Just another
day at the office…

Ring, ring….

**Super Awesome Atlas Employee:**Good Morning Atlas Bronze, how may I help you?

**Customer:**Well…I need a bearing and I’m not sure what kind. This is for a new project and we are starting from scratch so I could really use some help.

HELP…did you
hear that?…HELP! Dun da na na (trumpet
sound)…We have a guide for that!

**Bearing Design Guide: Chapter One: DESIGNING THE SLEEVE BEARING**

First, to
get started there are key things needed to know and all of these will influence
the final design, material or alloy of choice.
They are as follows:

- Load

- Speed

- Shaft Material

- Finishes

- Hardness

- Clearances

- Lubrication

All of these
factors must be considered to determine which is the most important so that the
bearing can be designed to meet the highest need for the application.

The more
obvious factors which are speed or type of motion, for example, rotating,
oscillating or reciprocating combined with the type of load as intermittent,
continuous, with or without shock or impact loading, usually point to the mode
of lubrication that may be indicated.

That is, the
“Pressure Velocity” factor (PV) gives a good clue of the possible success based
on its product.

In order to
get the PV, you need to convert the total weight (W) to be supported in pounds
to the unit load (P) in pounds per square inch (PSI) and the speed in
revolutions per minute to the velocity (V) in feet per minute.

Below you
will fine the formulas used for Rotary Motion, Linear Motion & Oscillating
Motion.

__Rotary Motion__**Pressure (P)**= Total Load (W)

*I*Projected Bearing Bronze Area = PSI

Note:
P is
the unit load in PSI

W is the total
load in pounds

PBA is the bearing diameter times the length

**Velocity (V)**= π x D x N/12=.262 DxN=fpm

Note:
V is surface feet per minute

π is a constant 3.1416

D is the shaft or
bearing dia.

N is the RPM

__Liner Motion__

**Pressure (P)**= Total Load (W)

*I*Projected Bearing Bronze Area = PSI

Note:
P is
the unit load in PSI

W is the total
load in pounds

PBA is the bearing diameter times the length

**Velocity (V)**= feet traveled per minute (length of stroke)

__Oscillating Motion__**Pressure (P)**= Total Load (W)

*I*Projected Bearing Bronze Area = PSI

Note:
P is
the unit load in PSI

W is the total
load in pounds

PBA is the bearing diameter times the length

**Velocity (V)**= .0029 x ID x Degree in one stroke

**For applications having ideal lubrication,**the PV factor

can range well above 150,000.

**For severe service,**the

**PV**factor should be reduced to 90,000 .

**For extreme severe duty,**the PV factor should be reduced to 60,000 .

Using an arbitrary
limiting bearing temperature of 250 degrees F, and using the power formula. MDWN, with an assumed constant
friction factor (M) of .075, a relatively
straight line value can be obtained. This result should only be used as a guide because other factors and considerations may modify
and affect the final decision.

The heat so generated by a load (P) in combination with a low velocity (V) will be substantially less
than with a low load. (P) and a high velocity (V) because velocity or speed influences the temperature
more than load or pressure does.

**Well...that's it for today. I hope your head isn't spinning as much as mine was the first time I read this! Until next time my metal loving friends...**

**Next Up: Week Two, Chapter 2: Lubricating Modes**

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