Autohelm 2000 ram ball bearings

[fishermantwo]

After just reading on a previous thread about a 2000 ram that had a warning about ball bearings, I pulled mine apart. Now just where do those bearings belong. Presumably in that brass section, but what holds them in? Pictures would be nice.

 

[misterg]

You haven't let them out, have you??

I'm not familiar with the innards of the 2000 (other than I believe it has a ball nut on the leadscrew), but have dismantled a 4000 (and put it back together ) :

The motor turns the long threaded rod - the leadscrew.

Riding on the leadscrew is a cylindrical nut - probably fixed to the rod that emerges through the case to connect to the tiller.

If they're the ones I warned about, they live inside that nut, held in by the leadscrew.

There is usually a return channel visible to send the balls back around from one end of the nut to the other. I believe it's generally the case that the balls are loaded via a gap this channel during manufacture, then the gap is pressed closed (or similar). It is the devils own job to get them back in if they've escaped - you may be able to feed them in with the lead screw partially through the nut, or you can find the gap they were filled through and open it up again.

Some photos here sounds like you may have a similar problem

Andy

Edit: Sounds like you may have a similar problem.- Sorry, I thought you were the OP of the other thread who had a problem with his TP making grinding noises.

Harumph! that means you took it to bits after I warned about the little balls!

You're as bad as the kids.....

Andy

 

[fishermantwo]

You haven't let them out, have you??

I'm not familiar with the innards of the 2000 (other than I believe it has a ball nut on the leadscrew), but have dismantled a 4000 (and put it back together ) :

The motor turns the long threaded rod - the leadscrew.

Riding on the leadscrew is a cylindrical nut - probably fixed to the rod that emerges through the case to connect to the tiller.

If they're the ones I warned about, they live inside that nut, held in by the leadscrew.

There is usually a return channel visible to send the balls back around from one end of the nut to the other. I believe it's generally the case that the balls are loaded via a gap this channel during manufacture, then the gap is pressed closed (or similar). It is the devils own job to get them back in if they've escaped - you may be able to feed them in with the lead screw partially through the nut, or you can find the gap they were filled through and open it up again.

Some photos here sounds like you may have a similar problem

Andy

Edit: Sounds like you may have a similar problem.- Sorry, I thought you were the OP of the other thread who had a problem with his TP making grinding noises.

Harumph! that means you took it to bits after I warned about the little balls!

You're as bad as the kids.....

Andy

Don't know about letting them out, they were in the threads of the rod, about 30 of them. I did notice when I peered into the brass bit on the end of the tube there is what looked like a hole in the thread, presumably there are other balls inside. There is nothing I would call a ball nut. I presumed the trapped ball bearings ran in the threaded rod and acted as a ball nut but can not see what stops them coming out. The rest of the ram looks and runs fine.

Thanks for your comments and assistance.

 

[misterg]

Don't know about letting them out, they were in the threads of the rod, about 30 of them. I did notice when I peered into the brass bit on the end of the tube there is what looked like a hole in the thread, presumably there are other balls inside. There is nothing I would call a ball nut. I presumed the trapped ball bearings ran in the threaded rod and acted as a ball nut but can not see what stops them coming out. The rest of the ram looks and runs fine.

Thanks for your comments and assistance.

This is roughly what it's supposed to do:

I guess the brass bit is the housing in the drawing.

NOTHING holds the balls in, but they can't fall out unless someone unscrews the leadscrew, or removes one end of the housing.

The sort of thing I'm thinking of is shown in videos here and here

Maybe worth posting a picture of what you've got.

Andy

 

[fishermantwo]

This is roughly what it's supposed to do:



I guess the brass bit is the housing in the drawing.

NOTHING holds the balls in, but they can't fall out unless someone unscrews the leadscrew, or removes one end of the housing.

The sort of thing I'm thinking of is shown in videos here and here

Maybe worth posting a picture of what you've got.

Andy

Thanks Andy, never occurred to me to look at Youtube. The unit in my case looks like just a brass tube with no access, inside I can see one hole. I will have to take a picture tomorrow.

 

[misterg]

Thanks Andy, never occurred to me to look at Youtube. The unit in my case looks like just a brass tube with no access, inside I can see one hole. I will have to take a picture tomorrow.

In that case, maybe the only way to reload it is to put the lead-screw partly through the brass tube so that it is level with the hole, and just keep feeding bearings back in, wiggling and tapping the lead screw to try to get the bearings to fall into place.

If there is an oval patch on the side of the brass tube, it might be a plug over a channel where the balls can 'hop back' one thread, rather than there being a separate return channel. In which case, reloading it through the end might be the only way.

You sure that the bearings came out of the brass tube? We are looking at the right thing here, are we?

I'll have a look at the pics when you post them.

Good luck!!

Andy

 

[fishermantwo]

Andy,
The brass bit does have two holes for the ball bearings, I can feel the second one with a bit of bent wire and another ball dropped out. Its possible this brass bit has a sleeve that slides forward to reveal the ball bearing compartment. Have not been game to lever it. Noticed on Youtube there was another bloke feeding the balls on the end of screw method but with larger items. These balls are about 1mm across. Photo should help.
Regards,
Graham

 

[fishermantwo]

Now have the sleeve off the ball nut. Takes a lot of levering to get it moving. Once off it exposes a clip that covers the ball bearings just like in the youtube videos that Andy posted links to. The clip is hard to get out but a piece of bent wire poked up through the inside of the brass threaded bit moves it out. Only a couple of extra bearings found so the grand total I recovered was 46, I am guessing there is suposed to be a hell of a lot more, so Monday I will zap into the local bearing shop and pick up a heap. Anyone know the correct amount? size etc?

I will take and save a few photos of the whole procedure in case someone else makes a galah of themselves and pull the lot apart and drop the bearings. I should imagine its pretty much the same procedure for all the rams like this. The later model ram pdf file omits any detail of the ball nut. Now that I have seen it apart its not such a big deal and for people that have tiller pilots that are making grating noises I would say its probably missing a few ball bearings out of the ball nut.

Thanks Andy.

 

[misterg]

Glad you hear you're making progress !

..the grand total I recovered was 46, I am guessing there is suposed to be a hell of a lot more...

Is there any reason that you think there should be more?

Have you tried re-loading the bearings? You are only missing some if there is a gap of > 1 or 2 bearings, and it would probably work OK with a few less. There does need to be a bit of a gap.

I think you'd have to get the balls measured very accurately (to the micron) to be able to match them properly.

Just for fun (and I don't think it applies to the small ball nut here) there are sometimes two different sized balls used - load balls & spacer balls. The difference in diameter might be only 0.01mm (half a thou), but they need to be loaded alternately. N.B. I doubt this applies to the one in the ST2000.

I also very much doubt that any balls could 'go missing' unless the leadscrew is (at least partially) removed from the nut, or the nut has suffered catastrophic damage.

Good luck! The photos of the reassembly might prove very useful!

Andy

 

[hightech]

Its buggered, you will never get them back in and if you do they won't stay there.

in the 17 years as service manager @ Autohelm, not once did a customer manage it, we always ended up replacing the ram.

Prepare for a big bill.

Sorry.

 

[KAM]

Its buggered, you will never get them back in and if you do they won't stay there.

in the 17 years as service manager @ Autohelm, not once did a customer manage it, we always ended up replacing the ram.

Prepare for a big bill.

Sorry.

This is a bit negative. Presumably the customers who managed it did not contact Autohelm. The balls (on my unit) were 2mm easily available on ebay. Its a simple matter to make an 8mm spacer from a cut down bolt on the end of a stick. This is placed inside the ball nut at the start of the thread then the balls stuck back in the thread and return hole using a dab of grease on the end of a piece of wire. Finally press all the balls into place with a small flat ended screwdriver as the spacer is pushed through the nut to keep the balls in place. Keep gentle pressure on the spacer as you re introduce the screw. After a few turns the spacer is pushed out leaving the balls in place. It helps visibility if you have the sun over your shoulder behind you. Mine now works perfectly and is nice an smooth. Hope this helps anyone else servicing this item.

 

[James_Calvert]

Bit of a zombie thread this? But just for the record it is possible to put this bit of the ram together again. I've done it twice on my 1985 unit. It involves some grease and tweezers to put every ball inside where it belongs, and a very steady hand to twist the wormscrew into place without knocking any of the balls out of position.