Wireless Set No. 52 Canadian - Project

[David Dunlop]

This part of the project was starting to raise my eyebrows and heart rate more than I felt was attractive.

Andoc-C was discontinued 15 to 20 years ago and from reading between the lines of the limited documentation on line, the main reason seemed to be that by that time, most smaller, electric high speed motors had switched to sealed bearings. If they failed and the motor died, there were no bearings to repack.

I ended up contacting ExxonMobil directly, the original makers of Andoc-C to find out what replacements they could recommend and they were very helpful.

Andoc-C (ExxonMobil refer to it as ‘Andok-C’) was discontinued without a direct replacement. It was a very firm NLGI 4 grease with a sodium complex thickener and a mineral base oil with a viscosity of 93 cSt at 40 degrees C. Based on the data I provided them for the 52-Set Dynamotors, they recommended a pair of NLGI 3 grease products that are currently available, the specifications of which come pretty close to the original Andok-C.

The first is Unirex N 3. This is a grease with a lithium complex thickener, for higher speed bearing applications as in smaller electric motors, using either roller or deep race ball bearings (as are in the two Robbins & Myers Dynamotors) and if the motor is mounted in a vertical position, the grease will not leak out the seals.

The second recommendation was Mobil Polyrex EM 103. This grease comes with a urea based thickener, a slightly narrower operating and spec range than the Unirex N 3, and is designed more for much larger, industrial electric motors. This latter focus shows up when you start pricing both greases on-line. Mobil Polyrex grease is very hard to find in quantities less than 15-kilo pails. On the other hand, the Unirex N 3 is readily available in standard grease gun cartridges.

So I am going to go with the Unirex N 3 product. The one other thing ExxonMobil commented on was I need to be sure to clean out all the old grease before repacking with either new grease. The sodium based Andok-C will not be compatible at all with either current grease as far as water/moisture is concerned.

One more step closer to being able to restore the main Supply Unit assembly.


David