In service manuals with details on 671 and 2020 it says, "When replacing the motor armature be careful to assembly the thrust ball bearings properly, following direction in the illustrations on page 4."
I didn't see any written directions. Illustration just shows where they go. How many ball bearings should be used? I assume you use grease to keep them in place while installing them? Can I use the Thrust Bearing 681-121 instead of the ball bearings?
Bob
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There is some variation over the years, so you need to work with what fits. The hardened steel thrust washers 671M-19 and/or 671M-23 need to be in place on each side of the balls. I install the steel washer for the rear bearing in the motor housing first. Then Red N Tack grease on the washer. A little grease on a toothpick to place 10 to 12 balls on the washer. Then install the upper washer and slide the armature in place.
Keeping the armature snugly in place, turn the motor over and follow the same process on the front bearing. With the front bearing balls in place and the outboard hardened washer in, install the e ring. At this point the lateral clearance needs to be checked. The clearance needs to be 0.010” or less. If the clearance is greater than 0.010, a second hardened washer needs to be added under the e ring. The washers are 0.010” thick. If there is more than 0.010” clearance there is a chance the bearing balls will fall out.
I believe that the 681-121 caged ball thrust bearing can replace the loose balls, but it is larger in diameter than the loose balls and the bronze bearings also have to be replaced. I have not done this so maybe someone with more experience can address this question. I have never had any trouble with the loose ball arrangement as long as the axial clearance is 0.010” or less.
I had the same question today (two years after the original post) - I found the attached photo in my files. Looks to me like the open end of the bearings are both facing towards the end of the armature shaft... your thoughts?
I see that line cutting across the balls on the commutator end as being the top of the formed race. That would support putting the open side up. But I would not put too much stock in how the industrial illustrator drew a sectional view of motor. Even the assemblers at Lionel were inconsistent in their assembly of the motors. The question is what makes since today, and I will stand by my earlier position.
@David Johnston posted:I see that line cutting across the balls on the commutator end as being the top of the formed race. That would support putting the open side up. But I would not put too much stock in how the industrial illustrator drew a sectional view of motor. Even the assemblers at Lionel were inconsistent in their assembly of the motors. The question is what makes since today, and I will stand by my earlier position.
Yes, I see it now, I believe you are correct. Thank you for the reply.
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