[GreenKeys] Oil Viscosity and Worn Bearings

[pbirkel at gmail.com]

Cross-posting as I thought that there was useful information provided that I hadn’t seen mentioned here on GK in at least the last few years.

 

Referenced web page: http://www.chemcas.com/msds112/cas/1761/64742-52-5_1302-78-9_68910-93-0_7632-00-0.asp 

 

From: TYPEWRITERS at groups.io <TYPEWRITERS at groups.io> On Behalf Of James Petroski
Sent: Friday, January 14, 2022 9:26 AM
Subject: Re: [TYPEWRITERS] Substitute for IBM #23 Oil, aka Nyogel 744 etc.

 

Don wrote:

Seems to me only an engineer can really grasp the information in the link you provided at The Engineering Tool Box.

 

It definitely helps.  I use that website occasionally in my engineering work but my understanding of the terms comes from my engineering degrees.  Fundamental equations develop constants in them and these become the characteristics we measure of the materials.  Absolute and kinematic viscosity are two of those.

SSU or Saybolt Seconds Universal wasn't even taught as a unit when I learned fluid mechanics in the 70s (probably was still used somewhere back then).  It's only specified at two temperatures (100F and 210F) so it is limited value in most fields for kinematic viscosity.  centiStokes for kinematic viscosity and centiPoise for absolute viscosity are the normally used units today, and they can be measured/specified at any temperature.

The IBM oils website must have gotten word of the "bum" because it now uses gum in that sentence.

The choice of oil viscosity depends much on the clearance in the bearings (loading being the other primary consideration).  The #10 oil / 30W oil for the electric motor bushings indicates it has a fairly large clearance.  I have an old bathroom ventilation fan in my home (60+ year old motor).  Previous owners didn't lubricate the motor often enough and standard 10W or 20W oil wasn't viscous enough anymore for the worn bearing clearances.  One option was to replace the motor or the just the bearings, but the cheaper option was to use 30W oil instead, and that's worked for the 30 years we've lived in the house.  The whole house fan I installed gets the regular 20W turbine oil.  The same principle works for typewriter motor bearings if they have worn from lack of lubrication; one grade higher viscosity can help.

Jim 

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