M75 Cupola bearings

[M813rc]

Does anyone know how to service the bearings in an M75 APC cupola? Best I can tell that is what is on my armoured car, and it sounds like there is a half pound of sand in there with them.
Closest info I can find is in the M113 tech manuals, but it isn't the same cupola, just similar. I haven't found anything specific to the M75.
Thanks.

 

[L1A1]

M813rc
If I'm not mistaken, the commander's cupola on the M75 is identical to the ones used on late model M4 Shermans tanks. It was also used on the first gen M59 APC's as well. I still have my maint. manual for my M59 here I'll check it today and see if it mentions anything about servicing those bearings.
Matt

 

[M813rc]

Thanks Matt!
Cheers.

 

[L1A1]

Rory
I just looked in my M59 OP/maint.manual and it has more info on the later style M13 cupolas. I remember the previous owner of my APC telling me about removing the cupola from one such track (I don't remember which cupola type) he said that the cupola sat on large plastic(?) ball bearings and that they were color coded IE: one black to one white all the way around. What you may have to do is get your hands on an M75 maint manual and see what it says in there. maybe a SS member can help you out with this. Sorry I couldn't.
Matt

 

[M813rc]

Thanks for trying Matt, I appreciate it. The M113 manual also talks about colour coded ball bearings, ratios of several of one to a few of the other.

Does anyone have an M75 manual they can sell/lend/copy/read to me?

Cheers.

 

[L1A1]

Rory
Just another thought (wow 2 in one day!) here, Try contacting www.Idahomotorpool.com I beleive that they have an M75 and may be able to help you. Or if you're register'd over on www.g503.com there are several M75 owners over there who may be able to help you out as well.
Matt

 

[M813rc]

I'll give them a try, thanks.

 

[twinfiftys]

What exactly are you working on when you say cupola. Our M75 has the same hatch as the M41 tank. What I would call the main traversing bearing is a timken bearing. It can not be dismantled but with a little work you can clean the rollers and regrease it with a needle attachment for your grease gun. The upper hatch cover bearings are just that ball bearings. Ours were rusted beyond use so we replaced them. There are two sizes, they are placed every other one so that the total drag is reduced.

 

[M813rc]

Well, if I had been smart, I would have attached a picture earlier...doh!

Here is what I am talking about when I say cupola. The lower part with the vision ports is, obviously, bolted to the roof. The upper part with the gun mount rotates 360 degrees. The gritty bearings are between the two.

My guess that this is from an M75 is based on pictures, and is just that, a guess. If anyone can properly identify it, that would be great.
I know zip about these, so any help is much appreciated.

Cheers

 

[twinfiftys]

M813rc,

Your setup is slightly different then ours but what your after is the bearing under the gun ring. That is going to be a large timken bearing. I think what you will find is that it is full of sand. These are very heavy built and take a lot of abuse. There should be a ring of bolts on the inside that you remove, then lift the gun ring off. I think the bearing will come with the ring. The bearing itself does not come abart but you should be able to inspect the rollers in-between the races. If they look ok get some spray cans of grease remover and clean then relubriacate them. I will look at ours tonight and see if there is anthing additional I can tell you.

 

[L1A1]

M813rc
It's been years since I've had a close look at one, but your cupola looks very similar to the ones used on late model M4 Shermans. What does your armored car look like? The images you've posted have intrieged me.
Matt

 

[M813rc]

Would that ring of bolts be the one visible between the vision ports and hatch pad on the interior shot? Looks like fairly simple access if that's the case. Bet that thing is on the heavy side though.

Once again, you folks are great. Seems you can post a question on the oddest bits of MV equipment and someone (or more usually someones) is going to jump up and go out of their way to help you answer it. Thanks!

Matt, here are a couple of earlier threads on this vehicle that give some info and a couple of pics. Progress has been slow for a variety of reasons, but I have gathered up most of the detail parts I need so once I get it together it should look presentable.

http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=15304&start=20

http://www.steelsoldiers.com/index.php?name=PNphpBB2&file=viewtopic&t=15336

Cheers.