Will these bearings work for a vacuum pump? - Page 2 - PeachParts Mercedes-Benz Forum

Stretch · #16 05-04-2013, 01:50 PM

Quote:

Originally Posted by Stevo

I saw that, I was wondering about Stretch's bearing.

I can't tell 'cos the shields are in the way...

...do I dare to try and remove the shield or live in ignorance?

What would be the problem with 8 balls instead of 6? The more the merrier I say - you'll have a stronger assembly with a greater contact area won't you?

funola · #17 05-04-2013, 02:12 PM

Quote:

Originally Posted by Stretch

I can't tell 'cos the shields are in the way...

...do I dare to try and remove the shield or live in ignorance?

What would be the problem with 8 balls instead of 6? The more the merrier I say - you'll have a stronger assembly with a greater contact area won't you?

get the spec drawing? there was a post on why 6 balls.

Stretch · #18 05-04-2013, 02:20 PM

Quote:

Originally Posted by funola

get the spec drawing? there was a post on why 6 balls.

I've been looking on the SKF website and I can't find the number of balls information.

Deep groove ball bearings, single row

Is the 6 balls or bust discussion in Beagle's thread?

Stretch · #19 05-04-2013, 02:23 PM

Here's Beagle's thread

http://www.peachparts.com/shopforum/diesel-discussion/320095-vacuum-pump-failure-you-neglecting-yours.html

for general reference - but it is a long one now...

Stretch · #20 05-04-2013, 02:25 PM

There is this comment in the thread linked above made by Beagle post #30

Quote:

Originally Posted by Beagle

...

Qwerty
You will need to go to a specialist bearing store and get them to order two 6 ball open "precision" 626 for you. The 8 and 6 ball non-precision bearings are very common so be careful and make sure it is a top quality brand. Check their catalog.

I think the cheaper 8 balled ones are bad but if it is a precision 8 balled bearing then it should be OK shouldn't it?

OM617YOTA · #21 05-06-2013, 12:25 AM

So, what's the final verdict? Am I good to go or am I inviting disaster?

Stretch · #22 05-06-2013, 03:05 AM

All I can do is cast my vote =>

I say they are fine because they come from a reputable brand - the six or eight bearing argument doesn't apply; these are meant to be good quality precision bearings. You either need to trust the name of SKF or not - tough call in these cut throat cost cutting times! (I'll be fitting my SKF 626 - 2Z bearings)

barry12345 · #23 05-06-2013, 10:01 AM

Remember to try to eliminate all vaccum leaks. This reduces the duty cvcle on the pump I expect. A couple of days with vaccum remaining in the system should indicate the system is pretty tight.

funola · #24 05-06-2013, 10:42 AM

Quote:

Originally Posted by Stretch

Here's Beagle's thread

http://www.peachparts.com/shopforum/diesel-discussion/320095-vacuum-pump-failure-you-neglecting-yours.html

for general reference - but it is a long one now...

That's the thread! Beagle specifically said you want the 6 ball precision bearing. I assumed he researched it and came up with that.

I haven't done anything with my vacuum pump other than take it out and inspect it and found nothing loose and put it back. Looking at pics of my spare vacuum pump that I posted in that thread, I just noticed the bearing has 8 balls. I am posting the pic below and you can see 4 balls occupying 180 degree of the circle so there's 4 more balls in the other half. I am assuming this pump has the original bearings. Did Beagle choose a better bearing with 6 balls? As Stretch already asked, why are the 6 ball bearings more precise and better than 8 balls?

Alastair · #25 05-06-2013, 11:52 AM

IF you have to replace these bearings, Use the SKF 'ETN-9' rated ones.

so, '6262 ETN-9' bearing. Its about twice or three times the price of the standard part but worth it!

These have a higher load capacity in comparison to the 'Std' SKF bearing

Stevo · #26 05-06-2013, 02:10 PM

Quote:

Originally Posted by funola

That's the thread! Beagle specifically said you want the 6 ball precision bearing. I assumed he researched it and came up with that.

I haven't done anything with my vacuum pump other than take it out and inspect it and found nothing loose and put it back. Looking at pics of my spare vacuum pump that I posted in that thread, I just noticed the bearing has 8 balls. I am posting the pic below and you can see 4 balls occupying 180 degree of the circle so there's 4 more balls in the other half. I am assuming this pump has the original bearings. Did Beagle choose a better bearing with 6 balls? As Stretch already asked, why are the 6 ball bearings more precise and better than 8 balls?

funola, I just went out to the shop and tore apart an early pump and it had 6 balls then I looked at a couple more, a piston and another early pump and they all had 6 balls. I think the one in your pic does also as the balls showing above the arm corresponds to when I hold one of my pumps at the same angle, number of balls above the horizon.

I pulled the long pin so I could swing the arm up the other way and see the whole bearing. I pulled the short pin holding the bearing but haven't figured out how to get the bearing/s out. I dont want to start beating on things, with the exception of lower joints.

This pump was in my "junk" box so I thought I would practice on it. Maybe take some pics if theres not some already.

Stretch · #27 05-06-2013, 03:05 PM

I've taken apart two piston vacuum pumps - one with a split piston; one without.

Both had 6 ball bearings

funola · #28 05-06-2013, 03:14 PM

Stevo, are you saying your pump balls look like my pic but have 6 balls? maybe some kind of optical illusion is going on in my pic? I'll have to dig out my spare pump and have a closer look.

Stretch · #29 05-06-2013, 03:37 PM

Quote:

Originally Posted by Alastair

IF you have to replace these bearings, Use the SKF 'ETN-9' rated ones.

so, '6262 ETN-9' bearing. Its about twice or three times the price of the standard part but worth it!

These have a higher load capacity in comparison to the 'Std' SKF bearing

I can't find those listed here Alastair =>

http://www.skf.com/group/products/bearings-units-housings/ball-bearings/deep-groove-ball-bearings/single-row/index.html

All of the static load and dynamic load ratings are the same for the 626, 626-2RSH, ... , 626-2Z types. Only the speed ratings change.

Stretch · #30 05-06-2013, 03:45 PM

Quote:

Originally Posted by Stevo

...

I pulled the long pin so I could swing the arm up the other way and see the whole bearing. I pulled the short pin holding the bearing but haven't figured out how to get the bearing/s out. I dont want to start beating on things, with the exception of lower joints.

This pump was in my "junk" box so I thought I would practice on it. Maybe take some pics if theres not some already.

Sorry I missed this post...

...speed reading again - it will be the death of me!

To remove the bearings you just need to press them out of their little housing. You will damage them by doing this though so you need to get replacements. If you look at the way in which it is all put together you can see that there is a central pin that goes through the two bearings and the wheel that runs on the timing device cam (= follower). This is a slight interference fit. You need to press this out - which will in turn bugger at least one of the bearings...

...once you've pushed the central pin and the wheel out of the way the bearing races can be pushed through and out of the assembly.

I'm using a hydraulic press for this but a screw thread and a bit of wood would be good.