to get the reaction forces at the two points A and B, and the shaft load at those points to consider into the bearing design

The loads at x-direction are neglected, and steady state working conditions, getting the reactions can be by getting ∑Fy=0 ?, if so, what about the shaft loads at those points?

Please take a look at the attached picture, it has the whole given data, i only need the procedures to get the loads right

Thanks

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2. May 28, 2014

### 256bits

Would you not just take moments about A to get the reaction at B, and/or vise-versa?

3. May 28, 2014

### gaber2611

yes, and what about the shaft load at the points A and B?, how to get?

4. May 28, 2014

### gaber2611

it will be equal to the reaction force i get?, at A and B?

5. May 28, 2014

### 256bits

The reaction forces at A and B balance the weight of the shaft and the weight of the disks. ∑Fy=0.

If the reaction force at A ( or B ) is found, then by using ∑Fy=0, the reaction at the other location is found.

6. May 28, 2014

### gaber2611

Okay bits, thanks for your help

7. Apr 10, 2016

### mehranx

Hi
I'm here to follow this topic,engaging same problem,worn journal bearings on cam seats.

8. Apr 10, 2016

### Tom.G

I had a similiar problem with rocker arms and shafts failing every 15 000 miles. It turned out to be the film strength of the engine oil I was using was inadequate. Here in the USA the high film strength stuff has a logo on it that says "For Gasoline Engines." I know, it's an oxymoron. The particular standard was promulgated by Ford Motor Co. maybe 20 years ago and they trademarked the phrase. Then they got it accepted by the API (American Petroleum Institute) as a standard. Honda Motor Co. specifies their own oil for motorcycles with appearently similiar requirements.