Dynamotor Bearing Grease

[David Dunlop]

I have a question about grades of grease and their application to the bearings in a wireless set dynamotor.

The two Robbins & Meyers dynamotors used in the Supply Unit of the Wireless set No. 52 used ANDOK-C grease in their bearings. This was a sodium based, Grade 4 grease manufactured by Imperial Oil which has been discontinued for several decades with no direct replacement. This was a high temperature grease popular in high speed electric motors, particularly those mounted in a vertical orientation. The two dynamotors are mounted horizontally in the 52-Set, however.

Imperial/Mobil Oil currently make a lithium based, Grade 3 grease that is a close match in specs to ANDOK-C. This Grade 3 grease, however, is very hard to find in cartridge format in single cartridge amounts, and pricy as a result. This Mobil grease has a sister, Grade 2 equivalent that is readily available locally in single cartridges.

I am simply not familiar with the grading system for grease to know if a jump down from Grade 4 to Grade 2 is a safe idea. I do know that the future active use of my 52-Set will be indoors, at ambient room temperatures, for probably no more than a half hour or so, a couple of times a week, and the transmit time when the dynamotors would be active would be less than half that time.

Anybodys thoughts would be appreciated.


David

[Bob Carriere]

Hi david

All kind of lithium grease available cheap in small tubes but not sure if the match the grade specs????? but a single tube of mobil is listed.......

How do you insert the grease in the dynamotor bearings..... can you use a hypo needle??? some lithium lubricant I would not call grease as it is semi liquid but then Lucas as a "tacky" red lithium grease so thick a hypo needle would not work.

I often use agricultural grease as it is easier to obtain and does not run off in water/heat situation such as 4x4 U joints..... I like grease that pulls whiskers between your index and thumb when you pull your digits apart.....and stays on your jeans when you wipe your fingers.

Cheers

[David Dunlop]

Hi Bob.

This is proving to be an interesting side step in the 52-Set Project.

Canadian Marconi did a fantastic job of researching the needs of the Wireless Operators in the Canadian Army as they proceeded with development of the Wireless Set No. 9 series of equipment leading to the No. 9 Mk II/52-Set. I suspect overheating of this equipment was not so much an issue in normal environments but was very likely at play when operating wireless gear in the desert or tropics where ambient air temperatures exceeded 100 degrees F. Their use of thermal cutoff switches for the two dynamotors if they overheated and the activation of the two blowers to increase airflow in the Carriers No. 4 Compartments compliment their decision to use Grade 4 High Temperature grease in the dynamotors. Once Robbins & Meyers had tweaked their two dynamotors, a very solid product emerged. I tend to forget sometimes my 52-Set will never again be operated in such extreme conditions so side-stepping the Grade 4 grease should not be an issue for the limited future use the set will be subjected to by me. It is interesting that one of the Modification Orders for the 52-Set issued in the late 1940's or early 1950's was how to relubricate the set so it would function reliably in the Canadian arctic. Perhaps for Operation Muskox and similar exercises.

The last time I re-greased bearings was on my M38Cdn and 1944 Chevy C15A Wireless. That involved the simple set of metal cones on a bench with the central hub lube fitting and a grease gun. I would be surprised if the bearings in the two dynamotors were large enough for that type of equipment. At this point even, I am not sure of the bearings are even ball or roller style, though I am leaning towards ball. The service instructions nicely lay out how to remove the two dynamotors with the Supply Unit on the bench, without removing electrical connections and opening up the end caps to expose the bearings for work...but not the work itself. So bit of a mystery there at the moment.

I also need to find out if the end cap sealing material is still available. It is that thin but very stiff, smooth tan board stuff. One dynamotor used rings of it the other solid circular discs.

It is nice to finally be gearing up for work on the Supply Unit, but ohhh, the adventures!


David

[Bob Carriere]

.... we have drifted from hand packing grease in wheel bearings or using a cone and a grease gun as you often waste more than actually goes into the bearing.

We have been using the large needle device sold in local flaps it attches to the grease fitting of the gun and allows you to insert the needle between the rollers in the bearing cage and direct evry ounce of grease where it is needed..... but that is on larger bearings...... on smaller ones I would use a hypo needle, from the farm store, and use a softer lithium or moly grease, maybe heated, and try to shoot it into the bearing cage.... we are talking drops now!!!!

Don't forget to wash your hands.