Replacement bearings for AC Motor

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cts_casemod
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Replacement bearings for AC Motor

Post by cts_casemod » Sun, 28 Oct 2012, 11:27

Hi all,

I am looking into a bit of information about bearings to my motor.

I am doing an AC Conversion on a Polo, and Ive noticed my motor is very load over 2000RPM, due to worn bearings.

Previously this motor had metal shielded bearings, which I believe are not the best for a car conversion as the motor will be in contact water and dirt from the roads on the winter.

I could use rubber seals, but I have been advised this are not adequate for high speed operation.

I am trying to know what does this high speed operation refers to as i have no figures on RPM's.
My Motor will go up to 2900RPM and will will usually work on the 1500-2000

Any advice on this?

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acmotor
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Replacement bearings for AC Motor

Post by acmotor » Mon, 29 Oct 2012, 05:53

Bearing manufacturer's data tables will give you all the information on seal types and working RPM.
SKF for instance
Image http://www.skf.com/portal/skf/home/prod ... link=1_1_3 click on table 1

I would use double full contact rubber seal bearings. (for max waterproofing and grease retention)
At a guess the OD of the (most likely) single row, deep groove ball bearings that you use is about 80mm ?
http://www.skf.com/skf/productcatalogue ... tartnum=17 say 6307-2RS1 (double rubber seal)

These have a limiting speed of 6000RPM and would suit your application.

What is the part number of your existing bearings ? DE and NDE

There are other options of temperature range, grease type and noise level. The standard types would be quite suitable for EV motor.

Image
edit: spelling !
Last edited by acmotor on Sun, 28 Oct 2012, 18:54, edited 1 time in total.
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cts_casemod
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Replacement bearings for AC Motor

Post by cts_casemod » Mon, 29 Oct 2012, 06:32

Thanks acmotor.

My bearings are 6206Z for the Fan side and 6208Z for the output shaft side.

The Z stands for metal shield, I am now replacing them with a SNR 6208EE ruber one and I am yet to buy the Fan side one.
This ones are quite expensive so they should have some quality. I am particulary concerned as I will keep the clutch and its heavy!! Any advice on this?

Checked the manufacturer datasheet they state 5200RPM for ruber and 15000RPM for metalic shied. I have no idea why a 4 Pole motor would come with metalic shild then lol ;)

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acmotor
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Replacement bearings for AC Motor

Post by acmotor » Mon, 29 Oct 2012, 06:53

You're on to it.

Have the cut down flywheel, pressure plate and clutch plate spring assembly balanced on the motor shaft. Either by a dynamic balancing shop or a least on your own bench. I assume the emotor rotor was balanced at manufacture.
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cts_casemod
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Replacement bearings for AC Motor

Post by cts_casemod » Mon, 29 Oct 2012, 08:11

What do you mean cut down? Reduce the flywheel weight/mass?
How do you balance the motor yourself on the bench?

Thanks
Last edited by cts_casemod on Mon, 29 Oct 2012, 06:47, edited 1 time in total.

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