Q&A forum: Plain Bearing Calculator
(Journals)

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I was wondering if your engineer can help me with my question re using the Journal programme. I am struggling with the angle “Theta” and dimension “z”. I have marked them on above pdf as I am thinking this is from max film thickness to the centre line of bearing, is it the bearing point between two surfaces or the centre line of the fixed bearing? In your programme default value for this angle was set as 73deg?

Also the dimension “z” is said to be longitudinal dimension from centre of bearing to the point of interest. Can this be zero as set in the default programme. Please refer to my sketch if this is what you mean.

Both of these values refer to the location of a user’s desired calculation point. They do not refer to any point of critical or limiting condition.

'z' is indeed the distance from the longitudinal centre of the bearing (as described in your client’s drawing) and affects only 'p' {oil pressure @ 'θ'} in the calculation.
This value can be set at zero but not less than zero as the calculation would otherwise fail (square-root of negative values). You can, however, set it greater than half the length of the bearing in accordance with CalQlata's GiGo principle, but the result would be meaningless in the practical sense.

The angular datum for the input data is the radial plane through the minimum film thickness; at point 'z'. In other words, the calculation provides the result ‘h’ at ‘z’ and 'θ' degrees from the resultant (calculated) plane of minimum thickness (as shown in the calculator image). It does not refer to a fixed dimensional plane through the bearing.
'θ' can be any value.

I have purchased the calculator “Journals Calculator v1”, see the order 1652. I like to clarify few details

1) Input Data: What is a meaning of the below parameter?
ρ [kg/mm³], 8.21E-07

Based on the unit and value it seems that this is a density. According to the Technical Help this should be an angle. There is no such angle on the image.
2) Output Data: What are three below pressure values? Specifically, what is the second value?
p [kgf/mm²], 0.876643
p' [kgf/mm²], 4,231.77
p̌ [kgf/mm²], 98,647.97

Help doesn’t explain above parameters.
3) On the image in Help, the below angle is marked from the Qb dimension line. Is this correct? Should it be marked from the min oil film thickness?
γ [°], 6.004232

4) Based on first calculations and as it is marked in the image, it seems that Wx and Wy components values are being switched. Please confirm.

 This customer was correct. There is an error in the Context and the Technical help pages.
The text for the mass density of the oil was missed out in the code, upsetting the Symbol>Text sequencing. The calculations, however, are not affected.
This has now been corrected in the calculator and any previous customer that wishes to be sent a revised copy of the calculator, please contact us and we will send you a copy of the corrected version free of charge.

(No relevant questions have been issued for this program to date)

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