spherical bronze bearings 1

[RUSO]

We make DC motors where we use spherical bronze bearings on both ends with an impregnated felt for extra lube and a brass retainer pressed against the bearing to hold every thing.
Trouble is...during shipment, they lock up and we have to ask the customer to use a hammer to tap them back into alignment.

I think the retainer is keeping the bearing for rotating in the seat and keeping itself aligned. But we also want the bearing from spinning.

Anyone know of any design specs on how to properly build a retaining system for a spherical bearing in a motor???

 

[THooper]

Suggestion: Install a shaft lock bar on the shaft attached to the end bell bolts and down to the shaft. This is how we ship babbitt motors that have end play and could have shaft movement during transporting. Also used on locking standard ball bearing motors. Works real well for keeping the shaft from movement and also eliminates the shaft pounding on the bearing rollers or balls in one spot during transportation.

Kind Regards
motorhead1

 

[Rwinder]

This is good info to know! thanks motorhead1

 

[jbartos]

Suggestion: It appears that some packing ingenuity is needed as well as some good packing experience that may eventually require basics of physics and materials.

 

[RUSO]

Try as we might, packaging did not work. Since bouncing in a truck for several days, even with our best packing still locked some of the motors.
But thanks for the help

 

[electricpete]

It sounds like your bearings are designed to handle thrust in one direction only. Are the thrust bearings on the two end aligned to take force in the same direction or opposite direction? Makes me wonder what would happen if they saw a momentary reverse thrust during operation.

I have seen in some vertical motors with similar spherical bearings there is a spring under the stationary bottom ring which pushes that ring up to keep the bearing together in the event of momentary upthrust. Otherwise skidding would occur during upthrust resulting in possible bearing damage.

Not sure if this has anything to do with your situation.

 

[jbartos]

Suggestion: If the motor bearing is so sensitive to transportation, why do not you assemble the motor at the destination? What kind of problems would be encountered?

 

[electricpete]

I agree with motorhead1's initial thought. If motor is having that tough of a ride, then false-brinneling damage will be another concern.

It seems like the clamping system should provide a thrust preload on the bearing to prevent them from separating.

Also maybe the motors should be oriented within the truck so that the shafts are pointed from side to side of the truck. That way the worst impacts (up/down bumps and impacts from braking) will not cause axial separation of the bearing.

jbartos - If motor shop required it's customers to assemble motors on-site, I suspect they would not have much business.

 

[RUSO]

jbartos: Assembly of the motor at the customer is financially prohibitive. We ship all over the US and Europe. And we ship hundreds of these things.

electricpete: I said that these are bronze spherical bearings held with a retainer in a pocket. They are considered self aligning( and dis aligning in this case too). There is no preload, since these are not ball bearings. So the armature is allowed to float with some endplay in the motor. Remember, this just happens in transport. Never locks up during operation.

 

[jbartos]

Question: If you ship hundreds of those motors, what percentage experiences the mentioned problem?

 

[electricpete]

Hi RUSO - what I'm saying is that the jolts which occur during transport may be equivalent to a reverse thrust which the motor bearings apparently are not designed for. If the races are allowed to move apart under the influence of the reverse thrust that is a bad thing. A clamping device providing preload in the forward thrust direction would increase the amount of reverse thrust (due to transport impacts) required to separate the races. Also aligning the shaft side-to-side in the truck minimizes the possibility of any axial thrust due to impacts (primarily vertical and forward/backward on truck) during transport.

Just my view from long distance. I'm sure you have a better appreciation of the problem than I do.

 

[jbartos]

Suggestion: What about giving that motor a Cadillac suspension?